MC9S08AC128, MC9S08AC96 - Reference Manual

MC9S08AC128
MC9S08AC96
Reference Manual
HCS08
Microcontrollers
Related Documentation:
MC9S08AC128 Series Data Sheet
contains the pin assignments, block diagrams,
electrical specifications, and mechanical drawings.
To find the latest version of a document, check
the website at: http://www.freescale.com
MC9S08AC128
Rev. 3
09/2008
freescale.com
MC9S08AC128 Features
8-Bit HCS08 Central Processor Unit (CPU)
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40-MHz HCS08 CPU (central processor unit)
20-MHz internal bus frequency
HC08 instruction set with added BGND, CALL and
RTC instructions
Memory Management Unit to support paged
memory.
Linear Address Pointer to allow direct page data
accesses of the entire memory map
Power-Saving Modes
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Peripherals
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Development Support
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Background debugging system
Breakpoint capability to allow single breakpoint
setting during in-circuit debugging (plus two more
breakpoints in on-chip debug module)
On-chip in-circuit emulator (ICE) Debug module
containing three comparators and nine trigger
modes. Eight deep FIFO for storing change-of-flow
addresses and event-only data. Supports both tag
and force breakpoints.
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Memory Options
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Up to 128K FLASH — read/program/erase over full
operating voltage and temperature
Up to 8K Random-access memory (RAM)
Security circuitry to prevent unauthorized access to
RAM and FLASH contents
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Clock Source Options
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Clock source options include crystal, resonator,
external clock, or internally generated clock with
precision NVM trimming using ICG module
System Protection
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Optional computer operating properly (COP) reset
with option to run from independent internal clock
source or bus clock
CRC module to support fast cyclic redundancy
checks on system memory
Low-voltage detection with reset or interrupt
Illegal opcode detection with reset
Master reset pin and power-on reset (POR)
Wait plus two stops
•
ADC — 16-channel, 10-bit resolution, 2.5 μs
conversion time, automatic compare function,
temperature sensor, internal bandgap reference
channel
SCIx — Two serial communications interface
modules supporting LIN 2.0 Protocol and SAE J2602
protocols; Full duplex non-return to zero (NRZ);
Master extended break generation; Slave extended
break detection; Wakeup on active edge
SPIx — One full and one master-only serial
peripheral interface modules; Full-duplex or
single-wire bidirectional; Double-buffered transmit
and receive; Master or Slave mode; MSB-first or
LSB-first shifting
IIC — Inter-integrated circuit bus module; Up to 100
kbps with maximum bus loading; Multi-master
operation; Programmable slave address; Interrupt
driven byte-by-byte data transfer; supports
broadcast mode and 10 bit addressing
TPMx — One 2-channel and two 6-channel 16-bit
timer/pulse-width modulator (TPM) modules:
Selectable input capture, output compare, and
edge-aligned PWM capability on each channel. Each
timer module may be configured for buffered,
centered PWM (CPWM) on all channels
KBI — 8-pin keyboard interrupt module
Input/Output
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Up to 70 general-purpose input/output pins
Software selectable pullups on input port pins
Software selectable drive strength and slew rate
control on ports when used as outputs
Package Options
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80-pin low-profile quad flat package (LQFP)
64-pin quad flat package (QFP)
44-pin low-profile quad flat package (LQFP)
MC9S08AC128 Series Data Sheet
Covers MC9S08AC128
MC9S08AC96
MC9S08AC128
Rev. 3
09/2008
Revision History
To provide the most up-to-date information, the revision of our documents on the World Wide Web will be
the most current. Your printed copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://freescale.com/
The following revision history table summarizes changes contained in this document. For your
convenience, the page number designators have been linked to the appropriate location.
Revision
Number
Revision
Date
1
8/2007
Initial draft.
2
4/2008
Preliminary Draft for the AC Series Launch at FTF 2008. Includes updates to the
80-LQFP pin assignments and includes a section on the Mass Erase Command.
9/2008
Initial release of a separate Data Sheet and Reference Manual of the documentation. Removed PTH7, clarified SPI as one full and one master-only, added missing
RoHS logo, updated back cover addresses, and incorporated general release edits
and updates. Added some finalized electrical characteristics.
3
Description of Changes
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
© Freescale Semiconductor, Inc., 2007-2008. All rights reserved.
List of Chapters
Chapter
Title
Page
Chapter 1
Introduction.............................................................................. 19
Chapter 2
Pins and Connections ............................................................. 25
Chapter 3
Modes of Operation ................................................................. 35
Chapter 4
Memory ..................................................................................... 41
Chapter 5
Resets, Interrupts, and System Configuration ..................... 81
Chapter 6
Parallel Input/Output ............................................................... 99
Chapter 7
Central Processor Unit (S08CPUV5) .................................... 121
Chapter 8
Analog-to-Digital Converter (S08ADC10V1)........................ 143
Chapter 9
Cyclic Redundancy Check (S08CRCV1).............................. 171
Chapter 10
Internal Clock Generator (S08ICGV4) .................................. 179
Chapter 11
Inter-Integrated Circuit (S08IICV2) ....................................... 207
Chapter 12
Keyboard Interrupt (S08KBIV1) ............................................ 227
Chapter 13
Serial Communications Interface (S08SCIV4)..................... 233
Chapter 14
Serial Peripheral Interface (S08SPIV3) ................................ 253
Chapter 15
Timer/PWM (S08TPMV3) ....................................................... 269
Chapter 16
Development Support ........................................................... 297
Chapter 17
Debug Module (S08DBGV3) (128K)...................................... 311
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
7
Section Number
Title
Page
Chapter 1
Introduction
1.1
1.2
1.3
Overview .........................................................................................................................................19
MCU Block Diagrams .....................................................................................................................20
System Clock Distribution ..............................................................................................................22
Chapter 2
Pins and Connections
2.1
2.2
2.3
Introduction .....................................................................................................................................25
Device Pin Assignment ...................................................................................................................25
Recommended System Connections ...............................................................................................27
2.3.1 Power (VDD, VSS, VDDAD, VSSAD) ..................................................................................29
2.3.2 Oscillator (XTAL, EXTAL) ..............................................................................................29
2.3.3 RESET Pin ........................................................................................................................29
2.3.4 Background/Mode Select (BKGD/MS) ............................................................................30
2.3.5 ADC Reference Pins (VREFH, VREFL) ..............................................................................30
2.3.6 External Interrupt Pin (IRQ) .............................................................................................30
2.3.7 General-Purpose I/O and Peripheral Ports ........................................................................31
Chapter 3
Modes of Operation
3.1
3.2
3.3
3.4
3.5
3.6
Introduction .....................................................................................................................................35
Features ...........................................................................................................................................35
Run Mode ........................................................................................................................................35
Active Background Mode ................................................................................................................35
Wait Mode .......................................................................................................................................36
Stop Modes ......................................................................................................................................36
3.6.1 Stop2 Mode .......................................................................................................................37
3.6.2 Stop3 Mode .......................................................................................................................38
3.6.3 Active BDM Enabled in Stop Mode .................................................................................38
3.6.4 LVD Enabled in Stop Mode ..............................................................................................39
3.6.5 On-Chip Peripheral Modules in Stop Modes ....................................................................39
Chapter 4
Memory
4.1
4.2
4.3
4.4
MC9S08AC128 Series Memory Map .............................................................................................41
4.1.1 Reset and Interrupt Vector Assignments ...........................................................................42
Register Addresses and Bit Assignments ........................................................................................44
RAM ................................................................................................................................................51
Memory Management Unit .............................................................................................................53
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Section Number
4.5
Title
Page
4.4.1 Features .............................................................................................................................53
4.4.2 Register Definition ............................................................................................................53
4.4.3 Functional Description ......................................................................................................57
Flash ................................................................................................................................................59
4.5.1 Features .............................................................................................................................59
4.5.2 Register Descriptions ........................................................................................................59
4.5.3 Functional Description ......................................................................................................67
4.5.4 Operating Modes ...............................................................................................................77
4.5.5 Flash Module Security ......................................................................................................77
4.5.6 Resets ................................................................................................................................79
Chapter 5
Resets, Interrupts, and System Configuration
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Introduction .....................................................................................................................................81
Features ...........................................................................................................................................81
MCU Reset ......................................................................................................................................81
Computer Operating Properly (COP) Watchdog .............................................................................82
Interrupts .........................................................................................................................................83
5.5.1 Interrupt Stack Frame .......................................................................................................84
5.5.2 External Interrupt Request (IRQ) Pin ...............................................................................85
5.5.3 Interrupt Vectors, Sources, and Local Masks ....................................................................85
Low-Voltage Detect (LVD) System ................................................................................................87
5.6.1 Power-On Reset Operation ...............................................................................................87
5.6.2 LVD Reset Operation ........................................................................................................87
5.6.3 LVD Interrupt Operation ...................................................................................................87
5.6.4 Low-Voltage Warning (LVW) ...........................................................................................88
Real-Time Interrupt (RTI) ...............................................................................................................88
MCLK Output .................................................................................................................................88
Reset, Interrupt, and System Control Registers and Control Bits ...................................................88
5.9.1 Interrupt Pin Request Status and Control Register (IRQSC) ............................................89
5.9.2 System Reset Status Register (SRS) .................................................................................90
5.9.3 System Background Debug Force Reset Register (SBDFR) ............................................91
5.9.4 System Options Register (SOPT) .....................................................................................92
5.9.5 System MCLK Control Register (SMCLK) .....................................................................93
5.9.6 System Device Identification Register (SDIDH, SDIDL) ................................................93
5.9.7 System Real-Time Interrupt Status and Control Register (SRTISC) ................................94
5.9.8 System Power Management Status and Control 1 Register (SPMSC1) ...........................95
5.9.9 System Power Management Status and Control 2 Register (SPMSC2) ...........................96
5.9.10 System Options Register 2 (SOPT2) ................................................................................97
MC9S08AC128 Series Reference Manual, Rev. 3
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Section Number
Title
Page
Chapter 6
Parallel Input/Output
6.1
6.2
6.3
6.4
6.5
6.6
Introduction .....................................................................................................................................99
Pin Descriptions ..............................................................................................................................99
Parallel I/O Control .........................................................................................................................99
Pin Control ....................................................................................................................................100
6.4.1 Internal Pullup Enable .....................................................................................................101
6.4.2 Output Slew Rate Control Enable ...................................................................................101
6.4.3 Output Drive Strength Select ..........................................................................................101
Pin Behavior in Stop Modes ..........................................................................................................102
Parallel I/O and Pin Control Registers ..........................................................................................102
6.6.1 Port A I/O Registers (PTAD and PTADD) .....................................................................102
6.6.2 Port A Pin Control Registers (PTAPE, PTASE, PTADS) ...............................................103
6.6.3 Port B I/O Registers (PTBD and PTBDD) .....................................................................105
6.6.4 Port B Pin Control Registers (PTBPE, PTBSE, PTBDS) ...............................................105
6.6.5 Port C I/O Registers (PTCD and PTCDD) .....................................................................107
6.6.6 Port C Pin Control Registers (PTCPE, PTCSE, PTCDS) ...............................................107
6.6.7 Port D I/O Registers (PTDD and PTDDD) .....................................................................109
6.6.8 Port D Pin Control Registers (PTDPE, PTDSE, PTDDS) ..............................................109
6.6.9 Port E I/O Registers (PTED and PTEDD) ......................................................................111
6.6.10 Port E Pin Control Registers (PTEPE, PTESE, PTEDS) ................................................111
6.6.11 Port F I/O Registers (PTFD and PTFDD) .......................................................................113
6.6.12 Port F Pin Control Registers (PTFPE, PTFSE, PTFDS) ................................................113
6.6.13 Port G I/O Registers (PTGD and PTGDD) .....................................................................115
6.6.14 Port G Pin Control Registers (PTGPE, PTGSE, PTGDS) ..............................................115
6.6.15 Port H I/O Registers (PTHD and PTHDD) .....................................................................117
6.6.16 Port H Pin Control Registers (PTHPE, PTHSE, PTHDS) ..............................................117
6.6.17 Port J I/O Registers (PTJD and PTJDD) .........................................................................119
6.6.18 Port J Pin Control Registers (PTJPE, PTJSE, PTJDS) ...................................................119
Chapter 7
Central Processor Unit (S08CPUV5)
7.1
7.2
7.3
Introduction ...................................................................................................................................121
7.1.1 Features ...........................................................................................................................121
Programmer’s Model and CPU Registers .....................................................................................122
7.2.1 Accumulator (A) .............................................................................................................122
7.2.2 Index Register (H:X) .......................................................................................................122
7.2.3 Stack Pointer (SP) ...........................................................................................................123
7.2.4 Program Counter (PC) ....................................................................................................123
7.2.5 Condition Code Register (CCR) .....................................................................................123
Addressing Modes .........................................................................................................................125
7.3.1 Inherent Addressing Mode (INH) ...................................................................................125
MC9S08AC128 Series Reference Manual, Rev. 3
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11
Section Number
7.4
7.5
Title
Page
7.3.2 Relative Addressing Mode (REL) ...................................................................................125
7.3.3 Immediate Addressing Mode (IMM) ..............................................................................125
7.3.4 Direct Addressing Mode (DIR) ......................................................................................126
7.3.5 Extended Addressing Mode (EXT) ................................................................................126
7.3.6 Indexed Addressing Mode ..............................................................................................126
Special Operations .........................................................................................................................127
7.4.1 Reset Sequence ...............................................................................................................127
7.4.2 Interrupt Sequence ..........................................................................................................127
7.4.3 Wait Mode Operation ......................................................................................................128
7.4.4 Stop Mode Operation ......................................................................................................128
7.4.5 BGND Instruction ...........................................................................................................129
HCS08 Instruction Set Summary ..................................................................................................131
Chapter 8
Analog-to-Digital Converter (S08ADC10V1)
8.1
8.2
8.3
8.4
8.5
Overview .......................................................................................................................................143
Channel Assignments ....................................................................................................................145
8.2.1 Alternate Clock ...............................................................................................................145
8.2.2 Hardware Trigger ............................................................................................................146
8.2.3 Temperature Sensor ........................................................................................................147
8.2.4 Features ...........................................................................................................................148
8.2.5 Block Diagram ................................................................................................................148
External Signal Description ..........................................................................................................149
8.3.1 Analog Power (VDDAD) ..................................................................................................150
8.3.2 Analog Ground (VSSAD) .................................................................................................150
8.3.3 Voltage Reference High (VREFH) ...................................................................................150
8.3.4 Voltage Reference Low (VREFL) .....................................................................................150
8.3.5 Analog Channel Inputs (ADx) ........................................................................................150
Register Definition ........................................................................................................................150
8.4.1 Status and Control Register 1 (ADCSC1) ......................................................................150
8.4.2 Status and Control Register 2 (ADCSC2) ......................................................................152
8.4.3 Data Result High Register (ADCRH) .............................................................................153
8.4.4 Data Result Low Register (ADCRL) ..............................................................................153
8.4.5 Compare Value High Register (ADCCVH) ....................................................................154
8.4.6 Compare Value Low Register (ADCCVL) .....................................................................154
8.4.7 Configuration Register (ADCCFG) ................................................................................154
8.4.8 Pin Control 1 Register (APCTL1) ..................................................................................156
8.4.9 Pin Control 2 Register (APCTL2) ..................................................................................157
8.4.10 Pin Control 3 Register (APCTL3) ..................................................................................158
Functional Description ..................................................................................................................159
8.5.1 Clock Select and Divide Control ....................................................................................159
8.5.2 Input Select and Pin Control ...........................................................................................160
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Section Number
8.6
8.7
Title
Page
8.5.3 Hardware Trigger ............................................................................................................160
8.5.4 Conversion Control .........................................................................................................160
8.5.5 Automatic Compare Function .........................................................................................163
8.5.6 MCU Wait Mode Operation ............................................................................................163
8.5.7 MCU Stop3 Mode Operation ..........................................................................................163
8.5.8 MCU Stop1 and Stop2 Mode Operation .........................................................................164
Initialization Information ..............................................................................................................164
8.6.1 ADC Module Initialization Example .............................................................................164
Application Information ................................................................................................................166
8.7.1 External Pins and Routing ..............................................................................................166
8.7.2 Sources of Error ..............................................................................................................168
Chapter 9
Cyclic Redundancy Check (S08CRCV1)
9.1
9.2
9.3
9.4
9.5
Introduction ...................................................................................................................................171
9.1.1 Features ...........................................................................................................................171
9.1.2 Features ...........................................................................................................................173
9.1.3 Modes of Operation ........................................................................................................173
9.1.4 Block Diagram ................................................................................................................174
External Signal Description ..........................................................................................................174
Register Definition .......................................................................................................................174
9.3.1 Memory Map ..................................................................................................................174
9.3.2 Register Descriptions ......................................................................................................175
Functional Description ..................................................................................................................176
9.4.1 ITU-T (CCITT) recommendations & expected CRC results ..........................................176
Initialization Information ..............................................................................................................177
Chapter 10
Internal Clock Generator (S08ICGV4)
10.1 Introduction ...................................................................................................................................181
10.1.1 Features ...........................................................................................................................181
10.1.2 Modes of Operation ........................................................................................................182
10.1.3 Block Diagram ................................................................................................................183
10.2 External Signal Description ..........................................................................................................183
10.2.1 EXTAL — External Reference Clock / Oscillator Input ................................................183
10.2.2 XTAL — Oscillator Output ............................................................................................183
10.2.3 External Clock Connections ...........................................................................................184
10.2.4 External Crystal/Resonator Connections ........................................................................184
10.3 Register Definition ........................................................................................................................185
10.3.1 ICG Control Register 1 (ICGC1) ....................................................................................185
10.3.2 ICG Control Register 2 (ICGC2) ....................................................................................187
10.3.3 ICG Status Register 1 (ICGS1) .......................................................................................188
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Section Number
Title
Page
10.3.4 ICG Status Register 2 (ICGS2) .......................................................................................189
10.3.5 ICG Filter Registers (ICGFLTU, ICGFLTL) ..................................................................189
10.3.6 ICG Trim Register (ICGTRM) .......................................................................................190
10.4 Functional Description ..................................................................................................................190
10.4.1 Off Mode (Off) ................................................................................................................191
10.4.2 Self-Clocked Mode (SCM) .............................................................................................191
10.4.3 FLL Engaged, Internal Clock (FEI) Mode .....................................................................192
10.4.4 FLL Engaged Internal Unlocked ....................................................................................193
10.4.5 FLL Engaged Internal Locked ........................................................................................193
10.4.6 FLL Bypassed, External Clock (FBE) Mode ..................................................................193
10.4.7 FLL Engaged, External Clock (FEE) Mode ...................................................................193
10.4.8 FLL Lock and Loss-of-Lock Detection ..........................................................................194
10.4.9 FLL Loss-of-Clock Detection .........................................................................................195
10.4.10Clock Mode Requirements .............................................................................................196
10.4.11Fixed Frequency Clock ...................................................................................................197
10.4.12High Gain Oscillator .......................................................................................................197
10.5 Initialization/Application Information ..........................................................................................197
10.5.1 Introduction .....................................................................................................................197
10.5.2 Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz ...........................199
10.5.3 Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz ..............................201
10.5.4 Example #3: No External Crystal Connection, 5.4 MHz Bus Frequency ......................203
10.5.5 Example #4: Internal Clock Generator Trim ..................................................................205
Chapter 11
Inter-Integrated Circuit (S08IICV2)
11.1 Introduction ...................................................................................................................................207
11.1.1 Features ...........................................................................................................................209
11.1.2 Modes of Operation ........................................................................................................209
11.1.3 Block Diagram ................................................................................................................210
11.2 External Signal Description ..........................................................................................................210
11.2.1 SCL — Serial Clock Line ...............................................................................................210
11.2.2 SDA — Serial Data Line ................................................................................................210
11.3 Register Definition ........................................................................................................................210
11.3.1 IIC Address Register (IICA) ...........................................................................................211
11.3.2 IIC Frequency Divider Register (IICF) ...........................................................................211
11.3.3 IIC Control Register (IICC1) ..........................................................................................214
11.3.4 IIC Status Register (IICS) ...............................................................................................215
11.3.5 IIC Data I/O Register (IICD) ..........................................................................................216
11.3.6 IIC Control Register 2 (IICC2) .......................................................................................216
11.4 Functional Description ..................................................................................................................217
11.4.1 IIC Protocol .....................................................................................................................217
11.4.2 10-bit Address .................................................................................................................221
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11.4.3 General Call Address ......................................................................................................222
11.5 Resets ............................................................................................................................................222
11.6 Interrupts .......................................................................................................................................222
11.6.1 Byte Transfer Interrupt ....................................................................................................222
11.6.2 Address Detect Interrupt .................................................................................................222
11.6.3 Arbitration Lost Interrupt ................................................................................................222
11.7 Initialization/Application Information ..........................................................................................224
Chapter 12
Keyboard Interrupt (S08KBIV1)
12.1 Introduction ...................................................................................................................................227
12.1.1 Features ...........................................................................................................................227
12.1.2 KBI Block Diagram ........................................................................................................229
12.2 Register Definition ........................................................................................................................229
12.2.1 KBI Status and Control Register (KBISC) .....................................................................230
12.2.2 KBI Pin Enable Register (KBIPE) ..................................................................................231
12.3 Functional Description ..................................................................................................................231
12.3.1 Pin Enables ......................................................................................................................231
12.3.2 Edge and Level Sensitivity ..............................................................................................231
12.3.3 KBI Interrupt Controls ....................................................................................................232
Chapter 13
Serial Communications Interface (S08SCIV4)
13.1 Introduction ...................................................................................................................................233
13.1.1 Features ...........................................................................................................................235
13.1.2 Modes of Operation ........................................................................................................235
13.1.3 Block Diagram ................................................................................................................236
13.2 Register Definition ........................................................................................................................238
13.2.1 SCI Baud Rate Registers (SCIxBDH, SCIxBDL) ..........................................................238
13.2.2 SCI Control Register 1 (SCIxC1) ...................................................................................239
13.2.3 SCI Control Register 2 (SCIxC2) ...................................................................................240
13.2.4 SCI Status Register 1 (SCIxS1) ......................................................................................241
13.2.5 SCI Status Register 2 (SCIxS2) ......................................................................................243
13.2.6 SCI Control Register 3 (SCIxC3) ...................................................................................244
13.2.7 SCI Data Register (SCIxD) .............................................................................................245
13.3 Functional Description ..................................................................................................................245
13.3.1 Baud Rate Generation .....................................................................................................245
13.3.2 Transmitter Functional Description ................................................................................246
13.3.3 Receiver Functional Description .....................................................................................247
13.3.4 Interrupts and Status Flags ..............................................................................................249
13.3.5 Additional SCI Functions ...............................................................................................250
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
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Section Number
Title
Page
Chapter 14
Serial Peripheral Interface (S08SPIV3)
14.1 Introduction ...................................................................................................................................253
14.1.1 Features ...........................................................................................................................255
14.1.2 Block Diagrams ..............................................................................................................255
14.1.3 SPI Baud Rate Generation ..............................................................................................257
14.2 External Signal Description ..........................................................................................................258
14.2.1 SPSCK — SPI Serial Clock ............................................................................................258
14.2.2 MOSI — Master Data Out, Slave Data In ......................................................................258
14.2.3 MISO — Master Data In, Slave Data Out ......................................................................258
14.2.4 SS — Slave Select ...........................................................................................................258
14.3 Modes of Operation .......................................................................................................................259
14.3.1 SPI in Stop Modes ..........................................................................................................259
14.4 Register Definition ........................................................................................................................259
14.4.1 SPI Control Register 1 (SPIxC1) ....................................................................................259
14.4.2 SPI Control Register 2 (SPIxC2) ....................................................................................260
14.4.3 SPI Baud Rate Register (SPIxBR) ..................................................................................261
14.4.4 SPI Status Register (SPIxS) ............................................................................................262
14.4.5 SPI Data Register (SPIxD) ..............................................................................................263
14.5 Functional Description ..................................................................................................................264
14.5.1 SPI Clock Formats ..........................................................................................................264
14.5.2 SPI Interrupts ..................................................................................................................267
14.5.3 Mode Fault Detection .....................................................................................................267
Chapter 15
Timer/PWM (S08TPMV3)
15.1 Introduction ...................................................................................................................................269
15.2 Features .........................................................................................................................................269
15.2.1 Features ...........................................................................................................................271
15.2.2 Modes of Operation ........................................................................................................271
15.2.3 Block Diagram ................................................................................................................272
15.3 Signal Description .........................................................................................................................274
15.3.1 Detailed Signal Descriptions ...........................................................................................274
15.4 Register Definition ........................................................................................................................278
15.4.1 TPM Status and Control Register (TPMxSC) ................................................................278
15.4.2 TPM-Counter Registers (TPMxCNTH:TPMxCNTL) ....................................................279
15.4.3 TPM Counter Modulo Registers (TPMxMODH:TPMxMODL) ....................................280
15.4.4 TPM Channel n Status and Control Register (TPMxCnSC) ..........................................281
15.4.5 TPM Channel Value Registers (TPMxCnVH:TPMxCnVL) ..........................................283
15.5 Functional Description ..................................................................................................................284
15.5.1 Counter ............................................................................................................................285
15.5.2 Channel Mode Selection .................................................................................................287
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Title
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15.6 Reset Overview .............................................................................................................................290
15.6.1 General ............................................................................................................................290
15.6.2 Description of Reset Operation .......................................................................................290
15.7 Interrupts .......................................................................................................................................290
15.7.1 General ............................................................................................................................290
15.7.2 Description of Interrupt Operation ..................................................................................291
15.8 The Differences from TPM v2 to TPM v3 ....................................................................................292
Chapter 16
Development Support
16.1 Introduction ...................................................................................................................................297
16.1.1 Features ...........................................................................................................................298
16.2 Background Debug Controller (BDC) ..........................................................................................298
16.2.1 BKGD Pin Description ...................................................................................................299
16.2.2 Communication Details ..................................................................................................299
16.2.3 BDC Commands .............................................................................................................303
16.2.4 BDC Hardware Breakpoint .............................................................................................305
16.3 Register Definition ........................................................................................................................305
16.3.1 BDC Registers and Control Bits .....................................................................................306
16.3.2 System Background Debug Force Reset Register (SBDFR) ..........................................308
Chapter 17
Debug Module (S08DBGV3) (128K)
17.1 Introduction ...................................................................................................................................311
17.1.1 Features ...........................................................................................................................311
17.1.2 Modes of Operation ........................................................................................................312
17.1.3 Block Diagram ................................................................................................................312
17.2 Signal Description .........................................................................................................................312
17.3 Memory Map and Registers ..........................................................................................................313
17.3.1 Module Memory Map .....................................................................................................313
17.3.2
314
17.3.3 Register Descriptions ......................................................................................................315
17.4 Functional Description ..................................................................................................................328
17.4.1 Comparator .....................................................................................................................328
17.4.2 Breakpoints .....................................................................................................................329
17.4.3 Trigger Selection .............................................................................................................329
17.4.4 Trigger Break Control (TBC) .........................................................................................330
17.4.5 FIFO ................................................................................................................................333
17.4.6 Interrupt Priority .............................................................................................................334
17.5 Resets ............................................................................................................................................334
17.6 Interrupts .......................................................................................................................................335
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
17
Chapter 1
Introduction
1.1
Overview
The MC9S08AC128 Series are members of the low-cost, high-performance HCS08 Family of 8-bit
microcontroller units (MCUs). All MCUs in the family use the enhanced HCS08 core and are available
with a variety of modules, memory sizes, memory types, and package types. Refer to Table 1-1 for
memory sizes and package types.
Table 1-1. Devices in the MC9S08AC128 Series
Device
FLASH
RAM
MC9S08AC128
131,072
8192
MC9S08AC96
98,304
6016
Package
80 LQFP
64 QFP
44 LQFP
80 LQFP
64 QFP
44 LQFP
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
19
Chapter 1 Introduction
Table 1-2 summarizes the feature set available in the MC9S08AC128 Series of MCUs.
Table 1-2. MC9S08AC128 Series Peripherals Available by Package Pin Count
MC9S08AC128/96
Feature
ADC
CRC
IIC
IRQ
KBI1
SCI1
SCI2
SPI1
SPI2
TPM1
TPM1CLK1
TPM2
TPM2CLK1
TPM3
TPMCLK 1
I/O pins
1
1.2
80-pin
64-pin
16-ch
44-pin
8-ch
yes
yes
yes
8
7
yes
yes
yes
no
yes
6-ch
yes
6-ch
yes
69
2-ch
yes
2-ch
yes
54
no
4-ch
no
2-ch
no
38
TPMCLK, TPM1CLK, and TPM2CLK options are configured via software using the
TPMCCFG bit; out of reset, TPM1CLK, TPM2CLK, and TPMCLK are available to TPM1,
TPM2, and TPM3 respectively. Reference the TPM chapter for a functional description of
the TPMxCLK and TPMCLK signals.
MCU Block Diagrams
The block diagram shows the structure of the MC9S08AC128 Series MCU.
MC9S08AC128 Series Reference Manual, Rev. 3
20
Freescale Semiconductor
Chapter 1 Introduction
HCS08 CORE
IRQ
LVD
VDDAD
EXTAL
XTAL
LOW-POWER OSC
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
PORT J
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
PORT H
PORT G
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
VOLTAGE REGULATOR
VSS
PORT A
COP
PORT B
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
PORT E
RQ/TPMCLK
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT C
HCS08 SYSTEM CONTROL
RESET
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT D
CPU
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
TPM1CLK or TPMCLK
TPM1CH0–TPM1CH5
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BDC
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 1-1. MC9S08AC128 Series Block Diagram
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
21
Chapter 1 Introduction
Table 1 lists the functional versions of the on-chip modules.
Table 1. Versions of On-Chip Modules
Module
1.3
Version
Analog-to-Digital Converter (ADC)
1
Central Processing Unit (CPU)
5
Cyclic Redundancy Check Module (CRC)
1
Debug Module (DBG)
3
External Interrupt (IRQ)
3
Internal Clock Generator (ICG)
4
Inter-Integrated Circuit (IIC)
2
Keyboard Interrupt (KBI)
1
Serial Communications Interface (SCI)
4
Serial Peripheral Interface (SPI)
3
Timer Pulse-Width Modulator (TPM)
3
System Clock Distribution
TPMCLK1*
TPMCLK2*
TPMCLK
1KHz
LPO
ICGERCLK
SYSTEM
CONTROL
LOGIC
TPM1
TPM2
TPM3
IIC1
SCI1,
SCI2
SPI1,
SPI2
RTI
FFE
÷2
ICG
XCLK
ICGOUT
XOSC
÷2
BUSCLK
ICGLCLK**
CPU
COP
BDC
CRC
ADC1
RAM
FLASH
* The TPMCLK pin can be used to provide an alternate external input clock source to TPM1 and TPM2 by setting option bits in SOPT2.
** ICGLCLK is the alternate BDC clock source.
- ADC1 has min and max frequency requirements. See the ADC chapter and electricals appendix for details.
- Flash has frequency requirements for program and erase operation. See the electricals appendix for details.
- The fixed frequency clock (XCLK) is internally synchronized to the bus clock and must not exceed one half of the bus clock frequency.
Figure 1-2. System Clock Distribution Diagram
MC9S08AC128 Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 1 Introduction
Some of the modules inside the MCU have clock source choices. Figure 1-2 shows a simplified clock
connection diagram. The ICG supplies the clock sources:
• ICGOUT is an output of the ICG module. It is one of the following:
— The external crystal oscillator
— An external clock source
— The output of the digitally-controlled oscillator (DCO) in the frequency-locked loop
sub-module
— Control bits inside the ICG determine which source is connected.
• FFE is a control signal generated inside the ICG. If the frequency of ICGOUT > 4 × the frequency
of ICGERCLK, this signal is a logic 1 and the fixed-frequency clock will be ICGERCLK/2.
Otherwise the fixed-frequency clock will be BUSCLK.
• ICGLCLK — Development tools can select this internal self-clocked source (~ 8 MHz) to speed
up BDC communications in systems where the bus clock is slow.
• ICGERCLK — External reference clock can be selected as the real-time interrupt clock source.
Can also be used as the ALTCLK input to the ADC module.
• XCLK — Fixed frequency clock can be selected as clock source for TPM1, TPM2, and TPM3.
• TPMCLK1, TPMCLK2, and TPMCLK — External input clock source for TPM1, TPM2, and
TPM3 respectively. The TPMCLK pin can be used to provide an alternate external input clock
source to TPM1 and TPM2 by setting option bits in SOPT2.
• BUSCLK — The frequency of the bus is always half of ICGOUT.
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
23
Chapter 1 Introduction
MC9S08AC128 Series Reference Manual, Rev. 3
24
Freescale Semiconductor
Chapter 2
Pins and Connections
2.1
Introduction
This chapter describes signals that connect to package pins. It includes a pinout diagram, a table of signal
properties, and detailed discussion of signals.
2.2
Device Pin Assignment
80-Pin
LQFP
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
PTG3/KBI1P3
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
VSSAD
VDDAD
PTD1/AD1P9
PTD0/AD1P8
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTA7
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
PTE4/SS1
PTE5/MISO1
PTE6/MOSI1
PTE7/SPSCK1
VSS
VDD
PTJ4
PTJ5
PTJ6
PTJ7
PTG0/KBI1P0
PTG1/KBI1P1
PTG2/KBI1P2
PTA0
PTA1
PTA2
PTA3
PTA4
PTA5
PTA6
PTC4
IRQ/TPMCLK
RESET
PTF0/TPM1CH2
PTF1/TPM1CH3
PTF2/TPM1CH4
PTF3/TPM1CH5
PTF4/TPM2CH0
PTC6
PTF7
PTF5/TPM2CH1
PTF6
PTJ0
PTJ1
PTJ2
PTJ3
PTE0/TxD1
PTE1/RxD1
PTE2/TPM1CH0
PTE3/TPM1CH1
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
PTC5/RxD2
PTC3/TxD2
PTC2/MCLK
PTH6/MISO2
PTH5/MIOSI2
PTH4/SPCK2
PTC1/SDA1
PTC0/SCL1
VDD (NC)
VSS
PTG6/EXTAL
PTG5/XTAL
BKGD/MS
VREFL
VREFH
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTG4/KBI1P4
Figure 2-1 shows the 80-pin LQFP package assignments for the MC9S08AC128 Series devices.
Note: Pin names in bold
are lost in lower pin count
packages.
Figure 2-1. MC9S08AC128 Series in 80-Pin LQFP Package
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
25
Chapter 2 Pins and Connections
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
VSS
PTG6/EXTAL
PTG5/XTAL
BKGD/MS
VREFL
VREFH
PTD7/AD1P15/KBI1P7
PTD6//TPM1CLK
PTD5/AD1P13
PTD4/AD1P12/TPM2CLK
63
62
61
60
59
58
57
56
55
54
53
52
51
50
64
PTC4 1
PTG4/KBI1P4
PTC3/TxD2
PTC5/RxD2
Figure 2-2 shows the 64-pin package assignments for the MC9S08AC128 Series devices.
49
48
PTG3/KBI1P3
IRQ/TPMCLK
2
47
PTD3/KBI1P6/AD1P11
RESET
3
46
PTD2KBI1P5/AD1P10
PTF0/TPM1CH2
4
45
VSSAD
PTF1/TPM1CH3
5
44
VDDAD
PTF2/TPM1CH4
6
43
PTD1/AD1P9
PTF3/TPM1CH5
7
42
PTD0/AD1P8
PTF4/TPM2CH0
8
41
PTB7/AD1P7
PTC6
9
40
PTB6/AD1P6
PTF7
10
39
PTB5/AD1P5
PTF5/TPM2CH1
11
38
PTB4/AD1P4
PTF6
12
37
PTB3/AD1P3
PTE0/TxD1
13
36
PTB2/AD1P2
PTE1/RxD1
14
35
PTB1/TPM3CH1/AD1P1
PTE2/TPM1CH0
15
34
PTB0/TPM3CH0/AD1P0
64-Pin QFP
PTE3/TPM1CH1 16
33 PTA7
18
19
20
21
22
23
24
25
26
27
28
29
30
31
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBI1P0
VDD
VSS
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTA6
32
17
Note: Pin names in bold
are lost in lower pin count
packages.
Figure 2-2. MC9S08AC128 Series in 64-Pin QFP Package
Figure 2-3 shows the 44-pin LQFP pin assignments for the MC9S08AC128 Series device.
MC9S08AC128 Series Reference Manual, Rev. 3
26
Freescale Semiconductor
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
VSS
PTG6/EXTAL
PTG5/XTAL
BKGD/MS
VREFL
43
42
41
40
39
38
37
36
35
34
44
PTC4 1
VREFH
PTC3/TxD2
PTC5/RxD2
Chapter 2 Pins and Connections
33 PTG3/KBI1P3
IRQ/TPMCLK
2
32
PTD3/KBI1P6/AD1P11
RESET
3
31
PTD2/KBI1P5/AD1P10
PTF0/TPM1CH2
4
30
VSSAD
PTF1/TPM1CH3
5
29
VDDAD
28
PTD1/AD1P9
44-Pin LQFP
PTF4/TPM2CH0
6
PTF5/TPM2CH1
7
27
PTD0/AD1P8
PTE0/TxD1
8
26
PTB3/AD1P3
PTE1/RxD1
9
25
PTB2/AD1P2
PTE2/TPM1CH0
10
24
PTB1/TPM3CH1/AD1P1
PTE3/TPM1CH1 11
23 PTB0/TPM3CH0/AD1P0
13
14
15
16
17
18
19
20
21
PTA0
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBI1P0
VDD
VSS
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTA1
22
12
Figure 2-3. MC9S08AC128 Series in 44-Pin LQFP Package
2.3
Recommended System Connections
Figure 2-4 shows pin connections that are common to almost all MC9S08AC128 Series application
systems.
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
27
Chapter 2 Pins and Connections
VREFH
CBYAD
0.1 μF
+
5V
CBLK +
10 μF
RF
C1
PORT
B
PTB0/TPM3CH0/AD1P0
PTB1/TPM3CH1/AD1P1
PTB2/AD1P2
PTB3/AD1P3
PTB4/AD1P4
PTB5/AD1P5
PTB6/AD1P6
PTB7/AD1P7
PORT
C
PTC0/SCL1
PTC1/SDA1
PTC2/MCLK
PTC3/TxD2
PTC4
PTC5/RxD2
PTC6
PORT
D
PTD0/AD1P8
PTD1/AD1P9
PTD2/KBI1P5/AD1P10
PTD3/KBI1P6/AD1P11
PTD4/TPM2CLK/AD1P12
PTD5/AD1P13
PTD6/TPM1CLK/AD1P14
PTD7/KBI1P7/AD1P15
PORT
E
PTE0/TxD1
PTE1/RxD1
PTE2/TPM1CH0
PTE3/TPM1CH1
PTE4/SS1
PTE5/MISO1
PTE6/MOSI1
PTE7/SPSCK1
PORT
F
PTF0/TPM1CH2
PTF1/TPM1CH3
PTF2/TPM1CH4
PTF3/TPM1CH5
PTF4/TPM2CH0
PTF5/TPM2CH1
PTF6
PTF7
PORT
G
PTG0/KBI1P0
PTG1/KBI1P1
PTG2/KBI1P2
PTG3/KBI1P3
PTG4/KBI1P4
PTG5/XTAL
PTG6/EXTAL
CBY
0.1 μF
VSS (x2)
NOTE 1
PORT
A
PTA0
PTA1
PTA2
PTA3
PTA4
PTA5
PTA6
PTA7
VSSAD
VREFL
VDD
VDD
SYSTEM
POWER
MC9S08AC128
VDDAD
RS
XTAL
NOTE 2
C2
X1
EXTAL
NOTE 2
BACKGROUND HEADER
1
VDD
BKGD/MS
VDD
4.7 kΩ–10 kΩ
RESET
0.1 μF VDD
OPTIONAL
MANUAL
RESET
4.7 kΩ–
10 kΩ
ASYNCHRONOUS
INTERRUPT
INPUT
NOTES:
1. Not required if
using the internal
clock option.
2. These are the
same pins as
PTG5 and PTG6
3. RC filters on
RESET and IRQ
are recommended
for EMC-sensitive
applications.
0.1 μF
PTJ0
PTJ1
PTJ2
PTJ3
PTJ4
PTJ5
PTJ6
PTJ7
PTH0/TPM2CH2
PTH1/TPM2CH3
PTH2/TPM2CH4
PTH3/TPM2CH5
PTH4/SPSCK2
PTH5/MOSI2
PTH6/MISO2
IRQ
NOTE 3
PORT
J
PORT
H
Figure 2-4. Basic System Connections
MC9S08AC128 Series Reference Manual, Rev. 3
28
Freescale Semiconductor
Chapter 2 Pins and Connections
2.3.1
Power (VDD, VSS, VDDAD, VSSAD)
VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all
I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides regulated
lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins. In this case, there
should be a bulk electrolytic capacitor, such as a 10-μF tantalum capacitor, to provide bulk charge storage
for the overall system and a 0.1-μF ceramic bypass capacitor located as near to the paired VDD and VSS
power pins as practical to suppress high-frequency noise. The MC9S08AC128 has a second VSS pin. This
pin should be connected to the system ground plane or to the primary VSS pin through a low-impedance
connection.
VDDAD and VSSAD are the analog power supply pins for the MCU. This voltage source supplies power to
the ADC module. A 0.1-μF ceramic bypass capacitor should be located as near to the analog power pins
as practical to suppress high-frequency noise.
2.3.2
Oscillator (XTAL, EXTAL)
Out of reset the MCU uses an internally generated clock (self-clocked mode — fSelf_reset) equivalent to
about 8-MHz crystal rate. This frequency source is used during reset startup and can be enabled as the
clock source for stop recovery to avoid the need for a long crystal startup delay. This MCU also contains
a trimmable internal clock generator (ICG) module that can be used to run the MCU. For more information
on the ICG, see the Chapter 10, “Internal Clock Generator (S08ICGV4).”
The oscillator in this MCU is a Pierce oscillator that can accommodate a crystal or ceramic resonator in
either of two frequency ranges selected by the RANGE bit in the ICGC1 register. Rather than a crystal or
ceramic resonator, an external oscillator can be connected to the EXTAL input pin.
Refer to Figure 2-4 for the following discussion. RS (when used) and RF should be low-inductance
resistors such as carbon composition resistors. Wire-wound resistors, and some metal film resistors, have
too much inductance. C1 and C2 normally should be high-quality ceramic capacitors that are specifically
designed for high-frequency applications.
RF is used to provide a bias path to keep the EXTAL input in its linear range during crystal startup and its
value is not generally critical. Typical systems use 1 MΩ to 10 MΩ. Higher values are sensitive to humidity
and lower values reduce gain and (in extreme cases) could prevent startup.
C1 and C2 are typically in the 5-pF to 25-pF range and are chosen to match the requirements of a specific
crystal or resonator. Be sure to take into account printed circuit board (PCB) capacitance and MCU pin
capacitance when sizing C1 and C2. The crystal manufacturer typically specifies a load capacitance which
is the series combination of C1 and C2 which are usually the same size. As a first-order approximation,
use 10 pF as an estimate of combined pin and PCB capacitance for each oscillator pin (EXTAL and
XTAL).
2.3.3
RESET Pin
RESET is a dedicated pin with a pullup device built in. It has input hysteresis, a high current output driver,
and no output slew rate control. Internal power-on reset and low-voltage reset circuitry typically make
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
29
Chapter 2 Pins and Connections
external reset circuitry unnecessary. This pin is normally connected to the standard 6-pin background
debug connector so a development system can directly reset the MCU system. If desired, a manual external
reset can be added by supplying a simple switch to ground (pull reset pin low to force a reset).
Whenever any reset is initiated (whether from an external signal or from an internal system), the reset pin
is driven low for approximately 34 cycles of fSelf_reset, released, and sampled again approximately 38
cycles of fSelf_reset later. If reset was caused by an internal source such as low-voltage reset or watchdog
timeout, the circuitry expects the reset pin sample to return a logic 1. The reset circuitry decodes the cause
of reset and records it by setting a corresponding bit in the system control reset status register (SRS).
In EMC-sensitive applications, an external RC filter is recommended on the reset pin. See Figure 2-4 for
an example.
2.3.4
Background/Mode Select (BKGD/MS)
While in reset, the BKGD/MS pin functions as a mode select pin. Immediately after reset rises the pin
functions as the background pin and can be used for background debug communication. While functioning
as a background/mode select pin, the pin includes an internal pullup device, input hysteresis, and no output
slew rate control. When the pin functions as a background pin, it includes a high-current output driver.
When the pin functions as mode select it is input only, so it does not have any output capability and
includes a pullup.
If nothing is connected to this pin, the MCU will enter normal operating mode at the rising edge of reset.
If a debug system is connected to the 6-pin standard background debug header, it can hold BKGD/MS low
during the rising edge of reset which forces the MCU to active background mode.
The BKGD pin is used primarily for background debug controller (BDC) communications using a custom
protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC
clock could be as fast as the bus clock rate, so there should never be any significant capacitance connected
to the BKGD/MS pin that could interfere with background serial communications.
Although the BKGD pin is a pseudo open-drain pin, the background debug communication protocol
provides brief, actively driven, high speedup pulses to ensure fast rise times. Small capacitances from
cables and the absolute value of the internal pullup device play almost no role in determining rise and fall
times on the BKGD pin.
2.3.5
ADC Reference Pins (VREFH, VREFL)
The VREFH and VREFL pins are the voltage reference high and voltage reference low inputs respectively
for the ADC module.
2.3.6
External Interrupt Pin (IRQ)
The IRQ pin is the input source for the IRQ interrupt and is also the input for the BIH and BIL instructions.
If the IRQ function is not enabled, this pin can still be configured as the TPMCLK (see the TPM chapter).
In EMC-sensitive applications, an external RC filter is recommended on the IRQ pin. See Figure 2-4 for
an example.
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Chapter 2 Pins and Connections
2.3.7
General-Purpose I/O and Peripheral Ports
The remaining pins are shared among general-purpose I/O and on-chip peripheral functions such as timers
and serial I/O systems. Immediately after reset, all of these pins are configured as high-impedance
general-purpose inputs with internal pullup devices disabled.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unused pins to outputs so the pins do not
float.
Not all general-purpose I/O pins are available on all packages. To avoid
extra current drain from floating input pins, the user’s reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unconnected pins to outputs so the pins
do not float.
When an on-chip peripheral system is controlling a pin, data direction control bits still determine what is
read from port data registers even though the peripheral module controls the pin direction by controlling
the enable for the pin’s output buffer. See the Chapter 6, “Parallel Input/Output” chapter for more details.
Pullup enable bits for each input pin control whether on-chip pullup devices are enabled whenever the pin
is acting as an input even if it is being controlled by an on-chip peripheral module. When the PTD7, PTD3,
PTD2, and PTG4 pins are controlled by the KBI module and are configured for rising-edge/high-level
sensitivity, the pullup enable control bits enable pulldown devices rather than pullup devices. Similarly,
when IRQ is configured as the IRQ input and is set to detect rising edges, the pullup enable control bit
enables a pulldown device rather than a pullup device.
NOTE
When an alternative function is first enabled it is possible to get a spurious
edge to the module, user software should clear out any associated flags
before interrupts are enabled. Table 2-1 illustrates the priority if multiple
modules are enabled. The highest priority module will have control over the
pin. Selecting a higher priority pin function with a lower priority function
already enabled can cause spurious edges to the lower priority module. It is
recommended that all modules that share a pin be disabled before enabling
another module.
Table 2-1. Pin Availability by Package Pin-Count
Pin Number
Lowest <--
Priority
--> Highest
Port Pin
Alt 1
Alt 2
80
64
44
1
1
1
PTC4
2
2
2
IRQ
3
3
3
RESET
4
4
4
PTF0
TPMCLK1
TPM1CH2
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Chapter 2 Pins and Connections
Table 2-1. Pin Availability by Package Pin-Count (continued)
Pin Number
Lowest <--
Priority
--> Highest
Port Pin
Alt 1
Alt 2
80
64
44
5
5
5
PTF1
TPM1CH3
6
6
—
PTF2
TPM1CH4
7
7
—
PTF3
TPM1CH5
8
8
6
PTF4
TPM2CH0
9
9
—
PTC6
10
10
—
PTF7
11
11
7
PTF5
12
12
—
PTF6
13
—
—
PTJ0
14
—
—
PTJ1
15
—
—
PTJ2
16
—
—
PTJ3
17
13
8
PTE0
18
14
9
PTE1
RxD1
19
15
10
PTE2
TPM1CH0
20
16
11
PTE3
TPM1CH1
21
17
12
PTE4
SS1
22
18
13
PTE5
MISO1
23
19
14
PTE6
MOSI1
24
20
15
PTE7
SPSCK1
25
21
16
VSS
26
22
17
VDD
27
—
—
PTJ4
28
—
—
PTJ5
29
—
—
PTJ6
TPM2CH1
TxD1
30
—
—
PTJ7
31
23
18
PTG0
KBI1P0
32
24
19
PTG1
KBI1P1
33
25
20
PTG2
KBI1P2
34
26
21
PTA0
35
27
22
PTA1
36
28
—
PTA2
37
29
—
PTA3
38
30
—
PTA4
39
31
—
PTA5
40
32
—
PTA6
41
33
—
PTA7
42
—
—
PTH0
TPM2CH2
43
—
—
PTH1
TPM2CH3
44
—
—
PTH2
TPM2CH4
45
—
—
PTH3
TPM2CH5
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Freescale Semiconductor
Chapter 2 Pins and Connections
Table 2-1. Pin Availability by Package Pin-Count (continued)
Pin Number
1
Lowest <--
Priority
--> Highest
Port Pin
Alt 1
Alt 2
80
64
44
46
34
23
PTB0
TPM3CH0 AD1P0
47
35
24
PTB1
TPM3CH1 AD1P1
48
36
25
PTB2
AD1P2
49
37
26
PTB3
AD1P3
50
38
—
PTB4
AD1P4
51
39
—
PTB5
AD1P5
52
40
—
PTB6
AD1P6
53
41
—
PTB7
AD1P7
54
42
27
PTD0
AD1P8
55
43
28
PTD1
AD1P9
56
44
29
VDDAD
57
45
30
VSSAD
58
46
31
PTD2
KBI1P5
AD1P10
59
47
32
PTD3
KBI1P6
AD1P11
60
48
33
PTG3
KBI1P3
61
49
—
PTG4
KBI1P4
62
50
—
PTD4
TPM2CLK AD1P12
63
51
—
PTD5
AD1P13
64
52
—
PTD6
TPM1CLK AD1P14
65
53
—
PTD7
KBI1P7
66
54
34
VREFH
67
55
35
VREFL
68
56
36
BKGD
MS
69
57
37
PTG5
XTAL
70
58
38
PTG6
EXTAL
71
59
39
VSS
72
—
—
VDD(NC)
73
60
40
PTC0
SCL1
74
61
41
PTC1
SDA1
75
—
—
PTH4
SPSCK2
76
—
—
PTH5
MOSI2
77
—
—
PTH6
MISO2
78
62
42
PTC2
MCLK
79
63
43
PTC3
TxD2
80
64
44
PTC5
RxD2
AD1P15
TPMCLK, TPM1CLK, and TPM2CLK options are
configured via software; out of reset, TPM1CLK,
TPM2CLK, and TPMCLK are available to TPM1,
TPM2, and TPM3 respectively.
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Chapter 2 Pins and Connections
MC9S08AC128 Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 3
Modes of Operation
3.1
Introduction
The operating modes of the MC9S08AC128 Series are described in this chapter. Entry into each mode,
exit from each mode, and functionality while in each of the modes are described.
3.2
•
•
•
3.3
Features
Active background mode for code development
Wait mode:
— CPU shuts down to conserve power
— System clocks running
— Full voltage regulation maintained
Stop modes:
— System clocks stopped; voltage regulator in standby
— Stop2 — Partial power down of internal circuits, RAM contents retained
— Stop3 — All internal circuits powered for fast recovery
Run Mode
This is the normal operating mode for the MC9S08AC128 Series. This mode is selected when the
BKGD/MS pin is high at the rising edge of reset. In this mode, the CPU executes code from internal
memory with execution beginning at the address fetched from memory at 0xFFFE:0xFFFF after reset.
3.4
Active Background Mode
The active background mode functions are managed through the background debug controller (BDC) in
the HCS08 core. The BDC, together with the on-chip ICE debug module (DBG), provide the means for
analyzing MCU operation during software development.
Active background mode is entered in any of five ways:
• When the BKGD/MS pin is low at the rising edge of reset
• When a BACKGROUND command is received through the BKGD pin
• When a BGND instruction is executed
• When encountering a BDC breakpoint
• When encountering a DBG breakpoint
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Chapter 3 Modes of Operation
After entering active background mode, the CPU is held in a suspended state waiting for serial background
commands rather than executing instructions from the user’s application program.
Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user program is
running. Non-intrusive commands can be issued through the BKGD pin while the MCU is in run
mode; non-intrusive commands can also be executed when the MCU is in the active background
mode. Non-intrusive commands include:
— Memory access commands
— Memory-access-with-status commands
— BDC register access commands
— The BACKGROUND command
• Active background commands, which can only be executed while the MCU is in active background
mode. Active background commands include commands to:
— Read or write CPU registers
— Trace one user program instruction at a time
— Leave active background mode to return to the user’s application program (GO)
3.5
Wait Mode
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU
enters a low-power state in which it is not clocked. The I bit in CCR is cleared when the CPU enters the
wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits the wait mode and
resumes processing, beginning with the stacking operations leading to the interrupt service routine.
While the MCU is in wait mode, there are some restrictions on which background debug commands can
be used. Only the BACKGROUND command and memory-access-with-status commands are available
when the MCU is in wait mode. The memory-access-with-status commands do not allow memory access,
but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND
command can be used to wake the MCU from wait mode and enter active background mode.
3.6
Stop Modes
One of two stop modes is entered upon execution of a STOP instruction when the STOPE bit in the system
option register is set. In both stop modes, all internal clocks are halted. If the STOPE bit is not set when
the CPU executes a STOP instruction, the MCU will not enter either of the stop modes and an illegal
opcode reset is forced. The stop modes are selected by setting the appropriate bits in SPMSC2.
HCS08 devices that are designed for low voltage operation (1.8V to 3.6V) also include stop1 mode. The
MC9S08AC128 Series of devices operates at 2.7 V to 5.5 V and does not include stop1 mode.
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Chapter 3 Modes of Operation
Table 3-1 summarizes the behavior of the MCU in each of the stop modes.
Table 3-1. Stop Mode Behavior
1
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop2
1
Off
Standby
Off
Disabled
Standby
States
held
Optionally on
Stop3
0
Standby
Standby
Off1
Optionally on
Standby
States
held
Optionally on
Crystal oscillator can be configured to run in stop3. Please see the ICG registers.
3.6.1
Stop2 Mode
The stop2 mode provides very low standby power consumption and maintains the contents of RAM and
the current state of all of the I/O pins. To enter stop2, the user must execute a STOP instruction with stop2
selected (PPDC = 1) and stop mode enabled (STOPE = 1). In addition, the LVD must not be enabled to
operate in stop (LVDSE = LVDE = 1). If the LVD is enabled in stop, then the MCU enters stop3 upon the
execution of the STOP instruction regardless of the state of PPDC.
Before entering stop2 mode, the user must save the contents of the I/O port registers, as well as any other
memory-mapped registers which they want to restore after exit of stop2, to locations in RAM. Upon exit
of stop2, these values can be restored by user software before pin latches are opened.
When the MCU is in stop2 mode, all internal circuits that are powered from the voltage regulator are turned
off, except for the RAM. The voltage regulator is in a low-power standby state, as is the ADC. Upon entry
into stop2, the states of the I/O pins are latched. The states are held while in stop2 mode and after exiting
stop2 mode until a logic 1 is written to PPDACK in SPMSC2.
Exit from stop2 is done by asserting either of the wake-up pins: RESET or IRQ, or by an RTI interrupt.
IRQ is always enabled and always an active low input when the MCU is in stop2, regardless of how it was
configured before entering stop2.
Upon wake-up from stop2 mode, the MCU will start up as from a power-on reset (POR) except pin states
remain latched. The CPU will take the reset vector. The system and all peripherals will be in their default
reset states and must be initialized.
After waking up from stop2, the PPDF bit in SPMSC2 is set. This flag may be used to direct user code to
go to a stop2 recovery routine. PPDF remains set and the I/O pin states remain latched until a logic 1 is
written to PPDACK in SPMSC2.
To maintain I/O state for pins that were configured as general-purpose I/O, the user must restore the
contents of the I/O port registers, which have been saved in RAM, to the port registers before writing to
the PPDACK bit. If the port registers are not restored from RAM before writing to PPDACK, then the
register bits will assume their reset states when the I/O pin latches are opened and the I/O pins will switch
to their reset states.
MC9S08AC128 Series Reference Manual, Rev. 3
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Chapter 3 Modes of Operation
For pins that were configured as peripheral I/O, the user must reconfigure the peripheral module that
interfaces to the pin before writing to the PPDACK bit. If the peripheral module is not enabled before
writing to PPDACK, the pins will be controlled by their associated port control registers when the I/O
latches are opened.
A separate self-clocked source (≈1 kHz) for the real-time interrupt allows a wakeup from stop2 or stop3
mode with no external components. When RTIS2:RTIS1:RTIS0 = 0:0:0, the real-time interrupt function
and this 1-kHz source are disabled. Power consumption is lower when the 1-kHz source is disabled, but in
that case the real-time interrupt cannot wake the MCU from stop.
3.6.2
Stop3 Mode
To enter stop3, the user must execute a STOP instruction with stop3 selected (PPDC = 0) and stop mode
enabled (STOPE = 1). Upon entering the stop3 mode, all of the clocks in the MCU, including the oscillator
itself, are halted. The ICG enters its standby state, as does the voltage regulator and the ADC. The states
of all of the internal registers and logic, as well as the RAM content, are maintained. The I/O pin states are
not latched at the pin as in stop2. Instead they are maintained by virtue of the states of the internal logic
driving the pins being maintained.
Exit from stop3 is done by asserting RESET, an asynchronous interrupt pin, or through the real-time
interrupt (RTI). The asynchronous interrupt pins are the IRQ or KBI pins. Exit from stop3 can also
facilitated by the SCI receive interrupt, the ADC, and LVI.
If stop3 is exited by means of the RESET pin, then the MCU will be reset and operation will resume after
taking the reset vector. Exit by means of an asynchronous interrupt or the real-time interrupt will result in
the MCU taking the appropriate interrupt vector.
A separate self-clocked source (≈1 kHz) for the real-time interrupt allows a wakeup from stop2 or stop3
mode with no external components. When RTIS2:RTIS1:RTIS0 = 0:0:0, the real-time interrupt function
and this 1-kHz source are disabled. Power consumption is lower when the 1-kHz source is disabled, but in
that case the real-time interrupt cannot wake the MCU from stop.
3.6.3
Active BDM Enabled in Stop Mode
Entry into the active background mode from run mode is enabled if the ENBDM bit in BDCSCR is set.
This register is described in Chapter 16, “Development Support” of this data sheet. If ENBDM is set when
the CPU executes a STOP instruction, the system clocks to the background debug logic remain active when
the MCU enters stop mode so background debug communication is still possible. In addition, the voltage
regulator does not enter its low-power standby state but maintains full internal regulation. If the user
attempts to enter stop2 with ENBDM set, the MCU will instead enter stop3.
Most background commands are not available in stop mode. The memory-access-with-status commands
do not allow memory access, but they report an error indicating that the MCU is in either stop or wait
mode. The BACKGROUND command can be used to wake the MCU from stop and enter active
background mode if the ENBDM bit is set. After entering background debug mode, all background
commands are available. Table 3-2 summarizes the behavior of the MCU in stop when entry into the
background debug mode is enabled.
MC9S08AC128 Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 3 Modes of Operation
Table 3-2. BDM Enabled Stop Mode Behavior
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop3
x
Standby
Standby
Active
Optionally on
Active
States
held
Optionally on
3.6.4
LVD Enabled in Stop Mode
The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below
the LVD voltage. If the LVD is enabled in stop by setting the LVDE and the LVDSE bits, then the voltage
regulator remains active during stop mode. If the user attempts to enter stop2 with the LVD enabled for
stop, the MCU will instead enter stop3. Table 3-3 summarizes the behavior of the MCU in stop when the
LVD is enabled.
Table 3-3. LVD Enabled Stop Mode Behavior
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop3
x
Standby
Standby
Off
Optionally on
Active
States
held
Optionally on
3.6.5
On-Chip Peripheral Modules in Stop Modes
When the MCU enters any stop mode, system clocks to the internal peripheral modules are stopped. Even
in the exception case (ENBDM = 1), where clocks to the background debug logic continue to operate,
clocks to the peripheral systems are halted to reduce power consumption. Refer to Section 3.6.1, “Stop2
Mode,” and Section 3.6.2, “Stop3 Mode,” for specific information on system behavior in stop modes.
Table 3-4. Stop Mode Behavior
Mode
Peripheral
Stop2
Stop3
CPU
Off
Standby
RAM
Standby
Standby
FLASH
Off
Standby
Parallel Port Registers
Off
Standby
ADC
Off
Optionally On1
CRC
Off
Standby
ICG
Off
Optionally On2
IIC
Off
RTI
Optionally on
SCIx
Off
Standby
3
Optionally on3
Standby
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
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Chapter 3 Modes of Operation
Table 3-4. Stop Mode Behavior (continued)
Mode
Peripheral
Stop2
Stop3
SPIx
Off
Standby
TPMx
Off
Standby
Standby
Standby
States Held
States Held
System Voltage Regulator
I/O Pins
1
Requires the asynchronous ADC clock and LVD to be enabled, else in standby.
OSCSTEN set in ICGC1, else in standby.
3
RTIS[2:0] in SRTISC does not equal 0 before entering stop, else off.
2
MC9S08AC128 Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 4
Memory
4.1
MC9S08AC128 Series Memory Map
As shown in Figure 4-1, on-chip memory in the MC9S08AC128 Series series of MCUs consists of RAM,
Flash program memory for nonvolatile data storage, plus I/O and control/status registers. The registers are
divided into three groups:
• Direct-page registers ($0000 through $007F)
• High-page registers ($1800 through $186F)
• Nonvolatile registers ($FFB0 through $FFBF)
Extended Address
0x0_0000
DIRECT PAGE
REGISTERS
128 BYTES
CPU Address
0x0000
0x007F
0x0080
RAM
6016 BYTES
0x7FFF
0x8000
Paging Window
Extended addresses
formed with PPAGE
and CPU addresses
A13:A0
0x0_BFFF
0x0_C000
FLASH
16384 BYTES
0xBFFF
0xC000
PPAGE=7
PPAGE=6
PPAGE=5
0x0_7FFF
0x0_8000
PPAGE=4
PPAGE=1
FLASH
16384 BYTES
0x1_4000 - 0x1_7FFF
0x1_0000 - 0x1_3FFF
0x0_C000 - 0x0_FFFF
0x0_8000 - 0x0_BFFF
0x0_4000 - 0x0_7FFF
0x0_0000 - 0x0_3FFF
PPAGE=3
0x3FFF
0x4000
Extended Address 0x1_C000 - 0x1_FFFF
0x1_8000 - 0x1_BFFF
PPAGE=2
0x0_3FFF
0x0_4000
PPAGE=0
FLASH
7952 BYTES
0x20EF
0x20F0
PPAGE=1
RAM
2176 BYTES
All 128K bytes of Flash can
also be accessed through
the linear address pointer.
0x186F
0x1870
PPAGE=0
HIGH PAGE
REGISTERS
112 BYTES
0x17FF
0x1800
PPAGE=3
FLASH
16384 BYTES
0x0_FFFF
0xFFFF
Figure 4-1. MC9S08AC128 Memory Map
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
41
Chapter 4 Memory
CPU Address
0x0000
0x186F
0x1870
All 96K bytes of Flash can
also be accessed through
the linear address pointer.
0x207F
0x2080
0x3FFF
0x4000
Extended Address 0x1_4000 - 0x1_7FFF
0x1_0000 - 0x1_3FFF
0x0_C000 - 0x0_FFFF
0x0_8000 - 0x0_BFFF
0x0_4000 - 0x0_7FFF
0x0_1870 - 0x0_3FFF
PPAGE=1
FLASH
16384 BYTES
0x0_7FFF
0x0_8000
0x7FFF
0x8000
Paging Window
Extended addresses
formed with PPAGE
and CPU addresses
A13:A0
0x0_BFFF
0x0_C000
FLASH
16384 BYTES
0xBFFF
0xC000
PPAGE=5
0x0_3FFF
0x0_4000
PPAGE=4
PPAGE=0
FLASH
10128 BYTES
0x17FF
0x1800
PPAGE=0
HIGH PAGE
REGISTERS
112 BYTES
UNIMPLEMENTED
16384 BYTES
PPAGE=7
RAM
6016 BYTES
PPAGE=6
0x1_C000 - 0x1_FFFF
0x1_8000 - 0x1_BFFF
0x007F
0x0080
PPAGE=3
DIRECT PAGE
REGISTERS
128 BYTES
PPAGE=2
0x0_0000
PPAGE=1
Extended Address
PPAGE=3
FLASH
16384 BYTES
0x0_FFFF
0xFFFF
Figure 4-2. MC9S08AC96 Memory Map
4.1.1
Reset and Interrupt Vector Assignments
Table 4-1 shows address assignments for reset and interrupt vectors. The vector names shown in this table
are the labels used in the Freescale-provided equate file for the MC9S08AC128 Series. For more details
about resets, interrupts, interrupt priority, and local interrupt mask controls, refer to Chapter 5, “Resets,
Interrupts, and System Configuration.”
Table 4-1. Reset and Interrupt Vectors
Address
(High/Low)
Vector
Vector Name
0xFF80:FF81
through
0xFF9A:FF9B
Unused Vector Space
(available for user program)
—
0xFF9C:FF9D
SPI2
Vspi2
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Freescale Semiconductor
Chapter 4 Memory
Table 4-1. Reset and Interrupt Vectors (continued)
Address
(High/Low)
Vector
Vector Name
0xFF9E:FF9F
TPM3 overflow
Vtpm3ovf
0xFFA0:FFA1 0xFFBE:FFBF
Non-vector space
Reserved
0xFFC0:FFC1
TPM3 channel 1
Vtpm3ch1
0xFFC2:FFC3
TPM3 channel 0
Vtpm3ch0
0xFFC4:FFC5
RTI
Vrti
0xFFC6:FFC7
IIC1
Viic1
0xFFC8:FFC9
ADC1 conversion
Vadc1
0xFFCA:FFCB
KBI1
Vkeyboard1
0xFFCC:FFCD
SCI2 transmit
Vsci2tx
0xFFCE:FFCF
SCI2 receive
Vsci2rx
0xFFD0:FFD1
SCI2 error
Vsci2err
0xFFD2:FFD3
SCI1 transmit
Vsci1tx
0xFFD4:FFD5
SCI1 receive
Vsci1rx
0xFFD6:FFD7
SCI1 error
Vsci1err
0xFFD8:FFD9
SPI1
Vspi1
0xFFDA:FFDB
TPM2 overflow
Vtpm2ovf
0xFFDC:FFDD
TPM2 channel 5
Vtpm2ch5
0xFFDE:FFDF
TPM2 channel 4
Vtpm2ch4
0xFFE0:FFE1
TPM2 channel 3
Vtpm2ch3
0xFFE2:FFE3
TPM2 channel 2
Vtpm2ch2
0xFFE4:FFE5
TPM2 channel 1
Vtpm2ch1
0xFFE6:FFE7
TPM2 channel 0
Vtpm2ch0
0xFFE8:FFE9
TPM1 overflow
Vtpm1ovf
0xFFEA:FFEB
TPM1 channel 5
Vtpm1ch5
0xFFEC:FFED
TPM1 channel 4
Vtpm1ch4
0xFFEE:FFEF
TPM1 channel 3
Vtpm1ch3
0xFFF0:FFF1
TPM1 channel 2
Vtpm1ch2
0xFFF2:FFF3
TPM1 channel 1
Vtpm1ch1
0xFFF4:FFF5
TPM1 channel 0
Vtpm1ch0
0xFFF6:FFF7
ICG
Vicg
0xFFF8:FFF9
Low voltage detect
Vlvd
0xFFFA:FFFB
IRQ
Virq
0xFFFC:FFFD
SWI
Vswi
0xFFFE:FFFF
Reset
Vreset
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
43
Chapter 4 Memory
4.2
Register Addresses and Bit Assignments
The registers in the MC9S08AC128 Series are divided into these three groups:
• Direct-page registers are located in the first 128 locations in the memory map, so they are
accessible with efficient direct addressing mode instructions.
• High-page registers are used much less often, so they are located above 0x1800 in the memory
map. This leaves more room in the direct page for more frequently used registers and variables.
• The nonvolatile register area consists of a block of 16 locations in Flash memory at $FFB0–$FFBF.
Nonvolatile register locations include:
— Three values which are loaded into working registers at reset
— An 8-byte backdoor comparison key which optionally allows a user to gain controlled access
to secure memory
Because the nonvolatile register locations are Flash memory, they must be erased and programmed
like other Flash memory locations.
Direct-page registers can be accessed with efficient direct addressing mode instructions. Bit manipulation
instructions can be used to access any bit in any direct-page register. Table 4-2 is a summary of all
user-accessible direct-page registers and control bits.
The direct page registers in Table 4-2 can use the more efficient direct addressing mode which only
requires the lower byte of the address. Because of this, the lower byte of the address in column one is
shown in bold text. In Table 4-3 and Table 4-4 the whole address in column one is shown in bold. In
Table 4-2, Table 4-3, and Table 4-4, the register names in column two are shown in bold to set them apart
from the bit names to the right. Cells that are not associated with named bits are shaded. A shaded cell with
a 0 indicates this unused bit always reads as a 0. Shaded cells with dashes indicate unused or reserved bit
locations that could read as 1s or 0s.
MC9S08AC128 Series Reference Manual, Rev. 3
44
Freescale Semiconductor
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 1 of 4)
Address
Register Name
0x0000
PTAD
0x0001
PTADD
0x0002
PTBD
0x0003
PTBDD
Bit 7
6
5
4
3
2
1
Bit 0
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
PTADD7
PTADD6
PTADD5
PTADD4
PTADD3
PTADD2
PTADD1
PTADD0
PTBD7
PTBD6
PTBD5
PTBD4
PTBD3
PTBD2
PTBD1
PTBD0
PTBDD7
PTBDD6
PTBDD5
PTBDD4
PTBDD3
PTBDD2
PTBDD1
PTBDD0
0x0004
PTCD
0
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0x0005
PTCDD
0
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0x0006
PTDD
0x0007
PTDDD
PTDD7
PTDD6
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
PTDDD7
PTDDD6
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
0x0008
PTED
0x0009
PTEDD
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
0x000A
PTFD
PTFD7
PTFD6
PTFD5
PTFD4
PTFD3
PTFD2
PTFD1
PTFD0
0x000B
PTFDD
PTFDD7
PTFDD6
PTFDD5
PTFDD4
PTFDD3
PTFDD2
PTFDD1
PTFDD0
0x000C
PTGD
0
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
0x000D
PTGDD
0
PTGDD6
PTGDD5
PTGDD4
PTGDD3
PTGDD2
PTGDD1
PTGDD0
0x000E
PTHD
0
PTHD6
PTHD5
PTHD4
PTHD3
PTHD2
PTHD1
PTHD0
0x000F
PTHDD
0
PTHDD6
PTHDD5
PTHDD4
PTHDD3
PTHDD2
PTHDD1
PTHDD0
0x0010
ADC1SC1
COCO
AIEN
ADCO
0x0011
ADC1SC2
ADACT
ADTRG
ACFE
ACFGT
0
0
R
R
ADCH
0x0012
ADC1RH
0
0
0
0
0
0
ADR9
ADR8
0x0013
ADC1RL
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
ADR0
0x0014
ADC1CVH
0
0
0
0
0
0
ADCV9
ADCV8
0x0015
ADC1CVL
ADCV7
ADCV6
ADCV5
ADCV4
ADCV3
ADCV2
ADCV1
ADCV0
0x0016
ADC1CFG
ADLPC
0x0017
APCTL1
ADPC7
ADPC6
ADIV
ADPC5
ADLSMP
ADPC4
ADPC3
MODE
ADPC2
ADPC1
ADICLK
ADPC0
0x0018
APCTL2
ADPC15
ADPC14
ADPC13
ADPC12
ADPC11
ADPC10
ADPC9
ADPC8
0x0019
Reserved
—
—
—
—
—
—
—
—
0x001A
PTJD
0x001B
PTJDD
0x001C
0x001D
0x001E
0x001F
0x0020
0x0021
0x0022
TPM1CNTL
Bit 7
6
5
4
0x0023
TPM1MODH
Bit 15
14
13
12
0x0024
TPM1MODL
Bit 7
6
5
4
3
0x0025
TPM1C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
0x0026
TPM1C0VH
Bit 15
14
13
12
11
0x0027
TPM1C0VL
Bit 7
6
5
4
3
0x0028
TPM1C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
0x0029
TPM1C1VH
Bit 15
14
13
12
11
10
9
Bit 8
PTJD7
PTJD6
PTJD5
PTJD4
PTJD3
PTJD2
PTJD1
PTJD0
PTJDD7
PTJDD6
PTJDD5
PTJDD4
PTJDD3
PTJDD2
PTJDD1
PTJDD0
IRQSC
0
IRQPDD
IRQEDG
IRQPE
IRQF
IRQACK
IRQIE
IRQMOD
Reserved
—
—
—
—
—
—
—
—
KBISC
KBEDG7
KBEDG6
KBEDG5
KBEDG4
KBF
KBACK
KBIE
KBIMOD
KBIPE
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
TPM1SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
TPM1CNTH
Bit 15
14
13
12
11
10
9
Bit 8
3
2
1
Bit 0
11
10
9
Bit 8
2
1
Bit 0
ELS0A
0
0
10
9
Bit 8
2
1
Bit 0
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
45
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 2 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x002A
TPM1C1VL
Bit 7
6
5
4
3
2
1
Bit 0
0x002B
TPM1C2SC
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
0x002C
TPM1C2VH
Bit 15
14
13
12
11
10
9
Bit 8
0x002D
TPM1C2VL
Bit 7
6
5
4
3
2
1
Bit 0
0x002E
TPM1C3SC
CH3F
CH3IE
MS3B
MS3A
ELS3B
ELS3A
0
0
0x002F
TPM1C3VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0030
TPM1C3VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0031
TPM1C4SC
CH4F
CH4IE
MS4B
MS4A
ELS4B
ELS4A
0
0
0x0032
TPM1C4VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0033
TPM1C4VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0034
TPM1C5SC
CH3F
CH5IE
MS5B
MS5A
ELS5B
ELS5A
0
0
0x0035
TPM1C5VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0036
TPM1C5VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0037
Reserved
—
—
—
—
—
—
—
—
0x0038
SCI1BDH
LBKDIE
RXEDGIE
0
SBR12
SBR11
SBR10
SBR9
SBR8
0x0039
SCI1BDL
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0x003A
SCI1C1
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0x003B
SCI1C2
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0x003C
SCI1S1
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
0x003D
SCI1S2
LBKDIF
RXEDGIF
0
RXINV
RWUID
BRK13
LBKDE
RAF
0x003E
SCI1C3
R8
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
0x003F
SCI1D
Bit 7
6
5
4
3
2
1
Bit 0
0x0040
SCI2BDH
LBKDIE
RXEDGIE
0
SBR12
SBR11
SBR10
SBR9
SBR8
0x0041
SCI2BDL
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0x0042
SCI2C1
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0x0043
SCI2C2
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0x0044
SCI2S1
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
0x0045
SCI2S2
LBKDIF
RXEDGIF
0
RXINV
RWUID
BRK13
LBKDE
RAF
0x0046
SCI2C3
R8
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
0x0047
SCI2D
Bit 7
6
5
4
3
2
1
Bit 0
0x0048
ICGC1
HGO
RANGE
REFS
OSCSTEN
LOCD
0
0x0049
ICGC2
LOLRE
0x004A
ICGS1
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
0x004B
ICGS2
0
0
0
0
0
0
0
DCOS
0x004C
ICGFLTU
0
0
0
0
0x004D
ICGFLTL
—
—
0x004E
ICGTRM
0x004F
Reserved
0x0050
0x0051
0x0052
SPI1BR
0x0053
SPI1S
CLKS
MFD
CLKST
LOCRE
RFD
FLT
FLT
TRIM
—
—
—
SPI1C1
SPIE
SPE
SPTIE
SPI1C2
0
0
0
0
SPPR2
SPPR1
SPRF
0
SPTEF
—
—
—
MSTR
CPOL
CPHA
SSOE
LSBFE
MODFEN
BIDIROE
0
SPISWAI
SPC0
SPPR0
0
SPR2
SPR1
SPR0
MODF
0
0
0
0
MC9S08AC128 Series Reference Manual, Rev. 3
46
Freescale Semiconductor
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 3 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x0054
Reserved
0
0
0
0
0
0
0
0
0x0055
SPI1D
Bit 7
6
5
4
3
2
1
Bit 0
0x0056
CRCH
Bit 15
14
13
12
11
10
9
Bit 8
0x0057
CRCL
Bit 7
6
5
4
3
2
1
Bit 0
0x0058
IIC1A
0x0059
IIC1F
0x005A
IIC1C1
0x005B
IIC1S
0
ADDR
MULT
ICR
IICEN
IICIE
MST
TX
TXAK
RSTA
0
0
TCF
IAAS
BUSY
ARBL
0
SRW
IICIF
RXAK
GCAEN
ADEXT
0
0
0
AD10
AD9
AD8
0x005C
IIC1D
0x005D
IIC1C2
DATA
0x005E–
0x005F
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0060
TPM2SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
0x0061
TPM2CNTH
Bit 15
14
13
12
11
10
9
Bit 8
0x0062
TPM2CNTL
Bit 7
6
5
4
3
2
1
Bit 0
0x0063
TPM2MODH
Bit 15
14
13
12
11
10
9
Bit 8
0x0064
TPM2MODL
Bit 7
6
5
4
3
2
1
Bit 0
0x0065
TPM2C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
0x0066
TPM2C0VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0067
TPM2C0VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0068
TPM2C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
0x0069
TPM2C1VH
Bit 15
14
13
12
11
10
9
Bit 8
0x006A
TPM2C1VL
Bit 7
6
5
4
3
2
1
Bit 0
0x006B
TPM2C2SC
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
0x006C
TPM2C2VH
Bit 15
14
13
12
11
10
9
Bit 8
0x006D
TPM2C2VL
Bit 7
6
5
4
3
2
1
Bit 0
0x006E
TPM2C3SC
CH3F
CH3IE
MS3B
MS3A
ELS3B
ELS3A
0
0
0x006F
TPM2C3VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0070
TPM2C3VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0071
TPM2C4SC
CH4F
CH4IE
MS4B
MS4A
ELS4B
ELS4A
0
0
0x0072
TPM2C4VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0073
TPM2C4VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0074
TPM2C5SC
CH5F
CH5IE
MS5B
MS5A
ELS5B
ELS5A
0
0
0x0075
TPM2C5VH
Bit 15
14
13
12
11
10
9
Bit 8
0x0076
TPM2C5VL
Bit 7
6
5
4
3
2
1
Bit 0
0x0077
Reserved
—
—
—
—
—
—
—
—
0x0078
PPAGE
0
0
0
0
0
XA16
XA15
XA14
0x0079
LAP2
0
0
0
0
0
0
0
LA16
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
47
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 4 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x007A
LAP1
LA15
LA14
LA13
LA12
LA11
LA10
LA9
LA8
0x007B
LAP0
LA7
LA6
LA5
LA4
LA3
LA2
LA1
LA0
0x007C
LWP
D7
D6
D5
D4
D3
D2
D1
D0
0x007D
LBP
D7
D6
D5
D4
D3
D2
D1
D0
0x007E
LB
D7
D6
D5
D4
D3
D2
D1
D0
0x007F
LAPAB
D7
D6
D5
D4
D3
D2
D1
D0
High-page registers, shown in Table 4-3, are accessed much less often than other I/O and control registers
so they have been located outside the direct addressable memory space, starting at 0x1800.
Table 4-3. High-Page Register Summary (Sheet 1 of 3)
Address
Register Name
0x1800
SRS
0x1801
0x1802
0x1803
0x1804 –
0x1805
0x1806
0x1807
0x1808
0x1809
0x180A
0x180B
0x180C
0x180D–
0x180F
0x1810
0x1811
0x1812
0x1813
0x1814
0x1815
0x1816
0x1817
0x1818
0x1819
0x181A
0x181B
0x181C
0x181D
SBDFR
SOPT
SMCLK
Reserved
SDIDH
SDIDL
SRTISC
SPMSC1
SPMSC2
Reserved
SOPT2
Reserved
DBGCAH
DBGCAL
DBGCBH
DBGCBL
DBGCCH
DBGCCL
DBGFH
DBGFL
DBGCAX
DBGCBX
DBGCCX
DBGFX
DBGC
DBGT
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
ILAD
ICG
LVD
0
0
0
0
0
0
0
0
BDFR
COPE
COPT
STOPE
—
0
0
—
—
0
0
0
MPE
0
—
—
—
—
—
—
—
—
—
—
—
—
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
RTIF
RTIACK
RTICLKS
RTIE
0
RTIS2
RTIS1
RTIS0
BGBE
MCSEL
—
—
—
—
LVDF
LVDACK
LVDIE
LVDRE
LVDSE
LVDE
01
LVWF
LVWACK
LVDV
LVWV
PPDF
PPDACK
—
PPDC
—
—
—
—
—
—
—
—
COPCLKS
—
—
—
TPMCCFG
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
RWAEN
RWA
PAGSEL
0
0
0
0
Bit 16
RWBEN
RWB
PAGSEL
0
0
0
0
Bit 16
RWCEN
RWC
PAGSEL
0
0
0
0
Bit 16
PPACC
0
0
0
0
0
0
Bit 16
DBGEN
ARM
TAG
BRKEN
0
0
0
LOOP1
TRGSEL
BEGIN
0
0
TRG
MC9S08AC128 Series Reference Manual, Rev. 3
48
Freescale Semiconductor
Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 2 of 3)
Address
Register Name
0x181E
0x181F
0x1820
0x1821
0x1822
0x1823
0x1824
0x1825
0x1826
0x1827–
0x182F
0x1830
DBGS
DBGCNT
FCDIV
FOPT
Reserved
FCNFG
FPROT
FSTAT
FCMD
0x1831
0x1832
0x1833
0x1834
0x1835
0x1836
0x1837
0x1838
0x1839
0x183A
0x183B
0x183F
0x1840
0x1841
0x1842
0x1843
0x1844
0x1845
0x1846
0x1847
0x1848
0x1849
0x184A
0x184B
0x184C
0x184D
0x184E
0x184F
Bit 7
6
5
4
3
2
1
Bit 0
AF
BF
CF
0
0
0
0
ARMF
0
0
0
0
0
0
0
0
DIVLD
CNT
PRDIV8
KEYEN
DIV
SEC
—
—
—
—
—
—
—
—
0
0
KEYACC
0
0
0
0
0
FCBEF
FCCF
FPVIOL
FACCERR
0
FBLANK
0
0
—
—
FPS
0
FPOPEN
FCMD
—
—
—
—
—
—
—
—
—
—
—
—
—
—
TPM3SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
TPM3CNTH
TPM3CNTL
TPM3MODH
TPM3MODL
TPM3C0SC
TPM3C0VH
TPM3C0VL
TPM3C1SC
TPM3C1VH
TPM3C1VL
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Reserved
Reserved
PTAPE
PTASE
PTADS
Reserved
PTBPE
PTBSE
PTBDS
Reserved
PTCPE
PTCSE
PTCDS
Reserved
PTDPE
PTDSE
PTDDS
Reserved
Bit 7
6
5
4
3
2
1
Bit 0
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
PTAPE7
PTAPE6
PTAPE5
PTAPE4
PTAPE3
PTAPE2
PTAPE1
PTAPE0
PTASE7
PTASE6
PTASE5
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
PTADS7
PTADS6
PTADS5
PTADS4
PTADS3
PTADS2
PTADS1
PTADS0
—
—
—
—
—
—
—
—
PTBPE7
PTBPE6
PTBPE5
PTBPE4
PTBPE3
PTBPE2
PTBPE1
PTBPE0
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
PTBDS7
PTBDS6
PTBDS5
PTBDS4
PTBDS3
PTBDS2
PTBDS1
PTBDS0
—
—
—
—
—
—
—
—
0
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
PTCSE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0
PTCDS6
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
—
—
—
—
—
—
—
—
PTDPE7
PTDPE6
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
PTDSE7
PTDSE6
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
PTDDS7
PTDDS6
PTDDS5
PTDDS4
PTDDS3
PTDDS2
PTDDS1
PTDDS0
—
—
—
—
—
—
—
—
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Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 3 of 3)
Address
Register Name
0x1850
0x1851
0x1852
0x1853
0x1854
0x1855
0x1856
0x1857
0x1858
0x1859
0x185A
0x185B
PTEPE
PTESE
PTEDS
Reserved
PTFPE
PTFSE
PTFDS
Reserved
PTGPE
PTGSE
PTGDS
Reserved
0x185C
0x185D
0x185E
0x185F
0x1860
0x1861
0x1862
0x1863
0x1864
0x1865
0x1866
0x1867
0x1868
0x1869
0x186A
0x186B
0x186C
0x186D
0x186E
0x186F
PTHPE
PTHSE
PTHDS
Reserved
PTJPE
PTJSE
PTJDS
Reserved
Reserved
Reserved
Reserved
Reserved
SPI2C1
SPI2C2
SPI2BR
SPI2S
Reserved
SPI2D
Reserved
Reserved
1
Bit 7
6
5
4
3
2
1
Bit 0
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
PTEDS7
PTEDS6
PTEDS5
PTEDS4
PTEDS3
PTEDS2
PTEDS1
PTEDS0
—
—
—
—
—
—
—
—
PTFPE7
PTFPE6
PTFPE5
PTFPE4
PTFPE3
PTFPE2
PTFPE1
PTFPE0
PTFSE7
PTFSE6
PTFSE5
PTFSE4
PTFSE3
PTFSE2
PTFSE1
PTFSE0
PTFDS7
PTFDS6
PTFDS5
PTFDS4
PTFDS3
PTFDS2
PTFDS1
PTFDS0
—
—
—
—
—
—
—
—
0
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
0
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
0
PTGDS6
PTGDS5
PTGDS4
PTGDS3
PTGDS2
PTGDS1
PTGDS0
—
—
—
—
—
—
—
—
0
PTHPE6
PTHPE5
PTHPE4
PTHPE3
PTHPE2
PTHPE1
PTHPE0
0
PTHSE6
PTHSE5
PTHSE4
PTHSE3
PTHSE2
PTHSE1
PTHSE0
0
PTHDS6
PTHDS5
PTHDS4
PTHDS3
PTHDS2
PTHDS1
PTHDS0
—
—
—
—
—
—
—
—
PTJPE7
PTJPE6
PTJPE5
PTJPE4
PTJPE3
PTJPE2
PTJPE1
PTJPE0
PTJSE7
PTJSE6
PTJSE5
PTJSE4
PTJSE3
PTJSE2
PTJSE1
PTJSE0
PTJDS7
PTJDS6
PTJDS5
PTJDS4
PTJDS3
PTJDS2
PTJDS1
PTJDS0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
0
0
0
MODFEN
BIDIROE
0
SPISWAI
SPC0
0
SPPR2
SPPR1
SPPR0
0
SPR2
SPR1
SPR0
SPRF
0
SPTEF
MODF
0
0
0
0
0
0
0
0
0
0
0
0
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
This reserved bit must always be written to 0.
Nonvolatile Flash registers, shown in Table 4-4, are located in the Flash memory. These registers include
an 8-byte backdoor key which optionally can be used to gain access to secure memory resources. During
reset events, the contents of NVPROT and NVOPT in the nonvolatile register area of the Flash memory
are transferred into corresponding FPROT and FOPT working registers in the high-page registers to
control security and block protection options.
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Table 4-4. Nonvolatile Register Summary
Address
$FFB0 –
$FFB7
$FFB8 –
$FFBB
$FFBC
0xFFBD
$FFBE
0xFFBF
Register Name
Bit 7
6
5
NVBACKKEY
Reserved
Reserved for storage of 250 kHz
ICGTRIM value.
NVPROT
Reserved for storage of 243 kHz
ICGTRIM value.
NVOPT
4
3
2
1
Bit 0
8-Byte Comparison Key
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
FPS
—
—
KEYEN
FPOPEN
—
—
—
—
0
0
0
0
—
—
SEC
Provided the key enable (KEYEN) bits are in the enabled state (1:0), the 8-byte comparison key can be
used to temporarily disengage memory security. This key mechanism can be accessed only through user
code running in secure memory. (A security key cannot be entered directly through background debug
commands.) This security key can be disabled completely by programming the KEYEN bits to a disabled
state. If the security key is disabled, the only way to disengage security is by mass erasing the Flash if
needed (normally through the background debug interface) and verifying that Flash is blank. To avoid
returning to secure mode after the next reset, program the security bits (SEC01:SEC00) to the unsecured
state (1:0).
4.3
RAM
The MC9S08AC128 Series includes static RAM. The locations in RAM below 0x0100 can be accessed
using the more efficient direct addressing mode, and any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed
program variables in this area of RAM is preferred.
The RAM retains data when the MCU is in low-power wait, stop2, or stop3 mode. At power-on, the
contents of RAM are uninitialized. RAM data is unaffected by any reset provided that the supply voltage
does not drop below the minimum value for RAM retention.
For compatibility with older M68HC05 MCUs, the HCS08 resets the stack pointer to 0x00FF. In the
MC9S08AC128 Series, it is usually best to re-initialize the stack pointer to the top of the RAM so the direct
page RAM can be used for frequently accessed RAM variables and bit-addressable program variables.
Include the following 2-instruction sequence in your reset initialization routine (where RamLast is equated
to the highest address of the RAM in the Freescale-provided equate file).
LDHX
TXS
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
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When security is enabled, the RAM is considered a secure memory resource and is not accessible through
BDM or through code executing from non-secure memory. See Section 4.5.5, “Flash Module Security” for
a detailed description of the security feature.
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Chapter 4 Memory
4.4
Memory Management Unit
The memory management unit (MMU) allows the program and data space for the HCS08 Family of
Microcontrollers to be extended beyond the 64K byte CPU addressable memory map. The MMU utilizes
a paging scheme similar to that seen on other MCU architectures, such as HCS12. The extended memory
when used for data can also be accessed linearly using a linear address pointer and data access registers.
4.4.1
Features
Key features of the MMU module are:
• Memory Management Unit extends the HCS08 memory space
— up to 4M bytes for program and data space
• Extended program space using paging scheme
— PPAGE register used for page selection
— fixed 16K byte memory window
— architecture supports up to 256, 16K pages
• Extended data space using linear address pointer
— up to 22-bit linear address pointer
— linear address pointer and data register provided in direct page allows access of complete Flash
memory map using direct page instructions
— optional auto increment of pointer when data accessed
— supports an 2s compliment addition/subtraction to address pointer without using any math
instructions or memory resources
— supports word accesses to any address specified by the linear address pointer when using
LDHX, STHX instructions
4.4.2
Register Definition
Figure 4-5 is a summary of MMU registers.
Table 4-5. MMU Register Summary
Name
R
7
6
5
4
3
0
0
0
0
0
PPAGE
2
1
0
XA16
XA15
XA14
0
0
W
R
0
0
0
0
0
LAP2
LA16
W
R
LAP1
LA15
LA14
LA13
LA12
LA11
LA10
LA9
LA8
LA7
LA6
LA5
LA4
LA3
LA2
LA1
LA0
W
R
LAP0
W
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Table 4-5. MMU Register Summary (continued)
Name
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
R
0
0
0
0
0
0
0
0
W
D7
D6
D5
D4
D3
D2
D1
D0
R
LWP
W
R
LBP
W
R
LB
W
LAPAB
4.4.2.1
Program Page Register (PPAGE)
The HCS08 Core architecture limits the CPU addressable space available to 64K bytes. The address space
can be extended to 128K bytes using a paging window scheme. The Program Page (PPAGE) allows for
selecting one of the 16K byte blocks to be accessed through the Program Page Window located at
$8000-$BFFF. The CALL and RTC instructions can load or store the value of PPAGE onto or from the
stack during program execution. After any reset, PPAGE is set to PAGE 2.
R
7
6
5
4
3
0
0
0
0
0
2
1
0
XA16
XA15
XA14
0
1
0
W
Reset:
0
0
0
0
0
Figure 4-3. Program Page Register (PPAGE)
Table 4-6. Program Page Register Field Descriptions
Field
Description
2:0
When the CPU addresses the paging window, $8000-$BFFF, the value in the PPAGE register along with the CPU
XA16:XA14 addresses A13:A0 are used to create a 17-bit extended address.
4.4.2.2
Linear Address Pointer Registers 2:0 (LAP2:LAP0)
The three registers, LAP2:LAP0 contain the 17-bit linear address that allows the user to access any Flash
location in the extended address map. This register is used in conjunction with the data registers, linear
byte (LB), linear byte post increment (LBP) and linear word post increment (LWP). The contents of
LAP2:LAP0 will auto-increment when accessing data using the LBP and LWP registers. The contents of
LAP2:LAP0 can be increased by writing an 8-bit value to LAPAB.
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R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
LA16
W
R
LA15
LA14
LA13
LA12
LA11
LA10
LA9
LA8
LA15
LA6
LA5
LA4
LA3
LA2
LA1
LA0
0
0
0
0
0
0
0
0
W
R
W
Reset:
Figure 4-4. Linear Address Pointer Registers 2:0 (LAP2:LAP0)
Table 4-7. Linear Address Pointer Registers 2:0 Field Descriptions
Field
Description
16:0
LA21:LA0
The values in LAP2:LAP0 are used to create a 17-bit linear address pointer. The value in these registers are used
as the extended address when accessing any of the data registers LB, LBP and LWP.
4.4.2.3
Linear Word Post Increment Register (LWP)
This register is one of three data registers that the user can use to access any Flash memory location in the
extended address map. When LWP is accessed the contents of LAP2:LAP0 make up the extended address
of the Flash memory location to be addressed. When accessing data using LWP, the contents of
LAP2:LAP0 will increment after the read or write is complete.
Accessing LWP does the same thing as accessing LBP. The MMU register ordering of LWP followed by
LBP, allow the user to access data by words using the LDHX or STHX instructions of the LWP register.
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 4-5. Linear Word Post Increment Register (LWP)
Table 4-8. Linear Word Post Increment Register Field Descriptions
Field
Description
7:0
D7:D0
Reads of this register will first return the data value pointed to by the linear address pointer, LAP2:LAP0 and then
will increment LAP2:LAP0. Writes to this register will first write the data value to the memory location specified
by the linear address pointer and then will increment LAP2:LAP0. Writes to this register are most commonly used
when writing to the Flash block(s) during programming.
4.4.2.4
Linear Byte Post Increment Register (LBP)
This register is one of three data registers that the user can use to access any Flash memory location in the
extended address map. When LBP is accessed the contents of LAP2:LAP0 make up the extended address
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Chapter 4 Memory
of the Flash memory location to be addressed. When accessing data using LBP, the contents of
LAP2:LAP0 will increment after the read or write is complete.
Accessing LBP does the same thing as accessing LWP. The MMU register ordering of LWP followed by
LBP, allow the user to access data by words using the LDHX or STHX instructions with the address of the
LWP register.
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 4-6. Linear Byte Post Increment Register (LBP)
Table 4-9. Linear Byte Post Increment Register Field Descriptions
Field
Description
7:0
D7:D0
Reads of this register will first return the data value pointed to by the linear address pointer, LAP2:LAP0 and then
will increment LAP2:LAP0. Writes to this register will first write the data value to the memory location specified
by the linear address pointer and then will increment LAP2:LAP0. Writes to this register are most commonly used
when writing to the Flash block(s) during programming.
4.4.2.5
Linear Byte Register (LB)
This register is one of three data registers that the user can use to access any Flash memory location in the
extended address map. When LB is accessed the contents of LAP2:LAP0 make up the extended address
of the Flash memory location to be addressed.
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 4-7. Linear Byte Register (LB)
Table 4-10. Linear Data Register Field Descriptions
Field
Description
7:0
D7:D0
Reads of this register returns the data value pointed to by the linear address pointer, LAP2:LAP0. Writes to this
register will write the data value to the memory location specified by the linear address pointer. Writes to this
register are most commonly used when writing to the Flash block(s) during programming.
4.4.2.6
Linear Address Pointer Add Byte Register (LAPAB)
The user can increase or decrease the contents of LAP2:LAP0 by writing a 2s compliment value to
LAPAB. The value written will be added to the current contents of LAP2:LAP0.
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7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
Reset:
Figure 4-8. Linear Address Pointer Add Byte Register (LAPAB)
Table 4-11. Linear Address Pointer Add Byte Register Field Descriptions
Field
Description
7:0
D7:D0
The 2s compliment value written to LAPAB will be added to contents of the linear address pointer register,
LAP2:LAP0. Writing a value of 0x7f to LAPAB will increase LAP by 127, and a value of 0x80 will decrease LAP
by 128.
4.4.3
Functional Description
4.4.3.1
Memory Expansion
The HCS08 Core architecture limits the CPU addressable space available to 64K bytes. The Program Page
(PPAGE) allows for integrating up to 4M byte of Flash into the system by selecting one of the 16K byte
blocks to be accessed through the Paging Window located at $8000-$BFFF. The MMU module also
provides a linear address pointer that allows extension of data access up to 4M bytes.
4.4.3.1.1
Program Space
The PPAGE register holds the page select value for the Paging Window. The value in PPAGE can be
manipulated by using normal read and write instructions as well as the CALL and RTC instructions. The
user should not change PPAGE directly when running from paged memory, only CALL and RTC should
be used.
When the MMU detects that the CPU is addressing the Paging Window, the value currently in PPAGE will
be used to create an extended address that the MCU’s decode logic will use to select the desired Flash
location.
As seen in Figure 4-1, the Flash blocks in the CPU addressable memory can be accessed directly or using
the Paging Window and PPAGE register. For example, the Flash from location $4000-$7FFF can be
accessed directly or using the paging window, PPAGE = 1, address $8000-$BFFF.
4.4.3.1.2
CALL and RTC (Return from Call) Instructions
CALL and RTC are instructions that perform automated page switching when executed in the user
program. CALL is similar to a JSR instruction, but the subroutine that is called can be located anywhere
in the normal 64K byte address space or on any page of program memory.
During the execution of a CALL instruction, the CPU:
•
•
Stacks the return address.
Pushes the current PPAGE value onto the stack.
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•
•
Writes the new instruction-supplied PPAGE value into the PPAGE register.
Transfers control to the subroutine of the new instruction-supplied address.
This sequence is not interruptible; there is no need to inhibit interrupts during CALL execution. A CALL
can be executed from any address in memory to any other address.
The new PPAGE value is provided by an immediate operand in the instruction along with the address
within the paging window, $8000-$BFFF.
RTC is similar to an RTS instruction.
The RTC instruction terminates subroutines invoked by a CALL instruction.
During the execution of an RTC instruction, the CPU:
•
Pulls the old PPAGE value from the stack and loads it into the PPAGE register
•
Pulls the 16-bit return address from the stack and loads it into the PC
•
Resumes execution at the return address
This sequence is not interruptible; there is no need to inhibit interrupts during RTC execution. An RTC
can be executed from any address in memory.
4.4.3.1.3
Data Space
The linear address pointer registers, LAP2:LAP0 along with the linear data register allow the CPU to read
or write any address in the extended Flash memory space. This linear address pointer may be used to access
data from any memory location while executing code from any location in extended memory, including
accessing data from a different PPAGE than the currently executing program.
To access data using the linear address pointer, the user would first setup the extended address in the 22-bit
address pointer, LAP2:LAP0. Accessing one of the three linear data registers LB, LBP and LWP will
access the extended memory location specified by LAP2:LAP0. The three linear data registers access the
memory locations in the same way, however the LBP and LWP will also increment LAP2:LAP0.
Accessing either the LBP or LWP registers allows a user program to read successive memory locations
without re-writing the linear address pointer. Accessing LBP or LWP does the exact same function.
However, because of the address mapping of the registers with LBP following LWP, a user can do word
accesses in the extended address space using the LDHX or STHX instructions to access location LWP.
The MMU supports the addition of a 2s compliment value to the linear address pointer without using any
math instructions or memory resources. Writes to LAPAB with a 2s compliment value will cause the
MMU to add that value to the existing value in LAP2:LAP0.
4.4.3.1.4
PPAGE and Linear Address Pointer to Extended Address
See Figure 4-1, on how the program PPAGE memory pages and the Linear Address Pointer are mapped to
extended address space.
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4.5
Flash
The Flash memory is intended primarily for program storage. In-circuit programming allows the operating
program to be loaded into the Flash memory after final assembly of the application product. It is possible
to program the entire array through the single-wire background debug interface. Because no special
voltages are needed for Flash erase and programming operations, in-application programming is also
possible through other software-controlled communication paths.
The Flash memory is ideal for single-supply applications allowing for field reprogramming without
requiring external high voltage sources for program or erase operations. The Flash module includes a
memory controller that executes commands to modify Flash memory contents.
Array read access time is one bus cycle per byte. For Flash memory, an erased bit reads 1 and a
programmed bit reads 0. It is not possible to read from a Flash block while any command is executing on
that specific Flash block. It is possible to read from a Flash block while a command is executing on a
different Flash block.
CAUTION
A Flash block address must be in the erased state before being programmed.
Cumulative programming of bits within a Flash block address is not allowed
except for status field updates required in EEPROM emulation applications.
For a more detailed discussion of in-circuit and in-application programming, refer to the HCS08 Family
Reference Manual, Volume I, Freescale Semiconductor document order number HCS08RMv1/D.
4.5.1
Features
Features of the Flash memory include:
• Flash size
— MC9S08AC128: 131,072 bytes (256 pages of 512 bytes each)
— MC9S08AC96: 98,304 bytes (192 pages of 512 bytes each)
• Single power supply program and erase
• Automated program and erase algorithm
• Fast program and erase operation
• Burst program command for faster Flash array program times
• Up to 100,000 program/erase cycles at typical voltage and temperature
• Flexible protection scheme to prevent accidental program or erase
• Security feature to prevent unauthorized access to the Flash and RAM
• Auto power-down for low-frequency read accesses
4.5.2
Register Descriptions
The Flash module contains a set of 16 control and status registers. Detailed descriptions of each register
bit are provided in the following sections.
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4.5.2.1
Flash Clock Divider Register (FCDIV)
The FCDIV register is used to control the length of timed events in program and erase algorithms executed
by the Flash memory controller.
7
6
5
FDIVLD
PRDIV8
0
0
4
3
2
1
0
0
0
0
R
FDIV
W
Reset
0
0
0
Figure 4-9. Flash Clock Divider Register (FCDIV)
All bits in the FCDIV register are readable and writable with restrictions as determined by the value of
FDIVLD when writing to the FCDIV register (see Table 4-12).
Table 4-12. FCDIV Field Descriptions
Field
Description
7
FDIVLD
Clock Divider Load Control — When writing to the FCDIV register for the first time after a reset, the value of
the FDIVLD bit written controls the future ability to write to the FCDIV register:
0 Writing a 0 to FDIVLD locks the FCDIV register contents; all future writes to FCDIV are ignored.
1 Writing a 1 to FDIVLD keeps the FCDIV register writable; next write to FCDIV is allowed.
When reading the FCDIV register, the value of the FDIVLD bit read indicates the following:
0 FCDIV register has not been written to since the last reset.
1 FCDIV register has been written to since the last reset.
6
PRDIV8
Enable Prescaler by 8.
0 The bus clock is directly fed into the clock divider.
1 The bus clock is divided by 8 before feeding into the clock divider.
5:0
FDIV[5:0]
Clock Divider Bits — The combination of PRDIV8 and FDIV[5:0] must divide the bus clock down to a frequency
of 150 kHz–200 kHz. The minimum divide ratio is 2 and the maximum divide ratio is 512. Please refer to
Section 4.5.3.1.1, “Writing the FCDIV Register” for more information.
if PRDIV8 = 0 — fFCLK = fBus ÷ (DIV + 1)
Eqn. 4-1
if PRDIV8 = 1 — fFCLK = fBus ÷ (8 × (DIV + 1))
Eqn. 4-2
Table 4-13 shows the appropriate values for PRDIV8 and DIV for selected bus frequencies.
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Table 4-13. Flash Clock Divider Settings
4.5.2.2
fBus
PRDIV8
(Binary)
DIV
(Decimal)
fFCLK
Program/Erase Timing Pulse
(5 μs Min, 6.7 μs Max)
20 MHz
1
12
192.3 kHz
5.2 μs
10 MHz
0
49
200 kHz
5 μs
8 MHz
0
39
200 kHz
5 μs
4 MHz
0
19
200 kHz
5 μs
2 MHz
0
9
200 kHz
5 μs
1 MHz
0
4
200 kHz
5 μs
200 kHz
0
0
200 kHz
5 μs
150 kHz
0
0
150 kHz
6.7 μs
Flash Options Register (FOPT and NVOPT)
The FOPT register holds all bits associated with the security of the MCU and Flash module.
7
R
6
KEYEN
5
4
3
2
0
0
0
0
0
0
0
0
1
0
SEC
W
Reset
1
1
1
1
= Unimplemented or Reserved
Figure 4-10. Flash Security Register (FOPT)
All bits in the FOPT register are readable but are not writable. To change the value in this register, erase
and reprogram the NVSEC location in Flash memory as usual and then issue an MCU reset.
The FOPT register is loaded from the Flash location, NVSEC, during the reset sequence, indicated by F
in Figure 4-10.
Table 4-14. FOPT Field Descriptions
Field
Description
7:6
Backdoor Key Security Enable Bits — The KEYEN[1:0] bits define the enabling of backdoor key access to the
KEYEN[1:0] Flash module as shown in Table 4-15.
1:0
SEC[1:0]
Flash Security Bits — The SEC[1:0] bits define the security state of the MCU as shown in Table 4-16. If the
Flash module is unsecured using backdoor key access, the SEC[1:0] bits are forced to the unsecured state.
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Table 4-15. Flash KEYEN States
KEYEN[1:0]
Status of Backdoor Key Access
00
DISABLED
1
DISABLED
10
ENABLED
11
DISABLED
01
1
Preferred KEYEN state to disable Backdoor Key Access.
Table 4-16. Flash Security States
SEC[1:0]
Status of Security
00
SECURED
1
SECURED
01
1
10
UNSECURED
11
SECURED
Preferred SEC state to set MCU to secured state.
The security feature in the Flash module is described in Section 4.5.5, “Flash Module Security”.
4.5.2.3
Flash Configuration Register (FCNFG)
The FCNFG register gates the security backdoor writes.
R
7
6
0
0
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
KEYACC
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 4-11. Flash Configuration Register (FCNFG)
The KEYACC bit is readable and writable while all remaining bits read 0 and are not writable. KEYACC
is only writable if KEYEN is set to the enabled state (see Section 4.5.2.2, “Flash Options Register (FOPT
and NVOPT)”.
Table 4-17. FCNFG Field Descriptions
Field
5
KEYACC
Description
Enable Security Key Writing
0 Writes to the Flash block are interpreted as the start of a command write sequence.
1 Writes to the Flash block are interpreted as keys to open the backdoor.
NOTE
Flash array reads are allowed while KEYACC is set.
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4.5.2.4
Flash Protection Register (FPROT and NVPROT)
The FPROT register defines which Flash sectors are protected against program or erase operations.
7
6
5
4
3
2
1
R
FPOPEN
FPS
W
Reset
1
1
1
1
0
1
1
1
1
Figure 4-12. Flash Protection Register (FPROT)
FPROT bits are readable and writable as long as the size of the protected Flash memory is being increased.
Any write to FPROT that attempts to decrease the size of the protected Flash memory will be ignored.
During the reset sequence, the FPROT register is loaded from the Flash protection byte, NVPROT. To
change the Flash protection that will be loaded during the reset sequence, the Flash sector containing
NVPROT must be unprotected and erased, then NVPROT can be reprogrammed.
Trying to alter data in any protected area in the Flash memory will result in a protection violation error and
the FPVIOL flag will be set in the FSTAT register. The mass erase of the Flash array is not possible if any
of the Flash sectors contained in the Flash array are protected.
Table 4-18. FPROT Field Descriptions
Field
Description
7:1
FPS[6:0]
Flash Protection Size — With FPOP set, the FPS bits determine the size of the protected Flash address range
as shown in Table 4-19.
0
FPOPEN
Flash Protection Open
0 Flash array fully protected.
1 Flash array protected address range determined by FPS bits.
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Table 4-19. Flash Protection Address Range
FPS[6:0]
Protected Address Range
Relative to Flash Array Base
FPOPEN
Protected
Size
Flash Array 0
Flash Array 1
-
0
0x0_0000–0x0_FFFF
0x1_0000–0x1_FFFF
128 Kbytes
0x00
1
0x0_0000–0x0_FFFF
0x1_0400–0x1_FFFF
127 Kbytes
0x01
0x0_0000–0x0_FFFF
0x1_0800–0x1_FFFF
126 Kbytes
0x02
0x0_0000–0x0_FFFF
0x1_0C00–0x1_FFFF
125 Kbytes
0x03
0x0_0000–0x0_FFFF
0x1_1000–0x1_FFFF
124 Kbytes
0x04
0x0_0000–0x0_FFFF
0x1_1400–0x1_FFFF
123 Kbytes
0x05
0x0_0000–0x0_FFFF
0x1_1800–0x1_FFFF
122 Kbytes
0x06
0x0_0000–0x0_FFFF
0x1_1C00–0x1_FFFF
121 Kbytes
...
...
...
...
0x37
0x0_0000–0x0_FFFF
0x1_E000–0x1_FFFF
72 Kbytes
0x38
0x0_0000–0x0_FFFF
0x1_E400–0x1_FFFF
71 Kbytes
0x39
0x0_0000–0x0_FFFF
0x1_E800–0x1_FFFF
70 Kbytes
0x3A
0x0_0000–0x0_FFFF
0x1_EC00–0x1_FFFF
69 Kbytes
0x3B
0x0_0000–0x0_FFFF
0x1_F000–0x1_FFFF
68 Kbytes
0x3C
0x0_0000–0x0_FFFF
0x1_F400–0x1_FFFF
67 Kbytes
0x3D
0x0_0000–0x0_FFFF
0x1_F800–0x1_FFFF
66 Kbytes
0x3E
0x0_0000–0x0_FFFF
0x1_FC00–0x1_FFFF
65 Kbytes
0x3F
0x0_0000–0x0_FFFF
64 Kbytes
0x40
0x0_0400–0x0_FFFF
63 Kbytes
0x41
0x0_0800–0x0_FFFF
62 Kbytes
0x42
0x0_0C00–0x0_FFFF
61 Kbytes
0x43
0x0_1000–0x0_FFFF
60 Kbytes
0x44
0x0_1400–0x0_FFFF
59 Kbytes
0x45
0x0_1800–0x0_FFFF
58 Kbytes
0x46
0x0_1C00–0x0_FFFF
57 Kbytes
...
...
...
0x77
0x0_E000–0x0_FFFF
8 Kbytes
0x78
0x0_E400–0x0_FFFF
7 Kbytes
0x79
0x0_E800–0x0_FFFF
6 Kbytes
0x7A
0x0_EC00–0x0_FFFF
5 Kbytes
0x7B
0x0_F000–0x0_FFFF
4 Kbytes
0x7C
0x0_F400–0x0_FFFF
3 Kbytes
0x7D
0x0_F800–0x0_FFFF
2 Kbytes
0x7E
0x0_FC00–0x0_FFFF
1 Kbyte
0x7F
No Protection
0 Kbytes
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4.5.2.5
Flash Status Register (FSTAT)
The FSTAT register defines the operational status of the Flash module.
FCBEF, FPVIOL, and FACCERR are readable and writable, FCCF and FBLANK are readable and not
writable, remaining bits read 0 and are not writable.
7
R
6
5
4
FPVIOL
FACCERR
0
0
FCCF
FCBEF
3
2
1
0
0
FBLANK
0
0
0
0
0
0
W
Reset
1
1
= Unimplemented or Reserved
Figure 4-13. Flash Status Register (FSTAT)
Table 4-20. FSTAT Field Descriptions
Field
Description
7
FCBEF
Flash Command Buffer Empty Flag — The FCBEF flag indicates that the command buffer is empty so that a
new command write sequence can be started when performing burst programming. Writing a 0 to the FCBEF
flag has no effect on FCBEF. Writing a 0 to FCBEF after writing an aligned address to the Flash array memory,
but before FCBEF is cleared, will abort a command write sequence and cause the FACCERR flag to be set.
Writing a 0 to FCBEF outside of a command write sequence will not set the FACCERR flag. The FCBEF flag is
cleared by writing a 1 to FCBEF.
0 Command buffers are full.
1 Command buffers are ready to accept a new command.
6
FCCF
Flash Command Complete Interrupt Flag — The FCCF flag indicates that there are no more commands
pending. The FCCF flag is cleared when FCBEF is cleared and sets automatically upon completion of all active
and pending commands. The FCCF flag does not set when an active program command completes and a
pending burst program command is fetched from the command buffer. Writing to the FCCF flag has no effect on
FCCF.
0 Command in progress.
1 All commands are completed.
5
FPVIOL
Flash Protection Violation Flag —The FPVIOL flag indicates an attempt was made to program or erase an
address in a protected area of the Flash memory or Flash IFR during a command write sequence. Writing a 0 to
the FPVIOL flag has no effect on FPVIOL. The FPVIOL flag is cleared by writing a 1 to FPVIOL. While FPVIOL
is set, it is not possible to launch a command or start a command write sequence.
0 No protection violation detected.
1 Protection violation has occurred.
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Table 4-20. FSTAT Field Descriptions
Field
Description
4
FACCERR
Flash Access Error Flag — The FACCERR flag indicates an illegal access has occurred to the Flash memory
or Flash IFR caused by either a violation of the command write sequence (see Section 4.5.3.1.2, “Command
Write Sequence”), issuing an illegal Flash command (see Table 4-22), or the execution of a CPU STOP
instruction while a command is executing (FCCF = 0). Writing a 0 to the FACCERR flag has no effect on
FACCERR. The FACCERR flag is cleared by writing a 1 to FACCERR.While FACCERR is set, it is not possible
to launch a command or start a command write sequence.
0 No access error detected.
1 Access error has occurred.
2
FBLANK
Flash Flag Indicating the Erase Verify Operation Status — When the FCCF flag is set after completion of an
erase verify command, the FBLANK flag indicates the result of the erase verify operation. The FBLANK flag is
cleared by the Flash module when FCBEF is cleared as part of a new valid command write sequence. Writing
to the FBLANK flag has no effect on FBLANK.
0 Flash block verified as not erased.
1 Flash block verified as erased.
4.5.2.6
Flash Command Register (FCMD)
The FCMD register is the Flash command register.
7
R
6
5
4
3
2
1
0
0
0
0
0
FCMD
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-14. Flash Command Register (FCMD)
All FCMD bits are readable and writable during a command write sequence while bit 7 reads 0 and is not
writable.
Table 4-21. FCMD Field Descriptions
Field
6:0
FCMD[6:0]
Description
Flash Command — Valid Flash commands are shown in Table 4-22. Writing any command other than those
listed in Table 4-22 sets the FACCERR flag in the FSTAT register.
Table 4-22. Valid Flash Command List
FCMD[6:0]
NVM Command
0x05
Erase Verify
0x20
Program
0x25
Burst Program
0x40
Sector Erase
0x41
Mass Erase
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4.5.3
4.5.3.1
Functional Description
Flash Command Operations
Flash command operations are used to execute program, erase, and erase verify algorithms described in
this section. The program and erase algorithms are controlled by the Flash memory controller whose time
base, FCLK, is derived from the bus clock via a programmable divider.
The next sections describe:
• How to write the FCDIV register to set FCLK
• Command write sequences to program, erase, and erase verify operations on the Flash memory
• Valid Flash commands
• Effects resulting from illegal Flash command write sequences or aborting Flash operations
4.5.3.1.1
Writing the FCDIV Register
Prior to issuing any Flash command after a reset, the user is required to write the FCDIV register to divide
the bus clock down to within the 150 kHz to 200 kHz range. This register can be written only once, so
normally this write is done during reset initialization. FCDIV cannot be written if the access error flag,
FACCERR in FSTAT, is set. The user must ensure that FACCERR is not set before writing to the FCDIV
register. One period of the resulting clock (1/fFCLK) is used by the command processor to time program
and erase pulses. An integer number of these timing pulses are used by the command processor to complete
a program or erase command.
Table 4-23 shows program and erase times. The bus clock frequency and FCDIV determine the frequency
of FCLK (fFCLK). The time for one cycle of FCLK is tFCLK = 1/fFCLK. The times are shown as a number
of cycles of FCLK and as an absolute time for the case where tFCLK = 5 μs. Program and erase times
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
Table 4-23. Program and Erase Times
Parameter
Cycles of FCLK
Time if FCLK = 200 kHz
Byte program
9
45 μs
Byte program (burst)
4
20 μs1
Page erase
4000
20 ms
Mass erase
20,000
100 ms
1
Excluding start/end overhead
NOTE
Program and erase command execution time will increase proportionally
with the period of FCLK. Programming or erasing the Flash memory with
FCLK < 150 kHz should be avoided. Setting FCDIV to a value such that
FCLK < 150 kHz can destroy the Flash memory due to overstress. Setting
FCDIV to a value such that FCLK > 200 kHz can result in incomplete
programming or erasure of the Flash memory cells.
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If the FCDIV register is written, the FDIVLD bit is set automatically. If the FDIVLD bit is 0, the FCDIV
register has not been written since the last reset. If the FCDIV register has not been written to, the Flash
command loaded during a command write sequence will not execute and the FACCERR flag in the FSTAT
register will set.
4.5.3.1.2
Command Write Sequence
The Flash command controller is used to supervise the command write sequence to execute program,
erase, and erase verify algorithms.
Before starting a command write sequence, the FACCERR and FPVIOL flags in the FSTAT register must
be clear and the FCBEF flag must be set (see Section 4.5.2.5).
A command write sequence consists of three steps which must be strictly adhered to with writes to the
Flash module not permitted between the steps. However, Flash register and array reads are allowed during
a command write sequence. The basic command write sequence is as follows:
1. Write to a valid address in the Flash array memory.
2. Write a valid command to the FCMD register.
3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the command.
Once a command is launched, the completion of the command operation is indicated by the setting of the
FCCF flag in the FSTAT register. The FCCF flag will set upon completion of all active and buffered burst
program commands.
4.5.3.2
Flash Commands
Table 4-24 summarizes the valid Flash commands along with the effects of the commands on the Flash
block.
Table 4-24. Flash Command Description
FCMDB
NVM
Command
Function on Flash Memory
0x05
Erase
Verify
Verify all memory bytes in the Flash array memory are erased.
If the Flash array memory is erased, the FBLANK flag in the FSTAT register will set upon
command completion.
0x20
Program
Program an address in the Flash array.
0x25
Burst
Program
Program an address in the Flash array with the internal address incrementing after the
program operation.
0x40
Sector
Erase
Erase all memory bytes in a sector of the Flash array.
0x41
Mass
Erase
Erase all memory bytes in the Flash array.
A mass erase of the full Flash array is only possible when no protection is enabled prior
to launching the command.
CAUTION
A Flash block address must be in the erased state before being programmed.
Cumulative programming of bits within a Flash block address is not allowed
except for status field updates required in EEPROM emulation applications.
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4.5.3.2.1
Erase Verify Command
The erase verify operation will verify that a Flash block is erased.
An example flow to execute the erase verify operation is shown in Figure 4-15. The erase verify command
write sequence is as follows:
1. Write to a Flash block address to start the command write sequence for the erase verify command.
The address and data written will be ignored.
2. Write the erase verify command, 0x05, to the FCMD register.
3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the erase verify
command.
After launching the erase verify command, the FCCF flag in the FSTAT register will set after the operation
has completed. The number of bus cycles required to execute the erase verify operation is equal to the
number of addresses in the Flash array memory plus several bus cycles as measured from the time the
FCBEF flag is cleared until the FCCF flag is set. Upon completion of the erase verify operation, the
FBLANK flag in the FSTAT register will be set if all addresses in the Flash array memory are verified to
be erased. If any address in the Flash array memory is not erased, the erase verify operation will terminate
and the FBLANK flag in the FSTAT register will remain clear.
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START
Read: FCDIV register
Clock Register
Written
Check
FDIVLD
Set?
yes
NOTE: FCDIV needs to
be set after each reset
no
Write: FCDIV register
Read: FSTAT register
no
FCBEF
Set?
Command
Buffer Empty Check
yes
Access Error and
Protection Violation
Check
1.
FACCERR/FPVIOL yes
Set?
no
Write: Flash Block Address
and Dummy Data
2.
Write: FCMD register
Erase Verify Command 0x05
3.
Write: FSTAT register
Clear FCBEF 0x80
Write: FSTAT register
Clear FACCERR/FPVIOL 0x30
Read: FSTAT register
Bit Polling for
Command Completion
Check
no
FCCF
Set?
yes
Erase Verify
Status
FBLANK
Set?
no
yes
EXIT
Flash Block
Erased
EXIT
Flash Block
Not Erased
Figure 4-15. Example Erase Verify Command Flow
4.5.3.2.2
Program Command
The program operation will program a previously erased address in the Flash memory using an embedded
algorithm.
An example flow to execute the program operation is shown in Figure 4-16. The program command write
sequence is as follows:
1. Write to a Flash block address to start the command write sequence for the program command. The
data written will be programmed to the address written.
2. Write the program command, 0x20, to the FCMD register.
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3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the program
command.
If an address to be programmed is in a protected area of the Flash block, the FPVIOL flag in the FSTAT
register will set and the program command will not launch. Once the program command has successfully
launched, the FCCF flag in the FSTAT register will set after the program operation has completed.
START
Read: FCDIV register
Clock Register
Written
Check
FDIVLD
Set?
yes
NOTE: FCDIV needs to
be set after each reset
no
Write: FCDIV register
Read: FSTAT register
FCBEF
Set?
Command
Buffer Empty Check
no
yes
Access Error and
Protection Violation
Check
1.
FACCERR/FPVIOL yes
Set?
no
Write: Flash Array Address
and Program Data
2.
Write: FCMD register
Program Command 0x20
3.
Write: FSTAT register
Clear FCBEF 0x80
Write: FSTAT register
Clear FACCERR/FPVIOL 0x30
Read: FSTAT register
Bit Polling for
Command Completion
Check
FCCF
Set?
no
yes
EXIT
Figure 4-16. Example Program Command Flow
4.5.3.2.3
Burst Program Command
The burst program operation will program previously erased data in the Flash memory using an embedded
algorithm.
While burst programming, two internal data registers operate as a buffer and a register (2-stage FIFO) so
that a second burst programming command along with the necessary data can be stored to the buffers while
the first burst programming command is still in progress. This pipelined operation allows a time
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optimization when programming more than one consecutive address on a specific row in the Flash array
as the high voltage generation can be kept active in between two programming commands.
An example flow to execute the burst program operation is shown in Figure 4-17. The burst program
command write sequence is as follows:
1. Write to a Flash block address to start the command write sequence for the burst program
command. The data written will be programmed to the address written.
2. Write the program burst command, 0x25, to the FCMD register.
3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the program burst
command.
4. After the FCBEF flag in the FSTAT register returns to a 1, repeat steps 1 through 3. The address
written is ignored but is incremented internally.
The burst program procedure can be used to program the entire Flash memory even while crossing row
boundaries within the Flash array. If data to be burst programmed falls within a protected area of the Flash
array, the FPVIOL flag in the FSTAT register will set and the burst program command will not launch.
Once the burst program command has successfully launched, the FCCF flag in the FSTAT register will set
after the burst program operation has completed unless a new burst program command write sequence has
been buffered. By executing a new burst program command write sequence on sequential addresses after
the FCBEF flag in the FSTAT register has been set, greater than 50% faster programming time for the
entire Flash array can be effectively achieved when compared to using the basic program command.
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START
Read: FCDIV register
Clock Register
Written
Check
NOTE: FCDIV needs to
be set after each reset
no
FDIVLD
Set?
yes
Write: FCDIV register
Read: FSTAT register
FCBEF
Set?
Command
Buffer Empty Check
no
yes
Access Error and
Protection Violation
Check
FACCERR/FPVIOL
Set?
no
yes
1.
Write: Flash Array Address
and Program Data
2.
Write: FCMD register
Burst Program Command 0x25
3.
Write: FSTAT register
Clear FCBEF 0x80
Write: FSTAT register
Clear FACCERR/FPVIOL 0x30
Read: FSTAT register
Bit Polling for
Command Buffer Empty
Check
FCBEF
Set?
no
yes
Sequential
Programming
Decision
Next
Address?
yes
no
Read: FSTAT register
Bit Polling for
Command Completion
Check
FCCF
Set?
no
yes
EXIT
Figure 4-17. Example Burst Program Command Flow
4.5.3.2.4
Sector Erase Command
The sector erase operation will erase all addresses in a 1 Kbyte sector of Flash memory using an embedded
algorithm.
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An example flow to execute the sector erase operation is shown in Figure 4-18. The sector erase command
write sequence is as follows:
1. Write to a Flash block address to start the command write sequence for the sector erase command.
The Flash address written determines the sector to be erased while global address bits [8:0] and the
data written are ignored.
2. Write the sector erase command, 0x40, to the FCMD register.
3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the sector erase
command.
If a Flash sector to be erased is in a protected area of the Flash block, the FPVIOL flag in the FSTAT
register will set and the sector erase command will not launch. Once the sector erase command has
successfully launched, the FCCF flag in the FSTAT register will set after the sector erase operation has
completed.
START
Read: FCDIV register
Clock Register
Written
Check
yes
NOTE: FCDIV needs to
be set after each reset
no
FDIVLD
Set?
Write: FCDIV register
Read: FSTAT register
FCBEF
Set?
Command
Buffer Empty Check
no
yes
Access Error and
Protection Violation
Check
FACCERR/FPVIOL
Set?
no
yes
1.
Write: Flash Sector Address
and Dummy Data
2.
Write: FCMD register
Sector Erase Command 0x40
3.
Write: FSTAT register
Clear FCBEF 0x80
Write: FSTAT register
Clear FACCERR/FPVIOL 0x30
Read: FSTAT register
Bit Polling for
Command Completion
Check
FCCF
Set?
no
yes
EXIT
Figure 4-18. Example Sector Erase Command Flow
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4.5.3.2.5
Mass Erase Command
The mass erase operation erases the entire flash array memory using an embedded algorithm. An example
flow to execute the mass erase operation is shown in Figure 4-19. The mass erase command write sequence
is as follows:
1. Write to a flash block address to start the command write sequence for the mass erase command.
The address and data written is ignored.
2. Write the mass erase command, 0x41, to the FCMD register.
3. Clear the FCBEF flag in the FSTAT register by writing a 1 to FCBEF to launch the mass erase
command.
If the flash array memory to be mass erased contains any protected area, FSTAT[FPVIOL] is set and the
mass erase command does not launch. After the mass erase command has successfully launched and the
mass erase operation has completed, FSTAT[FCCF] is set.
START
Read: FCDIV register
Clock Register
Written
Check
yes
Note: FCDIV needs to
be set after each reset
no
FDIVLD
Set?
Write: FCDIV register
Read: FSTAT register
FCBEF
Set?
Command
Buffer Empty Check
no
yes
Access Error and
Protection Violation
Check
FACCERR/FPVIOL
Set?
no
yes
1.
Write: Flash Memory Address
and Dummy Data
2.
Write: FCMD register
Mass Erase Command 0x41
3.
Write: FSTAT register
Clear FCBEF 0x80
Write: FSTAT register
Clear FACCERR/FPVIOL 0x30
Read: FSTAT register
Bit Polling for
Command Completion
Check
FCCF
Set?
no
yes
EXIT
Figure 4-19. Example Mass Erase Command Flow
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NOTE
The BDM can also perform a mass erase and verify command. See
Chapter 17, “Debug Module (S08DBGV3) (128K),” for details.
4.5.3.3
Illegal Flash Operations
4.5.3.3.1
Flash Access Violations
The FACCERR flag will be set during the command write sequence if any of the following illegal steps
are performed, causing the command write sequence to immediately abort:
• Writing to a Flash address before initializing the FCDIV register.
• Writing to any Flash register other than FCMD after writing to a Flash address.
• Writing to a second Flash address in the same command write sequence.
• Writing an invalid command to the FCMD register unless the address written was in a protected
area of the Flash array.
• Writing a command other than burst program while FCBEF is set and FCCF is clear.
• When security is enabled, writing a command other than mass erase to the FCMD register when
the write originates from a non-secure memory location or from the background debug mode.
• Writing to a Flash address after writing to the FCMD register.
• Writing to any Flash register other than FSTAT (to clear FCBEF) after writing to the FCMD
register.
• Writing a 0 to the FCBEF flag in the FSTAT register to abort a command write sequence.
The FACCERR flag will also be set if the MCU enters stop mode while a program or erase operation is
active. The operation is aborted immediately and, if burst programming, any pending burst program
command is purged (see Section 4.5.4.2, “Stop Mode”).
The FACCERR flag will not be set if any Flash register is read during a valid command write sequence.
If the Flash memory is read during execution of an algorithm (FCCF = 0), the read operation will return
invalid data and the FACCERR flag will not be set.
If the FACCERR flag is set in the FSTAT register, the user must clear the FACCERR flag before starting
another command write sequence (see Section 4.5.2.5, “Flash Status Register (FSTAT)”).
4.5.3.3.2
Flash Protection Violations
The FPVIOL flag will be set after the command is written to the FCMD register during a command write
sequence if any of the following illegal operations are attempted, causing the command write sequence to
immediately abort:
• Writing the program command if the address written in the command write sequence was in a
protected area of the Flash array.
• Writing the sector erase command if the address written in the command write sequence was in a
protected area of the Flash array.
• Writing the mass erase command while any Flash protection is enabled.
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•
Writing an invalid command if the address written in the command write sequence was in a
protected area of the Flash array.
If the FPVIOL flag is set in the FSTAT register, the user must clear the FPVIOL flag before starting another
command write sequence (see Section 4.5.2.5, “Flash Status Register (FSTAT)”).
4.5.4
4.5.4.1
Operating Modes
Wait Mode
If a command is active (FCCF = 0) when the MCU enters wait mode, the active command and any buffered
command will be completed.
4.5.4.2
Stop Mode
If a command is active (FCCF = 0) when the MCU enters stop mode, the operation will be aborted and, if
the operation is program or erase, the Flash array data being programmed or erased may be corrupted and
the FCCF and FACCERR flags will be set. If active, the high voltage circuitry to the Flash array will
immediately be switched off when entering stop mode. Upon exit from stop mode, the FCBEF flag is set
and any buffered command will not be launched. The FACCERR flag must be cleared before starting a
command write sequence (see Section 4.5.3.1.2, “Command Write Sequence”).
NOTE
As active commands are immediately aborted when the MCU enters stop
mode, it is strongly recommended that the user does not use the STOP
instruction during program or erase operations.
4.5.4.3
Background Debug Mode
In background debug mode (BDM), the FPROT register is writable. If the MCU is unsecured, then all
Flash commands listed in Table 4-24 can be executed.
4.5.5
Flash Module Security
The MC9S08AC128 Series includes circuitry to prevent unauthorized access to the contents of Flash and
RAM memory. When security is engaged, Flash and RAM are considered secure resources. Direct-page
registers, high-page registers, and the background debug controller are considered unsecured resources.
Programs executing within secure memory have normal access to any MCU memory locations and
resources. Attempts to access a secure memory location with a program executing from an unsecured
memory space or through the background debug interface are blocked (writes are ignored and reads return
all 0s).
The Flash module provides the necessary security information to the MCU. During each reset sequence,
the Flash module determines the security state of the MCU as defined in Section 4.5.2.2, “Flash Options
Register (FOPT and NVOPT)”.
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The contents of the Flash security byte in NVSEC must be changed directly by programming the NVSEC
location when the MCU is unsecured and the sector containing NVSEC is unprotected. If NVSEC is left
in a secured state, any reset will cause the MCU to initialize into a secure operating mode.
4.5.5.1
Unsecuring the MCU using Backdoor Key Access
The MCU may be unsecured by using the backdoor key access feature which requires knowledge of the
contents of the backdoor keys (NVBACKKEY through NVBACKKEY+7, see Table 4-4 for specific
addresses). If the KEYEN[1:0] bits are in the enabled state (see Section 4.5.2.2) and the KEYACC bit is
set, a write to a backdoor key address in the Flash memory triggers a comparison between the written data
and the backdoor key data stored in the Flash memory. If all backdoor keys are written to the correct
addresses in the correct order and the data matches the backdoor keys stored in the Flash memory, the
MCU will be unsecured. The data must be written to the backdoor keys sequentially. Values 0x0000 and
0xFFFF are not permitted as backdoor keys. While the KEYACC bit is set, reads of the Flash memory will
return invalid data.
The user code stored in the Flash memory must have a method of receiving the backdoor keys from an
external stimulus. This external stimulus would typically be through one of the on-chip serial ports.
If the KEYEN[1:0] bits are in the enabled state (see Section 4.5.2.2), the MCU can be unsecured by the
backdoor key access sequence described below:
1. Set the KEYACC bit in the Flash configuration register (FCNFG).
2. Sequentially write the correct eight 8-bit bytes to the Flash addresses containing the backdoor keys.
3. Clear the KEYACC bit. Depending on the user code used to write the backdoor keys, a wait cycle
(NOP) may be required before clearing the KEYACC bit.
4. If all data written match the backdoor keys, the MCU is unsecured and the SEC[1:0] bits in the
FSEC register are forced to the unsecure state of 1:0.
The backdoor key access sequence is monitored by an internal security state machine. An illegal operation
during the backdoor key access sequence will cause the security state machine to lock, leaving the MCU
in the secured state. A reset of the MCU will cause the security state machine to exit the lock state and
allow a new backdoor key access sequence to be attempted. The following operations during the backdoor
key access sequence will lock the security state machine:
1. If any of the keys written does not match the backdoor keys programmed in the Flash array.
2. If the keys are written in the wrong sequence.
3. If more keys than are required are written.
4. If any of the keys written are all 0’s or all 1’s.
5. If the KEYACC bit does not remain set while the keys are written.
6. If any of the keys are written on successive MCU clock cycles.
7. Executing a STOP instruction while the KEYACC bit is set.
After the backdoor keys have been correctly matched, the MCU will be unsecured. Once the MCU is
unsecured, the Flash security byte can be programmed to the unsecure state, if desired.
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In the unsecure state, the user has full control of the contents of the backdoor keys by programming the
associated addresses in NVBACKKEY through NVBACKKEY+7.
The security as defined in the Flash security byte is not changed by using the backdoor key access sequence
to unsecure. The stored backdoor keys are unaffected by the backdoor key access sequence. After the next
reset of the MCU, the security state of the Flash module is determined by the Flash security byte. The
backdoor key access sequence has no effect on the program and erase protections defined in the Flash
protection register (FPROT).
It is not possible to unsecure the MCU in special mode by using the backdoor key access sequence in
background debug mode (BDM).
4.5.6
Resets
If a reset occurs while any Flash command is in progress, that command will be immediately aborted. The
state of the Flash array address being programmed or the sector/block being erased is not guaranteed.
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Chapter 5
Resets, Interrupts, and System Configuration
5.1
Introduction
This chapter discusses basic reset and interrupt mechanisms and the various sources of reset and interrupts
in the MC9S08AC128 Series. Some interrupt sources from peripheral modules are discussed in greater
detail within other chapters of this data manual. This chapter gathers basic information about all reset and
interrupt sources in one place for easy reference. A few reset and interrupt sources, including the computer
operating properly (COP) watchdog and real-time interrupt (RTI), are not part of on-chip peripheral
systems with their own sections but are part of the system control logic.
5.2
Features
Reset and interrupt features include:
• Multiple sources of reset for flexible system configuration and reliable operation:
— Power-on detection (POR)
— Low voltage detection (LVD) with enable
— External RESET pin
— COP watchdog with enable and two timeout choices
— Illegal opcode
— Illegal address
— Serial command from a background debug host
• Reset status register (SRS) to indicate source of most recent reset
• Separate interrupt vectors for each module (reduces polling overhead) (see Table 5-11)
5.3
MCU Reset
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is loaded from the
reset vector (0xFFFE:0xFFFF). On-chip peripheral modules are disabled and I/O pins are initially
configured as general-purpose high-impedance inputs with pullup devices disabled. The I bit in the
condition code register (CCR) is set to block maskable interrupts so the user program has a chance to
initialize the stack pointer (SP) and system control settings. SP is forced to 0x00FF at reset.
The MC9S08AC128 Series has several sources for reset:
• Power-on reset (POR)
• Low-voltage detect (LVD)
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Chapter 5 Resets, Interrupts, and System Configuration
•
•
•
•
•
•
Computer operating properly (COP) timer
Illegal opcode detect
Illegal address detect
Background debug forced reset
The reset pin (RESET)
Clock generator loss of lock and loss of clock reset
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status register. Whenever the MCU enters reset, the internal clock generator (ICG) module
switches to self-clocked mode with the frequency of fSelf_reset selected. The reset pin is driven low for 34
bus cycles where the internal bus frequency is half the ICG frequency. After the 34 bus cycles are
completed, the pin is released and will be pulled up by the internal pullup resistor, unless it is held low
externally. After the pin is released, it is sampled after another 38 bus cycles to determine whether the reset
pin is the cause of the MCU reset.
5.4
Computer Operating Properly (COP) Watchdog
The COP watchdog is intended to force a system reset when the application software fails to execute as
expected. To prevent a system reset from the COP timer (when it is enabled), application software must
reset the COP counter periodically. If the application program gets lost and fails to reset the COP counter
before it times out, a system reset is generated to force the system back to a known starting point.
After any reset, the COPE becomes set in SOPT enabling the COP watchdog (see Section 5.9.4, “System
Options Register (SOPT),” for additional information). If the COP watchdog is not used in an application,
it can be disabled by clearing COPE. The COP counter is reset by writing any value to the address of SRS.
This write does not affect the data in the read-only SRS. Instead, the act of writing to this address is
decoded and sends a reset signal to the COP counter.
The COPCLKS bit in SOPT2 (see Section 5.9.10, “System Options Register 2 (SOPT2),” for additional
information) selects the clock source used for the COP timer. The clock source options are either the bus
clock or an internal 1-kHz clock source. With each clock source, there is an associated short and long
time-out controlled by COPT in SOPT. Table 5-1 summaries the control functions of the COPCLKS and
COPT bits. The COP watchdog defaults to operation from the bus clock source and the associated long
time-out (218 cycles).
Table 5-1. COP Configuration Options
Control Bits
1
Clock Source
COP Overflow Count
0
~1 kHz
25 cycles (32 ms)1
0
1
~1 kHz
28 cycles (256 ms)1
1
0
Bus
213 cycles
1
1
Bus
218 cycles
COPCLKS
COPT
0
Values are shown in this column based on tRTI = 1 ms. See tRTI in the appendix
Section 3.10.1, “Control Timing,” for the tolerance of this value.
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Even if the application will use the reset default settings of COPE, COPCLKS, and COPT, the user must
write to the write-once SOPT and SOPT2 registers during reset initialization to lock in the settings. That
way, they cannot be changed accidentally if the application program gets lost. The initial writes to SOPT
and SOPT2 will reset the COP counter.
The write to SRS that services (clears) the COP counter must not be placed in an interrupt service routine
(ISR) because the ISR could continue to be executed periodically even if the main application program
fails.
In background debug mode, the COP counter will not increment.
When the bus clock source is selected, the COP counter does not increment while the system is in stop
mode. The COP counter resumes as soon as the MCU exits stop mode.
When the 1-kHz clock source is selected, the COP counter is re-initialized to zero upon entry to stop mode.
The COP counter begins from zero after the MCU exits stop mode.
5.5
Interrupts
Interrupts provide a way to save the current CPU status and registers, execute an interrupt service routine
(ISR), and then restore the CPU status so processing resumes where it left off before the interrupt. Other
than the software interrupt (SWI), which is a program instruction, interrupts are caused by hardware events
such as an edge on the IRQ pin or a timer-overflow event. The debug module can also generate an SWI
under certain circumstances.
If an event occurs in an enabled interrupt source, an associated read-only status flag will become set. The
CPU will not respond until and unless the local interrupt enable is a logic 1 to enable the interrupt. The
I bit in the CCR is 0 to allow interrupts. The global interrupt mask (I bit) in the CCR is initially set after
reset which masks (prevents) all maskable interrupt sources. The user program initializes the stack pointer
and performs other system setup before clearing the I bit to allow the CPU to respond to interrupts.
When the CPU receives a qualified interrupt request, it completes the current instruction before responding
to the interrupt. The interrupt sequence obeys the same cycle-by-cycle sequence as the SWI instruction and
consists of:
•
•
•
•
Saving the CPU registers on the stack
Setting the I bit in the CCR to mask further interrupts
Fetching the interrupt vector for the highest-priority interrupt that is currently pending
Filling the instruction queue with the first three bytes of program information starting from the
address fetched from the interrupt vector locations
While the CPU is responding to the interrupt, the I bit is automatically set to avoid the possibility of another
interrupt interrupting the ISR itself (this is called nesting of interrupts). Normally, the I bit is restored to 0
when the CCR is restored from the value stacked on entry to the ISR. In rare cases, the I bit may be cleared
inside an ISR (after clearing the status flag that generated the interrupt) so that other interrupts can be
serviced without waiting for the first service routine to finish. This practice is not recommended for anyone
other than the most experienced programmers because it can lead to subtle program errors that are difficult
to debug.
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The interrupt service routine ends with a return-from-interrupt (RTI) instruction which restores the CCR,
A, X, and PC registers to their pre-interrupt values by reading the previously saved information off the
stack.
NOTE
For compatibility with the M68HC08, the H register is not automatically
saved and restored. It is good programming practice to push H onto the stack
at the start of the interrupt service routine (ISR) and restore it immediately
before the RTI that is used to return from the ISR.
When two or more interrupts are pending when the I bit is cleared, the highest priority source is serviced
first (see Table 5-2).
5.5.1
Interrupt Stack Frame
Figure 5-1 shows the contents and organization of a stack frame. Before the interrupt, the stack pointer
(SP) points at the next available byte location on the stack. The current values of CPU registers are stored
on the stack starting with the low-order byte of the program counter (PCL) and ending with the CCR. After
stacking, the SP points at the next available location on the stack which is the address that is one less than
the address where the CCR was saved. The PC value that is stacked is the address of the instruction in the
main program that would have executed next if the interrupt had not occurred.
UNSTACKING
ORDER
TOWARD LOWER ADDRESSES
7
0
SP AFTER
INTERRUPT STACKING
5
1
4
2
ACCUMULATOR
3
3
INDEX REGISTER (LOW BYTE X)*
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
STACKING
ORDER
CONDITION CODE REGISTER
SP BEFORE
THE INTERRUPT
TOWARD HIGHER ADDRESSES
* High byte (H) of index register is not automatically stacked.
Figure 5-1. Interrupt Stack Frame
When an RTI instruction is executed, these values are recovered from the stack in reverse order. As part of
the RTI sequence, the CPU fills the instruction pipeline by reading three bytes of program information,
starting from the PC address recovered from the stack.
The status flag causing the interrupt must be acknowledged (cleared) before returning from the ISR.
Typically, the flag should be cleared at the beginning of the ISR so that if another interrupt is generated by
this same source, it will be registered so it can be serviced after completion of the current ISR.
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5.5.2
External Interrupt Request (IRQ) Pin
External interrupts are managed by the IRQSC status and control register. When the IRQ function is
enabled, synchronous logic monitors the pin for edge-only or edge-and-level events. When the MCU is in
stop mode and system clocks are shut down, a separate asynchronous path is used so the IRQ (if enabled)
can wake the MCU.
5.5.2.1
Pin Configuration Options
The IRQ pin enable (IRQPE) control bit in the IRQSC register must be 1 in order for the IRQ pin to act as
the interrupt request (IRQ) input. As an IRQ input, the user can choose the polarity of edges or levels
detected (IRQEDG), whether the pin detects edges-only or edges and levels (IRQMOD), and whether an
event causes an interrupt or only sets the IRQF flag which can be polled by software.
The IRQ pin, when enabled, defaults to use an internal pull device (IRQPDD = 0), configured as a pull-up
or pull-down depending on the polarity chosen. If the user desires to use an external pull-up or pull-down,
the IRQPDD can be written to a 1 to turn off the internal device.
BIH and BIL instructions may be used to detect the level on the IRQ pin when the pin is configured to act
as the IRQ input.
NOTE
The voltage measured on the pulled up IRQ pin may be as low as VDD-0.7
V. The internal gates connected to this pin are pulled all the way to VDD. All
other pins with the enabled pullup resistor will have an unloaded
measurement of VDD.
5.5.2.2
Edge and Level Sensitivity
The IRQMOD control bit reconfigures the detection logic so it detects edge events and pin levels. In this
edge detection mode, the IRQF status flag becomes set when an edge is detected (when the IRQ pin
changes from the deasserted to the asserted level), but the flag is continuously set (and cannot be cleared)
as long as the IRQ pin remains at the asserted level.
5.5.3
Interrupt Vectors, Sources, and Local Masks
Table 5-2 provides a summary of all interrupt sources. Higher-priority sources are located toward the
bottom of the table. The high-order byte of the address for the interrupt service routine is located at the
first address in the vector address column, and the low-order byte of the address for the interrupt service
routine is located at the next higher address.
When an interrupt condition occurs, an associated flag bit becomes set. If the associated local interrupt
enable is 1, an interrupt request is sent to the CPU. Within the CPU, if the global interrupt mask (I bit in
the CCR) is 0, the CPU will finish the current instruction, stack the PCL, PCH, X, A, and CCR CPU
registers, set the I bit, and then fetch the interrupt vector for the highest priority pending interrupt.
Processing then continues in the interrupt service routine.
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Table 5-2. Vector Summary 1
Vector
No.
Address
(High/Low)
50 –
63
49
0xFF80/FF81 –
0xFF9A/0xFF9B
0xFF9C/FF9D
48
N/A
Vector Name
Vspi2
Module
SPI2
Vtpm3ovf
TPM3
31
30
29
0xFF9E/FF9F
0xFFA0/FFA1 –
0xFFBE/FFBF
0xFFC0/FFC1
0xFFC2/FFC3
0xFFC4/FFC5
Vtpm3ch1
Vtpm3ch0
Vrti
28
27
26
25
0xFFC6/FFC7
0xFFC8/FFC9
0xFFCA/FFCB
0xFFCC/FFCD
Viic1
Vadc1
Vkeyboard 1
Vsci2tx
TPM3
TPM3
System
control
IIC1
ADC1
KBI1
SCI2
24
0xFFCE/FFCF
Vsci2rx
SCI2
23
0xFFD0/FFD1
Vsci2err
SCI2
22
0xFFD2/FFD3
Vsci1tx
SCI1
21
0xFFD4/FFD5
Vsci1rx
SCI1
20
0xFFD6/FFD7
Vsci1err
SCI1
19
0xFFD8/FFD9
Vspi1
SPI1
18
17
16
15
14
13
12
11
10
9
8
7
0xFFDA/FFDB
0xFFDC/FFDD
0xFFDE/FFDF
0xFFE0/FFE1
0xFFE2/FFE3
0xFFE4/FFE5
0xFFE6/FFE7
0xFFE8/FFE9
0xFFEA/FFEB
0xFFEC/FFED
0xFFEE/FFEF
0xFFF0/FFF1
Vtpm2ovf
Vtpm2ch5
Vtpm2ch4
Vtpm2ch3
Vtpm2ch2
Vtpm2ch1
Vtpm2ch0
Vtpm1ovf
Vtpm1ch5
Vtpm1ch4
Vtpm1ch3
Vtpm1ch2
TPM2
TPM2
TPM2
TPM2
TPM2
TPM2
TPM2
TPM1
TPM1
TPM1
TPM1
TPM1
Source
Enable
Unused vector space
(available for user program)
SPIE
SPIF
SPIE
MODF
SPTIE
SPTEF
TOF
TOIE
Non-vector space
Description
SPI2
TPM3 overflow
CH1F
CH0F
RTIF
CH1IE
CH0IF
RTIE
TPM3 channel 1
TPM3 channel 0
Real-time interrupt
IICIF
COCO
KBF
TDRE
TC
IDLE
RDRF
LBKDIF
RXEDGIF
OR
NF
FE
PF
TDRE
TC
IDLE
RDRF
LBKDIF
RXEDGIF
OR
NF
FE
PF
SPIF
MODF
SPTEF
TOF
CH5F
CH4F
CH3F
CH2F
CH1F
CH0F
TOF
CH5F
CH4F
CH3F
CH2F
IICIE
AIEN
KBIE
TIE
TCIE
ILIE
RIE
LBKDIE
RXEDGIE
ORIE
NFIE
FEIE
PFIE
TIE
TCIE
ILIE
RIE
LBKDIE
RXEDGIE
ORIE
NFIE
FEIE
PFIE
SPIE
SPIE
SPTIE
TOIE
IIC1
ADC1
KBI1 pins
SCI2 transmit
CH1IE
CH0IE
TOIE
CH5IE
CH4IE
CH3IE
CH2IE
SCI2 receive
SCI2 error
SCI1 transmit
SCI1 receive
SCI1 error
SPI1
TPM2 overflow
TPM2 channel 5
TPM2 channel 4
TPM2 channel 3
TPM2 channel 2
TPM2 channel 1
TPM2 channel 0
TPM1 overflow
TPM1 channel 5
TPM1 channel 4
TPM1 channel 3
TPM1 channel 2
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Chapter 5 Resets, Interrupts, and System Configuration
Table 5-2. Vector Summary (continued)1
Vector
No.
Address
(High/Low)
Vector Name
Module
Source
Enable
Description
6
5
4
0xFFF2/FFF3
0xFFF4/FFF5
0xFFF6/FFF7
Vtpm1ch1
Vtpm1ch0
Vicg
TPM1
TPM1
ICG
CH1IE
CH0IE
LOLRE/LOCRE
TPM1 channel 1
TPM1 channel 0
ICG
3
0xFFF8/FFF9
Vlvd
LVDIE
Low-voltage detect
2
1
0xFFFA/FFFB
0xFFFC/FFFD
Virq
Vswi
System
control
IRQ
Core
CH1F
CH0F
ICGIF
(LOLS/LOCS)
LVDF
IRQIE
—
IRQ pin
Software interrupt
0
0xFFFE/FFFF
Vreset
IRQF
SWI
Instruction
COP
LVD
RESET pin
ILOP
ILAD
COPE
LVDRE
—
—
Watchdog timer
Low-voltage detect
External pin
Illegal opcode
Illegal address
1
5.6
System
control
Vector priority is shown from lowest (first row) to highest (last row). For example, Vreset is the highest priority
vector.
Low-Voltage Detect (LVD) System
The MC9S08AC128 Series includes a system to protect against low voltage conditions in order to protect
memory contents and control MCU system states during supply voltage variations. The system is
comprised of a power-on reset (POR) circuit and an LVD circuit with a user selectable trip voltage, either
high (VLVDH) or low (VLVDL). The LVD circuit is enabled when LVDE in SPMSC1 is high and the trip
voltage is selected by LVDV in SPMSC2. The LVD is disabled upon entering any of the stop modes unless
the LVDSE bit is set. If LVDSE and LVDE are both set, then the MCU cannot enter stop2, and the current
consumption in stop3 with the LVD enabled will be greater.
5.6.1
Power-On Reset Operation
When power is initially applied to the MCU, or when the supply voltage drops below the VPOR level, the
POR circuit will cause a reset condition. As the supply voltage rises, the LVD circuit will hold the chip in
reset until the supply has risen above the VLVDL level. Both the POR bit and the LVD bit in SRS are set
following a POR.
5.6.2
LVD Reset Operation
The LVD can be configured to generate a reset upon detection of a low voltage condition by setting
LVDRE to 1. After an LVD reset has occurred, the LVD system will hold the MCU in reset until the supply
voltage has risen above the level determined by LVDV. The LVD bit in the SRS register is set following
either an LVD reset or POR.
5.6.3
LVD Interrupt Operation
When a low voltage condition is detected and the LVD circuit is configured for interrupt operation (LVDE
set, LVDIE set, and LVDRE clear), then LVDF will be set and an LVD interrupt will occur.
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Chapter 5 Resets, Interrupts, and System Configuration
5.6.4
Low-Voltage Warning (LVW)
The LVD system has a low voltage warning flag to indicate that the supply voltage is approaching, the LVD
voltage. The LVW does not have an interrupt associated with it. There are two, user-selectable trip voltages
for the LVW, one high (VLVWH) and one low (VLVWL). The trip voltage is selected by LVWV in SPMSC2.
Setting the LVW trip voltage equal to the LVD trip voltage is not recommended. Typical use of the LVW
would be to select VLVWH and VLVWL.
5.7
Real-Time Interrupt (RTI)
The real-time interrupt function can be used to generate periodic interrupts. The RTI can accept two
sources of clocks, the 1-kHz internal clock or an external clock if available. The 1-kHz internal clock
source is completely independent of any bus clock source and is used only by the RTI module and, on some
MCUs, the COP watchdog. To use an external clock source, it must be available and active. The RTICLKS
bit in SRTISC is used to select the RTI clock source.
Either RTI clock source can be used when the MCU is in run, wait or stop3 mode. When using the external
oscillator in stop3, it must be enabled in stop (OSCSTEN = 1) and configured for low bandwidth operation
(RANGE = 0). Only the internal 1-kHz clock source can be selected to wake the MCU from stop2 mode.
The SRTISC register includes a read-only status flag, a write-only acknowledge bit, and a 3-bit control
value (RTIS2:RTIS1:RTIS0) used to disable the clock source to the real-time interrupt or select one of
seven wakeup periods. The RTI has a local interrupt enable, RTIE, to allow masking of the real-time
interrupt. The RTI can be disabled by writing each bit of RTIS to zeroes, and no interrupts will be
generated. See Section 5.9.7, “System Real-Time Interrupt Status and Control Register (SRTISC),” for
detailed information about this register.
5.8
MCLK Output
The PTC2 pin is shared with the MCLK clock output. Setting the pin enable bit, MPE, causes the PTC2
pin to output a divided version of the internal MCU bus clock. The divide ratio is determined by the
MCSEL bits. When MPE is set, the PTC2 pin is forced to operate as an output pin regardless of the state
of the port data direction control bit for the pin. If the MCSEL bits are all 0s, the pin is driven low. The
slew rate and drive strength for the pin are controlled by PTCSE2 and PTCDS2, respectively. The
maximum clock output frequency is limited if slew rate control is enabled, see the electrical chapter for
pin rise and fall times with slew rate enabled.
5.9
Reset, Interrupt, and System Control Registers and Control Bits
One 8-bit register in the direct page register space and eight 8-bit registers in the high-page register space
are related to reset and interrupt systems.
Refer to the direct-page register summary in Chapter 4, “Memory,” of this data sheet for the absolute
address assignments for all registers. This section refers to registers and control bits only by their names.
A Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
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Chapter 5 Resets, Interrupts, and System Configuration
Some control bits in the SOPT and SPMSC2 registers are related to modes of operation. Although brief
descriptions of these bits are provided here, the related functions are discussed in greater detail in
Chapter 3, “Modes of Operation.”
5.9.1
Interrupt Pin Request Status and Control Register (IRQSC)
This direct page register includes status and control bits which are used to configure the IRQ function,
report status, and acknowledge IRQ events.
7
R
6
5
4
IRQPDD
IRQEDG
IRQPE
0
3
2
IRQF
0
W
Reset
1
0
IRQIE
IRQMOD
0
0
IRQACK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-2. Interrupt Request Status and Control Register (IRQSC)
Table 5-3. IRQSC Register Field Descriptions
Field
Description
6
IRQPDD
Interrupt Request (IRQ) Pull Device Disable—This read/write control bit is used to disable the internal pullup
device when the IRQ pin is enabled (IRQPE = 1) allowing for an external device to be used.
0 IRQ pull device enabled if IRQPE = 1.
1 IRQ pull device disabled if IRQPE = 1.
5
IRQEDG
Interrupt Request (IRQ) Edge Select — This read/write control bit is used to select the polarity of edges or
levels on the IRQ pin that cause IRQF to be set. The IRQMOD control bit determines whether the IRQ pin is
sensitive to both edges and levels or only edges. When the IRQ pin is enabled as the IRQ input and is configured
to detect rising edges, the optional pullup resistor is re-configured as an optional pulldown resistor.
0 IRQ is falling edge or falling edge/low-level sensitive.
1 IRQ is rising edge or rising edge/high-level sensitive.
4
IRQPE
IRQ Pin Enable — This read/write control bit enables the IRQ pin function. When this bit is set the IRQ pin can
be used as an interrupt request. Also, when this bit is set, either an internal pull-up or an internal pull-down
resistor is enabled depending on the state of the IRQMOD bit.
0 IRQ pin function is disabled.
1 IRQ pin function is enabled.
3
IRQF
2
IRQACK
IRQ Flag — This read-only status bit indicates when an interrupt request event has occurred.
0 No IRQ request.
1 IRQ event detected.
IRQ Acknowledge — This write-only bit is used to acknowledge interrupt request events (write 1 to clear IRQF).
Writing 0 has no meaning or effect. Reads always return logic 0. If edge-and-level detection is selected
(IRQMOD = 1), IRQF cannot be cleared while the IRQ pin remains at its asserted level.
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Chapter 5 Resets, Interrupts, and System Configuration
Table 5-3. IRQSC Register Field Descriptions (continued)
Field
Description
1
IRQIE
0
IRQMOD
5.9.2
IRQ Interrupt Enable — This read/write control bit determines whether IRQ events generate a hardware
interrupt request.
0 Hardware interrupt requests from IRQF disabled (use polling).
1 Hardware interrupt requested whenever IRQF = 1.
IRQ Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. The IRQEDG control bit determines the polarity of edges and levels that are detected as interrupt
request events. See Section 5.5.2.2, “Edge and Level Sensitivity” for more details.
0 IRQ event on falling edges or rising edges only.
1 IRQ event on falling edges and low levels or on rising edges and high levels.
System Reset Status Register (SRS)
This register includes read-only status flags to indicate the source of the most recent reset. When a debug
host forces reset by writing 1 to BDFR in the SBDFR register, none of the status bits in SRS will be set.
Writing any value to this register address clears the COP watchdog timer without affecting the contents of
this register. The reset state of these bits depends on what caused the MCU to reset.
R
7
6
5
4
3
2
1
0
POR
PIN
COP
ILOP
ILAD
ICG
LVD
0
W
Writing any value to SIMRS address clears COP watchdog timer.
POR
1
0
0
0
0
0
1
0
LVR:
U
0
0
0
0
0
1
0
Any other
reset:
0
(1)
(1)
(1)
0
(1)
0
0
U = Unaffected by reset
1
Any of these reset sources that are active at the time of reset will cause the corresponding bit(s) to be set; bits corresponding
to sources that are not active at the time of reset will be cleared.
Figure 5-3. System Reset Status (SRS)
Table 5-4. SRS Register Field Descriptions
Field
Description
7
POR
Power-On Reset — Reset was caused by the power-on detection logic. Because the internal supply voltage was
ramping up at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
0 Reset not caused by POR.
1 POR caused reset.
6
PIN
External Reset Pin — Reset was caused by an active-low level on the external reset pin.
0 Reset not caused by external reset pin.
1 Reset came from external reset pin.
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Table 5-4. SRS Register Field Descriptions (continued)
Field
Description
5
COP
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source may be blocked by COPE = 0.
0 Reset not caused by COP timeout.
1 Reset caused by COP timeout.
4
ILOP
Illegal Opcode — Reset was caused by an attempt to execute an unimplemented or illegal opcode. The STOP
instruction is considered illegal if stop is disabled by STOPE = 0 in the SOPT register. The BGND instruction is
considered illegal if active background mode is disabled by ENBDM = 0 in the BDCSC register.
0 Reset not caused by an illegal opcode.
1 Reset caused by an illegal opcode.
3
ILAD
Illegal Address — Reset was caused by an attempt to access either data or an instruction at an unimplemented
memory address.
0 Reset not caused by an illegal address.
1 Reset caused by an illegal address.
2
ICG
Internal Clock Generation Module Reset — Reset was caused by an ICG module reset.
0 Reset not caused by ICG module.
1 Reset caused by ICG module.
1
LVD
Low Voltage Detect — If the LVDRE and LVDSE bits are set and the supply drops below the LVD trip voltage,
an LVD reset will occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Reset caused by LVD trip or POR.
5.9.3
System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial background command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
BDFR1
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
1
BDFR is writable only through serial background debug commands, not from user programs.
Figure 5-4. System Background Debug Force Reset Register (SBDFR)
Table 5-5. SBDFR Register Field Descriptions
Field
Description
0
BDFR
Background Debug Force Reset — A serial background command such as WRITE_BYTE may be used to
allow an external debug host to force a target system reset. Writing logic 1 to this bit forces an MCU reset. This
bit cannot be written from a user program.
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Chapter 5 Resets, Interrupts, and System Configuration
5.9.4
System Options Register (SOPT)
This register may be read at any time. Bits 3 and 2 are unimplemented and always read 0. This is a
write-once register so only the first write after reset is honored. Any subsequent attempt to write to SOPT
(intentionally or unintentionally) is ignored to avoid accidental changes to these sensitive settings. SOPT
should be written during the user’s reset initialization program to set the desired controls even if the desired
settings are the same as the reset settings.
7
6
5
COPE
COPT
STOPE
1
1
0
4
R
3
2
0
0
0
0
1
0
1
1
W
Reset
1
= Unimplemented or Reserved
Figure 5-5. System Options Register (SOPT)
Table 5-6. SOPT Register Field Descriptions
Field
Description
7
COPE
COP Watchdog Enable — This write-once bit defaults to 1 after reset.
0 COP watchdog timer disabled.
1 COP watchdog timer enabled (force reset on timeout).
6
COPT
COP Watchdog Timeout — This write-once bit defaults to 1 after reset.
0 Short timeout period selected.
1 Long timeout period selected.
5
STOPE
Stop Mode Enable — This write-once bit defaults to 0 after reset, which disables stop mode. If stop mode is
disabled and a user program attempts to execute a STOP instruction, an illegal opcode reset is forced.
0 Stop mode disabled.
1 Stop mode enabled.
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5.9.5
System MCLK Control Register (SMCLK)
This register is used to control the MCLK clock output.
R
7
6
5
0
0
0
4
3
2
1
0
0
MPE
MCSEL
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-6. System MCLK Control Register (SMCLK)
Table 5-7. SMCLK Register Field Descriptions
Field
4
MPE
2:0
MCSEL
Description
MCLK Pin Enable — This bit is used to enable the MCLK function.
0 MCLK output disabled.
1 MCLK output enabled on PTC2 pin.
MCLK Divide Select — These bits are used to select the divide ratio for the MCLK output according to the
formula below when the MCSEL bits are not equal to all zeroes. In the case that the MCSEL bits are all zero and
MPE is set, the pin is driven low. See Equation 5-1.
MCLK frequency = Bus Clock frequency ÷ (2 * MCSEL)
5.9.6
Eqn. 5-1
System Device Identification Register (SDIDH, SDIDL)
This read-only register is included so host development systems can identify the HCS08 derivative and
revision number. This allows the development software to recognize where specific memory blocks,
registers, and control bits are located in a target MCU.
7
6
5
4
R
3
2
1
0
ID11
ID10
ID9
ID8
0
0
0
0
W
Reset
—
—
—
—
= Unimplemented or Reserved
Figure 5-7. System Device Identification Register — High (SDIDH)
Table 5-8. SDIDH Register Field Descriptions
Field
7:4
Reserved
3:0
ID[11:8]
Description
Bits 7:4 are reserved. Reading these bits will result in an indeterminate value; writes have no effect.
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08AC128 Series is hard coded to the value 0x01B. See also ID bits in Table 5-9.
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Chapter 5 Resets, Interrupts, and System Configuration
R
7
6
5
4
3
2
1
0
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0
0
0
1
1
0
1
1
W
Reset
= Unimplemented or Reserved
Figure 5-8. System Device Identification Register — Low (SDIDL)
Table 5-9. SDIDL Register Field Descriptions
Field
7:0
ID[7:0]
5.9.7
Description
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08AC128 Series is hard coded to the value 0x01B. See also ID bits in Table 5-8.
System Real-Time Interrupt Status and Control Register (SRTISC)
This register contains one read-only status flag, one write-only acknowledge bit, three read/write delay
selects, and three unimplemented bits, which always read 0.
R
7
6
RTIF
0
W
Reset
5
4
RTICLKS
RTIE
0
0
3
2
1
0
RTIS2
RTIS1
RTIS0
0
0
0
0
RTIACK
0
0
0
= Unimplemented or Reserved
Figure 5-9. System RTI Status and Control Register (SRTISC)
Table 5-10. SRTISC Register Field Descriptions
Field
7
RTIF
Description
Real-Time Interrupt Flag — This read-only status bit indicates the periodic wakeup timer has timed out.
0 Periodic wakeup timer not timed out.
1 Periodic wakeup timer timed out.
6
RTIACK
Real-Time Interrupt Acknowledge — This write-only bit is used to acknowledge real-time interrupt request
(write 1 to clear RTIF). Writing 0 has no meaning or effect. Reads always return logic 0.
5
RTICLKS
Real-Time Interrupt Clock Select — This read/write bit selects the clock source for the real-time interrupt.
0 Real-time interrupt request clock source is internal 1-kHz oscillator.
1 Real-time interrupt request clock source is external clock.
4
RTIE
2:0
RTIS[2:0]
Real-Time Interrupt Enable — This read-write bit enables real-time interrupts.
0 Real-time interrupts disabled.
1 Real-time interrupts enabled.
Real-Time Interrupt Delay Selects — These read/write bits select the wakeup delay for the RTI. The clock
source for the real-time interrupt is a self-clocked source which oscillates at about 1 kHz, is independent of other
MCU clock sources. Using external clock source the delays will be crystal frequency divided by value in
RTIS2:RTIS1:RTIS0. See Table 5-11.
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Table 5-11. Real-Time Interrupt Frequency
1
RTIS2:RTIS1:RTIS0
1-kHz Clock Source Delay1
Using External Clock Source Delay
(Crystal Frequency)
0:0:0
Disable periodic wakeup timer
Disable periodic wakeup timer
0:0:1
8 ms
divide by 256
0:1:0
32 ms
divide by 1024
0:1:1
64 ms
divide by 2048
1:0:0
128 ms
divide by 4096
1:0:1
256 ms
divide by 8192
1:1:0
512 ms
divide by 16384
1:1:1
1.024 s
divide by 32768
Normal values are shown in this column based on fRTI = 1 kHz. See Chapter 3, “Electrical Characteristics and Timing
Specifications,” fRTI for the tolerance on these values.
5.9.8
R
System Power Management Status and Control 1 Register (SPMSC1)
7
6
LVDF
0
W
Reset
5
4
3
2
LVDIE
LVDRE(2)
LVDSE(2)
LVDE(2)
0
1
1
1
1
1
0
BGBE
LVDACK
0
0
0
0
= Unimplemented or Reserved
1
2
Bit 1 is a reserved bit that must always be written to 0.
This bit can be written only one time after reset. Additional writes are ignored.
Figure 5-10. System Power Management Status and Control 1 Register (SPMSC1)
Table 5-12. SPMSC1 Register Field Descriptions
Field
Description
7
LVDF
Low-Voltage Detect Flag — Provided LVDE = 1, this read-only status bit indicates a low-voltage detect event.
6
LVDACK
Low-Voltage Detect Acknowledge — This write-only bit is used to acknowledge low voltage detection errors
(write 1 to clear LVDF). Reads always return 0.
5
LVDIE
Low-Voltage Detect Interrupt Enable — This read/write bit enables hardware interrupt requests for LVDF.
0 Hardware interrupt disabled (use polling).
1 Request a hardware interrupt when LVDF = 1.
4
LVDRE
Low-Voltage Detect Reset Enable — This read/write bit enables LVDF events to generate a hardware reset
(provided LVDE = 1).
0 LVDF does not generate hardware resets.
1 Force an MCU reset when LVDF = 1.
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Table 5-12. SPMSC1 Register Field Descriptions (continued)
Field
Description
3
LVDSE
Low-Voltage Detect Stop Enable — Provided LVDE = 1, this read/write bit determines whether the low-voltage
detect function operates when the MCU is in stop mode.
0 Low-voltage detect disabled during stop mode.
1 Low-voltage detect enabled during stop mode.
2
LVDE
Low-Voltage Detect Enable — This read/write bit enables low-voltage detect logic and qualifies the operation
of other bits in this register.
0 LVD logic disabled.
1 LVD logic enabled.
0
BGBE
Bandgap Buffer Enable — The BGBE bit is used to enable an internal buffer for the bandgap voltage reference
for use by the ADC module on one of its internal channels.
0 Bandgap buffer disabled.
1 Bandgap buffer enabled.
5.9.9
System Power Management Status and Control 2 Register (SPMSC2)
This register is used to report the status of the low voltage warning function, and to configure the stop mode
behavior of the MCU.
R
7
6
LVWF
0
W
5
4
LVDV(1)
LVWV
3
2
PPDF
0
LVWACK
1
0
PPDC(2)
PPDACK
Power-on
reset:
0(3)
0
0
0
0
0
0
0
LVD
reset:
0(2)
0
U
U
0
0
0
0
Any other
reset:
0(2)
0
U
U
0
0
0
0
= Unimplemented or Reserved
U = Unaffected by reset
1
This bit can be written only one time after power-on reset. Additional writes are ignored.
This bit can be written only one time after reset. Additional writes are ignored.
3 LVWF will be set in the case when V
Supply transitions below the trip point or after reset and VSupply is already below VLVW.
2
Figure 5-11. System Power Management Status and Control 2 Register (SPMSC2)
Table 5-13. SPMSC2 Register Field Descriptions
Field
7
LVWF
6
LVWACK
Description
Low-Voltage Warning Flag — The LVWF bit indicates the low voltage warning status.
0 Low voltage warning not present.
1 Low voltage warning is present or was present.
Low-Voltage Warning Acknowledge — The LVWACK bit is the low-voltage warning acknowledge.
Writing a 1 to LVWACK clears LVWF to a 0 if a low voltage warning is not present.
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Table 5-13. SPMSC2 Register Field Descriptions (continued)
Field
Description
5
LVDV
Low-Voltage Detect Voltage Select — The LVDV bit selects the LVD trip point voltage (VLVD).
0 Low trip point selected (VLVD = VLVDL).
1 High trip point selected (VLVD = VLVDH).
4
LVWV
Low-Voltage Warning Voltage Select — The LVWV bit selects the LVW trip point voltage (VLVW).
0 Low trip point selected (VLVW = VLVWL).
1 High trip point selected (VLVW = VLVWH).
3
PPDF
Partial Power Down Flag — The PPDF bit indicates that the MCU has exited the stop2 mode.
0 Not stop2 mode recovery.
1 Stop2 mode recovery.
2
PPDACK
0
PPDC
Partial Power Down Acknowledge — Writing a 1 to PPDACK clears the PPDF bit.
Partial Power Down Control — The write-once PPDC bit controls whether stop2 or stop3 mode is selected.
0 Stop3 mode enabled.
1 Stop2, partial power down, mode enabled.
5.9.10
System Options Register 2 (SOPT2)
This high page register contains bits to configure MCU specific features on the MC9S08AC128 Series
devices.
7
R
COPCLKS1
6
5
4
0
0
0
3
2
1
0
0
0
0
0
0
0
TPMCCFG
W
Reset:
1
0
0
0
1
= Unimplemented or Reserved
Figure 5-12. System Options Register 2 (SOPT2)
1
This bit can be written only one time after reset. Additional writes are ignored.
Table 5-14. SOPT2 Register Field Descriptions
Field
Description
7
COPCLKS
COP Watchdog Clock Select — This write-once bit selects the clock source of the COP watchdog.
0 Internal 1-kHz clock is source to COP.
1 Bus clock is source to COP.
3
TPMCCFG
TPM Clock Configuration — Configures the timer/pulse-width modulator clock signal.
0 TPMCLK is available to TPM1, TPM2, and TPM3 via the IRQ pin; TPMCLK1 and TPMCLK2 are not available.
1 TPM1CLK, TPM2CLK, and TPMCLK are available to TPM1, TPM2, and TPM3 respectively.
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Chapter 5 Resets, Interrupts, and System Configuration
MC9S08AC128 Series Reference Manual, Rev. 3
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Chapter 6
Parallel Input/Output
6.1
Introduction
This chapter explains software controls related to parallel input/output (I/O). The MC9S08AC128 Series
has seven I/O ports which include a total of up to 70 general-purpose I/O pins. See Chapter 2, “Pins and
Connections” for more information about the logic and hardware aspects of these pins.
Many of these pins are shared with on-chip peripherals such as timer systems, communication systems, or
keyboard interrupts. When these other modules are not controlling the port pins, they revert to
general-purpose I/O control.
NOTE
Not all general-purpose I/O pins are available on all packages. To avoid
extra current drain from floating input pins, the user’s reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unconnected pins to outputs so the pins
do not float.
6.2
Pin Descriptions
The MC9S08AC128 Series has a total of 70 parallel I/O pins in nine ports (PTA–PTJ). Not all pins are
bonded out in all packages. Consult the pin assignment in Chapter 2, “Pins and Connections,” for available
parallel I/O pins. All of these pins are available for general-purpose I/O when they are not used by other
on-chip peripheral systems.
After reset, the shared peripheral functions are disabled so that the pins are controlled by the parallel I/O.
All of the parallel I/O are configured as inputs (PTxDDn = 0). The pin control functions for each pin are
configured as follows: slew rate control enabled (PTxSEn = 1), low drive strength selected (PTxDSn = 0),
and internal pullups disabled (PTxPEn = 0).
6.3
Parallel I/O Control
Reading and writing of parallel I/O is done through the port data registers. The direction, input or output,
is controlled through the port data direction registers. The parallel I/O port function for an individual pin
is illustrated in the block diagram below.
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Chapter 6 Parallel Input/Output
PTxDDn
D
Output Enable
Q
PTxDn
D
Output Data
Q
1
Port Read
Data
0
Synchronizer
Input Data
BUSCLK
Figure 6-1. Parallel I/O Block Diagram
The data direction control bits determine whether the pin output driver is enabled, and they control what
is read for port data register reads. Each port pin has a data direction register bit. When PTxDDn = 0, the
corresponding pin is an input and reads of PTxD return the pin value. When PTxDDn = 1, the
corresponding pin is an output and reads of PTxD return the last value written to the port data register.
When a peripheral module or system function is in control of a port pin, the data direction register bit still
controls what is returned for reads of the port data register, even though the peripheral system has
overriding control of the actual pin direction.
When a shared analog function is enabled for a pin, all digital pin functions are disabled. A read of the port
data register returns a value of 0 for any bits which have shared analog functions enabled. In general,
whenever a pin is shared with both an alternate digital function and an analog function, the analog function
has priority such that if both the digital and analog functions are enabled, the analog function controls the
pin.
It is a good programming practice to write to the port data register before changing the direction of a port
pin to become an output. This ensures that the pin will not be driven momentarily with an old data value
that happened to be in the port data register.
6.4
Pin Control
The pin control registers are located in the high page register block of the memory. These registers are used
to control pullups, slew rate, and drive strength for the I/O pins. The pin control registers operate
independently of the parallel I/O registers.
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Chapter 6 Parallel Input/Output
6.4.1
Internal Pullup Enable
An internal pullup device can be enabled for each port pin by setting the corresponding bit in one of the
pullup enable registers (PTxPEn). The pullup device is disabled if the pin is configured as an output by the
parallel I/O control logic or any shared peripheral function regardless of the state of the corresponding
pullup enable register bit. The pullup device is also disabled if the pin is controlled by an analog function.
6.4.2
Output Slew Rate Control Enable
Slew rate control can be enabled for each port pin by setting the corresponding bit in one of the slew rate
control registers (PTxSEn). When enabled, slew control limits the rate at which an output can transition in
order to reduce EMC emissions. Slew rate control has no effect on pins which are configured as inputs.
6.4.3
Output Drive Strength Select
An output pin can be selected to have high output drive strength by setting the corresponding bit in one of
the drive strength select registers (PTxDSn). When high drive is selected a pin is capable of sourcing and
sinking greater current. Even though every I/O pin can be selected as high drive, the user must ensure that
the total current source and sink limits for the chip are not exceeded. Drive strength selection is intended
to affect the DC behavior of I/O pins. However, the AC behavior is also affected. High drive allows a pin
to drive a greater load with the same switching speed as a low drive enabled pin into a smaller load.
Because of this the EMC emissions may be affected by enabling pins as high drive.
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Chapter 6 Parallel Input/Output
6.5
Pin Behavior in Stop Modes
Depending on the stop mode, I/O functions differently as the result of executing a STOP instruction. An
explanation of I/O behavior for the various stop modes follows:
• Stop2 mode is a partial power-down mode, whereby I/O latches are maintained in their state as
before the STOP instruction was executed. CPU register status and the state of I/O registers should
be saved in RAM before the STOP instruction is executed to place the MCU in stop2 mode. Upon
recovery from stop2 mode, before accessing any I/O, the user should examine the state of the PPDF
bit in the SPMSC2 register. If the PPDF bit is 0, I/O must be initialized as if a power on reset had
occurred. If the PPDF bit is 1, I/O data previously stored in RAM, before the STOP instruction was
executed, peripherals may require being initialized and restored to their pre-stop condition. The
user must then write a 1 to the PPDACK bit in the SPMSC2 register. Access to I/O is now permitted
again in the user’s application program.
• In stop3 mode, all I/O is maintained because internal logic circuity stays powered up. Upon
recovery, normal I/O function is available to the user.
6.6
Parallel I/O and Pin Control Registers
This section provides information about the registers associated with the parallel I/O ports and pin control
functions. These parallel I/O registers are located in page zero of the memory map and the pin control
registers are located in the high page register section of memory.
Refer to tables in Chapter 4, “Memory,” for the absolute address assignments for all parallel I/O and pin
control registers. This section refers to registers and control bits only by their names. A Freescale-provided
equate or header file normally is used to translate these names into the appropriate absolute addresses.
6.6.1
Port A I/O Registers (PTAD and PTADD)
Port A parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-2. Port A Data Register (PTAD)
Table 6-1. PTAD Register Field Descriptions
Field
Description
7:0
PTADn
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port A pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
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7
6
5
4
3
2
1
0
PTADD7
PTADD6
PTADD5
PTADD4
PTADD3
PTADD2
PTADD1
PTADD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-3. Data Direction for Port A Register (PTADD)
Table 6-2. PTADD Register Field Descriptions
Field
Description
7:0
PTADDn
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read for
PTAD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
6.6.2
Port A Pin Control Registers (PTAPE, PTASE, PTADS)
In addition to the I/O control, port A pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTAPE7
PTAPE6
PTAPE5
PTAPE4
PTAPE3
PTAPE2
PTAPE1
PTAPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-4. Internal Pullup Enable for Port A (PTAPE)
Table 6-3. PTADD Register Field Descriptions
Field
Description
7:0
PTAPEn
Internal Pullup Enable for Port A Bits — Each of these control bits determines if the internal pullup device is
enabled for the associated PTA pin. For port A pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port A bit n.
1 Internal pullup device enabled for port A bit n.
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7
6
5
4
3
2
1
0
PTASE7
PTASE6
PTASE5
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-5. Slew Rate Control Enable for Port A (PTASE)
Table 6-4. PTASE Register Field Descriptions
Field
Description
7:0
PTASEn
Output Slew Rate Control Enable for Port A Bits — Each of these control bits determine whether output slew
rate control is enabled for the associated PTA pin. For port A pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port A bit n.
1 Output slew rate control enabled for port A bit n.
7
6
5
4
3
2
1
0
PTADS7
PTADS6
PTADS5
PTADS4
PTADS3
PTADS2
PTADS1
PTADS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-6. Drive Strength Selection for Port A (PTADS)
Table 6-5. PTADS Register Field Descriptions
Field
7:0
PTADSn
Description
Output Drive Strength Selection for Port A Bits — Each of these control bits selects between low and high
output drive for the associated PTA pin.
0 Low output drive enabled for port A bit n.
1 High output drive enabled for port A bit n.
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Chapter 6 Parallel Input/Output
6.6.3
Port B I/O Registers (PTBD and PTBDD)
Port B parallel I/O function is controlled by the registers in this section.
7
6
5
4
3
2
1
0
PTBD7
PTBD6
PTBD5
PTBD4
PTBD3
PTBD2
PTBD1
PTBD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-7. Port B Data Register (PTBD)
Table 6-6. PTBD Register Field Descriptions
Field
Description
7:0
PTBD[7:0]
Port B Data Register Bits — For port B pins that are inputs, reads return the logic level on the pin. For port B
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port B pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTBD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTBDD7
PTBDD6
PTBDD5
PTBDD4
PTBDD3
PTBDD2
PTBDD1
PTBDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-8. Data Direction for Port B (PTBDD)
Table 6-7. PTBDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port B Bits — These read/write bits control the direction of port B pins and what is read for
PTBDD[7:0] PTBD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port B bit n and PTBD reads return the contents of PTBDn.
6.6.4
Port B Pin Control Registers (PTBPE, PTBSE, PTBDS)
In addition to the I/O control, port B pins are controlled by the registers listed below.
MC9S08AC128 Series Reference Manual, Rev. 3
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7
6
5
4
3
2
1
0
PTBPE7
PTBPE6
PTBPE5
PTBPE4
PTBPE3
PTBPE2
PTBPE1
PTBPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-9. Internal Pullup Enable for Port B (PTBPE)
Table 6-8. PTBPE Register Field Descriptions
Field
Description
7:0
Internal Pullup Enable for Port B Bits — Each of these control bits determines if the internal pullup device is
PTBPE[7:0] enabled for the associated PTB pin. For port B pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port B bit n.
1 Internal pullup device enabled for port B bit n.
7
6
5
4
3
2
1
0
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-10. Output Slew Rate Control Enable (PTBSE)
Table 6-9. PTBSE Register Field Descriptions
Field
Description
7:0
Output Slew Rate Control Enable for Port B Bits— Each of these control bits determine whether output slew
PTBSE[7:0] rate control is enabled for the associated PTB pin. For port B pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port B bit n.
1 Output slew rate control enabled for port B bit n.
7
6
5
4
3
2
1
0
PTBDS7
PTBDS6
PTBDS5
PTBDS4
PTBDS3
PTBDS2
PTBDS1
PTBDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-11. Internal Drive Strength Selection for Port B (PTBDS)
Table 6-10. PTBDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port B Bits — Each of these control bits selects between low and high
PTBDS[7:0] output drive for the associated PTB pin.
0 Low output drive enabled for port B bit n.
1 High output drive enabled for port B bit n.
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Chapter 6 Parallel Input/Output
6.6.5
Port C I/O Registers (PTCD and PTCDD)
Port C parallel I/O function is controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-12. Port C Data Register (PTCD)
Table 6-11. PTCD Register Field Descriptions
Field
Description
6:0
PTCD[6:0]
Port C Data Register Bits — For port C pins that are inputs, reads return the logic level on the pin. For port C
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port C pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTCD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
R
6
5
4
3
2
1
0
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-13. Data Direction for Port C (PTCDD)
Table 6-12. PTCDD Register Field Descriptions
Field
Description
6:0
Data Direction for Port C Bits — These read/write bits control the direction of port C pins and what is read for
PTCDD[6:0] PTCD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port C bit n and PTCD reads return the contents of PTCDn.
6.6.6
Port C Pin Control Registers (PTCPE, PTCSE, PTCDS)
In addition to the I/O control, port C pins are controlled by the registers listed below.
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7
R
6
5
4
3
2
1
0
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-14. Internal Pullup Enable for Port C (PTCPE)
Table 6-13. PTCPE Register Field Descriptions
Field
Description
6:0
Internal Pullup Enable for Port C Bits — Each of these control bits determines if the internal pullup device is
PTCPE[6:0] enabled for the associated PTC pin. For port C pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port C bit n.
1 Internal pullup device enabled for port C bit n.
7
R
6
5
4
3
2
1
0
PTCPE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
1
1
1
1
1
1
1
0
W
Reset
0
Figure 6-15. Output Slew Rate Control Enable for Port C (PTCSE)
Table 6-14. PTCSE Register Field Descriptions
Field
Description
6:0
Output Slew Rate Control Enable for Port C Bits — Each of these control bits determine whether output slew
PTCSE[6:0] rate control is enabled for the associated PTC pin. For port C pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port C bit n.
1 Output slew rate control enabled for port C bit n.
7
R
6
5
4
3
2
1
0
PTCDS6
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-16. Output Drive Strength Selection for Port C (PTCDS)
Table 6-15. PTCDS Register Field Descriptions
Field
Description
6:0
Output Drive Strength Selection for Port C Bits — Each of these control bits selects between low and high
PTCDS[6:0] output drive for the associated PTC pin.
0 Low output drive enabled for port C bit n.
1 High output drive enabled for port C bit n.
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Chapter 6 Parallel Input/Output
6.6.7
Port D I/O Registers (PTDD and PTDDD)
Port D parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTDD7
PTDD6
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-17. Port D Data Register (PTDD)
Table 6-16. PTDD Register Field Descriptions
Field
Description
7:0
PTDD[7:0]
Port D Data Register Bits — For port D pins that are inputs, reads return the logic level on the pin. For port D
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port D pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTDD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTDDD7
PTDDD6
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-18. Data Direction for Port D (PTDDD)
Table 6-17. PTDDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port D Bits — These read/write bits control the direction of port D pins and what is read for
PTDDD[7:0] PTDD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port D bit n and PTDD reads return the contents of PTDDn.
6.6.8
Port D Pin Control Registers (PTDPE, PTDSE, PTDDS)
In addition to the I/O control, port D pins are controlled by the registers listed below.
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7
6
5
4
3
2
1
0
PTDPE7
PTDPE6
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-19. Internal Pullup Enable for Port D (PTDPE)
Table 6-18. PTDPE Register Field Descriptions
Field
Description
7:0
Internal Pullup Enable for Port D Bits — Each of these control bits determines if the internal pullup device is
PTDPE[7:0] enabled for the associated PTD pin. For port D pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port D bit n.
1 Internal pullup device enabled for port D bit n.
7
6
5
4
3
2
1
0
PTDSE7
PTDSE6
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-20. Output Slew Rate Control Enable for Port D (PTDSE)
Table 6-19. PTDSE Register Field Descriptions
Field
Description
7:0
Output Slew Rate Control Enable for Port D Bits — Each of these control bits determine whether output slew
PTDSE[7:0] rate control is enabled for the associated PTD pin. For port D pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port D bit n.
1 Output slew rate control enabled for port D bit n.
7
6
5
4
3
2
1
0
PTDDS7
PTDDS6
PTDDS5
PTDDS4
PTDDS3
PTDDS2
PTDDS1
PTDDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-21. Output Drive Strength Selection for Port D (PTDDS)
Table 6-20. PTDDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port D Bits — Each of these control bits selects between low and high
PTDDS[7:0] output drive for the associated PTD pin.
0 Low output drive enabled for port D bit n.
1 High output drive enabled for port D bit n.
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6.6.9
Port E I/O Registers (PTED and PTEDD)
Port E parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-22. Port E Data Register (PTED)
Table 6-21. PTED Register Field Descriptions
Field
Description
7:0
PTED[7:0]
Port E Data Register Bits — For port E pins that are inputs, reads return the logic level on the pin. For port E
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port E pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTED to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-23. Data Direction for Port E (PTEDD)
Table 6-22. PTEDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port E Bits — These read/write bits control the direction of port E pins and what is read for
PTEDD[7:0] PTED reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port E bit n and PTED reads return the contents of PTEDn.
6.6.10
Port E Pin Control Registers (PTEPE, PTESE, PTEDS)
In addition to the I/O control, port E pins are controlled by the registers listed below.
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7
6
5
4
3
2
1
0
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-24. Internal Pullup Enable for Port E (PTEPE)
Table 6-23. PTEPE Register Field Descriptions
Field
Description
7:0
Internal Pullup Enable for Port E Bits— Each of these control bits determines if the internal pullup device is
PTEPE[7:0] enabled for the associated PTE pin. For port E pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port E bit n.
1 Internal pullup device enabled for port E bit n.
7
6
5
4
3
2
1
0
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-25. Output Slew Rate Control Enable for Port E (PTESE)
Table 6-24. PTESE Register Field Descriptions
Field
Description
7:0
Output Slew Rate Control Enable for Port E Bits — Each of these control bits determine whether output slew
PTESE[7:0] rate control is enabled for the associated PTE pin. For port E pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port E bit n.
1 Output slew rate control enabled for port E bit n.
7
6
5
4
3
2
1
0
PTEDS7
PTEDS6
PTEDS5
PTEDS4
PTEDS3
PTEDS2
PTEDS1
PTEDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-26. Output Drive Strength Selection for Port E (PTEDS)
Table 6-25. PTEDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port E Bits — Each of these control bits selects between low and high
PTEDS[7:0] output drive for the associated PTE pin.
0 Low output drive enabled for port E bit n.
1 High output drive enabled for port E bit n.
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Chapter 6 Parallel Input/Output
6.6.11
Port F I/O Registers (PTFD and PTFDD)
Port F parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTFD7
PTFD6
PTFD5
PTFD4
PTFD3
PTFD2
PTFD1
PTFD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-27. Port F Data Register (PTFD)
Table 6-26. PTFD Register Field Descriptions
Field
Description
7:0
PTFDn
Port F Data Register Bits— For port F pins that are inputs, reads return the logic level on the pin. For port F
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port F pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTFD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTFDD7
PTFDD6
PTFDD5
PTFDD4
PTFDD3
PTFDD2
PTFDD1
PTFDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-28. Data Direction for Port F (PTFDD)
Table 6-27. PTFDD Register Field Descriptions
Field
Description
7:0
PTFDDn
Data Direction for Port F Bits — These read/write bits control the direction of port F pins and what is read for
PTFD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port F bit n and PTFD reads return the contents of PTFDn.
6.6.12
Port F Pin Control Registers (PTFPE, PTFSE, PTFDS)
In addition to the I/O control, port F pins are controlled by the registers listed below.
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7
6
5
4
3
2
1
0
PTFPE7
PTFPE6
PTFPE5
PTFPE4
PTFPE3
PTFPE2
PTFPE1
PTFPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-29. Internal Pullup Enable for Port F (PTFPE)
Table 6-28. PTFPE Register Field Descriptions
Field
Description
7:0
PTFPEn
Internal Pullup Enable for Port F Bits — Each of these control bits determines if the internal pullup device is
enabled for the associated PTF pin. For port F pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port F bit n.
1 Internal pullup device enabled for port F bit n.
7
6
5
4
3
2
1
0
PTFSE7
PTFSE6
PTFSE5
PTFSE4
PTFSE3
PTFSE2
PTFSE1
PTFSE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-30. Output Slew Rate Control Enable for Port F (PTFSE)
Table 6-29. PTFSE Register Field Descriptions
Field
Description
7:0
PTFSEn
Output Slew Rate Control Enable for Port F Bits — Each of these control bits determine whether output slew
rate control is enabled for the associated PTF pin. For port F pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port F bit n.
1 Output slew rate control enabled for port F bit n.
7
6
5
4
3
2
1
0
PTFDS7
PTFDS6
PTFDS5
PTFDS4
PTFDS3
PTFDS2
PTFDS1
PTFDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-31. Output Drive Strength Selection for Port F (PTFDS)
Table 6-30. PTFDS Register Field Descriptions
Field
7:0
PTFDSn
Description
Output Drive Strength Selection for Port F Bits — Each of these control bits selects between low and high
output drive for the associated PTF pin.
0 Low output drive enabled for port F bit n.
1 High output drive enabled for port F bit n.
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Chapter 6 Parallel Input/Output
6.6.13
Port G I/O Registers (PTGD and PTGDD)
Port G parallel I/O function is controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-32. Port G Data Register (PTGD)
Table 6-31. PTGD Register Field Descriptions
Field
Description
6:0
PTGD[6:0]
Port G Data Register Bits — For port G pins that are inputs, reads return the logic level on the pin. For port G
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port G pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTGD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
R
6
5
4
3
2
1
0
PTGDD6
PTGDD5
PTGDD4
PTGDD3
PTGDD2
PTGDD1
PTGDD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-33. Data Direction for Port G (PTGDD)
Table 6-32. PTGDD Register Field Descriptions
Field
Description
6:0
Data Direction for Port G Bits — These read/write bits control the direction of port G pins and what is read for
PTGDD[6:0] PTGD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port G bit n and PTGD reads return the contents of PTGDn.
6.6.14
Port G Pin Control Registers (PTGPE, PTGSE, PTGDS)
In addition to the I/O control, port G pins are controlled by the registers listed below.
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7
R
6
5
4
3
2
1
0
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-34. Internal Pullup Enable for Port G Bits (PTGPE)
Table 6-33. PTGPE Register Field Descriptions
Field
Description
6:0
Internal Pullup Enable for Port G Bits — Each of these control bits determines if the internal pullup device is
PTGPE[6:0] enabled for the associated PTG pin. For port G pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port G bit n.
1 Internal pullup device enabled for port G bit n.
7
R
6
5
4
3
2
1
0
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
1
1
1
1
1
1
1
0
W
Reset
0
Figure 6-35. Output Slew Rate Control Enable for Port G Bits (PTGSE)
Table 6-34. PTGSE Register Field Descriptions
Field
Description
6:0
Output Slew Rate Control Enable for Port G Bits— Each of these control bits determine whether output slew
PTGSE[6:0] rate control is enabled for the associated PTG pin. For port G pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port G bit n.
1 Output slew rate control enabled for port G bit n.
7
R
6
5
4
3
2
1
0
PTGDS6
PTGDS5
PTGDS4
PTGDS3
PTGDS2
PTGDS1
PTGDS0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-36. Output Drive Strength Selection for Port G (PTGDS)
Table 6-35. PTGDS Register Field Descriptions
Field
Description
6:0
Output Drive Strength Selection for Port G Bits — Each of these control bits selects between low and high
PTGDS[6:0] output drive for the associated PTG pin.
0 Low output drive enabled for port G bit n.
1 High output drive enabled for port G bit n.
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Chapter 6 Parallel Input/Output
6.6.15
Port H I/O Registers (PTHD and PTHDD)
Port H parallel I/O function is controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
PTHD6
PTHD5
PTHD4
PTHD3
PTHD2
PTHD1
PTHD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-37. Port H Data Register (PTHD)
Table 6-36. PTHD Register Field Descriptions
Field
Description
6:0
PTHD[6:0]
Port H Data Register Bits — For port H pins that are inputs, reads return the logic level on the pin. For port H
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port H pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTHD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
R
6
5
4
3
2
1
0
PTHDD6
PTHDD5
PTHDD4
PTHDD3
PTHDD2
PTHDD1
PTHDD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-38. Data Direction for Port H (PTHDD)
Table 6-37. PTHDD Register Field Descriptions
Field
Description
6:0
Data Direction for Port H Bits — These read/write bits control the direction of port H pins and what is read for
PTHDD[6:0] PTHD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port H bit n and PTHD reads return the contents of PTHDn.
6.6.16
Port H Pin Control Registers (PTHPE, PTHSE, PTHDS)
In addition to the I/O control, port H pins are controlled by the registers listed below.
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7
R
6
5
4
3
2
1
0
PTHPE6
PTHPE5
PTHPE4
PTHPE3
PTHPE2
PTHPE1
PTHPE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-39. Internal Pullup Enable for Port H Bits (PTHPE)
Table 6-38. PTHPE Register Field Descriptions
Field
Description
6:0
Internal Pullup Enable for Port H Bits — Each of these control bits determines if the internal pullup device is
PTHPE[6:0] enabled for the associated PTH pin. For port H pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port H bit n.
1 Internal pullup device enabled for port H bit n.
7
R
6
5
4
3
2
1
0
PTHSE6
PTHSE5
PTHSE4
PTHSE3
PTHSE2
PTHSE1
PTHSE0
1
1
1
1
1
1
1
0
W
Reset
1
Figure 6-40. Output Slew Rate Control Enable for Port H Bits (PTHSE)
Table 6-39. PTHSE Register Field Descriptions
Field
Description
6:0
Output Slew Rate Control Enable for Port H Bits— Each of these control bits determine whether output slew
PTHSE[6:0] rate control is enabled for the associated PTH pin. For port H pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port H bit n.
1 Output slew rate control enabled for port H bit n.
7
R
6
5
4
3
2
1
0
PTHDS6
PTHDS5
PTHDS4
PTHDS3
PTHDS2
PTHDS1
PTHDS0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-41. Output Drive Strength Selection for Port H (PTHDS)
Table 6-40. PTHDS Register Field Descriptions
Field
Description
6:0
Output Drive Strength Selection for Port H Bits — Each of these control bits selects between low and high
PTHDS[6:0] output drive for the associated PTH pin.
0 Low output drive enabled for port H bit n.
1 High output drive enabled for port H bit n.
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Chapter 6 Parallel Input/Output
6.6.17
Port J I/O Registers (PTJD and PTJDD)
Port J parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTJD7
PTJD6
PTJD5
PTJD4
PTJD3
PTJD2
PTJD1
PTJD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-42. Port J Data Register (PTJD)
Table 6-41. PTJD Register Field Descriptions
Field
Description
7:0
PTJD[7:0]
Port J Data Register Bits — For port J pins that are inputs, reads return the logic level on the pin. For port J
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port J pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTJD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTJDD7
PTJDD6
PTJDD5
PTJDD4
PTJDD3
PTJDD2
PTJDD1
PTJDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-43. Data Direction for Port J (PTJDD)
Table 6-42. PTJDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port J Bits — These read/write bits control the direction of port J pins and what is read for
PTJDD[6:0] PTJD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port J bit n and PTJD reads return the contents of PTJDn.
6.6.18
Port J Pin Control Registers (PTJPE, PTJSE, PTJDS)
In addition to the I/O control, port J pins are controlled by the registers listed below.
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7
6
5
4
3
2
1
0
PTJPE7
PTJPE6
PTJPE5
PTJPE4
PTJPE3
PTJPE2
PTJPE1
PTJPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-44. Internal Pullup Enable for Port J Bits (PTJPE)
Table 6-43. PTJPE Register Field Descriptions
Field
Description
7:0
PTJPE[7:0]
Internal Pullup Enable for Port J Bits — Each of these control bits determines if the internal pullup device is
enabled for the associated PTJ pin. For port J pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port J bit n.
1 Internal pullup device enabled for port J bit n.
7
6
5
4
3
2
1
0
PTJSE0
PTJSE6
PTJSE5
PTJSE4
PTJSE3
PTJSE2
PTJSE1
PTJSE0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 6-45. Output Slew Rate Control Enable for Port J Bits (PTJSE)
Table 6-44. PTJSE Register Field Descriptions
Field
Description
7:0
PTJSE[7:0]
Output Slew Rate Control Enable for Port J Bits— Each of these control bits determine whether output slew
rate control is enabled for the associated PTJ pin. For port J pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port J bit n.
1 Output slew rate control enabled for port J bit n.
7
6
5
4
3
2
1
0
PTJDS7
PTJDS6
PTJDS5
PTJDS4
PTJDS3
PTJDS2
PTJDS1
PTJDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-46. Output Drive Strength Selection for Port J (PTJDS)
Table 6-45. PTJDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port J Bits — Each of these control bits selects between low and high
PTJDS[7:0] output drive for the associated PTJ pin.
0 Low output drive enabled for port J bit n.
1 High output drive enabled for port J bit n.
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Chapter 7
Central Processor Unit (S08CPUV5)
7.1
Introduction
This section provides summary information about the registers, addressing modes, and instruction set of
the CPU of the HCS08 Family. For a more detailed discussion, refer to the HCS08 Family Reference
Manual, volume 1, Freescale Semiconductor document order number HCS08RMV1/D.
The HCS08 CPU is fully source- and object-code-compatible with the M68HC08 CPU. Several
instructions and enhanced addressing modes were added to improve C compiler efficiency and to support
a new background debug system which replaces the monitor mode of earlier M68HC08 microcontrollers
(MCU).
7.1.1
Features
Features of the HCS08 CPU include:
• Object code fully upward-compatible with M68HC05 and M68HC08 Families
• 64-KB CPU address space with banked memory management unit for greater than 64 KB
• 16-bit stack pointer (any size stack anywhere in 64-KB CPU address space)
• 16-bit index register (H:X) with powerful indexed addressing modes
• 8-bit accumulator (A)
• Many instructions treat X as a second general-purpose 8-bit register
• Seven addressing modes:
— Inherent — Operands in internal registers
— Relative — 8-bit signed offset to branch destination
— Immediate — Operand in next object code byte(s)
— Direct — Operand in memory at 0x0000–0x00FF
— Extended — Operand anywhere in 64-Kbyte address space
— Indexed relative to H:X — Five submodes including auto increment
— Indexed relative to SP — Improves C efficiency dramatically
• Memory-to-memory data move instructions with four address mode combinations
• Overflow, half-carry, negative, zero, and carry condition codes support conditional branching on
the results of signed, unsigned, and binary-coded decimal (BCD) operations
• Efficient bit manipulation instructions
• Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
• STOP and WAIT instructions to invoke low-power operating modes
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Chapter 7 Central Processor Unit (S08CPUV5)
7.2
Programmer’s Model and CPU Registers
Figure 7-1 shows the five CPU registers. CPU registers are not part of the memory map.
7
0
ACCUMULATOR
A
16-BIT INDEX REGISTER H:X
H INDEX REGISTER (HIGH)
8
15
INDEX REGISTER (LOW)
7
X
0
SP
STACK POINTER
0
15
PROGRAM COUNTER
7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
PC
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 7-1. CPU Registers
7.2.1
Accumulator (A)
The A accumulator is a general-purpose 8-bit register. One operand input to the arithmetic logic unit
(ALU) is connected to the accumulator and the ALU results are often stored into the A accumulator after
arithmetic and logical operations. The accumulator can be loaded from memory using various addressing
modes to specify the address where the loaded data comes from, or the contents of A can be stored to
memory using various addressing modes to specify the address where data from A will be stored.
Reset has no effect on the contents of the A accumulator.
7.2.2
Index Register (H:X)
This 16-bit register is actually two separate 8-bit registers (H and X), which often work together as a 16-bit
address pointer where H holds the upper byte of an address and X holds the lower byte of the address. All
indexed addressing mode instructions use the full 16-bit value in H:X as an index reference pointer;
however, for compatibility with the earlier M68HC05 Family, some instructions operate only on the
low-order 8-bit half (X).
Many instructions treat X as a second general-purpose 8-bit register that can be used to hold 8-bit data
values. X can be cleared, incremented, decremented, complemented, negated, shifted, or rotated. Transfer
instructions allow data to be transferred from A or transferred to A where arithmetic and logical operations
can then be performed.
For compatibility with the earlier M68HC05 Family, H is forced to 0x00 during reset. Reset has no effect
on the contents of X.
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Chapter 7 Central Processor Unit (S08CPUV5)
7.2.3
Stack Pointer (SP)
This 16-bit address pointer register points at the next available location on the automatic last-in-first-out
(LIFO) stack. The stack may be located anywhere in the 64-Kbyte address space that has RAM and can
be any size up to the amount of available RAM. The stack is used to automatically save the return address
for subroutine calls, the return address and CPU registers during interrupts, and for local variables. The
AIS (add immediate to stack pointer) instruction adds an 8-bit signed immediate value to SP. This is most
often used to allocate or deallocate space for local variables on the stack.
SP is forced to 0x00FF at reset for compatibility with the earlier M68HC05 Family. HCS08 programs
normally change the value in SP to the address of the last location (highest address) in on-chip RAM
during reset initialization to free up direct page RAM (from the end of the on-chip registers to 0x00FF).
The RSP (reset stack pointer) instruction was included for compatibility with the M68HC05 Family and
is seldom used in new HCS08 programs because it only affects the low-order half of the stack pointer.
7.2.4
Program Counter (PC)
The program counter is a 16-bit register that contains the address of the next instruction or operand to be
fetched.
During normal program execution, the program counter automatically increments to the next sequential
memory location every time an instruction or operand is fetched. Jump, branch, interrupt, and return
operations load the program counter with an address other than that of the next sequential location. This
is called a change-of-flow.
During reset, the program counter is loaded with the reset vector that is located at 0xFFFE and 0xFFFF.
The vector stored there is the address of the first instruction that will be executed after exiting the reset
state.
7.2.5
Condition Code Register (CCR)
The 8-bit condition code register contains the interrupt mask (I) and five flags that indicate the results of
the instruction just executed. Bits 6 and 5 are set permanently to 1. The following paragraphs describe the
functions of the condition code bits in general terms. For a more detailed explanation of how each
instruction sets the CCR bits, refer to the HCS08 Family Reference Manual, volume 1, Freescale
Semiconductor document order number HCS08RMv1.
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Chapter 7 Central Processor Unit (S08CPUV5)
7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 7-2. Condition Code Register
Table 7-1. CCR Register Field Descriptions
Field
Description
7
V
Two’s Complement Overflow Flag — The CPU sets the overflow flag when a two’s complement overflow occurs.
The signed branch instructions BGT, BGE, BLE, and BLT use the overflow flag.
0 No overflow
1 Overflow
4
H
Half-Carry Flag — The CPU sets the half-carry flag when a carry occurs between accumulator bits 3 and 4 during
an add-without-carry (ADD) or add-with-carry (ADC) operation. The half-carry flag is required for binary-coded
decimal (BCD) arithmetic operations. The DAA instruction uses the states of the H and C condition code bits to
automatically add a correction value to the result from a previous ADD or ADC on BCD operands to correct the
result to a valid BCD value.
0 No carry between bits 3 and 4
1 Carry between bits 3 and 4
3
I
Interrupt Mask Bit — When the interrupt mask is set, all maskable CPU interrupts are disabled. CPU interrupts
are enabled when the interrupt mask is cleared. When a CPU interrupt occurs, the interrupt mask is set
automatically after the CPU registers are saved on the stack, but before the first instruction of the interrupt service
routine is executed.
Interrupts are not recognized at the instruction boundary after any instruction that clears I (CLI or TAP). This
ensures that the next instruction after a CLI or TAP will always be executed without the possibility of an intervening
interrupt, provided I was set.
0 Interrupts enabled
1 Interrupts disabled
2
N
Negative Flag — The CPU sets the negative flag when an arithmetic operation, logic operation, or data
manipulation produces a negative result, setting bit 7 of the result. Simply loading or storing an 8-bit or 16-bit value
causes N to be set if the most significant bit of the loaded or stored value was 1.
0 Non-negative result
1 Negative result
1
Z
Zero Flag — The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation
produces a result of 0x00 or 0x0000. Simply loading or storing an 8-bit or 16-bit value causes Z to be set if the
loaded or stored value was all 0s.
0 Non-zero result
1 Zero result
0
C
Carry/Borrow Flag — The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit
7 of the accumulator or when a subtraction operation requires a borrow. Some instructions — such as bit test and
branch, shift, and rotate — also clear or set the carry/borrow flag.
0 No carry out of bit 7
1 Carry out of bit 7
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7.3
Addressing Modes
Addressing modes define the way the CPU accesses operands and data. In the HCS08, memory, status and
control registers, and input/output (I/O) ports share a single 64-Kbyte CPU address space. This
arrangement means that the same instructions that access variables in RAM can also be used to access I/O
and control registers or nonvolatile program space.
NOTE
For more information about extended addressing modes, see the Memory
Management Unit section in the Memory chapter.
MCU derivatives with more than 64-Kbytes of memory also include a memory management unit (MMU)
to support extended memory space. A PPAGE register is used to manage 16-Kbyte pages of memory which
can be accessed by the CPU through a 16-Kbyte window from 0x8000 through 0xBFFF. The CPU includes
two special instructions (CALL and RTC). CALL operates like the JSR instruction except that CALL saves
the current PPAGE value on the stack and provides a new PPAGE value for the destination. RTC works
like the RTS instruction except RTC restores the old PPAGE value in addition to the PC during the return
from the called routine. The MMU also includes a linear address pointer register and data access registers
so that the extended memory space operates as if it was a single linear block of memory. For additional
information about the MMU, refer to the Memory chapter of this data sheet.
Some instructions use more than one addressing mode. For instance, move instructions use one addressing
mode to specify the source operand and a second addressing mode to specify the destination address.
Instructions such as BRCLR, BRSET, CBEQ, and DBNZ use one addressing mode to specify the location
of an operand for a test and then use relative addressing mode to specify the branch destination address
when the tested condition is true. For BRCLR, BRSET, CBEQ, and DBNZ, the addressing mode listed in
the instruction set tables is the addressing mode needed to access the operand to be tested, and relative
addressing mode is implied for the branch destination.
7.3.1
Inherent Addressing Mode (INH)
In this addressing mode, operands needed to complete the instruction (if any) are located within CPU
registers so the CPU does not need to access memory to get any operands.
7.3.2
Relative Addressing Mode (REL)
Relative addressing mode is used to specify the destination location for branch instructions. A signed 8-bit
offset value is located in the memory location immediately following the opcode. During execution, if the
branch condition is true, the signed offset is sign-extended to a 16-bit value and is added to the current
contents of the program counter, which causes program execution to continue at the branch destination
address.
7.3.3
Immediate Addressing Mode (IMM)
In immediate addressing mode, the operand needed to complete the instruction is included in the object
code immediately following the instruction opcode in memory. In the case of a 16-bit immediate operand,
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the high-order byte is located in the next memory location after the opcode, and the low-order byte is
located in the next memory location after that.
7.3.4
Direct Addressing Mode (DIR)
In direct addressing mode, the instruction includes the low-order eight bits of an address in the direct page
(0x0000–0x00FF). During execution a 16-bit address is formed by concatenating an implied 0x00 for the
high-order half of the address and the direct address from the instruction to get the 16-bit address where
the desired operand is located. This is faster and more memory efficient than specifying a complete 16-bit
address for the operand.
7.3.5
Extended Addressing Mode (EXT)
In extended addressing mode, the full 16-bit address of the operand is located in the next two bytes of
program memory after the opcode (high byte first).
7.3.6
Indexed Addressing Mode
Indexed addressing mode has seven variations including five that use the 16-bit H:X index register pair and
two that use the stack pointer as the base reference.
7.3.6.1
Indexed, No Offset (IX)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction.
7.3.6.2
Indexed, No Offset with Post Increment (IX+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction. The index register pair is then incremented
(H:X = H:X + 0x0001) after the operand has been fetched. This addressing mode is only used for MOV
and CBEQ instructions.
7.3.6.3
Indexed, 8-Bit Offset (IX1)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.4
Indexed, 8-Bit Offset with Post Increment (IX1+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
The index register pair is then incremented (H:X = H:X + 0x0001) after the operand has been fetched. This
addressing mode is used only for the CBEQ instruction.
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7.3.6.5
Indexed, 16-Bit Offset (IX2)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.6
SP-Relative, 8-Bit Offset (SP1)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus an unsigned 8-bit
offset included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.7
SP-Relative, 16-Bit Offset (SP2)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.4
Special Operations
The CPU performs a few special operations that are similar to instructions but do not have opcodes like
other CPU instructions. In addition, a few instructions such as STOP and WAIT directly affect other MCU
circuitry. This section provides additional information about these operations.
7.4.1
Reset Sequence
Reset can be caused by a power-on-reset (POR) event, internal conditions such as the COP (computer
operating properly) watchdog, or by assertion of an external active-low reset pin. When a reset event
occurs, the CPU immediately stops whatever it is doing (the MCU does not wait for an instruction
boundary before responding to a reset event). For a more detailed discussion about how the MCU
recognizes resets and determines the source, refer to the Resets, Interrupts, and System Configuration
chapter.
The reset event is considered concluded when the sequence to determine whether the reset came from an
internal source is done and when the reset pin is no longer asserted. At the conclusion of a reset event, the
CPU performs a 6-cycle sequence to fetch the reset vector from 0xFFFE and 0xFFFF and to fill the
instruction queue in preparation for execution of the first program instruction.
7.4.2
Interrupt Sequence
When an interrupt is requested, the CPU completes the current instruction before responding to the
interrupt. At this point, the program counter is pointing at the start of the next instruction, which is where
the CPU should return after servicing the interrupt. The CPU responds to an interrupt by performing the
same sequence of operations as for a software interrupt (SWI) instruction, except the address used for the
vector fetch is determined by the highest priority interrupt that is pending when the interrupt sequence
started.
The CPU sequence for an interrupt is:
1. Store the contents of PCL, PCH, X, A, and CCR on the stack, in that order.
2. Set the I bit in the CCR.
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3.
4.
5.
6.
Fetch the high-order half of the interrupt vector.
Fetch the low-order half of the interrupt vector.
Delay for one free bus cycle.
Fetch three bytes of program information starting at the address indicated by the interrupt vector
to fill the instruction queue in preparation for execution of the first instruction in the interrupt
service routine.
After the CCR contents are pushed onto the stack, the I bit in the CCR is set to prevent other interrupts
while in the interrupt service routine. Although it is possible to clear the I bit with an instruction in the
interrupt service routine, this would allow nesting of interrupts (which is not recommended because it
leads to programs that are difficult to debug and maintain).
For compatibility with the earlier M68HC05 MCUs, the high-order half of the H:X index register pair (H)
is not saved on the stack as part of the interrupt sequence. The user must use a PSHH instruction at the
beginning of the service routine to save H and then use a PULH instruction just before the RTI that ends
the interrupt service routine. It is not necessary to save H if you are certain that the interrupt service routine
does not use any instructions or auto-increment addressing modes that might change the value of H.
The software interrupt (SWI) instruction is like a hardware interrupt except that it is not masked by the
global I bit in the CCR and it is associated with an instruction opcode within the program so it is not
asynchronous to program execution.
7.4.3
Wait Mode Operation
The WAIT instruction enables interrupts by clearing the I bit in the CCR. It then halts the clocks to the
CPU to reduce overall power consumption while the CPU is waiting for the interrupt or reset event that
will wake the CPU from wait mode. When an interrupt or reset event occurs, the CPU clocks will resume
and the interrupt or reset event will be processed normally.
If a serial BACKGROUND command is issued to the MCU through the background debug interface while
the CPU is in wait mode, CPU clocks will resume and the CPU will enter active background mode where
other serial background commands can be processed. This ensures that a host development system can still
gain access to a target MCU even if it is in wait mode.
7.4.4
Stop Mode Operation
Usually, all system clocks, including the crystal oscillator (when used), are halted during stop mode to
minimize power consumption. In such systems, external circuitry is needed to control the time spent in
stop mode and to issue a signal to wake up the target MCU when it is time to resume processing. Unlike
the earlier M68HC05 and M68HC08 MCUs, the HCS08 can be configured to keep a minimum set of
clocks running in stop mode. This optionally allows an internal periodic signal to wake the target MCU
from stop mode.
When a host debug system is connected to the background debug pin (BKGD) and the ENBDM control
bit has been set by a serial command through the background interface (or because the MCU was reset into
active background mode), the oscillator is forced to remain active when the MCU enters stop mode. In this
case, if a serial BACKGROUND command is issued to the MCU through the background debug interface
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while the CPU is in stop mode, CPU clocks will resume and the CPU will enter active background mode
where other serial background commands can be processed. This ensures that a host development system
can still gain access to a target MCU even if it is in stop mode.
Recovery from stop mode depends on the particular HCS08 and whether the oscillator was stopped in stop
mode. Refer to the Modes of Operation chapter for more details.
7.4.5
BGND Instruction
The BGND instruction is new to the HCS08 compared to the M68HC08. BGND would not be used in
normal user programs because it forces the CPU to stop processing user instructions and enter the active
background mode. The only way to resume execution of the user program is through reset or by a host
debug system issuing a GO, TRACE1, or TAGGO serial command through the background debug
interface.
Software-based breakpoints can be set by replacing an opcode at the desired breakpoint address with the
BGND opcode. When the program reaches this breakpoint address, the CPU is forced to active background
mode rather than continuing the user program.
The CALL is similar to a jump-to-subroutine (JSR) instruction, but the subroutine that is called can be
located anywhere in the normal 64-Kbyte address space or on any page of program expansion memory.
When CALL is executed, a return address is calculated, then it and the current program page register value
are stacked, and a new instruction-supplied value is written to PPAGE. The PPAGE value controls which
of the possible 16-Kbyte pages is visible through the window in the 64-Kbyte memory map. Execution
continues at the address of the called subroutine.
The actual sequence of operations that occur during execution of CALL is:
1. CPU calculates the address of the next instruction after the CALL instruction (the return address)
and pushes this 16-bit value onto the stack, low byte first.
2. CPU reads the old PPAGE value and pushes it onto the stack.
3. CPU writes the new instruction-supplied page select value to PPAGE. This switches the destination
page into the program overlay window in the CPU address range 0x8000 0xBFFF.
4. Instruction queue is refilled starting from the destination address, and execution begins at the new
address.
This sequence of operations is an uninterruptable CPU instruction. There is no need to inhibit interrupts
during CALL execution. In addition, a CALL can be performed from any address in memory to any other
address. This is a big improvement over other bank-switching schemes, where the page switch operation
can be performed only by a program outside the overlay window.
For all practical purposes, the PPAGE value supplied by the instruction can be considered to be part of the
effective address. The new page value is provided by an immediate operand in the instruction.
The RTC instruction is used to terminate subroutines invoked by a CALL instruction. RTC unstacks the
PPAGE value and the return address, the queue is refilled, and execution resumes with the next instruction
after the corresponding CALL.
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The actual sequence of operations that occur during execution of RTC is:
1. The return value of the 8-bit PPAGE register is pulled from the stack.
2. The 16-bit return address is pulled from the stack and loaded into the PC.
3. The return PPAGE value is written to the PPAGE register.
4. The queue is refilled and execution begins at the new address.
Since the return operation is implemented as a single uninterruptable CPU instruction, the RTC can be
executed from anywhere in memory, including from a different page of extended memory in the overlay
window.
The CALL and RTC instructions behave like JSR and RTS, except they have slightly longer execution
times. Since extra execution cycles are required, routinely substituting CALL/RTC for JSR/RTS is not
recommended. JSR and RTS can be used to access subroutines that are located outside the program overlay
window or on the same memory page. However, if a subroutine can be called from other pages, it must be
terminated with an RTC. In this case, since RTC unstacks the PPAGE value as well as the return address,
all accesses to the subroutine, even those made from the same page, must use CALL instructions.
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7.5
HCS08 Instruction Set Summary
Table 7-2 provides a summary of the HCS08 instruction set in all possible addressing modes. The table
shows operand construction, execution time in internal bus clock cycles, and cycle-by-cycle details for
each addressing mode variation of each instruction.
ADC
ADC
ADC
ADC
ADC
ADC
ADC
ADC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ADD
ADD
ADD
ADD
ADD
ADD
ADD
ADD
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Add with Carry
A ← (A) + (M) + (C)
Add without Carry
A ← (A) + (M)
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A9
B9
C9
D9
E9
F9
9E D9
9E E9
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AB
BB
CB
DB
EB
FB
9E DB
9E EB
ii
dd
hh ll
ee ff
ff
ee ff
ff
ee ff
ff
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 1 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 ↕
– ↕ ↕ ↕
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 ↕
– ↕ ↕ ↕
AIS #opr8i
Add Immediate Value (Signed) to
Stack Pointer
SP ← (SP) + (M)
IMM
A7 ii
2
pp
– 1 1 –
– – – –
AIX #opr8i
Add Immediate Value (Signed) to
Index Register (H:X)
H:X ← (H:X) + (M)
IMM
AF ii
2
pp
– 1 1 –
– – – –
Logical AND
A ← (A) & (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A4
B4
C4
D4
E4
F4
9E D4
9E E4
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
DIR
INH
INH
IX1
IX
SP1
37 dd
47
57
67 ff
77
9E 67 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
AND
AND
AND
AND
AND
AND
AND
AND
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ASL opr8a
ASLA
ASLX
ASL oprx8,X
ASL ,X
ASL oprx8,SP
ASR opr8a
ASRA
ASRX
ASR oprx8,X
ASR ,X
ASR oprx8,SP
Arithmetic Shift Left
C
0
b7
b0
(Same as LSL)
Arithmetic Shift Right
C
b7
b0
ii
dd
hh ll
ee ff
ff
ee ff
ff
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Chapter 7 Central Processor Unit (S08CPUV5)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 2 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
Branch if Carry Bit Clear
(if C = 0)
REL
24 rr
3
ppp
– 1 1 –
– – – –
BCLR n,opr8a
Clear Bit n in Memory
(Mn ← 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 –
– – – –
BCS rel
Branch if Carry Bit Set (if C = 1)
(Same as BLO)
REL
25 rr
3
ppp
– 1 1 –
– – – –
BEQ rel
Branch if Equal (if Z = 1)
REL
27 rr
3
ppp
– 1 1 –
– – – –
BGE rel
Branch if Greater Than or Equal To
(if N ⊕ V = 0) (Signed)
REL
90 rr
3
ppp
– 1 1 –
– – – –
BGND
Enter active background if ENBDM=1
Waits for and processes BDM commands
until GO, TRACE1, or TAGGO
INH
82
5+
fp...ppp
– 1 1 –
– – – –
BGT rel
Branch if Greater Than (if Z | (N ⊕ V) = 0)
(Signed)
REL
92 rr
3
ppp
– 1 1 –
– – – –
BHCC rel
Branch if Half Carry Bit Clear (if H = 0)
REL
28 rr
3
ppp
– 1 1 –
– – – –
BHCS rel
Branch if Half Carry Bit Set (if H = 1)
REL
29 rr
3
ppp
– 1 1 –
– – – –
BHI rel
Branch if Higher (if C | Z = 0)
REL
22 rr
3
ppp
– 1 1 –
– – – –
BHS rel
Branch if Higher or Same (if C = 0)
(Same as BCC)
REL
24 rr
3
ppp
– 1 1 –
– – – –
BIH rel
Branch if IRQ Pin High (if IRQ pin = 1)
REL
2F rr
3
ppp
– 1 1 –
– – – –
BIL rel
Branch if IRQ Pin Low (if IRQ pin = 0)
REL
2E rr
3
ppp
– 1 1 –
– – – –
Bit Test
(A) & (M)
(CCR Updated but Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
BCC rel
BIT
BIT
BIT
BIT
BIT
BIT
BIT
BIT
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
A5
B5
C5
D5
E5
F5
9E D5
9E E5
ii
dd
hh ll
ee ff
ff
ee ff
ff
BLE rel
Branch if Less Than or Equal To
(if Z | (N ⊕ V) = 1) (Signed)
REL
93 rr
3
ppp
– 1 1 –
– – – –
BLO rel
Branch if Lower (if C = 1) (Same as BCS)
REL
25 rr
3
ppp
– 1 1 –
– – – –
BLS rel
Branch if Lower or Same (if C | Z = 1)
REL
23 rr
3
ppp
– 1 1 –
– – – –
BLT rel
Branch if Less Than (if N ⊕ V = 1) (Signed)
REL
91 rr
3
ppp
– 1 1 –
– – – –
BMC rel
Branch if Interrupt Mask Clear (if I = 0)
REL
2C rr
3
ppp
– 1 1 –
– – – –
BMI rel
Branch if Minus (if N = 1)
REL
2B rr
3
ppp
– 1 1 –
– – – –
BMS rel
Branch if Interrupt Mask Set (if I = 1)
REL
2D rr
3
ppp
– 1 1 –
– – – –
BNE rel
Branch if Not Equal (if Z = 0)
REL
26 rr
3
ppp
– 1 1 –
– – – –
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Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 3 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
BPL rel
Branch if Plus (if N = 0)
REL
2A rr
3
ppp
– 1 1 –
– – – –
BRA rel
Branch Always (if I = 1)
REL
20 rr
3
ppp
– 1 1 –
– – – –
BRCLR n,opr8a,rel
Branch if Bit n in Memory Clear (if (Mn) = 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 –
– – – ↕
BRN rel
Branch Never (if I = 0)
REL
21 rr
3
ppp
– 1 1 –
– – – –
Branch if Bit n in Memory Set (if (Mn) = 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 –
– – – ↕
BSET n,opr8a
Set Bit n in Memory (Mn ← 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 –
– – – –
BSR rel
Branch to Subroutine
PC ← (PC) + $0002
push (PCL); SP ← (SP) – $0001
push (PCH); SP ← (SP) – $0001
PC ← (PC) + rel
REL
AD rr
5
ssppp
– 1 1 –
– – – –
CALL page, opr16a
Call Subroutine
EXT
AC pg hhll
8
ppsssppp
– 1 1 –
– – – –
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and...
5
4
4
5
5
6
rpppp
pppp
pppp
rpppp
rfppp
prpppp
– 1 1 –
– – – –
CLC
Clear Carry Bit (C ← 0)
INH
98
1
p
– 1 1 –
– – – 0
CLI
Clear Interrupt Mask Bit (I ← 0)
INH
9A
1
p
– 1 1 –
0 – – –
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
Clear
DIR
INH
INH
INH
IX1
IX
SP1
3F dd
4F
5F
8C
6F ff
7F
9E 6F ff
5
1
1
1
5
4
6
rfwpp
p
p
p
rfwpp
rfwp
prfwpp
0 1 1 –
– 0 1 –
BRSET n,opr8a,rel
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (X) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
DIR
IMM
IMM
IX1+
IX+
SP1
31
41
51
61
71
9E 61
dd
dd
dd
dd
dd
dd
dd
dd
dd
ii
ii
ff
rr
ff
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
133
Chapter 7 Central Processor Unit (S08CPUV5)
CMP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Compare Accumulator with Memory
A–M
(CCR Updated But Operands Not Changed)
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A1
B1
C1
D1
E1
F1
9E D1
9E E1
ii
dd
hh ll
ee ff
ff
ee ff
ff
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 4 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 –
– ↕ ↕ ↕
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
Complement
M ← (M)= $FF – (M)
(One’s Complement) A ← (A) = $FF – (A)
X ← (X) = $FF – (X)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
INH
IX1
IX
SP1
33 dd
43
53
63 ff
73
9E 63 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
0 1 1 –
– ↕ ↕ 1
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
Compare Index Register (H:X) with Memory
(H:X) – (M:M + $0001)
(CCR Updated But Operands Not Changed)
EXT
IMM
DIR
SP1
3E
65
75
9E F3
hh ll
jj kk
dd
ff
6
3
5
6
prrfpp
ppp
rrfpp
prrfpp
↕ 1 1 –
– ↕ ↕ ↕
Compare X (Index Register Low) with
Memory
X–M
(CCR Updated But Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A3
B3
C3
D3
E3
F3
9E D3
9E E3
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 –
– ↕ ↕ ↕
1
p
U 1 1 –
– ↕ ↕ ↕
7
4
4
7
6
8
rfwpppp
fppp
fppp
rfwpppp
rfwppp
prfwpppp
– 1 1 –
– – – –
CPX
CPX
CPX
CPX
CPX
CPX
CPX
CPX
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
DAA
Decimal Adjust Accumulator
After ADD or ADC of BCD Values
INH
72
DBNZ opr8a,rel
DBNZA rel
DBNZX rel
DBNZ oprx8,X,rel
DBNZ ,X,rel
DBNZ oprx8,SP,rel
DIR
INH
Decrement A, X, or M and Branch if Not Zero
INH
(if (result) ≠ 0)
IX1
DBNZX Affects X Not H
IX
SP1
3B
4B
5B
6B
7B
9E 6B
DEC opr8a
DECA
DECX
DEC oprx8,X
DEC ,X
DEC oprx8,SP
Decrement
Divide
A ← (H:A)÷(X); H ← Remainder
DIV
EOR
EOR
EOR
EOR
EOR
EOR
EOR
EOR
M ← (M) – $01
A ← (A) – $01
X ← (X) – $01
M ← (M) – $01
M ← (M) – $01
M ← (M) – $01
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Exclusive OR Memory with Accumulator
A ← (A ⊕ M)
ee ff
ff
dd rr
rr
rr
ff rr
rr
ff rr
DIR
INH
INH
IX1
IX
SP1
3A dd
4A
5A
6A ff
7A
9E 6A ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ –
INH
52
6
fffffp
– 1 1 –
– – ↕ ↕
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A8
B8
C8
D8
E8
F8
9E D8
9E E8
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
ii
dd
hh ll
ee ff
ff
ee ff
ff
MC9S08AC128 Series Reference Manual, Rev. 3
134
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV5)
INC opr8a
INCA
INCX
INC oprx8,X
INC ,X
INC oprx8,SP
Operation
Increment
M ← (M) + $01
A ← (A) + $01
X ← (X) + $01
M ← (M) + $01
M ← (M) + $01
M ← (M) + $01
Object Code
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 5 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
DIR
INH
INH
IX1
IX
SP1
3C dd
4C
5C
6C ff
7C
9E 6C ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ –
BC
CC
DC
EC
FC
dd
hh ll
ee ff
ff
3
4
4
3
3
ppp
pppp
pppp
ppp
ppp
– 1 1 –
– – – –
JMP
JMP
JMP
JMP
JMP
opr8a
opr16a
oprx16,X
oprx8,X
,X
Jump
PC ← Jump Address
DIR
EXT
IX2
IX1
IX
JSR
JSR
JSR
JSR
JSR
opr8a
opr16a
oprx16,X
oprx8,X
,X
Jump to Subroutine
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
PC ← Unconditional Address
DIR
EXT
IX2
IX1
IX
BD
CD
DD
ED
FD
dd
hh ll
ee ff
ff
5
6
6
5
5
ssppp
pssppp
pssppp
ssppp
ssppp
– 1 1 –
– – – –
LDA
LDA
LDA
LDA
LDA
LDA
LDA
LDA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Load Accumulator from Memory
A ← (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A6
B6
C6
D6
E6
F6
9E D6
9E E6
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
Load Index Register (H:X)
H:X ← (M:M + $0001)
IMM
DIR
EXT
IX
IX2
IX1
SP1
jj kk
dd
hh ll
9E
9E
9E
9E
45
55
32
AE
BE
CE
FE
3
4
5
5
6
5
5
ppp
rrpp
prrpp
prrfp
pprrpp
prrpp
prrpp
0 1 1 –
– ↕ ↕ –
Load X (Index Register Low) from Memory
X ← (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AE
BE
CE
DE
EE
FE
9E DE
9E EE
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
DIR
INH
INH
IX1
IX
SP1
34 dd
44
54
64 ff
74
9E 64 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– 0 ↕ ↕
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
LDX
LDX
LDX
LDX
LDX
LDX
LDX
LDX
#opr16i
opr8a
opr16a
,X
oprx16,X
oprx8,X
oprx8,SP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
LSL opr8a
LSLA
LSLX
LSL oprx8,X
LSL ,X
LSL oprx8,SP
LSR opr8a
LSRA
LSRX
LSR oprx8,X
LSR ,X
LSR oprx8,SP
Logical Shift Left
C
0
b7
b0
(Same as ASL)
Logical Shift Right
0
C
b7
b0
ee ff
ff
ee ff
ff
ff
ee ff
ff
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
135
Chapter 7 Central Processor Unit (S08CPUV5)
Operation
Object Code
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
Move
(M)destination ← (M)source
In IX+/DIR and DIR/IX+ Modes,
H:X ← (H:X) + $0001
DIR/DIR
DIR/IX+
IMM/DIR
IX+/DIR
4E
5E
6E
7E
MUL
Unsigned multiply
X:A ← (X) × (A)
INH
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
Negate
M ← – (M) = $00 – (M)
(Two’s Complement) A ← – (A) = $00 – (A)
X ← – (X) = $00 – (X)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
NOP
NSA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 6 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
5
5
4
5
rpwpp
rfwpp
pwpp
rfwpp
0 1 1 –
– ↕ ↕ –
42
5
ffffp
– 1 1 0
– – – 0
DIR
INH
INH
IX1
IX
SP1
30 dd
40
50
60 ff
70
9E 60 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
No Operation — Uses 1 Bus Cycle
INH
9D
1
p
– 1 1 –
– – – –
Nibble Swap Accumulator
A ← (A[3:0]:A[7:4])
INH
62
1
p
– 1 1 –
– – – –
Inclusive OR Accumulator and Memory
A ← (A) | (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9E DA
9E EA
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 –
– ↕ ↕ –
dd dd
dd
ii dd
dd
ii
dd
hh ll
ee ff
ff
ee ff
ff
PSHA
Push Accumulator onto Stack
Push (A); SP ← (SP) – $0001
INH
87
2
sp
– 1 1 –
– – – –
PSHH
Push H (Index Register High) onto Stack
Push (H); SP ← (SP) – $0001
INH
8B
2
sp
– 1 1 –
– – – –
PSHX
Push X (Index Register Low) onto Stack
Push (X); SP ← (SP) – $0001
INH
89
2
sp
– 1 1 –
– – – –
PULA
Pull Accumulator from Stack
SP ← (SP + $0001); Pull (A)
INH
86
3
ufp
– 1 1 –
– – – –
PULH
Pull H (Index Register High) from Stack
SP ← (SP + $0001); Pull (H)
INH
8A
3
ufp
– 1 1 –
– – – –
PULX
Pull X (Index Register Low) from Stack
SP ← (SP + $0001); Pull (X)
INH
88
3
ufp
– 1 1 –
– – – –
DIR
INH
INH
IX1
IX
SP1
39 dd
49
59
69 ff
79
9E 69 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
DIR
INH
INH
IX1
IX
SP1
36 dd
46
56
66 ff
76
9E 66 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
↕ 1 1 –
– ↕ ↕ ↕
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
Rotate Left through Carry
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Rotate Right through Carry
C
b7
b0
C
b7
b0
MC9S08AC128 Series Reference Manual, Rev. 3
136
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV5)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 7 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
RSP
Reset Stack Pointer (Low Byte)
SPL ← $FF
(High Byte Not Affected)
INH
9C
1
p
– 1 1 –
– – – –
RTC
Return from CALL
INH
8D
7
uuufppp
– 1 1 –
– – – –
RTI
Return from Interrupt
SP ← (SP) + $0001; Pull (CCR)
SP ← (SP) + $0001; Pull (A)
SP ← (SP) + $0001; Pull (X)
SP ← (SP) + $0001; Pull (PCH)
SP ← (SP) + $0001; Pull (PCL)
INH
80
9
uuuuufppp
↕ 1 1 ↕
↕ ↕ ↕ ↕
RTS
Return from Subroutine
SP ← SP + $0001; Pull (PCH)
SP ← SP + $0001; Pull (PCL)
INH
81
5
ufppp
– 1 1 –
– – – –
Subtract with Carry
A ← (A) – (M) – (C)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A2
B2
C2
D2
E2
F2
9E D2
9E E2
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 –
– ↕ ↕ ↕
SBC
SBC
SBC
SBC
SBC
SBC
SBC
SBC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ii
dd
hh ll
ee ff
ff
ee ff
ff
SEC
Set Carry Bit
(C ← 1)
INH
99
1
p
– 1 1 –
– – – 1
SEI
Set Interrupt Mask Bit
(I ← 1)
INH
9B
1
p
– 1 1 –
1 – – –
Store Accumulator in Memory
M ← (A)
DIR
EXT
IX2
IX1
IX
SP2
SP1
B7
C7
D7
E7
F7
9E D7
9E E7
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 –
– ↕ ↕ –
ee ff
ff
3
4
4
3
2
5
4
35 dd
96 hh ll
9E FF ff
4
5
5
wwpp
pwwpp
pwwpp
0 1 1 –
– ↕ ↕ –
2
fp...
– 1 1 –
0 – – –
3
4
4
3
2
5
4
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 –
– ↕ ↕ –
STA
STA
STA
STA
STA
STA
STA
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
STHX opr8a
STHX opr16a
STHX oprx8,SP
Store H:X (Index Reg.)
(M:M + $0001) ← (H:X)
DIR
EXT
SP1
STOP
Enable Interrupts: Stop Processing
Refer to MCU Documentation
I bit ← 0; Stop Processing
INH
8E
Store X (Low 8 Bits of Index Register)
in Memory
M ← (X)
DIR
EXT
IX2
IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9E DF
9E EF
STX
STX
STX
STX
STX
STX
STX
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
dd
hh ll
ee ff
ff
dd
hh ll
ee ff
ff
ee ff
ff
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
137
Chapter 7 Central Processor Unit (S08CPUV5)
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A0
B0
C0
D0
E0
F0
9E D0
9E E0
SWI
Software Interrupt
PC ← (PC) + $0001
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
Push (X); SP ← (SP) – $0001
Push (A); SP ← (SP) – $0001
Push (CCR); SP ← (SP) – $0001
I ← 1;
PCH ← Interrupt Vector High Byte
PCL ← Interrupt Vector Low Byte
INH
TAP
Transfer Accumulator to CCR
CCR ← (A)
TAX
TPA
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 8 of 9)
Cyc-by-Cyc
Details
Affect
on CCR
V11H
INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
↕ 1 1 –
– ↕ ↕ ↕
83
11
sssssvvfppp
– 1 1 –
1 – – –
INH
84
1
p
↕ 1 1 ↕
↕ ↕ ↕ ↕
Transfer Accumulator to X (Index Register
Low)
X ← (A)
INH
97
1
p
– 1 1 –
– – – –
Transfer CCR to Accumulator
A ← (CCR)
INH
85
1
p
– 1 1 –
– – – –
DIR
INH
INH
IX1
IX
SP1
3D dd
4D
5D
6D ff
7D
9E 6D ff
4
1
1
4
3
5
rfpp
p
p
rfpp
rfp
prfpp
0 1 1 –
– ↕ ↕ –
Subtract
A ← (A) – (M)
Test for Negative or Zero
(M) – $00
(A) – $00
(X) – $00
(M) – $00
(M) – $00
(M) – $00
ii
dd
hh ll
ee ff
ff
ee ff
ff
TSX
Transfer SP to Index Reg.
H:X ← (SP) + $0001
INH
95
2
fp
– 1 1 –
– – – –
TXA
Transfer X (Index Reg. Low) to Accumulator
A ← (X)
INH
9F
1
p
– 1 1 –
– – – –
MC9S08AC128 Series Reference Manual, Rev. 3
138
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV5)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 9 of 9)
Affect
on CCR
Cyc-by-Cyc
Details
V11H
INZC
TXS
Transfer Index Reg. to SP
SP ← (H:X) – $0001
INH
94
2
fp
– 1 1 –
– – – –
WAIT
Enable Interrupts; Wait for Interrupt
I bit ← 0; Halt CPU
INH
8F
2+
fp...
– 1 1 –
0 – – –
Source Form: Everything in the source forms columns, except expressions in italic characters, is literal information which must appear in the
assembly source file exactly as shown. The initial 3- to 5-letter mnemonic and the characters (# , ( ) and +) are always a literal characters.
n
Any label or expression that evaluates to a single integer in the range 0-7.
opr8i
Any label or expression that evaluates to an 8-bit immediate value.
opr16i Any label or expression that evaluates to a 16-bit immediate value.
opr8a
Any label or expression that evaluates to an 8-bit direct-page address ($00xx).
opr16a Any label or expression that evaluates to a 16-bit address.
oprx8
Any label or expression that evaluates to an unsigned 8-bit value, used for indexed addressing.
oprx16 Any label or expression that evaluates to a 16-bit value, used for indexed addressing.
rel
Any label or expression that refers to an address that is within –128 to +127 locations from the start of the next instruction.
Operation Symbols:
A
Accumulator
CCR Condition code register
H
Index register high byte
M
Memory location
n
Any bit
opr
Operand (one or two bytes)
PC
Program counter
PCH Program counter high byte
PCL Program counter low byte
rel
Relative program counter offset byte
SP
Stack pointer
SPL Stack pointer low byte
X
Index register low byte
&
Logical AND
|
Logical OR
⊕
Logical EXCLUSIVE OR
()
Contents of
+
Add
–
Subtract, Negation (two’s complement)
×
Multiply
÷
Divide
#
Immediate value
←
Loaded with
:
Concatenated with
Addressing Modes:
DIR Direct addressing mode
EXT Extended addressing mode
IMM Immediate addressing mode
INH Inherent addressing mode
IX
Indexed, no offset addressing mode
IX1
Indexed, 8-bit offset addressing mode
IX2
Indexed, 16-bit offset addressing mode
IX+
Indexed, no offset, post increment addressing mode
IX1+ Indexed, 8-bit offset, post increment addressing mode
REL Relative addressing mode
SP1 Stack pointer, 8-bit offset addressing mode
SP2 Stack pointer 16-bit offset addressing mode
CCR Bits:
V
Overflow bit
H
Half-carry bit
I
Interrupt mask
N
Negative bit
Z
Zero bit
C
Carry/borrow bit
CCR Effects:
↕
Set or cleared
–
Not affected
U
Undefined
Cycle-by-Cycle Codes:
f
Free cycle. This indicates a cycle where the CPU
does not require use of the system buses. An f
cycle is always one cycle of the system bus clock
and is always a read cycle.
p
Program fetch; read from next consecutive
location in program memory
r
Read 8-bit operand
s
Push (write) one byte onto stack
u
Pop (read) one byte from stack
v
Read vector from $FFxx (high byte first)
w
Write 8-bit operand
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
139
Chapter 7 Central Processor Unit (S08CPUV5)
Table 7-3. Opcode Map (Sheet 1 of 2)
Bit-Manipulation
00
5 10
5
BRSET0
3
01
BRCLR1
3
04
BRSET2
3
05
3
07
BRSET4
3
09
3
0B
BRCLR5
3
0C
BRSET6
3
0D
BRCLR6
3
0E
BRSET7
3
0F
BRCLR7
3
INH
IMM
DIR
EXT
DD
IX+D
DIR 2
5 2F
Inherent
Immediate
Direct
Extended
DIR to DIR
IX+ to DIR
CPHX
REL 3
3 3F
BIH
REL 2
REL
IX
IX1
IX2
IMD
DIX+
MOV
EXT 3
5 4F
CLR
DIR 1
ASR
INH 2
1 68
ROL
INH 2
4 6B
DBNZ
INH 1
2 9B
TST
MOV
STOP
CLR
Page 2
INH
2+ 9F
WAIT
IX 1
Stack Pointer, 8-Bit Offset
Stack Pointer, 16-Bit Offset
Indexed, No Offset with
Post Increment
Indexed, 1-Byte Offset with
Post Increment
INH 1
1
JSR
REL 2
2 BE
LDX
2
AF
TXA
INH 2
JMP
DIR 3
5 CD
JSR
DIR 3
3 CE
LDX
IMM 2
2 BF
AIX
LDX
DIR 3
3 CF
STX
IMM 2
EXT 3
4 DF
STX
DIR 3
EXT 3
Opcode in
Hexadecimal F0
EOR
ADC
IX2 2
IX
2
STA
IX
3
EOR
IX
3
ADC
IX1 1
3 FA
ORA
IX
3
ORA
IX1 1
3 FB
ADD
JSR
LDX
IX1 1
3 FF
IX
5
JSR
IX1 1
3 FE
IX1 1
IX
3
JMP
IX1 1
5 FD
STX
IX
3
ADD
IX1 1
3 FC
JMP
IX2 2
4 EF
STX
IX
3
LDA
IX1 1
3 F9
IX2 2
4 EE
LDX
BIT
IX1 1
3 F8
IX2 2
6 ED
JSR
EXT 3
4 DE
IX
3
STA
IX2 2
4 EC
JMP
EXT 3
6 DD
AND
IX1 1
3 F7
IX2 2
4 EB
ADD
EXT 3
4 DC
IX
3
LDA
IX2 2
4 EA
ORA
EXT 3
4 DB
ADD
JMP
EXT 2
5 BD
BSR
INH 2
AE
ORA
CPX
IX1 1
3 F6
IX2 2
4 E9
ADC
EXT 3
4 DA
IX
3
BIT
IX2 2
4 E8
EOR
IX
3
SBC
IX1 1
3 F5
STA
ADC
DIR 3
3 CC
AND
IX2 2
4 E7
EXT 3
4 D9
CMP
IX1 1
3 F4
IX2 2
4 E6
EXT 3
4 D8
EOR
DIR 3
3 CB
ADD
IMM 2
8 BC
CALL
INH 4
1 AD
NOP
INH 1
2+ 9E
IMM 2
2 BB
CPX
LDA
STA
IX
3
IX1 1
3 F3
IX2 2
4 E5
EXT 3
4 D7
DIR 3
3 CA
ORA
ADD
INH 2
1 AC
RSP
INH 1
7 9D
ADC
SBC
BIT
LDA
DIR 3
3 C9
IMM 2
2 BA
ORA
SEI
RTC
IX 1
5 8E
ADC
INH 2
1 AB
INH 1
1 9C
EOR
AND
3
SUB
IX1 1
3 F2
IX2 2
4 E4
EXT 3
4 D6
DIR 3
3 C8
IMM 2
2 B9
INH 2
1 AA
CLI
CLRH
IMD 2
IX+D 1
5 7F
4 8F
IX1 1
SEC
INH 1
3 9A
PSHH
IX 1
3 8D
EOR
CPX
BIT
STA
CMP
IX2 2
4 E3
EXT 3
4 D5
DIR 3
3 C7
IMM 2
2 B8
INH 2
1 A9
PULH
IX 1
4 8C
INC
IX1 1
4 7E
CLR
INH 2
IX1+
DBNZ
IX1 1
4 7D
MOV
PSHX
IX 1
6 8B
IX1 2
5 7C
CLC
INH 1
2 99
IX 1
4 8A
DEC
TST
INH 2
5 6E
SP1
SP2
IX+
ROL
INC
INH 2
1 6D
PULX
AND
LDA
AIS
INH 2
1 A8
SBC
F0
IX1 1
3 F1
IX2 2
4 E2
EXT 3
4 D4
DIR 3
3 C6
IMM 2
2 B7
TAX
INH 1
3 98
CPX
BIT
LDA
CMP
EXT 3
4 D3
DIR 3
3 C5
IMM 2
2 B6
EXT 2
1 A7
PSHA
IX 1
4 89
IX1 1
7 7B
INH 3
1 6C
CLRX
Relative
Indexed, No Offset
Indexed, 8-Bit Offset
Indexed, 16-Bit Offset
IMM to DIR
DIR to IX+
LSL
STHX
INH 3
2 97
IX 1
4 88
IX1 1
5 7A
DEC
DD 2
DIX+ 3
1 5F
1 6F
INH 1
ASR
IX1 1
5 79
INH 2
1 6A
MOV
CLRA
IX 1
4 87
LSL
INH 2
1 69
PULA
AND
BIT
INH 2
5 A6
SBC
3
SUB
IX2 2
4 E1
EXT 3
4 D2
DIR 3
3 C4
IMM 2
2 B5
TSX
INH 1
3 96
CPX
AND
CMP
E0
SUB
EXT 3
4 D1
DIR 3
3 C3
IMM 2
2 B4
INH 2
2 A5
TPA
DIR 1
4 86
IX1 1
5 78
TSTX
INH 1
5 5E
CPHX
ROR
TXS
INH 1
1 95
SBC
CPX
SUB
DIR 3
3 C2
IMM 2
2 B3
REL 2
2 A4
TAP
IX 1
5 85
IX1 1
5 77
INCX
INH 1
1 5D
TSTA
DIR 1
6 4E
INH 2
1 67
DBNZX
INH 2
1 5C
INCA
DIR 1
4 4D
TST
REL 2
3 3E
INH 1
4 5B
LSR
CMP
SBC
BLE
Register/Memory
C0
4 D0
4
DIR 3
3 C1
IMM 2
2 B2
REL 2
3 A3
INH 2
1 94
3
SUB
CMP
BGT
SWI
B0
IMM 2
2 B1
REL 2
3 A2
INH 2
11 93
IX 1
4 84
IMM 2
5 76
ROR
DECX
DBNZA
DIR 2
5 4C
INC
REL 2
3 3D
BIL
DECA
DIR 1
7 4B
DBNZ
BMS
DIR 2
5 2E
DIR 2
DEC
CPHX
DIR 3
1 66
BGND
2
SUB
BLT
INH 2
5+ 92
COM
A0
REL 2
3 A1
RTS
INH 1
4 83
IX1 1
3 75
ROLX
INH 1
1 5A
DAA
3
BGE
INH 2
6 91
IX+ 1
1 82
LSR
LSLX
INH 1
1 59
CBEQ
IX1 1
5 74
INH 2
4 65
ASRX
INH 1
1 58
ROLA
DIR 1
5 4A
BMC
DIR 2
5 2D
BCLR7
DIR 2
ROL
REL 3
3 3C
INH 1
1 57
LSLA
DIR 1
5 49
REL 2
3 3B
BMI
DIR 2
5 2C
BSET7
DIR 2
5 1F
LSL
COM
RTI
IX 1
5 81
INH 1
5 73
INH 2
1 64
RORX
ASRA
DIR 1
5 48
REL 2
3 3A
DIR 2
5 2B
BCLR6
DIR 2
5 1E
ASR
BHCS
BPL
RORA
DIR 1
5 47
REL 2
3 39
DIR 2
5 2A
BSET6
DIR 2
5 1D
ROR
INH 1
1 63
Control
9 90
80
NEG
NSA
LDHX
IMM 2
1 56
4
IX1+ 2
1 72
LSRX
INH 1
3 55
LDHX
DIR 3
5 46
BHCC
DIR 2
5 29
BCLR5
DIR 2
5 1C
STHX
CBEQ
COMX
INH 1
1 54
LSRA
DIR 1
4 45
REL 2
3 38
INH 1
1 53
70
IX1 1
5 71
IMM 3
6 62
DIV
COMA
DIR 1
5 44
LSR
BEQ
BSET5
DIR 2
5 1B
COM
REL 2
3 37
DIR 2
5 28
BCLR4
DIR 2
5 1A
BRSET5
BNE
MUL
5
NEG
INH 2
4 61
CBEQX
IMM 3
5 52
EXT 1
5 43
REL 2
3 36
DIR 2
5 27
BSET4
DIR 2
5 19
BRCLR4
3
0A
BCS
DIR 2
5 26
CBEQA
LDHX
REL 2
3 35
NEGX
INH 1
4 51
DIR 3
5 42
BCC
BCLR3
DIR 2
5 18
CBEQ
REL 2
3 34
DIR 2
5 25
BSET3
DIR 2
5 17
BRCLR3
3
08
BLS
NEGA
DIR 1
5 41
REL 3
3 33
DIR 2
5 24
BCLR2
DIR 2
5 16
BRSET3
DIR 2
5 23
Read-Modify-Write
1 50
1 60
40
NEG
REL 3
3 32
BHI
BSET2
DIR 2
5 15
BRCLR2
3
06
BRN
DIR 2
5 22
BCLR1
DIR 2
5 14
5
REL 2
3 31
BSET1
DIR 2
5 13
30
BRA
DIR 2
5 21
BCLR0
DIR 2
5 12
BRSET1
3
03
BSET0
DIR 2
5 11
BRCLR0
3
02
Branch
20
3
IX
3
LDX
IX
2
STX
IX
3 HCS08 Cycles
Instruction Mnemonic
IX Addressing Mode
SUB
Number of Bytes 1
MC9S08AC128 Series Reference Manual, Rev. 3
140
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV5)
Table 7-3. Opcode Map (Sheet 2 of 2)
Bit-Manipulation
Branch
Read-Modify-Write
9E60
Control
Register/Memory
9ED0 5
6
NEG
CMP
SP1
CMP
4
SP2 3
SP1
9ED2 5 9EE2 4
SBC
9E63
SBC
4
SP2 3
SP1
9ED3 5 9EE3 4 9EF3
6
COM
CPX
3
SP1
9E64
6
CPX
AND
SP1
SP1
AND
4
SP2 3
SP1
9ED5 5 9EE5 4
BIT
BIT
6
4
SP2 3
SP1
9ED6 5 9EE6 4
3
SP1
9E67
6
4
SP2 3
SP1
9ED7 5 9EE7 4
9E66
6
CPHX
4
SP2 3
SP1 3
9ED4 5 9EE4 4
LSR
3
4
SUB
4
SP2 3
SP1
9ED1 5 9EE1 4
CBEQ
4
9EE0
SUB
3
SP1
9E61
6
ROR
LDA
ASR
LDA
STA
3
SP1
9E68
6
STA
4
SP2 3
SP1
9ED8 5 9EE8 4
LSL
EOR
3
SP1
9E69
6
EOR
4
SP2 3
SP1
9ED9 5 9EE9 4
ROL
ADC
3
SP1
9E6A 6
ADC
4
SP2 3
SP1
9EDA 5 9EEA 4
DEC
ORA
3
SP1
9E6B 8
ORA
4
SP2 3
SP1
9EDB 5 9EEB 4
DBNZ
ADD
4
SP1
9E6C 6
4
ADD
SP2 3
SP1
INC
3
SP1
9E6D 5
TST
3
SP1
9EAE
5
9EBE
LDHX
2
9E6F
IX 4
6
9ECE
LDHX
5
9EDE
LDHX
IX2 3
6
CLR
3
INH
IMM
DIR
EXT
DD
IX+D
Inherent
Immediate
Direct
Extended
DIR to DIR
IX+ to DIR
REL
IX
IX1
IX2
IMD
DIX+
Relative
Indexed, No Offset
Indexed, 8-Bit Offset
Indexed, 16-Bit Offset
IMM to DIR
DIR to IX+
SP1
SP2
IX+
IX1+
Note: All Sheet 2 Opcodes are Preceded by the Page 2 Prebyte (9E)
5
9EEE
LDX
4
9EFE
LDX
5
LDHX
IX1 4
SP2 3
SP1 3
SP1
9EDF 5 9EEF 4 9EFF 5
STX
SP1
4
SP2 3
STX
SP1 3
STHX
SP1
Stack Pointer, 8-Bit Offset
Stack Pointer, 16-Bit Offset
Indexed, No Offset with
Post Increment
Indexed, 1-Byte Offset with
Post Increment
Prebyte (9E) and Opcode in
Hexadecimal 9E60
6
HCS08 Cycles
Instruction Mnemonic
SP1 Addressing Mode
NEG
Number of Bytes 3
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
141
Chapter 7 Central Processor Unit (S08CPUV5)
MC9S08AC128 Series Reference Manual, Rev. 3
142
Freescale Semiconductor
Chapter 8
Analog-to-Digital Converter (S08ADC10V1)
8.1
Overview
The 10-bit analog-to-digital converter (ADC) is a successive approximation ADC designed for operation
within an integrated microcontroller system-on-chip. The ADC module design supports up to 28 separate
analog inputs (AD0-AD27). Only 18 (AD0-AD15, AD26 and AD27) of the possible inputs are
implemented on the MC9S08AC128 Series Family of MCUs. These inputs are selected by the ADCH bits.
Some inputs are shared with I/O pins as shown in Figure 8-1. All of the channel assignments of the ADC
for the MC9S08AC128 Series devices are summarized in Table 8-1.
MC9S08AC128 Series Reference Manual, Rev. 3
Freescale Semiconductor
143
Chapter 8 Analog-to-Digital Converter (S08ADC10V1)
HCS08 CORE
IRQ
LVD
VDDAD
EXTAL
XTAL
LOW-POWER OSC
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
VOLTAGE REGULATOR
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT H
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
TPM1CH0–TPM1CH5
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PORT J
VSS
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
PORT E
VDD
PORT A
COP
PORT B
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
IRQ/TPMCLK
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT C
HCS08 SYSTEM CONTROL
RESET
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
PORT D
CPU
BDC
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 8-1. MC9S08AC128 Block Diagram Highlighting ADC Block and Pins
MC9S08AC128 Series Reference Manual, Rev. 3
144
Freescale Semiconductor
Chapter 8 Analog-to-Digital Converter (S08ADC10V1)
8.2
Channel Assignments
The ADC channel assignments for the MC9S08AC128 Series devices are shown in the table below.
Channels that are unimplemented are internally connected to VREFL. Reserved channels convert to an
unknown value. Channels which are connected to an I/O pin have an associated pin control bit as shown.
Table 8-1. ADC Channel Assignment
1
ADCH
Channel
Input
Pin Control
ADCH
Channel
Input
Pin Control
00000
AD0
PTB0/ADCP0
ADPC0
10000
AD16
VREFL
N/A
00001
AD1
PTB1/ADCP1
ADPC1
10001
AD17
VREFL
N/A
00010
AD2
PTB2/ADCP2
ADPC2
10010
AD18
VREFL
N/A
00011
AD3
PTB3/ADCP3
ADPC3
10011
AD19
VREFL
N/A
00100
AD4
PTB4/ADCP4
ADPC4
10100
AD20
VREFL
N/A
00101
AD5
PTB5/ADCP5
ADPC5
10101
AD21
VREFL
N/A
00110
AD6
PTB6/ADCP6
ADPC6
10110
AD22
Reserved
N/A
00111
AD7
PTB7/ADCP7
ADPC7
10111
AD23
Reserved
N/A
01000
AD8
PTD0/ADCP8
ADPC8
11000
AD24
Reserved
N/A
01001
AD9
PTD1/ADCP9
ADPC9
11001
AD25
Reserved
N/A
01010
AD10
PTD2/KBI1P5/
ADCP10
ADPC10
11010
AD26
Temperature
Sensor1
N/A
01011
AD11
PTD3/KBI1P6/
ADCP11
ADPC11
11011
AD27
Internal Bandgap
N/A
01100
AD12
PTD4/TPM2CLK/
ADCP12
ADPC12
11100
-
Reserved
N/A
01101
AD13
PTD5/ADCP13
ADPC13
11101
VREFH
VREFH
N/A
01110
AD14
PTD6/TPM1CLK/
ADCP14
ADPC14
11110
VREFL
VREFL
N/A
01111
AD15
PTD7/KBI1P7/
ADCP15
ADPC15
11111
module
disabled
None
N/A
See Section 8.2.3, “Temperature Sensor,” for more information.
NOTE
Selecting the internal bandgap channel requires BGBE =1 in SPMSC1 see
Section 5.9.8, “System Power Management Status and Control 1 Register
(SPMSC1).” For value of bandgap voltage reference see Section 3.6, “DC
Characteristics.”
8.2.1
Alternate Clock
The ADC module is capable of performing conversions using the MCU bus clock, the bus clock divided
by two, the local asynchronous clock (ADACK) within the module, or the alternate clock, ALTCLK. The
alternate clock for the MC9S08AC128 Series MCU devices is the external reference clock (ICGERCLK)
from the internal clock generator (ICG) module.
Because ICGERCLK is active only while an external clock source is enabled, the ICG must be configured
for either FBE or FEE mode (CLKS1 = 1). ICGERCLK must run at a frequency such that the ADC
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conversion clock (ADCK) runs at a frequency within its specified range (fADCK) after being divided down
from the ALTCLK input as determined by the ADIV bits. For example, if the ADIV bits are set up to divide
by four, then the minimum frequency for ALTCLK (ICGERCLK) is four times the minimum value for
fADCK and the maximum frequency is four times the maximum value for fADCK. Because of the minimum
frequency requirement, when an oscillator circuit is used it must be configured for high range operation
(RANGE = 1).
ALTCLK is active while the MCU is in wait mode provided the conditions described above are met. This
allows ALTCLK to be used as the conversion clock source for the ADC while the MCU is in wait mode.
ALTCLK cannot be used as the ADC conversion clock source while the MCU is in stop3.
8.2.2
Hardware Trigger
The ADC hardware trigger, ADHWT, is output from the real time interrupt (RTI) counter. The RTI counter
can be clocked by either ICGERCLK or a nominal 1 kHz clock source within the RTI block. The 1-kHz
clock source can be used with the MCU in run, wait, or stop3. With the ICG configured for either FBE or
FEE mode, ICGERCLK can be used with the MCU in run or wait.
The period of the RTI is determined by the input clock frequency and the RTIS bits. When the ADC
hardware trigger is enabled, a conversion is initiated upon an RTI counter overflow.
NOTE
An ADC trigger is generated on the first RTI overflow and every two RTI
counter overflows that follow. This is due to the fact that the RTI output
toggles when the counter expires and the ADC trigger is generated on RTI
output rising edge.
The RTI counter is a free running counter that generates an overflow at the RTI rate determined by the RTIS
bits.
8.2.2.1
Analog Pin Enables
The ADC on MC9S08AC128 Series contains only two analog pin enable registers, APCTL1 and
APCTL2.
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8.2.3
Temperature Sensor
The ADC module includes a temperature sensor whose output is connected to one of the ADC analog
channel inputs. Equation 8-1 provides an approximate transfer function of the temperature sensor.
TempC = 25 - ((VTEMP -VTEMP25) ÷ m)
Eqn. 8-1
where:
— VTEMP is the voltage of the temperature sensor channel at the ambient temperature.
— VTEMP25 is the voltage of the temperature sensor channel at 25 °C.
— m is the hot or cold voltage versus temperature slope in V/°C.
For temperature calculations, use the VTEMP25 and m values from the ADC Electricals table.
In application code, the user reads the temperature sensor channel, calculates VTEMP, and compares to
VTEMP25. If VTEMP is greater than VTEMP25 the cold slope value is applied in Equation 8-1. If VTEMP is
less than VTEMP25 the hot slope value is applied in Equation 8-1.
To improve accuracy, calibrate the bandgap voltage reference and temperature sensor.
• Calibrating at 25 °C will improve accuracy to +/- 4.5 °C.
• Calibration at 3 points, -40 °C, 25 °C, and 125 °C will improve accuracy to +/- 2.5 °C. Once
calibration has been completed, the user will need to calculate the slope for both hot and cold. In
application code, the user would then calculate the temperature using Equation 8-1 as detailed
above and then determine if the temperature is above or below 25 °C. Once determined if the
temperature is above or below 25 °C, the user can recalculate the temperature using the hot or cold
slope value obtained during calibration.
For more information on using the temperature sensor, consult AN3031.
8.2.3.1
Low-Power Mode Operation
The ADC is capable of running in stop3 mode but requires LVDSE and LVDE in SPMSC1 to be set.
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8.2.4
Features
Features of the ADC module include:
• Linear successive approximation algorithm with 10 bits resolution.
• Up to 28 analog inputs.
• Output formatted in 10- or 8-bit right-justified format.
• Single or continuous conversion (automatic return to idle after single conversion).
• Configurable sample time and conversion speed/power.
• Conversion complete flag and interrupt.
• Input clock selectable from up to four sources.
• Operation in wait or stop3 modes for lower noise operation.
• Asynchronous clock source for lower noise operation.
• Selectable asynchronous hardware conversion trigger.
• Automatic compare with interrupt for less-than, or greater-than or equal-to, programmable value.
8.2.5
Block Diagram
Figure 8-2 provides a block diagram of the ADC module
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ADIV
ADLPC
MODE
ADLSMP
2
ADTRG
ADCO
ADCH
1
ADCCFG
complete
COCO
ADCSC1
ADICLK
Compare true
AIEN
3
Async
Clock Gen
ADACK
MCU STOP
ADCK
÷2
ALTCLK
abort
transfer
sample
initialize
•••
AD0
convert
Control Sequencer
ADHWT
Bus Clock
Clock
Divide
AIEN 1
Interrupt
COCO 2
ADVIN
SAR Converter
AD27
VREFH
Data Registers
Sum
VREFL
Compare true
3
Compare Value Registers
ACFGT
Value
Compare
Logic
ADCSC2
Figure 8-2. ADC Block Diagram
8.3
External Signal Description
The ADC module supports up to 28 separate analog inputs. It also requires four supply/reference/ground
connections.
Table 8-2. Signal Properties
Name
Function
AD27–AD0
Analog Channel inputs
VREFH
High reference voltage
VREFL
Low reference voltage
VDDAD
Analog power supply
VSSAD
Analog ground
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8.3.1
Analog Power (VDDAD)
The ADC analog portion uses VDDAD as its power connection. In some packages, VDDAD is connected
internally to VDD. If externally available, connect the VDDAD pin to the same voltage potential as VDD.
External filtering may be necessary to ensure clean VDDAD for good results.
8.3.2
Analog Ground (VSSAD)
The ADC analog portion uses VSSAD as its ground connection. In some packages, VSSAD is connected
internally to VSS. If externally available, connect the VSSAD pin to the same voltage potential as VSS.
8.3.3
Voltage Reference High (VREFH)
VREFH is the high reference voltage for the converter. In some packages, VREFH is connected internally to
VDDAD. If externally available, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD).
8.3.4
Voltage Reference Low (VREFL)
VREFL is the low reference voltage for the converter. In some packages, VREFL is connected internally to
VSSAD. If externally available, connect the VREFL pin to the same voltage potential as VSSAD.
8.3.5
Analog Channel Inputs (ADx)
The ADC module supports up to 28 separate analog inputs. An input is selected for conversion through the
ADCH channel select bits.
8.4
Register Definition
These memory mapped registers control and monitor operation of the ADC:
•
•
•
•
•
•
8.4.1
Status and control register, ADCSC1
Status and control register, ADCSC2
Data result registers, ADCRH and ADCRL
Compare value registers, ADCCVH and ADCCVL
Configuration register, ADCCFG
Pin enable registers, APCTL1, APCTL2, APCTL3
Status and Control Register 1 (ADCSC1)
This section describes the function of the ADC status and control register (ADCSC1). Writing ADCSC1
aborts the current conversion and initiates a new conversion (if the ADCH bits are equal to a value other
than all 1s).
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7
R
6
5
4
AIEN
ADCO
0
0
3
2
1
0
1
1
COCO
ADCH
W
Reset:
0
1
1
1
= Unimplemented or Reserved
Figure 8-3. Status and Control Register (ADCSC1)
Table 8-3. ADCSC1 Register Field Descriptions
Field
Description
7
COCO
Conversion Complete Flag — The COCO flag is a read-only bit which is set each time a conversion is
completed when the compare function is disabled (ACFE = 0). When the compare function is enabled (ACFE =
1) the COCO flag is set upon completion of a conversion only if the compare result is true. This bit is cleared
whenever ADCSC1 is written or whenever ADCRL is read.
0 Conversion not completed
1 Conversion completed
6
AIEN
Interrupt Enable — AIEN is used to enable conversion complete interrupts. When COCO becomes set while
AIEN is high, an interrupt is asserted.
0 Conversion complete interrupt disabled
1 Conversion complete interrupt enabled
5
ADCO
Continuous Conversion Enable — ADCO is used to enable continuous conversions.
0 One conversion following a write to the ADCSC1 when software triggered operation is selected, or one
conversion following assertion of ADHWT when hardware triggered operation is selected.
1 Continuous conversions initiated following a write to ADCSC1 when software triggered operation is selected.
Continuous conversions are initiated by an ADHWT event when hardware triggered operation is selected.
4:0
ADCH
Input Channel Select — The ADCH bits form a 5-bit field which is used to select one of the input channels. The
input channels are detailed in Figure 8-4.
The successive approximation converter subsystem is turned off when the channel select bits are all set to 1.
This feature allows for explicit disabling of the ADC and isolation of the input channel from all sources.
Terminating continuous conversions this way will prevent an additional, single conversion from being performed.
It is not necessary to set the channel select bits to all 1s to place the ADC in a low-power state when continuous
conversions are not enabled because the module automatically enters a low-power state when a conversion
completes.
Figure 8-4. Input Channel Select
ADCH
Input Select
ADCH
Input Select
00000
AD0
10000
AD16
00001
AD1
10001
AD17
00010
AD2
10010
AD18
00011
AD3
10011
AD19
00100
AD4
10100
AD20
00101
AD5
10101
AD21
00110
AD6
10110
AD22
00111
AD7
10111
AD23
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Figure 8-4. Input Channel Select (continued)
8.4.2
ADCH
Input Select
ADCH
Input Select
01000
AD8
11000
AD24
01001
AD9
11001
AD25
01010
AD10
11010
AD26
01011
AD11
11011
AD27
01100
AD12
11100
Reserved
01101
AD13
11101
VREFH
01110
AD14
11110
VREFL
01111
AD15
11111
Module disabled
Status and Control Register 2 (ADCSC2)
The ADCSC2 register is used to control the compare function, conversion trigger and conversion active of
the ADC module.
7
R
6
5
4
ADTRG
ACFE
ACFGT
0
0
0
ADACT
3
2
0
0
0
0
1
0
R1
R1
0
0
W
Reset:
0
= Unimplemented or Reserved
1
Bits 1 and 0 are reserved bits that must always be written to 0.
Figure 8-5. Status and Control Register 2 (ADCSC2)
Table 8-4. ADCSC2 Register Field Descriptions
Field
Description
7
ADACT
Conversion Active — ADACT indicates that a conversion is in progress. ADACT is set when a conversion is
initiated and cleared when a conversion is completed or aborted.
0 Conversion not in progress
1 Conversion in progress
6
ADTRG
Conversion Trigger Select — ADTRG is used to select the type of trigger to be used for initiating a conversion.
Two types of trigger are selectable: software trigger and hardware trigger. When software trigger is selected, a
conversion is initiated following a write to ADCSC1. When hardware trigger is selected, a conversion is initiated
following the assertion of the ADHWT input.
0 Software trigger selected
1 Hardware trigger selected
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Table 8-4. ADCSC2 Register Field Descriptions (continued)
Field
Description
5
ACFE
Compare Function Enable — ACFE is used to enable the compare function.
0 Compare function disabled
1 Compare function enabled
4
ACFGT
Compare Function Greater Than Enable — ACFGT is used to configure the compare function to trigger when
the result of the conversion of the input being monitored is greater than or equal to the compare value. The
compare function defaults to triggering when the result of the compare of the input being monitored is less than
the compare value.
0 Compare triggers when input is less than compare level
1 Compare triggers when input is greater than or equal to compare level
8.4.3
Data Result High Register (ADCRH)
ADCRH contains the upper two bits of the result of a 10-bit conversion. When configured for 8-bit
conversions both ADR8 and ADR9 are equal to zero. ADCRH is updated each time a conversion
completes except when automatic compare is enabled and the compare condition is not met. In 10-bit
MODE, reading ADCRH prevents the ADC from transferring subsequent conversion results into the result
registers until ADCRL is read. If ADCRL is not read until after the next conversion is completed, then the
intermediate conversion result will be lost. In 8-bit mode there is no interlocking with ADCRL. In the case
that the MODE bits are changed, any data in ADCRH becomes invalid.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
ADR9
ADR8
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented or Reserved
Figure 8-6. Data Result High Register (ADCRH)
8.4.4
Data Result Low Register (ADCRL)
ADCRL contains the lower eight bits of the result of a 10-bit conversion, and all eight bits of an 8-bit
conversion. This register is updated each time a conversion completes except when automatic compare is
enabled and the compare condition is not met. In 10-bit mode, reading ADCRH prevents the ADC from
transferring subsequent conversion results into the result registers until ADCRL is read. If ADCRL is not
read until the after next conversion is completed, then the intermediate conversion results will be lost. In
8-bit mode, there is no interlocking with ADCRH. In the case that the MODE bits are changed, any data
in ADCRL becomes invalid.
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R
7
6
5
4
3
2
1
0
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
ADR0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented or Reserved
Figure 8-7. Data Result Low Register (ADCRL)
8.4.5
Compare Value High Register (ADCCVH)
This register holds the upper two bits of the 10-bit compare value. These bits are compared to the upper
two bits of the result following a conversion in 10-bit mode when the compare function is enabled.In 8-bit
operation, ADCCVH is not used during compare.
R
7
6
5
4
0
0
0
0
3
2
1
0
ADCV9
ADCV8
0
0
W
Reset:
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 8-8. Compare Value High Register (ADCCVH)
8.4.6
Compare Value Low Register (ADCCVL)
This register holds the lower 8 bits of the 10-bit compare value, or all 8 bits of the 8-bit compare value.
Bits ADCV7:ADCV0 are compared to the lower 8 bits of the result following a conversion in either 10-bit
or 8-bit mode.
7
6
5
4
3
2
1
0
ADCV7
ADCV6
ADCV5
ADCV4
ADCV3
ADCV2
ADCV1
ADCV0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 8-9. Compare Value Low Register(ADCCVL)
8.4.7
Configuration Register (ADCCFG)
ADCCFG is used to select the mode of operation, clock source, clock divide, and configure for low power
or long sample time.
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7
6
5
4
3
2
1
0
R
ADLPC
ADIV
ADLSMP
MODE
ADICLK
W
Reset:
0
0
0
0
0
0
0
0
Figure 8-10. Configuration Register (ADCCFG)
Table 8-5. ADCCFG Register Field Descriptions
Field
Description
7
ADLPC
Low Power Configuration — ADLPC controls the speed and power configuration of the successive
approximation converter. This is used to optimize power consumption when higher sample rates are not required.
0 High speed configuration
1 Low power configuration: {FC31}The power is reduced at the expense of maximum clock speed.
6:5
ADIV
Clock Divide Select — ADIV select the divide ratio used by the ADC to generate the internal clock ADCK.
Table 8-6 shows the available clock configurations.
4
ADLSMP
Long Sample Time Configuration — ADLSMP selects between long and short sample time. This adjusts the
sample period to allow higher impedance inputs to be accurately sampled or to maximize conversion speed for
lower impedance inputs. Longer sample times can also be used to lower overall power consumption when
continuous conversions are enabled if high conversion rates are not required.
0 Short sample time
1 Long sample time
3:2
MODE
Conversion Mode Selection — MODE bits are used to select between 10- or 8-bit operation. See Table 8-7.
1:0
ADICLK
Input Clock Select — ADICLK bits select the input clock source to generate the internal clock ADCK. See
Table 8-8.
Table 8-6. Clock Divide Select
ADIV
Divide Ratio
Clock Rate
00
1
Input clock
01
2
Input clock ÷ 2
10
4
Input clock ÷ 4
11
8
Input clock ÷ 8
Table 8-7. Conversion Modes
MODE
Mode Description
00
8-bit conversion (N=8)
01
Reserved
10
10-bit conversion (N=10)
11
Reserved
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Table 8-8. Input Clock Select
ADICLK
8.4.8
Selected Clock Source
00
Bus clock
01
Bus clock divided by 2
10
Alternate clock (ALTCLK)
11
Asynchronous clock (ADACK)
Pin Control 1 Register (APCTL1)
The pin control registers are used to disable the I/O port control of MCU pins used as analog inputs.
APCTL1 is used to control the pins associated with channels 0–7 of the ADC module.
7
6
5
4
3
2
1
0
ADPC7
ADPC6
ADPC5
ADPC4
ADPC3
ADPC2
ADPC1
ADPC0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 8-11. Pin Control 1 Register (APCTL1)
Table 8-9. APCTL1 Register Field Descriptions
Field
Description
7
ADPC7
ADC Pin Control 7 — ADPC7 is used to control the pin associated with channel AD7.
0 AD7 pin I/O control enabled
1 AD7 pin I/O control disabled
6
ADPC6
ADC Pin Control 6 — ADPC6 is used to control the pin associated with channel AD6.
0 AD6 pin I/O control enabled
1 AD6 pin I/O control disabled
5
ADPC5
ADC Pin Control 5 — ADPC5 is used to control the pin associated with channel AD5.
0 AD5 pin I/O control enabled
1 AD5 pin I/O control disabled
4
ADPC4
ADC Pin Control 4 — ADPC4 is used to control the pin associated with channel AD4.
0 AD4 pin I/O control enabled
1 AD4 pin I/O control disabled
3
ADPC3
ADC Pin Control 3 — ADPC3 is used to control the pin associated with channel AD3.
0 AD3 pin I/O control enabled
1 AD3 pin I/O control disabled
2
ADPC2
ADC Pin Control 2 — ADPC2 is used to control the pin associated with channel AD2.
0 AD2 pin I/O control enabled
1 AD2 pin I/O control disabled
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Table 8-9. APCTL1 Register Field Descriptions (continued)
Field
Description
1
ADPC1
ADC Pin Control 1 — ADPC1 is used to control the pin associated with channel AD1.
0 AD1 pin I/O control enabled
1 AD1 pin I/O control disabled
0
ADPC0
ADC Pin Control 0 — ADPC0 is used to control the pin associated with channel AD0.
0 AD0 pin I/O control enabled
1 AD0 pin I/O control disabled
8.4.9
Pin Control 2 Register (APCTL2)
APCTL2 is used to control channels 8–15 of the ADC module.
7
6
5
4
3
2
1
0
ADPC15
ADPC14
ADPC13
ADPC12
ADPC11
ADPC10
ADPC9
ADPC8
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 8-12. Pin Control 2 Register (APCTL2)
Table 8-10. APCTL2 Register Field Descriptions
Field
Description
7
ADPC15
ADC Pin Control 15 — ADPC15 is used to control the pin associated with channel AD15.
0 AD15 pin I/O control enabled
1 AD15 pin I/O control disabled
6
ADPC14
ADC Pin Control 14 — ADPC14 is used to control the pin associated with channel AD14.
0 AD14 pin I/O control enabled
1 AD14 pin I/O control disabled
5
ADPC13
ADC Pin Control 13 — ADPC13 is used to control the pin associated with channel AD13.
0 AD13 pin I/O control enabled
1 AD13 pin I/O control disabled
4
ADPC12
ADC Pin Control 12 — ADPC12 is used to control the pin associated with channel AD12.
0 AD12 pin I/O control enabled
1 AD12 pin I/O control disabled
3
ADPC11
ADC Pin Control 11 — ADPC11 is used to control the pin associated with channel AD11.
0 AD11 pin I/O control enabled
1 AD11 pin I/O control disabled
2
ADPC10
ADC Pin Control 10 — ADPC10 is used to control the pin associated with channel AD10.
0 AD10 pin I/O control enabled
1 AD10 pin I/O control disabled
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Table 8-10. APCTL2 Register Field Descriptions (continued)
Field
Description
1
ADPC9
ADC Pin Control 9 — ADPC9 is used to control the pin associated with channel AD9.
0 AD9 pin I/O control enabled
1 AD9 pin I/O control disabled
0
ADPC8
ADC Pin Control 8 — ADPC8 is used to control the pin associated with channel AD8.
0 AD8 pin I/O control enabled
1 AD8 pin I/O control disabled
8.4.10
Pin Control 3 Register (APCTL3)
APCTL3 is used to control channels 16–23 of the ADC module.
7
6
5
4
3
2
1
0
ADPC23
ADPC22
ADPC21
ADPC20
ADPC19
ADPC18
ADPC17
ADPC16
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 8-13. Pin Control 3 Register (APCTL3)
Table 8-11. APCTL3 Register Field Descriptions
Field
Description
7
ADPC23
ADC Pin Control 23 — ADPC23 is used to control the pin associated with channel AD23.
0 AD23 pin I/O control enabled
1 AD23 pin I/O control disabled
6
ADPC22
ADC Pin Control 22 — ADPC22 is used to control the pin associated with channel AD22.
0 AD22 pin I/O control enabled
1 AD22 pin I/O control disabled
5
ADPC21
ADC Pin Control 21 — ADPC21 is used to control the pin associated with channel AD21.
0 AD21 pin I/O control enabled
1 AD21 pin I/O control disabled
4
ADPC20
ADC Pin Control 20 — ADPC20 is used to control the pin associated with channel AD20.
0 AD20 pin I/O control enabled
1 AD20 pin I/O control disabled
3
ADPC19
ADC Pin Control 19 — ADPC19 is used to control the pin associated with channel AD19.
0 AD19 pin I/O control enabled
1 AD19 pin I/O control disabled
2
ADPC18
ADC Pin Control 18 — ADPC18 is used to control the pin associated with channel AD18.
0 AD18 pin I/O control enabled
1 AD18 pin I/O control disabled
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Table 8-11. APCTL3 Register Field Descriptions (continued)
Field
Description
1
ADPC17
ADC Pin Control 17 — ADPC17 is used to control the pin associated with channel AD17.
0 AD17 pin I/O control enabled
1 AD17 pin I/O control disabled
0
ADPC16
ADC Pin Control 16 — ADPC16 is used to control the pin associated with channel AD16.
0 AD16 pin I/O control enabled
1 AD16 pin I/O control disabled
8.5
Functional Description
The ADC module is disabled during reset or when the ADCH bits are all high. The module is idle when a
conversion has completed and another conversion has not been initiated. When idle, the module is in its
lowest power state.
The ADC can perform an analog-to-digital conversion on any of the software selectable channels. The
selected channel voltage is converted by a successive approximation algorithm into an 11-bit digital result.
In 8-bit mode, the selected channel voltage is converted by a successive approximation algorithm into a
9-bit digital result.
When the conversion is completed, the result is placed in the data registers (ADCRH and ADCRL).In
10-bit mode, the result is rounded to 10 bits and placed in ADCRH and ADCRL. In 8-bit mode, the result
is rounded to 8 bits and placed in ADCRL. The conversion complete flag (COCO) is then set and an
interrupt is generated if the conversion complete interrupt has been enabled (AIEN = 1).
The ADC module has the capability of automatically comparing the result of a conversion with the
contents of its compare registers. The compare function is enabled by setting the ACFE bit and operates
in conjunction with any of the conversion modes and configurations.
8.5.1
Clock Select and Divide Control
One of four clock sources can be selected as the clock source for the ADC module. This clock source is
then divided by a configurable value to generate the input clock to the converter (ADCK). The clock is
selected from one of the following sources by means of the ADICLK bits.
•
•
•
•
The bus clock, which is equal to the frequency at which software is executed. This is the default
selection following reset.
The bus clock divided by 2. For higher bus clock rates, this allows a maximum divide by 16 of the
bus clock.
ALTCLK, as defined for this MCU (See module section introduction).
The asynchronous clock (ADACK) – This clock is generated from a clock source within the ADC
module. When selected as the clock source this clock remains active while the MCU is in wait or
stop3 mode and allows conversions in these modes for lower noise operation.
Whichever clock is selected, its frequency must fall within the specified frequency range for ADCK. If the
available clocks are too slow, the ADC will not perform according to specifications. If the available clocks
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are too fast, then the clock must be divided to the appropriate frequency. This divider is specified by the
ADIV bits and can be divide-by 1, 2, 4, or 8.
8.5.2
Input Select and Pin Control
The pin control registers (APCTL3, APCTL2, and APCTL1) are used to disable the I/O port control of the
pins used as analog inputs.When a pin control register bit is set, the following conditions are forced for the
associated MCU pin:
• The output buffer is forced to its high impedance state.
• The input buffer is disabled. A read of the I/O port returns a zero for any pin with its input buffer
disabled.
• The pullup is disabled.
8.5.3
Hardware Trigger
The ADC module has a selectable asynchronous hardware conversion trigger, ADHWT, that is enabled
when the ADTRG bit is set. This source is not available on all MCUs. Consult the module introduction for
information on the ADHWT source specific to this MCU.
When ADHWT source is available and hardware trigger is enabled (ADTRG=1), a conversion is initiated
on the rising edge of ADHWT. If a conversion is in progress when a rising edge occurs, the rising edge is
ignored. In continuous convert configuration, only the initial rising edge to launch continuous conversions
is observed. The hardware trigger function operates in conjunction with any of the conversion modes and
configurations.
8.5.4
Conversion Control
Conversions can be performed in either 10-bit mode or 8-bit mode as determined by the MODE bits.
Conversions can be initiated by either a software or hardware trigger. In addition, the ADC module can be
configured for low power operation, long sample time, continuous conversion, and automatic compare of
the conversion result to a software determined compare value.
8.5.4.1
Initiating Conversions
A conversion is initiated:
• Following a write to ADCSC1 (with ADCH bits not all 1s) if software triggered operation is
selected.
• Following a hardware trigger (ADHWT) event if hardware triggered operation is selected.
• Following the transfer of the result to the data registers when continuous conversion is enabled.
If continuous conversions are enabled a new conversion is automatically initiated after the completion of
the current conversion. In software triggered operation, continuous conversions begin after ADCSC1 is
written and continue until aborted. In hardware triggered operation, continuous conversions begin after a
hardware trigger event and continue until aborted.
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8.5.4.2
Completing Conversions
A conversion is completed when the result of the conversion is transferred into the data result registers,
ADCRH and ADCRL. This is indicated by the setting of COCO. An interrupt is generated if AIEN is high
at the time that COCO is set.
A blocking mechanism prevents a new result from overwriting previous data in ADCRH and ADCRL if
the previous data is in the process of being read while in 10-bit MODE (the ADCRH register has been read
but the ADCRL register has not). When blocking is active, the data transfer is blocked, COCO is not set,
and the new result is lost. In the case of single conversions with the compare function enabled and the
compare condition false, blocking has no effect and ADC operation is terminated. In all other cases of
operation, when a data transfer is blocked, another conversion is initiated regardless of the state of ADCO
(single or continuous conversions enabled).
If single conversions are enabled, the blocking mechanism could result in several discarded conversions
and excess power consumption. To avoid this issue, the data registers must not be read after initiating a
single conversion until the conversion completes.
8.5.4.3
Aborting Conversions
Any conversion in progress will be aborted when:
•
A write to ADCSC1 occurs (the current conversion will be aborted and a new conversion will be
initiated, if ADCH are not all 1s).
•
A write to ADCSC2, ADCCFG, ADCCVH, or ADCCVL occurs. This indicates a mode of
operation change has occurred and the current conversion is therefore invalid.
•
The MCU is reset.
•
The MCU enters stop mode with ADACK not enabled.
When a conversion is aborted, the contents of the data registers, ADCRH and ADCRL, are not altered but
continue to be the values transferred after the completion of the last successful conversion. In the case that
the conversion was aborted by a reset, ADCRH and ADCRL return to their reset states.
8.5.4.4
Power Control
The ADC module remains in its idle state until a conversion is initiated. If ADACK is selected as the
conversion clock source, the ADACK clock generator is also enabled.
Power consumption when active can be reduced by setting ADLPC. This results in a lower maximum value
for fADCK (see the electrical specifications).
8.5.4.5
Total Conversion Time
The total conversion time depends on the sample time (as determined by ADLSMP), the MCU bus
frequency, the conversion mode (8-bit or 10-bit), and the frequency of the conversion clock (fADCK). After
the module becomes active, sampling of the input begins. ADLSMP is used to select between short and
long sample times.When sampling is complete, the converter is isolated from the input channel and a
successive approximation algorithm is performed to determine the digital value of the analog signal. The
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result of the conversion is transferred to ADCRH and ADCRL upon completion of the conversion
algorithm.
If the bus frequency is less than the fADCK frequency, precise sample time for continuous conversions
cannot be guaranteed when short sample is enabled (ADLSMP=0). If the bus frequency is less than 1/11th
of the fADCK frequency, precise sample time for continuous conversions cannot be guaranteed when long
sample is enabled (ADLSMP=1).
The maximum total conversion time for different conditions is summarized in Table 8-12.
Table 8-12. Total Conversion Time vs. Control Conditions
Conversion Type
ADICLK
ADLSMP
Max Total Conversion Time
Single or first continuous 8-bit
0x, 10
0
20 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit
0x, 10
0
23 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit
0x, 10
1
40 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit
0x, 10
1
43 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit
11
0
5 μs + 20 ADCK + 5 bus clock cycles
Single or first continuous 10-bit
11
0
5 μs + 23 ADCK + 5 bus clock cycles
Single or first continuous 8-bit
11
1
5 μs + 40 ADCK + 5 bus clock cycles
Single or first continuous 10-bit
11
1
5 μs + 43 ADCK + 5 bus clock cycles
Subsequent continuous 8-bit;
fBUS > fADCK
xx
0
17 ADCK cycles
Subsequent continuous 10-bit;
fBUS > fADCK
xx
0
20 ADCK cycles
Subsequent continuous 8-bit;
fBUS > fADCK/11
xx
1
37 ADCK cycles
Subsequent continuous 10-bit;
fBUS > fADCK/11
xx
1
40 ADCK cycles
The maximum total conversion time is determined by the clock source chosen and the divide ratio selected.
The clock source is selectable by the ADICLK bits, and the divide ratio is specified by the ADIV bits. For
example, in 10-bit mode, with the bus clock selected as the input clock source, the input clock divide-by-1
ratio selected, and a bus frequency of 8 MHz, then the conversion time for a single conversion is:
Conversion time =
23 ADCK cyc
8 MHz/1
+
5 bus cyc
8 MHz
= 3.5 μs
Number of bus cycles = 3.5 μs x 8 MHz = 28 cycles
NOTE
The ADCK frequency must be between fADCK minimum and fADCK
maximum to meet ADC specifications.
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8.5.5
Automatic Compare Function
The compare function can be configured to check for either an upper limit or lower limit. After the input
is sampled and converted, the result is added to the two’s complement of the compare value (ADCCVH
and ADCCVL). When comparing to an upper limit (ACFGT = 1), if the result is greater-than or equal-to
the compare value, COCO is set. When comparing to a lower limit (ACFGT = 0), if the result is less than
the compare value, COCO is set. The value generated by the addition of the conversion result and the two’s
complement of the compare value is transferred to ADCRH and ADCRL.
Upon completion of a conversion while the compare function is enabled, if the compare condition is not
true, COCO is not set and no data is transferred to the result registers. An ADC interrupt is generated upon
the setting of COCO if the ADC interrupt is enabled (AIEN = 1).
NOTE
The compare function can be used to monitor the voltage on a channel while
the MCU is in either wait or stop3 mode. The ADC interrupt will wake the
MCU when the compare condition is met.
8.5.6
MCU Wait Mode Operation
The WAIT instruction puts the MCU in a lower power-consumption standby mode from which recovery
is very fast because the clock sources remain active. If a conversion is in progress when the MCU enters
wait mode, it continues until completion. Conversions can be initiated while the MCU is in wait mode by
means of the hardware trigger or if continuous conversions are enabled.
The bus clock, bus clock divided by two, and ADACK are available as conversion clock sources while in
wait mode. The use of ALTCLK as the conversion clock source in wait is dependent on the definition of
ALTCLK for this MCU. Consult the module introduction for information on ALTCLK specific to this
MCU.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from wait
mode if the ADC interrupt is enabled (AIEN = 1).
8.5.7
MCU Stop3 Mode Operation
The STOP instruction is used to put the MCU in a low power-consumption standby mode during which
most or all clock sources on the MCU are disabled.
8.5.7.1
Stop3 Mode With ADACK Disabled
If the asynchronous clock, ADACK, is not selected as the conversion clock, executing a STOP instruction
aborts the current conversion and places the ADC in its idle state. The contents of ADCRH and ADCRL
are unaffected by stop3 mode.After exiting from stop3 mode, a software or hardware trigger is required to
resume conversions.
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8.5.7.2
Stop3 Mode With ADACK Enabled
If ADACK is selected as the conversion clock, the ADC continues operation during stop3 mode. For
guaranteed ADC operation, the MCU’s voltage regulator must remain active during stop3 mode. Consult
the module introduction for configuration information for this MCU.
If a conversion is in progress when the MCU enters stop3 mode, it continues until completion. Conversions
can be initiated while the MCU is in stop3 mode by means of the hardware trigger or if continuous
conversions are enabled.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from stop3
mode if the ADC interrupt is enabled (AIEN = 1).
NOTE
It is possible for the ADC module to wake the system from low power stop
and cause the MCU to begin consuming run-level currents without
generating a system level interrupt. To prevent this scenario, software
should ensure that the data transfer blocking mechanism (discussed in
Section 8.5.4.2, “Completing Conversions) is cleared when entering stop3
and continuing ADC conversions.
8.5.8
MCU Stop1 and Stop2 Mode Operation
The ADC module is automatically disabled when the MCU enters either stop1 or stop2 mode. All module
registers contain their reset values following exit from stop1 or stop2. Therefore the module must be
re-enabled and re-configured following exit from stop1 or stop2.
8.6
Initialization Information
This section gives an example which provides some basic direction on how a user would initialize and
configure the ADC module. The user has the flexibility of choosing between configuring the module for
8-bit or 10-bit resolution, single or continuous conversion, and a polled or interrupt approach, among many
other options. Refer to Table 8-6, Table 8-7, and Table 8-8 for information used in this example.
NOTE
Hexadecimal values designated by a preceding 0x, binary values designated
by a preceding %, and decimal values have no preceding character.
8.6.1
8.6.1.1
ADC Module Initialization Example
Initialization Sequence
Before the ADC module can be used to complete conversions, an initialization procedure must be
performed. A typical sequence is as follows:
1. Update the configuration register (ADCCFG) to select the input clock source and the divide ratio
used to generate the internal clock, ADCK. This register is also used for selecting sample time and
low-power configuration.
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2. Update status and control register 2 (ADCSC2) to select the conversion trigger (hardware or
software) and compare function options, if enabled.
3. Update status and control register 1 (ADCSC1) to select whether conversions will be continuous
or completed only once, and to enable or disable conversion complete interrupts. The input channel
on which conversions will be performed is also selected here.
8.6.1.2
Pseudo — Code Example
In this example, the ADC module will be set up with interrupts enabled to perform a single 10-bit
conversion at low power with a long sample time on input channel 1, where the internal ADCK clock will
be derived from the bus clock divided by 1.
ADCCFG = 0x98 (%10011000)
Bit 7
ADLPC
1
Configures for low power (lowers maximum clock speed)
Bit 6:5 ADIV
00
Sets the ADCK to the input clock ÷ 1
Bit 4
ADLSMP 1
Configures for long sample time
Bit 3:2 MODE
10
Sets mode at 10-bit conversions
Bit 1:0 ADICLK 00
Selects bus clock as input clock source
ADCSC2 = 0x00 (%00000000)
Bit 7
ADACT
0
Bit 6
ADTRG
0
Bit 5
ACFE
0
Bit 4
ACFGT
0
Bit 3:2
00
Bit 1:0
00
Flag indicates if a conversion is in progress
Software trigger selected
Compare function disabled
Not used in this example
Unimplemented or reserved, always reads zero
Reserved for Freescale’s internal use; always write zero
ADCSC1 = 0x41 (%01000001)
Bit 7
COCO
0
Bit 6
AIEN
1
Bit 5
ADCO
0
Bit 4:0 ADCH
00001
Read-only flag which is set when a conversion completes
Conversion complete interrupt enabled
One conversion only (continuous conversions disabled)
Input channel 1 selected as ADC input channel
ADCRH/L = 0xxx
Holds results of conversion. Read high byte (ADCRH) before low byte (ADCRL) so that conversion
data cannot be overwritten with data from the next conversion.
ADCCVH/L = 0xxx
Holds compare value when compare function enabled
APCTL1=0x02
AD1 pin I/O control disabled. All other AD pins remain general purpose I/O pins
APCTL2=0x00
All other AD pins remain general purpose I/O pins
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RESET
INITIALIZE ADC
ADCCFG = $98
ADCSC2 = $00
ADCSC1 = $41
CHECK
COCO=1?
NO
YES
READ ADCRH
THEN ADCRL TO
CLEAR COCO BIT
CONTINUE
Figure 8-14. Initialization Flowchart for Example
8.7
Application Information
This section contains information for using the ADC module in applications. The ADC has been designed
to be integrated into a microcontroller for use in embedded control applications requiring an A/D
converter.
8.7.1
External Pins and Routing
The following sections discuss the external pins associated with the ADC module and how they should be
used for best results.
8.7.1.1
Analog Supply Pins
The ADC module has analog power and ground supplies (VDDAD and VSSAD) which are available as
separate pins on some devices. On other devices, VSSAD is shared on the same pin as the MCU digital VSS,
and on others, both VSSAD and VDDAD are shared with the MCU digital supply pins. In these cases, there
are separate pads for the analog supplies which are bonded to the same pin as the corresponding digital
supply so that some degree of isolation between the supplies is maintained.
When available on a separate pin, both VDDAD and VSSAD must be connected to the same voltage potential
as their corresponding MCU digital supply (VDD and VSS) and must be routed carefully for maximum
noise immunity and bypass capacitors placed as near as possible to the package.
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In cases where separate power supplies are used for analog and digital power, the ground connection
between these supplies must be at the VSSAD pin. This should be the only ground connection between these
supplies if possible. The VSSAD pin makes a good single point ground location.
8.7.1.2
Analog Reference Pins
In addition to the analog supplies, the ADC module has connections for two reference voltage inputs. The
high reference is VREFH, which may be shared on the same pin as VDDAD on some devices. The low
reference is VREFL, which may be shared on the same pin as VSSAD on some devices.
When available on a separate pin, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD). When available on a separate pin, VREFL must be connected to the same
voltage potential as VSSAD. Both VREFH and VREFL must be routed carefully for maximum noise
immunity and bypass capacitors placed as near as possible to the package.
AC current in the form of current spikes required to supply charge to the capacitor array at each successive
approximation step is drawn through the VREFH and VREFL loop. The best external component to meet this
current demand is a 0.1 μF capacitor with good high frequency characteristics. This capacitor is connected
between VREFH and VREFL and must be placed as near as possible to the package pins. Resistance in the
path is not recommended because the current will cause a voltage drop which could result in conversion
errors. Inductance in this path must be minimum (parasitic only).
8.7.1.3
Analog Input Pins
The external analog inputs are typically shared with digital I/O pins on MCU devices. The pin I/O control
is disabled by setting the appropriate control bit in one of the pin control registers. Conversions can be
performed on inputs without the associated pin control register bit set. It is recommended that the pin
control register bit always be set when using a pin as an analog input. This avoids problems with contention
because the output buffer will be in its high impedance state and the pullup is disabled. Also, the input
buffer draws dc current when its input is not at either VDD or VSS. Setting the pin control register bits for
all pins used as analog inputs should be done to achieve lowest operating current.
Empirical data shows that capacitors on the analog inputs improve performance in the presence of noise
or when the source impedance is high. Use of 0.01 μF capacitors with good high-frequency characteristics
is sufficient. These capacitors are not necessary in all cases, but when used they must be placed as near as
possible to the package pins and be referenced to VSSA.
For proper conversion, the input voltage must fall between VREFH and VREFL. If the input is equal to or
exceeds VREFH, the converter circuit converts the signal to $3FF (full scale 10-bit representation) or $FF
(full scale 8-bit representation). If the input is equal to or less than VREFL, the converter circuit converts it
to $000. Input voltages between VREFH and VREFL are straight-line linear conversions. There will be a
brief current associated with VREFL when the sampling capacitor is charging. The input is sampled for
3.5 cycles of the ADCK source when ADLSMP is low, or 23.5 cycles when ADLSMP is high.
For minimal loss of accuracy due to current injection, pins adjacent to the analog input pins should not be
transitioning during conversions.
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8.7.2
Sources of Error
Several sources of error exist for A/D conversions. These are discussed in the following sections.
8.7.2.1
Sampling Error
For proper conversions, the input must be sampled long enough to achieve the proper accuracy. Given the
maximum input resistance of approximately 7kΩ and input capacitance of approximately 5.5 pF, sampling
to within 1/4LSB (at 10-bit resolution) can be achieved within the minimum sample window (3.5 cycles @
8 MHz maximum ADCK frequency) provided the resistance of the external analog source (RAS) is kept
below 5 kΩ.
Higher source resistances or higher-accuracy sampling is possible by setting ADLSMP (to increase the
sample window to 23.5 cycles) or decreasing ADCK frequency to increase sample time.
8.7.2.2
Pin Leakage Error
Leakage on the I/O pins can cause conversion error if the external analog source resistance (RAS) is high.
If this error cannot be tolerated by the application, keep RAS lower than VDDAD / (2N*ILEAK) for less than
1/4LSB leakage error (N = 8 in 8-bit mode or 10 in 10-bit mode).
8.7.2.3
Noise-Induced Errors
System noise which occurs during the sample or conversion process can affect the accuracy of the
conversion. The ADC accuracy numbers are guaranteed as specified only if the following conditions are
met:
• There is a 0.1 μF low-ESR capacitor from VREFH to VREFL.
• There is a 0.1 μF low-ESR capacitor from VDDAD to VSSAD.
• If inductive isolation is used from the primary supply, an additional 1 μF capacitor is placed from
VDDAD to VSSAD.
• VSSAD (and VREFL, if connected) is connected to VSS at a quiet point in the ground plane.
• Operate the MCU in wait or stop3 mode before initiating (hardware triggered conversions) or
immediately after initiating (hardware or software triggered conversions) the ADC conversion.
— For software triggered conversions, immediately follow the write to the ADCSC1 with a WAIT
instruction or STOP instruction.
— For stop3 mode operation, select ADACK as the clock source. Operation in stop3 reduces VDD
noise but increases effective conversion time due to stop recovery.
• There is no I/O switching, input or output, on the MCU during the conversion.
There are some situations where external system activity causes radiated or conducted noise emissions or
excessive VDD noise is coupled into the ADC. In these situations, or when the MCU cannot be placed in
wait or stop3 or I/O activity cannot be halted, these recommended actions may reduce the effect of noise
on the accuracy:
• Place a 0.01 μF capacitor (CAS) on the selected input channel to VREFL or VSSAD (this will
improve noise issues but will affect sample rate based on the external analog source resistance).
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•
•
Average the result by converting the analog input many times in succession and dividing the sum
of the results. Four samples are required to eliminate the effect of a 1LSB, one-time error.
Reduce the effect of synchronous noise by operating off the asynchronous clock (ADACK) and
averaging. Noise that is synchronous to ADCK cannot be averaged out.
8.7.2.4
Code Width and Quantization Error
The ADC quantizes the ideal straight-line transfer function into 1024 steps (in 10-bit mode). Each step
ideally has the same height (1 code) and width. The width is defined as the delta between the transition
points to one code and the next. The ideal code width for an N bit converter (in this case N can be 8 or 10),
defined as 1LSB, is:
1LSB = (VREFH - VREFL) / 2N
Eqn. 8-2
There is an inherent quantization error due to the digitization of the result. For 8-bit or 10-bit conversions
the code will transition when the voltage is at the midpoint between the points where the straight line
transfer function is exactly represented by the actual transfer function. Therefore, the quantization error
will be ± 1/2LSB in 8- or 10-bit mode. As a consequence, however, the code width of the first ($000)
conversion is only 1/2LSB and the code width of the last ($FF or $3FF) is 1.5LSB.
8.7.2.5
Linearity Errors
The ADC may also exhibit non-linearity of several forms. Every effort has been made to reduce these
errors but the system should be aware of them because they affect overall accuracy. These errors are:
• Zero-scale error (EZS) (sometimes called offset) — This error is defined as the difference between
the actual code width of the first conversion and the ideal code width (1/2LSB). Note, if the first
conversion is $001, then the difference between the actual $001 code width and its ideal (1LSB) is
used.
• Full-scale error (EFS) — This error is defined as the difference between the actual code width of
the last conversion and the ideal code width (1.5LSB). Note, if the last conversion is $3FE, then the
difference between the actual $3FE code width and its ideal (1LSB) is used.
• Differential non-linearity (DNL) — This error is defined as the worst-case difference between the
actual code width and the ideal code width for all conversions.
• Integral non-linearity (INL) — This error is defined as the highest-value the (absolute value of the)
running sum of DNL achieves. More simply, this is the worst-case difference of the actual
transition voltage to a given code and its corresponding ideal transition voltage, for all codes.
• Total unadjusted error (TUE) — This error is defined as the difference between the actual transfer
function and the ideal straight-line transfer function, and therefore includes all forms of error.
8.7.2.6
Code Jitter, Non-Monotonicity and Missing Codes
Analog-to-digital converters are susceptible to three special forms of error. These are code jitter,
non-monotonicity, and missing codes.
Code jitter is when, at certain points, a given input voltage converts to one of two values when sampled
repeatedly. Ideally, when the input voltage is infinitesimally smaller than the transition voltage, the
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converter yields the lower code (and vice-versa). However, even very small amounts of system noise can
cause the converter to be indeterminate (between two codes) for a range of input voltages around the
transition voltage. This range is normally around 1/2LSB and will increase with noise. This error may be
reduced by repeatedly sampling the input and averaging the result. Additionally the techniques discussed
in Section 8.7.2.3 will reduce this error.
Non-monotonicity is defined as when, except for code jitter, the converter converts to a lower code for a
higher input voltage. Missing codes are those values which are never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and to have no missing codes.
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Chapter 9
Cyclic Redundancy Check (S08CRCV1)
9.1
Introduction
The MC9S08AC128 Series includes a CRC module to support fast cyclic redundancy checks on memory.
9.1.1
Features
Features of the CRC module include:
• Hardware CRC generator circuit using 16-bit shift register
• CRC16-CCITT compliancy with x16 + x12 + x5 + 1 polynomial
• Error detection for all single, double, odd, and most multi-bit errors
• Programmable initial seed value
• High-speed CRC calculation
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Chapter 9 Cyclic Redundancy Check (S08CRCV1)
HCS08 CORE
IRQ
LVD
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
VOLTAGE REGULATOR
VSS
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT H
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
TPM1CH0–TPM1CH5
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PORT J
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
PORT D
COP
EXTAL
XTAL
LOW-POWER OSC
PORT E
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
RESET
IRQ/TPMCLK
PORT A
HCS08 SYSTEM CONTROL
PORT B
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT C
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 9-1. Block Diagram Highlighting the CRC Module
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
9.1.2
Features
Features of the CRC module include:
• Hardware CRC generator circuit using 16-bit shift register
• CRC16-CCITT compliancy with x16 + x12 + x5 + 1 polynomial
• Error detection for all single, double, odd, and most multi-bit errors
• Programmable initial seed value
• High-speed CRC calculation
9.1.3
Modes of Operation
This section defines the CRC operation in run, wait, and stop modes.
• Run Mode - This is the basic mode of operation.
• Wait Mode - The CRC module is operational.
• Stop 1 and 2 Modes- The CRC module is not functional in these modes and will be put into its reset
state upon recovery from stop.
• Stop 3 Mode - In this mode, the CRC module will go into a low power standby state. Any CRC
calculations in progress will stop and resume after the CPU goes into run mode.
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
9.1.4
Block Diagram
Figure 9-2 provides a block diagram of the CRC module
7
0
CRC Low Register (CRCL)
15
14
12
13
11
6
......
5
4
3
2
1
0
16-bit CRC Generator Circuit
15
8
CRC High Register (CRCH)
Figure 9-2. Cyclic Redundancy Check (CRC) Module Block Diagram
9.2
External Signal Description
There are no CRC signals that connect off chip.
9.3
Register Definition
9.3.1
Memory Map
Table 9-1. CRC Register Summary
Name
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
CRCH
W
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
Table 9-1. CRC Register Summary
Name
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
CRCL
W
9.3.2
Register Descriptions
The CRC module includes:
• A 16-bit CRC result and seed register (CRCH:CRCL)
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all CRC registers. This section refers to registers only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
9.3.2.1
CRC High Register (CRCH)
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 9-3. CRC High Register (CRCH)
Table 9-2. Register Field Descriptions
Field
Description
7:0
CRCH
CRCH -- This is the high byte of the 16-bit CRC register. A write to CRCH will load the high byte of the initial 16-bit
seed value directly into bits 15-8 of the shift register in the CRC generator. The CRC generator will then expect the
low byte of the seed value to be written to CRCL and loaded directly into bits 7-0 of the shift register. Once both seed
bytes written to CRCH:CRCL have been loaded into the CRC generator, and a byte of data has been written to
CRCL, the shift register will begin shifting. A read of CRCH will read bits 15-8 of the current CRC calculation result
directly out of the shift register in the CRC generator.
9.3.2.2
CRC Low Register (CRCL)
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 9-4. CRC High Register (CRCH)
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
Table 9-3. Register Field Descriptions
Field
Description
7:0
CRCL
CRCL -- This is the low byte of the 16-bit CRC register. Normally, a write to CRCL will cause the CRC generator to
begin clocking through the 16-bit CRC generator. As a special case, if a write to CRCH has occurred previously, a
subsequent write to CRCL will load the value in the register as the low byte of a 16-bit seed value directly into bits
7-0 of the shift register in the CRC generator. A read of CRCL will read bits 7-0 of the current CRC calculation result
directly out of the shift register in the CRC generator.
9.4
Functional Description
To enable the CRC function, a write to the CRCH register will trigger the first half of the seed mechanism
which will place the CRCH value directly into bits 15-8 of the CRC generator shift register. The CRC
generator will then expect a write to CRCL to complete the seed mechanism.
As soon as the CRCL register is written to, its value will be loaded directly into bits 7-0 of the shift register,
and the second half of the seed mechanism will be complete. This value in CRCH:CRCL will be the initial
seed value in the CRC generator.
Now the first byte of the data on which the CRC calculation will be applied should be written to CRCL.
This write after the completion of the seed mechanism will trigger the CRC module to begin the CRC
checking process. The CRC generator will shift the bits in the CRCL register (MSB first) into the shift
register of the generator. After all 8 bits have been shifted into the CRC generator (in the next bus cycle
after the data write to CRCL), the result of the shifting, or the value currently in the shift register, can be
read directly from CRCH:CRCL, and the next data byte to include in the CRC calculation can be written
to the CRCL register.
This next byte will then also be shifted through the CRC generator’s 16-bit shift register, and after the
shifting has been completed, the result of this second calculation can be read directly from CRCH:CRCL.
After each byte has finished shifting, a new CRC result will appear in CRCH:CRCL, and an additional
byte may be written to the CRCL register to be included within the CRC16-CCITT calculation. A new
CRC result will appear in CRCH:CRCL each time 8-bits have been shifted into the shift register.
To start a new CRC calculation, write to CRCH, and the seed mechanism for a new CRC calculation will
begin again.
9.4.1
ITU-T (CCITT) recommendations & expected CRC results
The CRC polynomial 0x1021 (x16 + x12 + x5 + 1) is popularly known as CRC-CCITT since it was initially
proposed by the ITU-T (formerly CCITT) committee.
Although the ITU-T recommendations are very clear about the polynomial to be used, 0x1021, they accept
variations in the way they are implemented:
- ITU-T V.41 implements the same circuit shown in Figure 9-2, but it recommends a SEED = 0x0000.
- ITU-T T.30 and ITU-T X.25 implement the same circuit shown in Figure 9-2, but they recommend the
final CRC result to be negated (one-complement operation). Also, they recommend a SEED = 0xFFFF.
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
Moreover, it is common to find circuits in literature slightly different from the one suggested by the
recommendations above, but also known as CRC-CCITT circuits (many variations require the message to
be augmented with zeros).
The circuit implemented in CRC module is exactly the one suggested by the ITU-T V.41 recommendation,
with an added flexibility of a programmable SEED. As in ITU-T V.41, no augmentation is needed and the
CRC result is not negated. Below are some expected results that can be used as a reference:
Table 9-4. Expected CRC results
Message
9.5
SEED
CRC result
(initial CRC value)
A
0x0000
0x58e5
A
0xffff
0xb915
123456789
0x0000
0x31c3
123456789
0xffff
0x29b1
A string of 256 upper case “A”
characters with no line breaks
0x0000
0xabe3
A string of 256 upper case “A”
characters with no line breaks
0xffff
0xea0b
Initialization Information
To initialize the CRC Module and initiate a CRC16-CCITT calculation, follow this procedure:
1. Write high byte of initial seed value to CRCH.
2. Write low byte of initial seed value to CRCL.
3. Write first byte of data on which CRC is to be calculated to CRCL.
4. In the next bus cycle after step 3, if desired, the CRC result from the first byte can be read from
CRCH:CRCL.
5. Repeat steps 3-4 until the end of all data to be checked.
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Chapter 9 Cyclic Redundancy Check Generator (S08CRCV1)
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Chapter 10
Internal Clock Generator (S08ICGV4)
The internal clock generation (ICG) module is used to generate the system clocks for the MC9S08AC128
Series MCU. A diagram of the System Clock Distribution is provide in the figure below.
TPMCLK1*
TPMCLK2*
TPMCLK
1KHz
LPO
ICGERCLK
SYSTEM
CONTROL
LOGIC
TPM1
TPM2
TPM3
IIC1
SCI1,
SCI2
SPI1,
SPI2
RTI
FFE
÷2
ICG
XCLK
ICGOUT
XOSC
÷2
BUSCLK
ICGLCLK**
CPU
COP
BDC
CRC
ADC1
RAM
FLASH
* The TPMCLK pin can be used to provide an alternate external input clock source to TPM1 and TPM2 by setting option bits in SOPT2.
** ICGLCLK is the alternate BDC clock source.
- ADC1 has min and max frequency requirements. See the ADC chapter and electricals appendix for details.
- Flash has frequency requirements for program and erase operation. See the electricals appendix for details.
- The fixed frequency clock (XCLK) is internally synchronized to the bus clock and must not exceed one half of the bus clock frequency.
Figure 10-1. System Clock Distribution Diagram
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Chapter 10 Internal Clock Generator (S08ICGV4)
HCS08 CORE
IRQ
LVD
VDDAD
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
EXTAL
XTAL
LOW-POWER OSC
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT J
PORT H
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
VOLTAGE REGULATOR
VSS
PORT A
COP
PORT B
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
PORT E
IRQ/TPMCLK
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT C
HCS08 SYSTEM CONTROL
RESET
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT D
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
TPM1CH0–TPM1CH5
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 10-2. Block Diagram Highlighting ICG Module
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Chapter 10 Internal Clock Generator (S08ICGV4)
10.1
Introduction
The ICG provides multiple options for clock sources. This offers a user great flexibility when making
choices between cost, precision, current draw, and performance. As seen in Figure 10-3, the ICG consists
of four functional blocks. Each of these is briefly described here and then in more detail in a later section.
• Oscillator block — The oscillator block provides means for connecting an external crystal or
resonator. Two frequency ranges are software selectable to allow optimal startup and stability.
Alternatively, the oscillator block can be used to route an external square wave to the system clock.
External sources can provide a very precise clock source. The oscillator is capable of being
configured for low power mode or high amplitude mode as selected by HGO.
• Internal reference generator — The internal reference generator consists of two controlled clock
sources. One is designed to be approximately 8 MHz and can be selected as a local clock for the
background debug controller. The other internal reference clock source is typically 243 kHz and
can be trimmed for finer accuracy via software when a precise timed event is input to the MCU.
This provides a highly reliable, low-cost clock source.
• Frequency-locked loop — A frequency-locked loop (FLL) stage takes either the internal or
external clock source and multiplies it to a higher frequency. Status bits provide information when
the circuit has achieved lock and when it falls out of lock. Additionally, this block can monitor the
external reference clock and signals whether the clock is valid or not.
• Clock select block — The clock select block provides several switch options for connecting
different clock sources to the system clock tree. ICGDCLK is the multiplied clock frequency out
of the FLL, ICGERCLK is the reference clock frequency from the crystal or external clock source,
and FFE (fixed frequency enable) is a control signal used to control the system fixed frequency
clock (XCLK). ICGLCLK is the clock source for the background debug controller (BDC).
10.1.1
Features
The module is intended to be very user friendly with many of the features occurring automatically without
user intervention. To quickly configure the module, go to Section 10.5, “Initialization/Application
Information” and pick an example that best suits the application needs.
Features of the ICG and clock distribution system:
• Several options for the primary clock source allow a wide range of cost, frequency, and precision
choices:
— 32 kHz–100 kHz crystal or resonator
— 1 MHz–16 MHz crystal or resonator
— External clock
— Internal reference generator
• Defaults to self-clocked mode to minimize startup delays
• Frequency-locked loop (FLL) generates 8 MHz to 40 MHz (for bus rates up to 20 MHz)
— Uses external or internal clock as reference frequency
• Automatic lockout of non-running clock sources
• Reset or interrupt on loss of clock or loss of FLL lock
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•
•
•
•
•
•
•
Digitally-controlled oscillator (DCO) preserves previous frequency settings, allowing fast
frequency lock when recovering from stop3 mode
DCO will maintain operating frequency during a loss or removal of reference clock
Post-FLL divider selects 1 of 8 bus rate divisors (/1 through /128)
Separate self-clocked source for real-time interrupt
Trimmable internal clock source supports SCI communications without additional external
components
Automatic FLL engagement after lock is acquired
External oscillator selectable for low power or high gain
10.1.2
Modes of Operation
This is a high-level description only. Detailed descriptions of operating modes are contained in
Section 10.4, “Functional Description.”
• Mode 1 — Off
The output clock, ICGOUT, is static. This mode may be entered when the STOP instruction is
executed.
• Mode 2 — Self-clocked (SCM)
Default mode of operation that is entered immediately after reset. The ICG’s FLL is open loop and
the digitally controlled oscillator (DCO) is free running at a frequency set by the filter bits.
• Mode 3 — FLL engaged internal (FEI)
In this mode, the ICG’s FLL is used to create frequencies that are programmable multiples of the
internal reference clock.
— FLL engaged internal unlocked is a transition state that occurs while the FLL is attempting to
lock. The FLL DCO frequency is off target and the FLL is adjusting the DCO to match the
target frequency.
— FLL engaged internal locked is a state that occurs when the FLL detects that the DCO is locked
to a multiple of the internal reference.
• Mode 4 — FLL bypassed external (FBE)
In this mode, the ICG is configured to bypass the FLL and use an external clock as the clock source.
• Mode 5 — FLL engaged external (FEE)
The ICG’s FLL is used to generate frequencies that are programmable multiples of the external
clock reference.
— FLL engaged external unlocked is a transition state that occurs while the FLL is attempting to
lock. The FLL DCO frequency is off target and the FLL is adjusting the DCO to match the
target frequency.
— FLL engaged external locked is a state which occurs when the FLL detects that the DCO is
locked to a multiple of the internal reference.
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10.1.3
Block Diagram
Figure 10-3 is a top-level diagram that shows the functional organization of the internal clock generation
(ICG) module. This section includes a general description and a feature list.
EXTAL
OSCILLATOR (OSC)
WITH EXTERNAL REF
SELECT
ICG
CLOCK
SELECT
ICGERCLK
XTAL
ICGDCLK
REF
SELECT
VDDA
(SEE NOTE 2)
FREQUENCY
LOCKED
LOOP (FLL)
DCO
OUTPUT
CLOCK
SELECT
/R
ICGOUT
LOSS OF LOCK
AND CLOCK DETECTOR
V SSA
(SEE NOTE 2)
FIXED
CLOCK
SELECT
IRG
INTERNAL TYP 243 kHz
REFERENCE
8 MHz
GENERATORS
RG
FFE
ICGIRCLK
LOCAL CLOCK FOR OPTIONAL USE WITH BDC
ICGLCLK
NOTES:
1. See Table 8-1 for specific use of ICGOUT, FFE, ICGLCLK, ICGERCLK
2. Not all HCS08 microcontrollers have unique supply pins for the ICG. See the device pin assignments.
Figure 10-3. ICG Block Diagram
10.2
External Signal Description
The oscillator pins are used to provide an external clock source for the MCU. The oscillator pins are gain
controlled in low-power mode (default). Oscillator amplitudes in low-power mode are limited to
approximately 1 V, peak-to-peak.
10.2.1
EXTAL — External Reference Clock / Oscillator Input
If upon the first write to ICGC1, either the FEE mode or FBE mode is selected, this pin functions as either
the external clock input or the input of the oscillator circuit as determined by REFS. If upon the first write
to ICGC1, either the FEI mode or SCM mode is selected, this pin is not used by the ICG.
10.2.2
XTAL — Oscillator Output
If upon the first write to ICGC1, either the FEE mode or FBE mode is selected, this pin functions as the
output of the oscillator circuit. If upon the first write to ICGC1, either the FEI mode or SCM mode is
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Chapter 10 Internal Clock Generator (S08ICGV4)
selected, this pin is not used by the ICG. The oscillator is capable of being configured to provide a higher
amplitude output for improved noise immunity. This mode of operation is selected by HGO = 1.
10.2.3
External Clock Connections
If an external clock is used, then the pins are connected as shown Figure 10-4.
ICG
EXTAL
XTAL
VSS
NOT CONNECTED
CLOCK INPUT
Figure 10-4. External Clock Connections
10.2.4
External Crystal/Resonator Connections
If an external crystal/resonator frequency reference is used, then the pins are connected as shown in
Figure 10-5. Recommended component values are listed in the Electrical Characteristics chapter.
ICG
EXTAL
VSS
XTAL
RS
C1
C2
RF
CRYSTAL OR RESONATOR
Figure 10-5. External Frequency Reference Connection
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10.3
Register Definition
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all ICG registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
10.3.1
R
ICG Control Register 1 (ICGC1)
7
6
5
HGO1
RANGE
REFS
0
1
0
4
3
2
1
OSCSTEN
LOCD
1
0
0
0
CLKS
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 10-6. ICG Control Register 1 (ICGC1)
1
This bit can be written only once after reset. Additional writes are ignored.
Table 10-1. ICGC1 Register Field Descriptions
Field
7
HGO
Description
High Gain Oscillator Select — The HGO bit is used to select between low power operation and high gain
operation for improved noise immunity. This bit is write-once after reset.
0 Oscillator configured for low power operation.
1 Oscillator configured for high gain operation.
6
RANGE
Frequency Range Select — The RANGE bit controls the oscillator, reference divider, and FLL loop prescaler
multiplication factor (P). It selects one of two reference frequency ranges for the ICG. The RANGE bit is
write-once after a reset. The RANGE bit only has an effect in FLL engaged external and FLL bypassed external
modes.
0 Oscillator configured for low frequency range. FLL loop prescale factor P is 64.
1 Oscillator configured for high frequency range. FLL loop prescale factor P is 1.
5
REFS
External Reference Select — The REFS bit controls the external reference clock source for ICGERCLK. The
REFS bit is write-once after a reset.
0 External clock requested.
1 Oscillator using crystal or resonator requested.
4:3
CLKS
Clock Mode Select — The CLKS bits control the clock mode as described below. If FLL bypassed external is
requested, it will not be selected until ERCS = 1. If the ICG enters off mode, the CLKS bits will remain
unchanged. Writes to the CLKS bits will not take effect if a previous write is not complete.
00 Self-clocked
01 FLL engaged, internal reference
10 FLL bypassed, external reference
11 FLL engaged, external reference
The CLKS bits are writable at any time, unless the first write after a reset was CLKS = 0X, the CLKS bits cannot
be written to 1X until after the next reset (because the EXTAL pin was not reserved).
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Table 10-1. ICGC1 Register Field Descriptions (continued)
Field
2
OSCSTEN
1
LOCD
Description
Enable Oscillator in Off Mode — The OSCSTEN bit controls whether or not the oscillator circuit remains
enabled when the ICG enters off mode. This bit has no effect if HGO = 1 and RANGE = 1.
0 Oscillator disabled when ICG is in off mode unless ENABLE is high, CLKS = 10, and REFST = 1.
1 Oscillator enabled when ICG is in off mode, CLKS = 1X and REFST = 1.
Loss of Clock Disable
0 Loss of clock detection enabled.
1 Loss of clock detection disabled.
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10.3.2
ICG Control Register 2 (ICGC2)
7
6
5
4
3
2
1
0
R
LOLRE
MFD
LOCRE
RFD
W
Reset
0
0
0
0
0
0
0
0
Figure 10-7. ICG Control Register 2 (ICGC2)
Table 10-2. ICGC2 Register Field Descriptions
Field
Description
7
LOLRE
Loss of Lock Reset Enable — The LOLRE bit determines what type of request is made by the ICG following a
loss of lock indication. The LOLRE bit only has an effect when LOLS is set.
0
Generate an interrupt request on loss of lock.
1
Generate a reset request on loss of lock.
6:4
MFD
Multiplication Factor — The MFD bits control the programmable multiplication factor in the FLL loop. The value
specified by the MFD bits establishes the multiplication factor (N) applied to the reference frequency. Writes to
the MFD bits will not take effect if a previous write is not complete. Select a low enough value for N such that
fICGDCLK does not exceed its maximum specified value.
000 Multiplication factor = 4
001 Multiplication factor = 6
010 Multiplication factor = 8
011 Multiplication factor = 10
100 Multiplication factor = 12
101 Multiplication factor = 14
110 Multiplication factor = 16
111 Multiplication factor = 18
3
LOCRE
Loss of Clock Reset Enable — The LOCRE bit determines how the system manages a loss of clock condition.
0
Generate an interrupt request on loss of clock.
1
Generate a reset request on loss of clock.
2:0
RFD
Reduced Frequency Divider — The RFD bits control the value of the divider following the clock select circuitry.
The value specified by the RFD bits establishes the division factor (R) applied to the selected output clock source.
Writes to the RFD bits will not take effect if a previous write is not complete.
000 Division factor = 1
001 Division factor = 2
010 Division factor = 4
011 Division factor = 8
100 Division factor = 16
101 Division factor = 32
110 Division factor = 64
111 Division factor = 128
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10.3.3
ICG Status Register 1 (ICGS1)
7
R
6
CLKST
5
4
3
2
1
0
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
W
Reset
1
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-8. ICG Status Register 1 (ICGS1)
Table 10-3. ICGS1 Register Field Descriptions
Field
Description
7:6
CLKST
Clock Mode Status — The CLKST bits indicate the current clock mode. The CLKST bits don’t update
immediately after a write to the CLKS bits due to internal synchronization between clock domains.
00 Self-clocked
01 FLL engaged, internal reference
10 FLL bypassed, external reference
11 FLL engaged, external reference
5
REFST
Reference Clock Status — The REFST bit indicates which clock reference is currently selected by the
Reference Select circuit.
0 External Clock selected.
1 Crystal/Resonator selected.
4
LOLS
FLL Loss of Lock Status — The LOLS bit is a sticky indication of FLL lock status.
0 FLL has not unexpectedly lost lock since LOLS was last cleared.
1 FLL has unexpectedly lost lock since LOLS was last cleared, LOLRE determines action taken.FLL has
unexpectedly lost lock since LOLS was last cleared, LOLRE determines action taken.
3
LOCK
FLL Lock Status — The LOCK bit indicates whether the FLL has acquired lock. The LOCK bit is cleared in off,
self-clocked, and FLL bypassed modes.
0 FLL is currently unlocked.
1 FLL is currently locked.
2
LOCS
Loss Of Clock Status — The LOCS bit is an indication of ICG loss of clock status.
0 ICG has not lost clock since LOCS was last cleared.
1 ICG has lost clock since LOCS was last cleared, LOCRE determines action taken.
1
ERCS
External Reference Clock Status — The ERCS bit is an indication of whether or not the external reference
clock (ICGERCLK) meets the minimum frequency requirement.
0 External reference clock is not stable, frequency requirement is not met.
1 External reference clock is stable, frequency requirement is met.
0
ICGIF
ICG Interrupt Flag — The ICGIF read/write flag is set when an ICG interrupt request is pending. It is cleared by
a reset or by reading the ICG status register when ICGIF is set and then writing a logic 1 to ICGIF. If another ICG
interrupt occurs before the clearing sequence is complete, the sequence is reset so ICGIF would remain set after
the clear sequence was completed for the earlier interrupt. Writing a logic 0 to ICGIF has no effect.
0 No ICG interrupt request is pending.
1 An ICG interrupt request is pending.
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10.3.4
R
ICG Status Register 2 (ICGS2)
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
DCOS
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 10-9. ICG Status Register 2 (ICGS2)
Table 10-4. ICGS2 Register Field Descriptions
Field
Description
0
DCOS
DCO Clock Stable — The DCOS bit is set when the DCO clock (ICG2DCLK) is stable, meaning the count error
has not changed by more than nunlock for two consecutive samples and the DCO clock is not static. This bit is
used when exiting off state if CLKS = X1 to determine when to switch to the requested clock mode. It is also used
in self-clocked mode to determine when to start monitoring the DCO clock. This bit is cleared upon entering the
off state.
0 DCO clock is unstable.
1 DCO clock is stable.
10.3.5
R
ICG Filter Registers (ICGFLTU, ICGFLTL)
7
6
5
4
0
0
0
0
3
2
1
0
0
0
FLT
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-10. ICG Upper Filter Register (ICGFLTU)
Table 10-5. ICGFLTU Register Field Descriptions
Field
Description
3:0
FLT
Filter Value — The FLT bits indicate the current filter value, which controls the DCO frequency. The FLT bits are
read only except when the CLKS bits are programmed to self-clocked mode (CLKS = 00). In self-clocked mode,
any write to ICGFLTU updates the current 12-bit filter value. Writes to the ICGFLTU register will not affect FLT if
a previous latch sequence is not complete.
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Chapter 10 Internal Clock Generator (S08ICGV4)
7
6
5
4
3
2
1
0
0
0
0
0
R
FLT
W
Reset
1
1
0
0
Figure 10-11. ICG Lower Filter Register (ICGFLTL)
Table 10-6. ICGFLTL Register Field Descriptions
Field
Description
7:0
FLT
Filter Value — The FLT bits indicate the current filter value, which controls the DCO frequency. The FLT bits are
read only except when the CLKS bits are programmed to self-clocked mode (CLKS = 00). In self-clocked mode,
any write to ICGFLTU updates the current 12-bit filter value. Writes to the ICGFLTU register will not affect FLT if
a previous latch sequence is not complete. The filter registers show the filter value (FLT).
10.3.6
ICG Trim Register (ICGTRM)
7
6
5
4
3
2
1
0
R
TRIM
W
POR
1
0
0
0
0
0
0
0
Reset:
U
U
U
U
U
U
U
U
U = Unaffected by MCU reset
Figure 10-12. ICG Trim Register (ICGTRM)
Table 10-7. ICGTRM Register Field Descriptions
Field
Description
7
TRIM
ICG Trim Setting — The TRIM bits control the internal reference generator frequency. They allow a ±25%
adjustment of the nominal (POR) period. The bit’s effect on period is binary weighted (i.e., bit 1 will adjust twice
as much as changing bit 0). Increasing the binary value in TRIM will increase the period and decreasing the value
will decrease the period.
10.4
Functional Description
This section provides a functional description of each of the five operating modes of the ICG. Also
discussed are the loss of clock and loss of lock errors and requirements for entry into each mode. The ICG
is very flexible, and in some configurations, it is possible to exceed certain clock specifications. When
using the FLL, configure the ICG so that the frequency of ICGDCLK does not exceed its maximum value
to ensure proper MCU operation.
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10.4.1
Off Mode (Off)
Normally when the CPU enters stop mode, the ICG will cease all clock activity and is in the off state.
However there are two cases to consider when clock activity continues while the CPU is in stop mode,
10.4.1.1
BDM Active
When the BDM is enabled, the ICG continues activity as originally programmed. This allows access to
memory and control registers via the BDC controller.
10.4.1.2
OSCSTEN Bit Set
When the oscillator is enabled in stop mode (OSCSTEN = 1), the individual clock generators are enabled
but the clock feed to the rest of the MCU is turned off. This option is provided to avoid long oscillator
startup times if necessary, or to run the RTI from the oscillator during stop3.
10.4.1.3
Stop/Off Mode Recovery
Upon the CPU exiting stop mode due to an interrupt, the previously set control bits are valid and the system
clock feed resumes. If FEE is selected, the ICG will source the internal reference until the external clock
is stable. If FBE is selected, the ICG will wait for the external clock to stabilize before enabling ICGOUT.
Upon the CPU exiting stop mode due to a reset, the previously set ICG control bits are ignored and the
default reset values applied. Therefore the ICG will exit stop in SCM mode configured for an
approximately 8 MHz DCO output (4 MHz bus clock) with trim value maintained. If using a crystal, 4096
clocks are detected prior to engaging ICGERCLK. This is incorporated in crystal start-up time.
10.4.2
Self-Clocked Mode (SCM)
Self-clocked mode (SCM) is the default mode of operation and is entered when any of the following
conditions occur:
• After any reset.
• Exiting from off mode when CLKS does not equal 10. If CLKS = X1, the ICG enters this state
temporarily until the DCO is stable (DCOS = 1).
• CLKS bits are written from X1 to 00.
• CLKS = 1X and ICGERCLK is not detected (both ERCS = 0 and LOCS = 1).
In this state, the FLL loop is open. The DCO is on, and the output clock signal ICGOUT frequency is given
by fICGDCLK / R. The ICGDCLK frequency can be varied from 8 MHz to 40 MHz by writing a new value
into the filter registers (ICGFLTH and ICGFLTL). This is the only mode in which the filter registers can
be written.
If this mode is entered due to a reset, fICGDCLK will default to fSelf_reset which is nominally 8 MHz. If this
mode is entered from FLL engaged internal, fICGDCLK will maintain the previous frequency.If this mode
is entered from FLL engaged external (either by programming CLKS or due to a loss of external reference
clock), fICGDCLK will maintain the previous frequency, but ICGOUT will double if the FLL was unlocked.
If this mode is entered from off mode, fICGDCLK will be equal to the frequency of ICGDCLK before
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Chapter 10 Internal Clock Generator (S08ICGV4)
entering off mode. If CLKS bits are set to 01 or 11 coming out of the Off state, the ICG enters this mode
until ICGDCLK is stable as determined by the DCOS bit. After ICGDCLK is considered stable, the ICG
automatically closes the loop by switching to FLL engaged (internal or external) as selected by the CLKS
bits.
CLKST
REFERENCE
DIVIDER (/7)
ICGIRCLK
CLKS
RFD
CLOCK
SELECT
CIRCUIT
REDUCED
FREQUENCY
DIVIDER (R)
RANGE
ICGOUT
ICGDCLK
FLT
MFD
1x
DIGITALLY
CONTROLLED
OSCILLATOR
2x
DIGITAL
LOOP
FILTER
SUBTRACTOR
FLL ANALOG
ICGERCLK
CLKST
FREQUENCYLOCKED
LOOP (FLL)
OVERFLOW
ICG2DCLK
PULSE
COUNTER
COUNTER ENABLE
RANGE
LOCK AND
LOSS OF CLOCK
DETECTOR
DCOS LOCK LOLS
LOCS ERCS
RESET AND
INTERRUPT
CONTROL
LOCD
IRQ
RESET
ICGIF LOLRE LOCRE
Figure 10-13. Detailed Frequency-Locked Loop Block Diagram
10.4.3
FLL Engaged, Internal Clock (FEI) Mode
FLL engaged internal (FEI) is entered when any of the following conditions occur:
• CLKS bits are written to 01
• The DCO clock stabilizes (DCOS = 1) while in SCM upon exiting the off state with CLKS = 01
In FLL engaged internal mode, the reference clock is derived from the internal reference clock
ICGIRCLK, and the FLL loop will attempt to lock the ICGDCLK frequency to the desired value, as
selected by the MFD bits.
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10.4.4
FLL Engaged Internal Unlocked
FEI unlocked is a temporary state that is entered when FEI is entered and the count error (Δn) output from
the subtractor is greater than the maximum nunlock or less than the minimum nunlock, as required by the
lock detector to detect the unlock condition.
The ICG will remain in this state while the count error (Δn) is greater than the maximum nlock or less than
the minimum nlock, as required by the lock detector to detect the lock condition.
In this state the output clock signal ICGOUT frequency is given by fICGDCLK / R.
10.4.5
FLL Engaged Internal Locked
FLL engaged internal locked is entered from FEI unlocked when the count error (Δn), which comes from
the subtractor, is less than nlock (max) and greater than nlock (min) for a given number of samples, as
required by the lock detector to detect the lock condition. The output clock signal ICGOUT frequency is
given by fICGDCLK / R. In FEI locked, the filter value is updated only once every four comparison cycles.
The update made is an average of the error measurements taken in the four previous comparisons.
10.4.6
FLL Bypassed, External Clock (FBE) Mode
FLL bypassed external (FBE) is entered when any of the following conditions occur:
• From SCM when CLKS = 10 and ERCS is high
• When CLKS = 10, ERCS = 1 upon entering off mode, and off is then exited
• From FLL engaged external mode if a loss of DCO clock occurs and the external reference remains
valid (both LOCS = 1 and ERCS = 1)
In this state, the DCO and IRG are off and the reference clock is derived from the external reference clock,
ICGERCLK. The output clock signal ICGOUT frequency is given by fICGERCLK / R. If an external clock
source is used (REFS = 0), then the input frequency on the EXTAL pin can be anywhere in the range
0 MHz to 40 MHz. If a crystal or resonator is used (REFS = 1), then frequency range is either low for
RANGE = 0 or high for RANGE = 1.
10.4.7
FLL Engaged, External Clock (FEE) Mode
The FLL engaged external (FEE) mode is entered when any of the following conditions occur:
• CLKS = 11 and ERCS and DCOS are both high.
• The DCO stabilizes (DCOS = 1) while in SCM upon exiting the off state with CLKS = 11.
In FEE mode, the reference clock is derived from the external reference clock ICGERCLK, and the FLL
loop will attempt to lock the ICGDCLK frequency to the desired value, as selected by the MFD bits. To
run in FEE mode, there must be a working 32 kHz–100 kHz or 2 MHz–10 MHz external clock source. The
maximum external clock frequency is limited to 10 MHz in FEE mode to prevent over-clocking the DCO.
The minimum multiplier for the FLL, from Table 10-12 is 4. Because 4 X 10 MHz is 40MHz, which is the
operational limit of the DCO, the reference clock cannot be any faster than 10 MHz.
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10.4.7.1
FLL Engaged External Unlocked
FEE unlocked is entered when FEE is entered and the count error (Δn) output from the subtractor is greater
than the maximum nunlock or less than the minimum nunlock, as required by the lock detector to detect the
unlock condition.
The ICG will remain in this state while the count error (Δn) is greater than the maximum nlock or less than
the minimum nlock, as required by the lock detector to detect the lock condition.
In this state, the pulse counter, subtractor, digital loop filter, and DCO form a closed loop and attempt to
lock it according to their operational descriptions later in this section. Upon entering this state and until
the FLL becomes locked, the output clock signal ICGOUT frequency is given by fICGDCLK / (2×R) This
extra divide by two prevents frequency overshoots during the initial locking process from exceeding
chip-level maximum frequency specifications. After the FLL has locked, if an unexpected loss of lock
causes it to re-enter the unlocked state while the ICG remains in FEE mode, the output clock signal
ICGOUT frequency is given by fICGDCLK / R.
10.4.7.2
FLL Engaged External Locked
FEE locked is entered from FEE unlocked when the count error (Δn) is less than nlock (max) and greater
than nlock (min) for a given number of samples, as required by the lock detector to detect the lock
condition. The output clock signal ICGOUT frequency is given by fICGDCLK/R. In FLL engaged external
locked, the filter value is updated only once every four comparison cycles. The update made is an average
of the error measurements taken in the four previous comparisons.
10.4.8
FLL Lock and Loss-of-Lock Detection
To determine the FLL locked and loss-of-lock conditions, the pulse counter counts the pulses of the DCO
for one comparison cycle (see Table 10-9 for explanation of a comparison cycle) and passes this number
to the subtractor. The subtractor compares this value to the value in MFD and produces a count error, Δn.
To achieve locked status, Δn must be between nlock (min) and nlock (max). After the FLL has locked, Δn
must stay between nunlock (min) and nunlock (max) to remain locked. If Δn goes outside this range
unexpectedly, the LOLS status bit is set and remains set until cleared by software or until the MCU is reset.
LOLS is cleared by reading ICGS1 then writing 1 to ICGIF (LOLRE = 0), or by a loss-of-lock induced
reset (LOLRE = 1), or by any MCU reset.
If the ICG enters the off state due to stop mode when ENBDM = OSCSTEN = 0, the FLL loses locked
status (LOCK is cleared), but LOLS remains unchanged because this is not an unexpected loss-of-lock
condition. Though it would be unusual, if ENBDM is cleared to 0 while the MCU is in stop, the ICG enters
the off state. Because this is an unexpected stopping of clocks, LOLS will be set when the MCU wakes up
from stop.
Expected loss of lock occurs when the MFD or CLKS bits are changed or in FEI mode only, when the
TRIM bits are changed. In these cases, the LOCK bit will be cleared until the FLL regains lock, but the
LOLS will not be set.
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10.4.9
FLL Loss-of-Clock Detection
The reference clock and the DCO clock are monitored under different conditions (see Table 10-8).
Provided the reference frequency is being monitored, ERCS = 1 indicates that the reference clock meets
minimum frequency requirements. When the reference and/or DCO clock(s) are being monitored, if either
one falls below a certain frequency, fLOR and fLOD, respectively, the LOCS status bit will be set to indicate
the error. LOCS will remain set until it is acknowledged or until the MCU is reset. LOCS is cleared by
reading ICGS1 then writing 1 to ICGIF (LOCRE = 0), or by a loss-of-clock induced reset (LOCRE = 1),
or by any MCU reset.
If the ICG is in FEE, a loss of reference clock causes the ICG to enter SCM, and a loss of DCO clock causes
the ICG to enter FBE mode. If the ICG is in FBE mode, a loss of reference clock will cause the ICG to
enter SCM. In each case, the CLKST and CLKS bits will be automatically changed to reflect the new state.
If the ICG is in FEE mode when a loss of clock occurs and the ERCS is still set to 1, then the CLKST bits
are set to 10 and the ICG reverts to FBE mode.
A loss of clock will also cause a loss of lock when in FEE or FEI modes. Because the method of clearing
the LOCS and LOLS bits is the same, this would only be an issue in the unlikely case that LOLRE = 1 and
LOCRE = 0. In this case, the interrupt would be overridden by the reset for the loss of lock.
Table 10-8. Clock Monitoring (When LOCD = 0)
Mode
CLKS
REFST
ERCS
External Reference
Clock
Monitored?
DCO Clock
Monitored?
Off
0X or 11
X
Forced Low
No
No
SCM
(CLKST = 00)
FEI
(CLKST = 01)
FBE
(CLKST = 10)
FEE
(CLKST = 11)
1
2
10
0
Forced Low
No
No
10
1
Real-Time1
Yes(1)
No
0X
X
Forced Low
No
Yes2
10
0
Forced High
No
Yes(2)
10
1
Real-Time
Yes
Yes(2)
11
X
Real-Time
Yes
Yes(2)
0X
X
Forced Low
No
Yes
11
X
Real-Time
Yes
Yes
10
0
Forced High
No
No
10
1
Real-Time
Yes
No
11
X
Real-Time
Yes
Yes
If ENABLE is high (waiting for external crystal start-up after exiting stop).
DCO clock will not be monitored until DCOS = 1 upon entering SCM from off or FLL bypassed external mode.
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10.4.10 Clock Mode Requirements
A clock mode is requested by writing to CLKS1:CLKS0 and the actual clock mode is indicated by
CLKST1:CLKST0. Provided minimum conditions are met, the status shown in CLKST1:CLKST0 should
be the same as the requested mode in CLKS1:CLKS0. Table 10-9 shows the relationship between CLKS,
CLKST, and ICGOUT. It also shows the conditions for CLKS = CLKST or the reason CLKS ≠ CLKST.
NOTE
If a crystal will be used before the next reset, then be sure to set REFS = 1
and CLKS = 1x on the first write to the ICGC1 register. Failure to do so will
result in “locking” REFS = 0 which will prevent the oscillator amplifier
from being enabled until the next reset occurs.
Table 10-9. ICG State Table
Actual
Mode
(CLKST)
Off
(XX)
SCM
(00)
FEI
(01)
FBE
(10)
FEE
(11)
Desired
Mode
(CLKS)
Range
Reference
Frequency
(fREFERENCE)
Comparison
Cycle Time
ICGOUT
Conditions1 for
CLKS = CLKST
Reason
CLKS1 ≠
CLKST
Off
(XX)
X
0
—
0
—
—
FBE
(10)
X
0
—
0
—
ERCS = 0
SCM
(00)
X
fICGIRCLK/72
8/fICGIRCLK
ICGDCLK/R
Not switching
from FBE to
SCM
—
FEI
(01)
0
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
DCOS = 0
FBE
(10)
X
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
ERCS = 0
FEE
(11)
X
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
DCOS = 0 or
ERCS = 0
FEI
(01)
0
fICGIRCLK/7
8/fICGIRCLK
ICGDCLK/R
DCOS = 1
—
FEE
(11)
X
fICGIRCLK/7
8/fICGIRCLK
ICGDCLK/R
—
ERCS = 0
FBE
(10)
X
0
—
ICGERCLK/R
ERCS = 1
—
FEE
(11)
X
0
—
ICGERCLK/R
—
LOCS = 1 &
ERCS = 1
0
fICGERCLK
2/fICGERCLK
ICGDCLK/R3
ERCS = 1 and
DCOS = 1
—
1
fICGERCLK
128/fICGERCLK
ICGDCLK/R(2)
ERCS = 1 and
DCOS = 1
—
FEE
(11)
1
CLKST will not update immediately after a write to CLKS. Several bus cycles are required before CLKST updates to the new
value.
2
The reference frequency has no effect on ICGOUT in SCM, but the reference frequency is still used in making the comparisons
that determine the DCOS bit
3 After initial LOCK; will be ICGDCLK/2R during initial locking process and while FLL is re-locking after the MFD bits are changed.
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Chapter 10 Internal Clock Generator (S08ICGV4)
10.4.11 Fixed Frequency Clock
The ICG provides a fixed frequency clock output, XCLK, for use by on-chip peripherals. This output is
equal to the internal bus clock, BUSCLK, in all modes except FEE. In FEE mode, XCLK is equal to
ICGERCLK ÷ 2 when the following conditions are met:
• (P × N) ÷ R ≥ 4 where P is determined by RANGE (see Table 10-11), N and R are determined by
MFD and RFD respectively (see Table 10-12).
• LOCK = 1.
If the above conditions are not true, then XCLK is equal to BUSCLK.
When the ICG is in either FEI or SCM mode, XCLK is turned off. Any peripherals which can use XCLK
as a clock source must not do so when the ICG is in FEI or SCM mode.
10.4.12 High Gain Oscillator
The oscillator has the option of running in a high gain oscillator (HGO) mode, which improves the
oscillator's resistance to EMC noise when running in FBE or FEE modes. This option is selected by writing
a 1 to the HGO bit in the ICGC1 register. HGO is used with both the high and low range oscillators but is
only valid when REFS = 1 in the ICGC1 register. When HGO = 0, the standard low-power oscillator is
selected. This bit is writable only once after any reset.
10.5
10.5.1
Initialization/Application Information
Introduction
The section is intended to give some basic direction on which configuration a user would want to select
when initializing the ICG. For some applications, the serial communication link may dictate the accuracy
of the clock reference. For other applications, lowest power consumption may be the chief clock
consideration. Still others may have lowest cost as the primary goal. The ICG allows great flexibility in
choosing which is best for any application.
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Chapter 10 Internal Clock Generator (S08ICGV4)
Table 10-10. ICG Configuration Consideration
Clock Reference Source = Internal
1
Clock Reference Source = External
FLL
Engaged
FEI
4 MHz < fBus < 20 MHz.
Medium power (will be less than FEE if oscillator
range = high)
Good clock accuracy (After IRG is trimmed)
Lowest system cost (no external components
required)
IRG is on. DCO is on. 1
FEE
4 MHz < fBus < 20 MHz
Medium power (will be less than FEI if oscillator
range = low)
High clock accuracy
Medium/High system cost (crystal, resonator or
external clock source required)
IRG is off. DCO is on.
FLL
Bypassed
SCM
This mode is mainly provided for quick and reliable
system startup.
3 MHz < fBus < 5 MHz (default).
3 MHz < fBus < 20 MHz (via filter bits).
Medium power
Poor accuracy.
IRG is off. DCO is on and open loop.
FBE
fBus range ≤ 8 MHz when crystal or resonator is
used.
Lowest power
Highest clock accuracy
Medium/High system cost (Crystal, resonator or
external clock source required)
IRG is off. DCO is off.
The IRG typically consumes 100 μA. The FLL and DCO typically consumes 0.5 to 2.5 mA, depending upon output frequency.
For minimum power consumption and minimum jitter, choose N and R to be as small as possible.
The following sections contain initialization examples for various configurations.
NOTE
Hexadecimal values designated by a preceding $, binary values designated
by a preceding %, and decimal values have no preceding character.
Important configuration information is repeated here for reference.
Table 10-11. ICGOUT Frequency Calculation Options
Clock Scheme
SCM — self-clocked mode (FLL bypassed
internal)
FBE — FLL bypassed external
FEI — FLL engaged internal
FEE — FLL engaged external
1
fICGOUT1
P
Note
fICGDCLK / R
NA
Typical fICGOUT = 8 MHz
immediately after reset
fext / R
NA
(fIRG / 7)* 64 * N / R
64
fext * P * N / R
Range = 0 ; P = 64
Range = 1; P = 1
Typical fIRG = 243 kHz
Ensure that fICGDCLK, which is equal to fICGOUT * R, does not exceed fICGDCLKmax.
Table 10-12. MFD and RFD Decode Table
MFD Value
Multiplication Factor (N)
RFD
Division Factor (R)
000
001
010
011
100
4
6
8
10
12
000
001
010
011
100
÷1
÷2
÷4
÷8
÷16
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Table 10-12. MFD and RFD Decode Table
101
110
111
10.5.2
14
16
18
101
110
111
÷32
÷64
÷128
Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz
In this example, the FLL will be used (in FEE mode) to multiply the external 32 kHz oscillator up to
8.38 MHz to achieve 4.19 MHz bus frequency.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT, which corresponds to a 4 MHz bus frequency (fBus).
The clock scheme will be FLL engaged, external (FEE). So
fICGOUT = fext * P * N / R ; P = 64, fext = 32 kHz
Eqn. 10-1
N / R = 8.38 MHz /(32 kHz * 64) = 4 ; we can choose N = 4 and R =1
Eqn. 10-2
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $38 (%00111000)
Bit 7
Bit 6
Bit 5
Bits 4:3
Bit 2
Bit 1
Bit 0
HGO
RANGE
REFS
CLKS
OSCSTEN
LOCD
0
0
1
11
0
0
0
Configures oscillator for low power
Configures oscillator for low-frequency range; FLL prescale factor is 64
Oscillator using crystal or resonator is requested
FLL engaged, external reference clock mode
Oscillator disabled
Loss-of-clock detection enabled
Unimplemented or reserved, always reads zero
ICGC2 = $00 (%00000000)
Bit 7
Bits 6:4
Bit 3
Bits 2:0
LOLRE
MFD
LOCRE
RFD
0
Generates an interrupt request on loss of lock
000 Sets the MFD multiplication factor to 4
0
Generates an interrupt request on loss of clock
000 Sets the RFD division factor to ÷1
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only; should read DCOS = 1 before performing any time critical tasks
ICGFLTLU/L = $xx
Only needed in self-clocked mode; FLT will be adjusted by loop to give 8.38 MHz DCO clock
Bits 15:12 unused
0000
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Chapter 10 Internal Clock Generator (S08ICGV4)
Bits 11:0 FLT
No need for user initialization
ICGTRM = $xx
Bits 7:0
TRIM
Only need to write when trimming internal oscillator; not used when external
crystal is clock source
Figure 10-14 shows flow charts for three conditions requiring ICG initialization.
RESET
INITIALIZE ICG
ICGC1 = $38
ICGC2 = $00
CHECK
FLL LOCK STATUS.
LOCK = 1?
QUICK RECOVERY FROM STOP
MINIMUM CURRENT DRAW IN STOP
RECOVERY FROM STOP
OSCSTEN = 1
RECOVERY FROM STOP
OSCSTEN = 0
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
YES
YES
NO
CONTINUE
CONTINUE
YES
CONTINUE
NOTE: THIS WILL REQUIRE THE OSCILLATOR TO START AND
STABILIZE. ACTUAL TIME IS DEPENDENT ON CRYSTAL /RESONATOR
AND EXTERNAL CIRCUITRY.
Figure 10-14. ICG Initialization for FEE in Example #1
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Chapter 10 Internal Clock Generator (S08ICGV4)
10.5.3
Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz
In this example, the FLL will be used (in FEE mode) to multiply the external 4 MHz oscillator up to
40-MHz to achieve 20 MHz bus frequency.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT which corresponds to a 4 MHz bus frequency (fBus).
During reset initialization software, the clock scheme will be set to FLL engaged, external (FEE). So
fICGOUT = fext * P * N / R ; P = 1, fext = 4.00 MHz
Eqn. 10-3
N / R = 40 MHz /(4 MHz * 1) = 10 ; We can choose N = 10 and R = 1
Eqn. 10-4
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $78
Bit 7
Bit 6
Bit 5
Bits 4:3
Bit 2
Bit 1
Bit 0
HGO
RANGE
REFS
CLKS
OSCSTEN
LOCD
ICGC2 = $30
Bit 7
Bit 6:4
Bit 3
Bit 2:0
(%01111000)
0
1
1
11
0
0
0
Configures oscillator for low power
Configures oscillator for high-frequency range; FLL prescale factor is 1
Requests an oscillator
FLL engaged, external reference clock mode
Disables the oscillator
Loss-of-clock detection enabled
Unimplemented or reserved, always reads zero
(%00110000)
LOLRE
MFD
LOCRE
RFD
0
Generates an interrupt request on loss of lock
011 Sets the MFD multiplication factor to 10
0
Generates an interrupt request on loss of clock
000 Sets the RFD division factor to ÷1
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only. Should read DCOS before performing any time critical tasks
ICGFLTLU/L = $xx
Not used in this example
ICGTRM
Not used in this example
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Chapter 10 Internal Clock Generator (S08ICGV4)
RECOVERY
FROM STOP
RESET
INITIALIZE ICG
ICGC1 = $7A
ICGC2 = $30
CHECK
FLL LOCK STATUS
LOCK = 1?
YES
SERVICE INTERRUPT
SOURCE (fBus = 4 MHz)
NO
CHECK
FLL LOCK STATUS
LOCK = 1?
NO
YES
CONTINUE
CONTINUE
Figure 10-15. ICG Initialization and Stop Recovery for Example #2
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Chapter 10 Internal Clock Generator (S08ICGV4)
10.5.4
Example #3: No External Crystal Connection, 5.4 MHz Bus
Frequency
In this example, the FLL will be used (in FEI mode) to multiply the internal 243 kHz (approximate)
reference clock up to 10.8 MHz to achieve 5.4 MHz bus frequency. This system will also use the trim
function to fine tune the frequency based on an external reference signal.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT which corresponds to a 4 MHz bus frequency (fBus).
The clock scheme will be FLL engaged, internal (FEI). So
fICGOUT = (fIRG / 7) * P * N / R ; P = 64, fIRG = 243 kHz
Eqn. 10-5
Solving for N / R gives:
N / R = 10.8 MHz /(243/7 kHz * 64) = 4.86 ; We can choose N = 10 and R = 2.
Eqn. 10-6
A trim procedure will be required to hone the frequency to exactly 5.4 MHz. An example of the trim
procedure is shown in example #4.
The values needed in each register to set up the desired operation are:
ICGC1 = $28 (%00101000)
Bit 7
HGO
0
Bit 6
RANGE
0
Bit 5
REFS
1
Bits 4:3 CLKS
01
Bit 2
OSCSTEN 0
Bit 1
LOCD
0
Bit 0
0
Configures oscillator for low power
Configures oscillator for low-frequency range; FLL prescale factor is 64
Oscillator using crystal or resonator requested (bit is really a don’t care)
FLL engaged, internal reference clock mode
Disables the oscillator
Loss-of-clock enabled
Unimplemented or reserved, always reads zero
ICGC2 = $31 (%00110001)
Bit 7
LOLRE
0
Generates an interrupt request on loss of lock
Bit 6:4 MFD
011 Sets the MFD multiplication factor to 10
Bit 3
LOCRE
0
Generates an interrupt request on loss of clock
Bit 2:0 RFD
001 Sets the RFD division factor to ÷2
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only; good idea to read this before performing time critical operations
ICGFLTLU/L = $xx
Not used in this example
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Chapter 10 Internal Clock Generator (S08ICGV4)
ICGTRM = $xx
Bit 7:0 TRIM
Only need to write when trimming internal oscillator; done in separate
operation (see example #4)
RECOVERY
FROM STOP
RESET
INITIALIZE ICG
ICGC1 = $28
ICGC2 = $31
CHECK
FLL LOCK STATUS.
LOCK = 1?
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
YES
NO
CONTINUE
YES
CONTINUE
NOTE: THIS WILL REQUIRE THE INTERAL REFERENCE CLOCK TO START AND
STABILIZE.
Figure 10-16. ICG Initialization and Stop Recovery for Example #3
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Chapter 10 Internal Clock Generator (S08ICGV4)
10.5.5
Example #4: Internal Clock Generator Trim
The internally generated clock source is guaranteed to have a period ± 25% of the nominal value. In some
cases, this may be sufficient accuracy. For other applications that require a tight frequency tolerance, a
trimming procedure is provided that will allow a very accurate source. This section outlines one example
of trimming the internal oscillator. Many other possible trimming procedures are valid and can be used.
Initial conditions:
1) Clock supplied from ATE has 500 μsec duty period
2) ICG configured for internal reference with 4 MHz bus
START TRIM PROCEDURE
ICGTRM = $80, n = 1
MEASURE
INCOMING CLOCK WIDTH
(COUNT = # OF BUS CLOCKS / 4)
COUNT < EXPECTED = 500
(RUNNING TOO SLOW)
.
CASE STATEMENT
COUNT = EXPECTED = 500
COUNT > EXPECTED = 500
(RUNNING TOO FAST)
ICGTRM =
ICGTRM - 128 / (2**n)
(DECREASING ICGTRM
INCREASES THE FREQUENCY)
ICGTRM =
ICGTRM + 128 / (2**n)
(INCREASING ICGTRM
DECREASES THE FREQUENCY)
STORE ICGTRM VALUE
IN NON-VOLATILE
MEMORY
CONTINUE
n = n+1
YES
IS n > 8?
NO
Figure 10-17. Trim Procedure
In this particular case, the MCU has been attached to a PCB and the entire assembly is undergoing final
test with automated test equipment. A separate signal or message is provided to the MCU operating under
user provided software control. The MCU initiates a trim procedure as outlined in Figure 10-17 while the
tester supplies a precision reference signal.
If the intended bus frequency is near the maximum allowed for the device, it is recommended to trim using
a reduction divisor (R) twice the final value. After the trim procedure is complete, the reduction divisor
can be restored. This will prevent accidental overshoot of the maximum clock frequency.
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Chapter 10 Internal Clock Generator (S08ICGV4)
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Freescale Semiconductor
Chapter 11
Inter-Integrated Circuit (S08IICV2)
11.1
Introduction
The inter-integrated circuit (IIC) provides a method of communication between a number of devices. The
interface is designed to operate up to 100 kbps with maximum bus loading and timing. The device is
capable of operating at higher baud rates, up to a maximum of clock/20, with reduced bus loading. The
maximum communication length and the number of devices that can be connected are limited by a
maximum bus capacitance of 400 pF.
For additional detail, please refer to volume 1 of the HCS08 Reference Manual, (Freescale Semiconductor
document order number HCS08RMv1/D).
The MC9S08AC128 Series series of microcontrollers has an inter-integrated circuit (IIC) module for
communication with other integrated circuits.
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
HCS08 CORE
COP
IRQ
LVD
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
EXTAL
XTAL
LOW-POWER OSC
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VSSAD
VREFL
VREFH
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT J
PORT H
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTC0/SCL1
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
VOLTAGE REGULATOR
VSS
PORT A
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
PORT E
RQ/TPMCLK
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT B
HCS08 SYSTEM CONTROL
RESET
PORT C
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT D
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
TPM1CH0–TPM1CH5
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
- Pin not connected in 48-pin package
Figure 11-1. Block Diagram Highlighting the IIC Module
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
11.1.1
Features
The IIC includes these distinctive features:
• Compatible with IIC bus standard
• Multi-master operation
• Software programmable for one of 64 different serial clock frequencies
• Software selectable acknowledge bit
• Interrupt driven byte-by-byte data transfer
• Arbitration lost interrupt with automatic mode switching from master to slave
• Calling address identification interrupt
• Start and stop signal generation/detection
• Repeated start signal generation
• Acknowledge bit generation/detection
• Bus busy detection
• General call recognition
• 10-bit address extension
11.1.2
Modes of Operation
A brief description of the IIC in the various MCU modes is given here.
• Run mode — This is the basic mode of operation. To conserve power in this mode, disable the
module.
• Wait mode — The module continues to operate while the MCU is in wait mode and can provide
a wake-up interrupt.
• Stop mode — The IIC is inactive in stop3 mode for reduced power consumption. The stop
instruction does not affect IIC register states. Stop2 resets the register contents.
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
11.1.3
Block Diagram
Figure 11-2 is a block diagram of the IIC.
Address
Data Bus
Interrupt
ADDR_DECODE
CTRL_REG
DATA_MUX
FREQ_REG
ADDR_REG
STATUS_REG
DATA_REG
Input
Sync
Start
Stop
Arbitration
Control
Clock
Control
In/Out
Data
Shift
Register
Address
Compare
SCL
SDA
Figure 11-2. IIC Functional Block Diagram
11.2
External Signal Description
This section describes each user-accessible pin signal.
11.2.1
SCL — Serial Clock Line
The bidirectional SCL is the serial clock line of the IIC system.
11.2.2
SDA — Serial Data Line
The bidirectional SDA is the serial data line of the IIC system.
11.3
Register Definition
This section consists of the IIC register descriptions in address order.
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
Refer to the direct-page register summary in the memory chapter of this document for the absolute address
assignments for all IIC registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
11.3.1
IIC Address Register (IICA)
7
6
5
4
3
2
1
AD7
AD6
AD5
AD4
AD3
AD2
AD1
0
0
0
0
0
0
0
R
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 11-3. IIC Address Register (IICA)
Table 11-1. IICA Field Descriptions
Field
Description
7–1
AD[7:1]
Slave Address. The AD[7:1] field contains the slave address to be used by the IIC module. This field is used on
the 7-bit address scheme and the lower seven bits of the 10-bit address scheme.
11.3.2
IIC Frequency Divider Register (IICF)
7
6
5
4
3
2
1
0
0
0
0
R
MULT
ICR
W
Reset
0
0
0
0
0
Figure 11-4. IIC Frequency Divider Register (IICF)
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
Table 11-2. IICF Field Descriptions
Field
7–6
MULT
5–0
ICR
Description
IIC Multiplier Factor. The MULT bits define the multiplier factor, mul. This factor, along with the SCL divider,
generates the IIC baud rate. The multiplier factor mul as defined by the MULT bits is provided below.
00 mul = 01
01 mul = 02
10 mul = 04
11 Reserved
IIC Clock Rate. The ICR bits are used to prescale the bus clock for bit rate selection. These bits and the MULT
bits determine the IIC baud rate, the SDA hold time, the SCL Start hold time, and the SCL Stop hold time.
Table 11-4 provides the SCL divider and hold values for corresponding values of the ICR.
The SCL divider multiplied by multiplier factor mul generates IIC baud rate.
bus speed (Hz)
IIC baud rate = --------------------------------------------mul × SCLdivider
Eqn. 11-1
SDA hold time is the delay from the falling edge of SCL (IIC clock) to the changing of SDA (IIC data).
SDA hold time = bus period (s) × mul × SDA hold value
Eqn. 11-2
SCL start hold time is the delay from the falling edge of SDA (IIC data) while SCL is high (Start condition) to the
falling edge of SCL (IIC clock).
SCL Start hold time = bus period (s) × mul × SCL Start hold value
Eqn. 11-3
SCL stop hold time is the delay from the rising edge of SCL (IIC clock) to the rising edge of SDA
SDA (IIC data) while SCL is high (Stop condition).
SCL Stop hold time = bus period (s) × mul × SCL Stop hold value
Eqn. 11-4
For example, if the bus speed is 8 MHz, the table below shows the possible hold time values with different
ICR and MULT selections to achieve an IIC baud rate of 100kbps.
Table 11-3. Hold Time Values for 8 MHz Bus Speed
Hold Times (μs)
MULT
ICR
SDA
SCL Start
SCL Stop
0x2
0x00
3.500
3.000
5.500
0x1
0x07
2.500
4.000
5.250
0x1
0x0B
2.250
4.000
5.250
0x0
0x14
2.125
4.250
5.125
0x0
0x18
1.125
4.750
5.125
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
Table 11-4. IIC Divider and Hold Values
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SDA Hold
(Stop)
Value
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SCL Hold
(Stop)
Value
00
20
7
6
11
20
160
17
78
81
01
22
7
7
12
21
192
17
94
97
02
24
8
8
13
22
224
33
110
113
03
26
8
9
14
23
256
33
126
129
04
28
9
10
15
24
288
49
142
145
05
30
9
11
16
25
320
49
158
161
06
34
10
13
18
26
384
65
190
193
07
40
10
16
21
27
480
65
238
241
08
28
7
10
15
28
320
33
158
161
09
32
7
12
17
29
384
33
190
193
0A
36
9
14
19
2A
448
65
222
225
0B
40
9
16
21
2B
512
65
254
257
0C
44
11
18
23
2C
576
97
286
289
0D
48
11
20
25
2D
640
97
318
321
0E
56
13
24
29
2E
768
129
382
385
0F
68
13
30
35
2F
960
129
478
481
10
48
9
18
25
30
640
65
318
321
11
56
9
22
29
31
768
65
382
385
12
64
13
26
33
32
896
129
446
449
13
72
13
30
37
33
1024
129
510
513
14
80
17
34
41
34
1152
193
574
577
15
88
17
38
45
35
1280
193
638
641
16
104
21
46
53
36
1536
257
766
769
17
128
21
58
65
37
1920
257
958
961
18
80
9
38
41
38
1280
129
638
641
19
96
9
46
49
39
1536
129
766
769
1A
112
17
54
57
3A
1792
257
894
897
1B
128
17
62
65
3B
2048
257
1022
1025
1C
144
25
70
73
3C
2304
385
1150
1153
1D
160
25
78
81
3D
2560
385
1278
1281
1E
192
33
94
97
3E
3072
513
1534
1537
1F
240
33
118
121
3F
3840
513
1918
1921
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11.3.3
IIC Control Register (IICC1)
7
6
5
4
3
IICEN
IICIE
MST
TX
TXAK
R
W
Reset
2
1
0
0
0
0
0
0
RSTA
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-5. IIC Control Register (IICC1)
Table 11-5. IICC1 Field Descriptions
Field
Description
7
IICEN
IIC Enable. The IICEN bit determines whether the IIC module is enabled.
0 IIC is not enabled
1 IIC is enabled
6
IICIE
IIC Interrupt Enable. The IICIE bit determines whether an IIC interrupt is requested.
0 IIC interrupt request not enabled
1 IIC interrupt request enabled
5
MST
Master Mode Select. The MST bit changes from a 0 to a 1 when a start signal is generated on the bus and
master mode is selected. When this bit changes from a 1 to a 0 a stop signal is generated and the mode of
operation changes from master to slave.
0 Slave mode
1 Master mode
4
TX
Transmit Mode Select. The TX bit selects the direction of master and slave transfers. In master mode, this bit
should be set according to the type of transfer required. Therefore, for address cycles, this bit is always high.
When addressed as a slave, this bit should be set by software according to the SRW bit in the status register.
0 Receive
1 Transmit
3
TXAK
Transmit Acknowledge Enable. This bit specifies the value driven onto the SDA during data acknowledge
cycles for master and slave receivers.
0 An acknowledge signal is sent out to the bus after receiving one data byte
1 No acknowledge signal response is sent
2
RSTA
Repeat start. Writing a 1 to this bit generates a repeated start condition provided it is the current master. This
bit is always read as cleared. Attempting a repeat at the wrong time results in loss of arbitration.
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11.3.4
IIC Status Register (IICS)
7
R
6
TCF
5
4
BUSY
IAAS
3
2
0
SRW
ARBL
1
0
RXAK
IICIF
W
Reset
1
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-6. IIC Status Register (IICS)
Table 11-6. IICS Field Descriptions
Field
Description
7
TCF
Transfer Complete Flag. This bit is set on the completion of a byte transfer. This bit is only valid during or
immediately following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the
IICD register in receive mode or writing to the IICD in transmit mode.
0 Transfer in progress
1 Transfer complete
6
IAAS
Addressed as a Slave. The IAAS bit is set when the calling address matches the programmed slave address
or when the GCAEN bit is set and a general call is received. Writing the IICC register clears this bit.
0 Not addressed
1 Addressed as a slave
5
BUSY
Bus Busy. The BUSY bit indicates the status of the bus regardless of slave or master mode. The BUSY bit is
set when a start signal is detected and cleared when a stop signal is detected.
0 Bus is idle
1 Bus is busy
4
ARBL
Arbitration Lost. This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared
by software by writing a 1 to it.
0 Standard bus operation
1 Loss of arbitration
2
SRW
Slave Read/Write. When addressed as a slave, the SRW bit indicates the value of the R/W command bit of the
calling address sent to the master.
0 Slave receive, master writing to slave
1 Slave transmit, master reading from slave
1
IICIF
IIC Interrupt Flag. The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by
writing a 1 to it in the interrupt routine. One of the following events can set the IICIF bit:
• One byte transfer completes
• Match of slave address to calling address
• Arbitration lost
0 No interrupt pending
1 Interrupt pending
0
RXAK
Receive Acknowledge. When the RXAK bit is low, it indicates an acknowledge signal has been received after
the completion of one byte of data transmission on the bus. If the RXAK bit is high it means that no acknowledge
signal is detected.
0 Acknowledge received
1 No acknowledge received
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11.3.5
IIC Data I/O Register (IICD)
7
6
5
4
3
2
1
0
0
0
0
0
R
DATA
W
Reset
0
0
0
0
Figure 11-7. IIC Data I/O Register (IICD)
Table 11-7. IICD Field Descriptions
Field
Description
7–0
DATA
Data — In master transmit mode, when data is written to the IICD, a data transfer is initiated. The most significant
bit is sent first. In master receive mode, reading this register initiates receiving of the next byte of data.
NOTE
When transitioning out of master receive mode, the IIC mode should be
switched before reading the IICD register to prevent an inadvertent
initiation of a master receive data transfer.
In slave mode, the same functions are available after an address match has occurred.
The TX bit in IICC must correctly reflect the desired direction of transfer in master and slave modes for
the transmission to begin. For instance, if the IIC is configured for master transmit but a master receive is
desired, reading the IICD does not initiate the receive.
Reading the IICD returns the last byte received while the IIC is configured in master receive or slave
receive modes. The IICD does not reflect every byte transmitted on the IIC bus, nor can software verify
that a byte has been written to the IICD correctly by reading it back.
In master transmit mode, the first byte of data written to IICD following assertion of MST is used for the
address transfer and should comprise of the calling address (in bit 7 to bit 1) concatenated with the required
R/W bit (in position bit 0).
11.3.6
IIC Control Register 2 (IICC2)
7
6
GCAEN
ADEXT
0
0
R
5
4
3
0
0
0
2
1
0
AD10
AD9
AD8
0
0
0
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 11-8. IIC Control Register (IICC2)
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Table 11-8. IICC2 Field Descriptions
Field
Description
7
GCAEN
General Call Address Enable. The GCAEN bit enables or disables general call address.
0 General call address is disabled
1 General call address is enabled
6
ADEXT
Address Extension. The ADEXT bit controls the number of bits used for the slave address.
0 7-bit address scheme
1 10-bit address scheme
2–0
AD[10:8]
Slave Address. The AD[10:8] field contains the upper three bits of the slave address in the 10-bit address
scheme. This field is only valid when the ADEXT bit is set.
11.4
Functional Description
This section provides a complete functional description of the IIC module.
11.4.1
IIC Protocol
The IIC bus system uses a serial data line (SDA) and a serial clock line (SCL) for data transfer. All devices
connected to it must have open drain or open collector outputs. A logic AND function is exercised on both
lines with external pull-up resistors. The value of these resistors is system dependent.
Normally, a standard communication is composed of four parts:
• Start signal
• Slave address transmission
• Data transfer
• Stop signal
The stop signal should not be confused with the CPU stop instruction. The IIC bus system communication
is described briefly in the following sections and illustrated in Figure 11-9.
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msb
SCL
1
SDA
lsb
2
3
4
5
6
7
8
msb
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
1
SDA
3
4
5
6
7
8
Calling Address
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
1
XX
Read/ Ack
Write Bit
Repeated
Start
Signal
9
No
Ack
Bit
msb
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
2
Data Byte
lsb
2
1
Read/ Ack
Write Bit
Calling Address
msb
SCL
XXX
lsb
Stop
Signal
lsb
2
3
4
5
6
7
8
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
New Calling Address
Read/
Write
No
Ack
Bit
Stop
Signal
Figure 11-9. IIC Bus Transmission Signals
11.4.1.1
Start Signal
When the bus is free, no master device is engaging the bus (SCL and SDA lines are at logical high), a
master may initiate communication by sending a start signal. As shown in Figure 11-9, a start signal is
defined as a high-to-low transition of SDA while SCL is high. This signal denotes the beginning of a new
data transfer (each data transfer may contain several bytes of data) and brings all slaves out of their idle
states.
11.4.1.2
Slave Address Transmission
The first byte of data transferred immediately after the start signal is the slave address transmitted by the
master. This is a seven-bit calling address followed by a R/W bit. The R/W bit tells the slave the desired
direction of data transfer.
1 = Read transfer, the slave transmits data to the master.
0 = Write transfer, the master transmits data to the slave.
Only the slave with a calling address that matches the one transmitted by the master responds by sending
back an acknowledge bit. This is done by pulling the SDA low at the ninth clock (see Figure 11-9).
No two slaves in the system may have the same address. If the IIC module is the master, it must not transmit
an address equal to its own slave address. The IIC cannot be master and slave at the same time. However,
if arbitration is lost during an address cycle, the IIC reverts to slave mode and operates correctly even if it
is being addressed by another master.
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11.4.1.3
Data Transfer
Before successful slave addressing is achieved, the data transfer can proceed byte-by-byte in a direction
specified by the R/W bit sent by the calling master.
All transfers that come after an address cycle are referred to as data transfers, even if they carry sub-address
information for the slave device
Each data byte is 8 bits long. Data may be changed only while SCL is low and must be held stable while
SCL is high as shown in Figure 11-9. There is one clock pulse on SCL for each data bit, the msb being
transferred first. Each data byte is followed by a 9th (acknowledge) bit, which is signalled from the
receiving device. An acknowledge is signalled by pulling the SDA low at the ninth clock. In summary, one
complete data transfer needs nine clock pulses.
If the slave receiver does not acknowledge the master in the ninth bit time, the SDA line must be left high
by the slave. The master interprets the failed acknowledge as an unsuccessful data transfer.
If the master receiver does not acknowledge the slave transmitter after a data byte transmission, the slave
interprets this as an end of data transfer and releases the SDA line.
In either case, the data transfer is aborted and the master does one of two things:
• Relinquishes the bus by generating a stop signal.
• Commences a new calling by generating a repeated start signal.
11.4.1.4
Stop Signal
The master can terminate the communication by generating a stop signal to free the bus. However, the
master may generate a start signal followed by a calling command without generating a stop signal first.
This is called repeated start. A stop signal is defined as a low-to-high transition of SDA while SCL at
logical 1 (see Figure 11-9).
The master can generate a stop even if the slave has generated an acknowledge at which point the slave
must release the bus.
11.4.1.5
Repeated Start Signal
As shown in Figure 11-9, a repeated start signal is a start signal generated without first generating a stop
signal to terminate the communication. This is used by the master to communicate with another slave or
with the same slave in different mode (transmit/receive mode) without releasing the bus.
11.4.1.6
Arbitration Procedure
The IIC bus is a true multi-master bus that allows more than one master to be connected on it. If two or
more masters try to control the bus at the same time, a clock synchronization procedure determines the bus
clock, for which the low period is equal to the longest clock low period and the high is equal to the shortest
one among the masters. The relative priority of the contending masters is determined by a data arbitration
procedure, a bus master loses arbitration if it transmits logic 1 while another master transmits logic 0. The
losing masters immediately switch over to slave receive mode and stop driving SDA output. In this case,
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
the transition from master to slave mode does not generate a stop condition. Meanwhile, a status bit is set
by hardware to indicate loss of arbitration.
11.4.1.7
Clock Synchronization
Because wire-AND logic is performed on the SCL line, a high-to-low transition on the SCL line affects all
the devices connected on the bus. The devices start counting their low period and after a device’s clock has
gone low, it holds the SCL line low until the clock high state is reached. However, the change of low to
high in this device clock may not change the state of the SCL line if another device clock is still within its
low period. Therefore, synchronized clock SCL is held low by the device with the longest low period.
Devices with shorter low periods enter a high wait state during this time (see Figure 11-10). When all
devices concerned have counted off their low period, the synchronized clock SCL line is released and
pulled high. There is then no difference between the device clocks and the state of the SCL line and all the
devices start counting their high periods. The first device to complete its high period pulls the SCL line
low again.
Delay
Start Counting High Period
SCL1
SCL2
SCL
Internal Counter Reset
Figure 11-10. IIC Clock Synchronization
11.4.1.8
Handshaking
The clock synchronization mechanism can be used as a handshake in data transfer. Slave devices may hold
the SCL low after completion of one byte transfer (9 bits). In such a case, it halts the bus clock and forces
the master clock into wait states until the slave releases the SCL line.
11.4.1.9
Clock Stretching
The clock synchronization mechanism can be used by slaves to slow down the bit rate of a transfer. After
the master has driven SCL low the slave can drive SCL low for the required period and then release it. If
the slave SCL low period is greater than the master SCL low period then the resulting SCL bus signal low
period is stretched.
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11.4.2
10-bit Address
For 10-bit addressing, 0x11110 is used for the first 5 bits of the first address byte. Various combinations of
read/write formats are possible within a transfer that includes 10-bit addressing.
11.4.2.1
Master-Transmitter Addresses a Slave-Receiver
The transfer direction is not changed (see Table 11-9). When a 10-bit address follows a start condition,
each slave compares the first seven bits of the first byte of the slave address (11110XX) with its own
address and tests whether the eighth bit (R/W direction bit) is 0. More than one device can find a match
and generate an acknowledge (A1). Then, each slave that finds a match compares the eight bits of the
second byte of the slave address with its own address. Only one slave finds a match and generates an
acknowledge (A2). The matching slave remains addressed by the master until it receives a stop condition
(P) or a repeated start condition (Sr) followed by a different slave address.
S
Slave Address 1st 7 bits
R/W
11110 + AD10 + AD9
0
A1
Slave Address 2nd byte
AD[8:1]
A2
Data
A
...
Data
A/A
P
Table 11-9. Master-Transmitter Addresses Slave-Receiver with a 10-bit Address
After the master-transmitter has sent the first byte of the 10-bit address, the slave-receiver sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
11.4.2.2
Master-Receiver Addresses a Slave-Transmitter
The transfer direction is changed after the second R/W bit (see Table 11-10). Up to and including
acknowledge bit A2, the procedure is the same as that described for a master-transmitter addressing a
slave-receiver. After the repeated start condition (Sr), a matching slave remembers that it was addressed
before. This slave then checks whether the first seven bits of the first byte of the slave address following
Sr are the same as they were after the start condition (S) and tests whether the eighth (R/W) bit is 1. If there
is a match, the slave considers that it has been addressed as a transmitter and generates acknowledge A3.
The slave-transmitter remains addressed until it receives a stop condition (P) or a repeated start condition
(Sr) followed by a different slave address.
After a repeated start condition (Sr), all other slave devices also compare the first seven bits of the first byte
of the slave address with their own addresses and test the eighth (R/W) bit. However, none of them are
addressed because R/W = 1 (for 10-bit devices) or the 11110XX slave address (for 7-bit devices) does not
match.
S
Slave Address
1st 7 bits
R/W
11110 + AD10 + AD9
0
A1
Slave Address
2nd byte
AD[8:1]
A2
Sr
Slave Address
1st 7 bits
R/W
11110 + AD10 + AD9
1
A3
Data
A
...
Data
A
P
Table 11-10. Master-Receiver Addresses a Slave-Transmitter with a 10-bit Address
After the master-receiver has sent the first byte of the 10-bit address, the slave-transmitter sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
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11.4.3
General Call Address
General calls can be requested in 7-bit address or 10-bit address. If the GCAEN bit is set, the IIC matches
the general call address as well as its own slave address. When the IIC responds to a general call, it acts as
a slave-receiver and the IAAS bit is set after the address cycle. Software must read the IICD register after
the first byte transfer to determine whether the address matches is its own slave address or a general call.
If the value is 00, the match is a general call. If the GCAEN bit is clear, the IIC ignores any data supplied
from a general call address by not issuing an acknowledgement.
11.5
Resets
The IIC is disabled after reset. The IIC cannot cause an MCU reset.
11.6
Interrupts
The IIC generates a single interrupt.
An interrupt from the IIC is generated when any of the events in Table 11-11 occur, provided the IICIE bit
is set. The interrupt is driven by bit IICIF (of the IIC status register) and masked with bit IICIE (of the IIC
control register). The IICIF bit must be cleared by software by writing a 1 to it in the interrupt routine. You
can determine the interrupt type by reading the status register.
Table 11-11. Interrupt Summary
11.6.1
Interrupt Source
Status
Flag
Local Enable
Complete 1-byte transfer
TCF
IICIF
IICIE
Match of received calling address
IAAS
IICIF
IICIE
Arbitration Lost
ARBL
IICIF
IICIE
Byte Transfer Interrupt
The TCF (transfer complete flag) bit is set at the falling edge of the ninth clock to indicate the completion
of byte transfer.
11.6.2
Address Detect Interrupt
When the calling address matches the programmed slave address (IIC address register) or when the
GCAEN bit is set and a general call is received, the IAAS bit in the status register is set. The CPU is
interrupted, provided the IICIE is set. The CPU must check the SRW bit and set its Tx mode accordingly.
11.6.3
Arbitration Lost Interrupt
The IIC is a true multi-master bus that allows more than one master to be connected on it. If two or more
masters try to control the bus at the same time, the relative priority of the contending masters is determined
by a data arbitration procedure. The IIC module asserts this interrupt when it loses the data arbitration
process and the ARBL bit in the status register is set.
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Arbitration is lost in the following circumstances:
• SDA sampled as a low when the master drives a high during an address or data transmit cycle.
• SDA sampled as a low when the master drives a high during the acknowledge bit of a data receive
cycle.
• A start cycle is attempted when the bus is busy.
• A repeated start cycle is requested in slave mode.
• A stop condition is detected when the master did not request it.
This bit must be cleared by software writing a 1 to it.
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11.7
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
6.
7.
Initialization/Application Information
Module Initialization (Slave)
Write: IICC2
— to enable or disable general call
— to select 10-bit or 7-bit addressing mode
Write: IICA
— to set the slave address
Write: IICC1
— to enable IIC and interrupts
Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
Initialize RAM variables used to achieve the routine shown in Figure 11-12
Module Initialization (Master)
Write: IICF
— to set the IIC baud rate (example provided in this chapter)
Write: IICC1
— to enable IIC and interrupts
Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
Initialize RAM variables used to achieve the routine shown in Figure 11-12
Write: IICC1
— to enable TX
Write: IICC1
— to enable MST (master mode)
Write: IICD
— with the address of the target slave. (The lsb of this byte determines whether the communication is
master receive or transmit.)
Module Use
The routine shown in Figure 11-12 can handle both master and slave IIC operations. For slave operation, an
incoming IIC message that contains the proper address begins IIC communication. For master operation,
communication must be initiated by writing to the IICD register.
Register Model
0
AD[7:1]
IICA
When addressed as a slave (in slave mode), the module responds to this address
MULT
IICF
ICR
Baud rate = BUSCLK / (2 x MULT x (SCL DIVIDER))
IICC1
IICEN
IICIE
MST
TX
TXAK
RSTA
0
0
BUSY
ARBL
0
SRW
IICIF
RXAK
AD9
AD8
Module configuration
IICS
TCF
IAAS
Module status flags
DATA
IICD
Data register; Write to transmit IIC data read to read IIC data
IICC2 GCAEN ADEXT
0
0
0
AD10
Address configuration
Figure 11-11. IIC Module Quick Start
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Clear
IICIF
Master
Mode
?
Y
TX
N
Y
RX
Tx/Rx
?
Arbitration
Lost
?
N
Last Byte
Transmitted
?
N
Clear ARBL
Y
RXAK=0
?
Last
Byte to Be Read
?
N
N
N
Y
Y
IAAS=1
?
Y
IAAS=1
?
Y
Address Transfer
See Note 1
Y
End of
Addr Cycle
(Master Rx)
?
Y
Y
(Read)
2nd Last
Byte to Be Read
?
N
SRW=1
?
Write Next
Byte to IICD
Set TXACK =1
Generate
Stop Signal
(MST = 0)
Switch to
Rx Mode
Generate
Stop Signal
(MST = 0)
Read Data
from IICD
and Store
ACK from
Receiver
?
N
Read Data
from IICD
and Store
Tx Next
Byte
Write Data
to IICD
Dummy Read
from IICD
TX
Y
Set TX
Mode
RX
TX/RX
?
N (Write)
N
N
Data Transfer
See Note 2
Set RX
Mode
Switch to
Rx Mode
Dummy Read
from IICD
Dummy Read
from IICD
RTI
NOTES:
1. If general call is enabled, a check must be done to determine whether the received address was a general call address (0x00). If the received address was a
general call address, then the general call must be handled by user software.
2. When 10-bit addressing is used to address a slave, the slave sees an interrupt following the first byte of the extended address. User software must ensure that for
this interrupt, the contents of IICD are ignored and not treated as a valid data transfer
Figure 11-12. Typical IIC Interrupt Routine
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Chapter 11 Inter-Integrated Circuit (S08IICV2)
MC9S08AC128 Series Reference Manual, Rev. 3
226
Freescale Semiconductor
Chapter 12
Keyboard Interrupt (S08KBIV1)
12.1
Introduction
The MC9S08AC128 Series has one KBI module with up to eight keyboard interrupt inputs available
depending on package.
12.1.1
Features
The keyboard interrupt (KBI) module features include:
• Four falling edge/low level sensitive
• Four falling edge/low level or rising edge/high level sensitive
• Choice of edge-only or edge-and-level sensitivity
• Common interrupt flag and interrupt enable control
• Capable of waking up the MCU from stop3 or wait mode
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Chapter 12 Keyboard Interrupt (S08KBIV1)
HCS08 CORE
COP
IRQ
LVD
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
EXTAL
XTAL
LOW-POWER OSC
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VSSAD
VREFL
VREFH
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT J
PORT H
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PTC0/SCL1
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
VOLTAGE REGULATOR
VSS
PORT A
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
PORT E
RQ/TPMCLK
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT B
HCS08 SYSTEM CONTROL
RESET
PORT C
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT D
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
TPM1CH0–TPM1CH5
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
- Pin not connected in 48-pin package
Figure 12-1. Block Diagram Highlighting KBI Module
MC9S08AC128 Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 12 Keyboard Interrupt (S08KBIV1)
12.1.2
KBI Block Diagram
Figure 12-2 shows the block diagram for a KBI module.
KBIP0
KBIPE0
VDD
KBIPE3
0
SYNCHRONIZER
S
KBIPE4
KEYBOARD
INTERRUPT FF
STOP
STOP BYPASS
KEYBOARD
INTERRUPT
REQUEST
KBIMOD
1
0
KBF
CK
KBEDG4
KBIPn
RESET
D CLR Q
1
KBIP4
BUSCLK
KBACK
KBIP3
KBIE
S
KBIPEn
KBEDGn
Figure 12-2. KBI Block Diagram
12.2
Register Definition
This section provides information about all registers and control bits associated with the KBI module.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all KBI registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
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Chapter 12 Keyboard Interrupt (S08KBIV1)
12.2.1
KBI Status and Control Register (KBISC)
7
6
5
4
KBEDG7
KBEDG6
KBEDG5
KBEDG4
R
3
2
KBF
0
W
Reset
1
0
KBIE
KBIMOD
0
0
KBACK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 12-3. KBI Status and Control Register (KBISC)
Table 12-1. KBISC Register Field Descriptions
Field
Description
7:4
Keyboard Edge Select for KBI Port Bits — Each of these read/write bits selects the polarity of the edges and/or
KBEDG[7:4] levels that are recognized as trigger events on the corresponding KBI port pin when it is configured as a keyboard
interrupt input (KBIPEn = 1). Also see the KBIMOD control bit, which determines whether the pin is sensitive to
edges-only or edges and levels.
0 Falling edges/low levels
1 Rising edges/high levels
3
KBF
Keyboard Interrupt Flag — This read-only status flag is set whenever the selected edge event has been
detected on any of the enabled KBI port pins. This flag is cleared by writing a 1 to the KBACK control bit. The
flag will remain set if KBIMOD = 1 to select edge-and-level operation and any enabled KBI port pin remains at
the asserted level.
KBF can be used as a software pollable flag (KBIE = 0) or it can generate a hardware interrupt request to the
CPU (KBIE = 1).
0 No KBI interrupt pending
1 KBI interrupt pending
2
KBACK
Keyboard Interrupt Acknowledge — This write-only bit (reads always return 0) is used to clear the KBF status
flag by writing a 1 to KBACK. When KBIMOD = 1 to select edge-and-level operation and any enabled KBI port
pin remains at the asserted level, KBF is being continuously set so writing 1 to KBACK does not clear the KBF
flag.
1
KBIE
Keyboard Interrupt Enable — This read/write control bit determines whether hardware interrupts are generated
when the KBF status flag equals 1. When KBIE = 0, no hardware interrupts are generated, but KBF can still be
used for software polling.
0 KBF does not generate hardware interrupts (use polling)
1 KBI hardware interrupt requested when KBF = 1
KBIMOD
Keyboard Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. KBI port bits 3 through 0 can detect falling edges-only or falling edges and low levels. KBI port bits 7
through 4 can be configured to detect either:
• Rising edges-only or rising edges and high levels (KBEDGn = 1)
• Falling edges-only or falling edges and low levels (KBEDGn = 0)
0 Edge-only detection
1 Edge-and-level detection
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Chapter 12 Keyboard Interrupt (S08KBIV1)
12.2.2
KBI Pin Enable Register (KBIPE)
7
6
5
4
3
2
1
0
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
0
0
0
0
0
0
0
0
R
W
Reset
= Unimplemented or Reserved
Figure 12-4. KBI Pin Enable Register (KBIPE)
Table 12-2. KBIPE Register Field Descriptions
Field
Description
7:0
KBIPE[7:0]
12.3
12.3.1
Keyboard Pin Enable for KBI Port Bits — Each of these read/write bits selects whether the associated KBI
port pin is enabled as a keyboard interrupt input or functions as a general-purpose I/O pin.
0 Bit n of KBI port is a general-purpose I/O pin not associated with the KBI
1 Bit n of KBI port enabled as a keyboard interrupt input
Functional Description
Pin Enables
The KBIPEn control bits in the KBIPE register allow a user to enable (KBIPEn = 1) any combination of
KBI-related port pins to be connected to the KBI module. Pins corresponding to 0s in KBIPE are
general-purpose I/O pins that are not associated with the KBI module.
12.3.2
Edge and Level Sensitivity
Synchronous logic is used to detect edges. Prior to detecting an edge, enabled keyboard inputs in a KBI
module must be at the deasserted logic level.
A falling edge is detected when an enabled keyboard input signal is seen as a logic 1 (the deasserted level)
during one bus cycle and then a logic 0 (the asserted level) during the next cycle.
A rising edge is detected when the input signal is seen as a logic 0 during one bus cycle and then a logic 1
during the next cycle.
The KBIMOD control bit can be set to reconfigure the detection logic so that it detects edges and levels.
In KBIMOD = 1 mode, the KBF status flag becomes set when an edge is detected (when one or more
enabled pins change from the deasserted to the asserted level while all other enabled pins remain at their
deasserted levels), but the flag is continuously set (and cannot be cleared) as long as any enabled keyboard
input pin remains at the asserted level. When the MCU enters stop mode, the synchronous edge-detection
logic is bypassed (because clocks are stopped). In stop mode, KBI inputs act as asynchronous
level-sensitive inputs so they can wake the MCU from stop mode.
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Chapter 12 Keyboard Interrupt (S08KBIV1)
12.3.3
KBI Interrupt Controls
The KBF status flag becomes set (1) when an edge event has been detected on any KBI input pin. If
KBIE = 1 in the KBISC register, a hardware interrupt will be requested whenever KBF = 1. The KBF flag
is cleared by writing a 1 to the keyboard acknowledge (KBACK) bit.
When KBIMOD = 0 (selecting edge-only operation), KBF is always cleared by writing 1 to KBACK.
When KBIMOD = 1 (selecting edge-and-level operation), KBF cannot be cleared as long as any keyboard
input is at its asserted level.
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Freescale Semiconductor
Chapter 13
Serial Communications Interface (S08SCIV4)
13.1
Introduction
The MC9S08AC128 Series includes up to two independent serial communications interface (SCI)
modules depending on package. An SCI is sometimes called universal asynchronous receiver/transmitters
(UARTs). For the MC9S08AC128 Series, stop1 is not a valid mode, so ignore these references.
MC9S08AC128 Series Reference Manual, Rev. 3
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Chapter 13 Serial Communications Interface (S08SCIV4)
HCS08 CORE
IRQ
LVD
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
VOLTAGE REGULATOR
VSS
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT H
PTC0/SCL1
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PORT J
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
PORT D
COP
EXTAL
XTAL
LOW-POWER OSC
PORT E
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
RESET
IRQ/TPMCLK
PORT A
HCS08 SYSTEM CONTROL
PORT B
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT C
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
TPM1CH0–TPM1CH5
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
- Pin not connected in 48-pin package
Figure 13-1. Block Diagram Highlighting the SCI Modules
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Chapter 13 Serial Communications Interface (S08SCIV4)
13.1.1
Features
Features of SCI module include:
• Full-duplex, standard non-return-to-zero (NRZ) format
• Double-buffered transmitter and receiver with separate enables
• Programmable baud rates (13-bit modulo divider)
• Interrupt-driven or polled operation:
— Transmit data register empty and transmission complete
— Receive data register full
— Receive overrun, parity error, framing error, and noise error
— Idle receiver detect
— Active edge on receive pin
— Break detect supporting LIN
• Hardware parity generation and checking
• Programmable 8-bit or 9-bit character length
• Receiver wakeup by idle-line or address-mark
• Optional 13-bit break character generation / 11-bit break character detection
• Selectable transmitter output polarity
13.1.2
Modes of Operation
See Section 13.3, “Functional Description,” For details concerning SCI operation in these modes:
• 8- and 9-bit data modes
• Stop mode operation
• Loop mode
• Single-wire mode
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Chapter 13 Serial Communications Interface (S08SCIV4)
13.1.3
Block Diagram
Figure 13-2 shows the transmitter portion of the SCI.
INTERNAL BUS
(WRITE-ONLY)
LOOPS
SCID – Tx BUFFER
RSRC
LOOP
CONTROL
STOP
M
START
11-BIT TRANSMIT SHIFT REGISTER
8
7
6
5
4
3
2
1
0
TO TxD PIN
L
LSB
H
1 × BAUD
RATE CLOCK
TO RECEIVE
DATA IN
SHIFT DIRECTION
PT
BREAK (ALL 0s)
PARITY
GENERATION
PREAMBLE (ALL 1s)
PE
SHIFT ENABLE
T8
LOAD FROM SCIxD
TXINV
SCI CONTROLS TxD
TE
SBK
TRANSMIT CONTROL
TXDIR
TxD DIRECTION
TO TxD
PIN LOGIC
BRK13
TDRE
TIE
TC
Tx INTERRUPT
REQUEST
TCIE
Figure 13-2. SCI Transmitter Block Diagram
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Chapter 13 Serial Communications Interface (S08SCIV4)
Figure 13-3 shows the receiver portion of the SCI.
INTERNAL BUS
(READ-ONLY)
16 × BAUD
RATE CLOCK
DIVIDE
BY 16
SCID – Rx BUFFER
FROM RxD PIN
RXINV
LBKDE
H
DATA RECOVERY
WAKE
ILT
8
7
6
5
4
3
2
1
START
M
LSB
RSRC
11-BIT RECEIVE SHIFT REGISTER
MSB
SINGLE-WIRE
LOOP CONTROL
ALL 1s
LOOPS
STOP
FROM
TRANSMITTER
0
L
SHIFT DIRECTION
WAKEUP
LOGIC
RWU
RWUID
ACTIVE EDGE
DETECT
RDRF
RIE
IDLE
ILIE
LBKDIF
Rx INTERRUPT
REQUEST
LBKDIE
RXEDGIF
RXEDGIE
OR
ORIE
FE
FEIE
ERROR INTERRUPT
REQUEST
NF
NEIE
PE
PT
PARITY
CHECKING
PF
PEIE
Figure 13-3. SCI Receiver Block Diagram
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Chapter 13 Serial Communications Interface (S08SCIV4)
13.2
Register Definition
The SCI has eight 8-bit registers to control baud rate, select SCI options, report SCI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SCI registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
13.2.1
SCI Baud Rate Registers (SCIxBDH, SCIxBDL)
This pair of registers controls the prescale divisor for SCI baud rate generation. To update the 13-bit baud
rate setting [SBR12:SBR0], first write to SCIxBDH to buffer the high half of the new value and then write
to SCIxBDL. The working value in SCIxBDH does not change until SCIxBDL is written.
SCIxBDL is reset to a non-zero value, so after reset the baud rate generator remains disabled until the first
time the receiver or transmitter is enabled (RE or TE bits in SCIxC2 are written to 1).
7
6
5
LBKDIE
RXEDGIE
0
0
R
4
3
2
1
0
SBR12
SBR11
SBR10
SBR9
SBR8
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 13-4. SCI Baud Rate Register (SCIxBDH)
Table 13-1. SCIxBDH Field Descriptions
Field
7
LBKDIE
Description
LIN Break Detect Interrupt Enable (for LBKDIF)
0 Hardware interrupts from LBKDIF disabled (use polling).
1 Hardware interrupt requested when LBKDIF flag is 1.
6
RXEDGIE
RxD Input Active Edge Interrupt Enable (for RXEDGIF)
0 Hardware interrupts from RXEDGIF disabled (use polling).
1 Hardware interrupt requested when RXEDGIF flag is 1.
4:0
SBR[12:8]
Baud Rate Modulo Divisor — The 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in
Table 13-2.
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Chapter 13 Serial Communications Interface (S08SCIV4)
7
6
5
4
3
2
1
0
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0
0
0
0
0
1
0
0
R
W
Reset
Figure 13-5. SCI Baud Rate Register (SCIxBDL)
Table 13-2. SCIxBDL Field Descriptions
Field
7:0
SBR[7:0]
13.2.2
Description
Baud Rate Modulo Divisor — These 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in
Table 13-1.
SCI Control Register 1 (SCIxC1)
This read/write register is used to control various optional features of the SCI system.
7
6
5
4
3
2
1
0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0
0
0
0
0
0
0
0
R
W
Reset
Figure 13-6. SCI Control Register 1 (SCIxC1)
Table 13-3. SCIxC1 Field Descriptions
Field
7
LOOPS
6
SCISWAI
5
RSRC
4
M
Description
Loop Mode Select — Selects between loop back modes and normal 2-pin full-duplex modes. When
LOOPS = 1, the transmitter output is internally connected to the receiver input.
0 Normal operation — RxD and TxD use separate pins.
1 Loop mode or single-wire mode where transmitter outputs are internally connected to receiver input. (See
RSRC bit.) RxD pin is not used by SCI.
SCI Stops in Wait Mode
0 SCI clocks continue to run in wait mode so the SCI can be the source of an interrupt that wakes up the CPU.
1 SCI clocks freeze while CPU is in wait mode.
Receiver Source Select — This bit has no meaning or effect unless the LOOPS bit is set to 1. When
LOOPS = 1, the receiver input is internally connected to the TxD pin and RSRC determines whether this
connection is also connected to the transmitter output.
0 Provided LOOPS = 1, RSRC = 0 selects internal loop back mode and the SCI does not use the RxD pins.
1 Single-wire SCI mode where the TxD pin is connected to the transmitter output and receiver input.
9-Bit or 8-Bit Mode Select
0 Normal — start + 8 data bits (LSB first) + stop.
1 Receiver and transmitter use 9-bit data characters
start + 8 data bits (LSB first) + 9th data bit + stop.
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Chapter 13 Serial Communications Interface (S08SCIV4)
Table 13-3. SCIxC1 Field Descriptions (continued)
Field
3
WAKE
Description
Receiver Wakeup Method Select — Refer to Section 13.3.3.2, “Receiver Wakeup Operation” for more
information.
0 Idle-line wakeup.
1 Address-mark wakeup.
2
ILT
Idle Line Type Select — Setting this bit to 1 ensures that the stop bit and logic 1 bits at the end of a character
do not count toward the 10 or 11 bit times of logic high level needed by the idle line detection logic. Refer to
Section 13.3.3.2.1, “Idle-Line Wakeup” for more information.
0 Idle character bit count starts after start bit.
1 Idle character bit count starts after stop bit.
1
PE
Parity Enable — Enables hardware parity generation and checking. When parity is enabled, the most significant
bit (MSB) of the data character (eighth or ninth data bit) is treated as the parity bit.
0 No hardware parity generation or checking.
1 Parity enabled.
0
PT
Parity Type — Provided parity is enabled (PE = 1), this bit selects even or odd parity. Odd parity means the total
number of 1s in the data character, including the parity bit, is odd. Even parity means the total number of 1s in
the data character, including the parity bit, is even.
0 Even parity.
1 Odd parity.
13.2.3
SCI Control Register 2 (SCIxC2)
This register can be read or written at any time.
7
6
5
4
3
2
1
0
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
R
W
Reset
Figure 13-7. SCI Control Register 2 (SCIxC2)
Table 13-4. SCIxC2 Field Descriptions
Field
7
TIE
6
TCIE
Description
Transmit Interrupt Enable (for TDRE)
0 Hardware interrupts from TDRE disabled (use polling).
1 Hardware interrupt requested when TDRE flag is 1.
Transmission Complete Interrupt Enable (for TC)
0 Hardware interrupts from TC disabled (use polling).
1 Hardware interrupt requested when TC flag is 1.
5
RIE
Receiver Interrupt Enable (for RDRF)
0 Hardware interrupts from RDRF disabled (use polling).
1 Hardware interrupt requested when RDRF flag is 1.
4
ILIE
Idle Line Interrupt Enable (for IDLE)
0 Hardware interrupts from IDLE disabled (use polling).
1 Hardware interrupt requested when IDLE flag is 1.
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Table 13-4. SCIxC2 Field Descriptions (continued)
Field
Description
3
TE
Transmitter Enable
0 Transmitter off.
1 Transmitter on.
TE must be 1 in order to use the SCI transmitter. When TE = 1, the SCI forces the TxD pin to act as an output
for the SCI system.
When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the direction of
traffic on the single SCI communication line (TxD pin).
TE also can be used to queue an idle character by writing TE = 0 then TE = 1 while a transmission is in progress.
Refer to Section 13.3.2.1, “Send Break and Queued Idle” for more details.
When TE is written to 0, the transmitter keeps control of the port TxD pin until any data, queued idle, or queued
break character finishes transmitting before allowing the pin to revert to a general-purpose I/O pin.
2
RE
Receiver Enable — When the SCI receiver is off, the RxD pin reverts to being a general-purpose port I/O pin.
If LOOPS = 1 the RxD pin reverts to being a general-purpose I/O pin even if RE = 1.
0 Receiver off.
1 Receiver on.
1
RWU
Receiver Wakeup Control — This bit can be written to 1 to place the SCI receiver in a standby state where it
waits for automatic hardware detection of a selected wakeup condition. The wakeup condition is either an idle
line between messages (WAKE = 0, idle-line wakeup), or a logic 1 in the most significant data bit in a character
(WAKE = 1, address-mark wakeup). Application software sets RWU and (normally) a selected hardware
condition automatically clears RWU. Refer to Section 13.3.3.2, “Receiver Wakeup Operation” for more details.
0 Normal SCI receiver operation.
1 SCI receiver in standby waiting for wakeup condition.
0
SBK
Send Break — Writing a 1 and then a 0 to SBK queues a break character in the transmit data stream. Additional
break characters of 10 or 11 (13 or 14 if BRK13 = 1) bit times of logic 0 are queued as long as SBK = 1.
Depending on the timing of the set and clear of SBK relative to the information currently being transmitted, a
second break character may be queued before software clears SBK. Refer to Section 13.3.2.1, “Send Break and
Queued Idle” for more details.
0 Normal transmitter operation.
1 Queue break character(s) to be sent.
13.2.4
SCI Status Register 1 (SCIxS1)
This register has eight read-only status flags. Writes have no effect. Special software sequences (which do
not involve writing to this register) are used to clear these status flags.
R
7
6
5
4
3
2
1
0
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
1
1
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 13-8. SCI Status Register 1 (SCIxS1)
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Table 13-5. SCIxS1 Field Descriptions
Field
Description
7
TDRE
Transmit Data Register Empty Flag — TDRE is set out of reset and when a transmit data value transfers from
the transmit data buffer to the transmit shifter, leaving room for a new character in the buffer. To clear TDRE, read
SCIxS1 with TDRE = 1 and then write to the SCI data register (SCIxD).
0 Transmit data register (buffer) full.
1 Transmit data register (buffer) empty.
6
TC
Transmission Complete Flag — TC is set out of reset and when TDRE = 1 and no data, preamble, or break
character is being transmitted.
0 Transmitter active (sending data, a preamble, or a break).
1 Transmitter idle (transmission activity complete).
TC is cleared automatically by reading SCIxS1 with TC = 1 and then doing one of the following three things:
• Write to the SCI data register (SCIxD) to transmit new data
• Queue a preamble by changing TE from 0 to 1
• Queue a break character by writing 1 to SBK in SCIxC2
5
RDRF
Receive Data Register Full Flag — RDRF becomes set when a character transfers from the receive shifter into
the receive data register (SCIxD). To clear RDRF, read SCIxS1 with RDRF = 1 and then read the SCI data
register (SCIxD).
0 Receive data register empty.
1 Receive data register full.
4
IDLE
Idle Line Flag — IDLE is set when the SCI receive line becomes idle for a full character time after a period of
activity. When ILT = 0, the receiver starts counting idle bit times after the start bit. So if the receive character is
all 1s, these bit times and the stop bit time count toward the full character time of logic high (10 or 11 bit times
depending on the M control bit) needed for the receiver to detect an idle line. When ILT = 1, the receiver doesn’t
start counting idle bit times until after the stop bit. So the stop bit and any logic high bit times at the end of the
previous character do not count toward the full character time of logic high needed for the receiver to detect an
idle line.
To clear IDLE, read SCIxS1 with IDLE = 1 and then read the SCI data register (SCIxD). After IDLE has been
cleared, it cannot become set again until after a new character has been received and RDRF has been set. IDLE
will get set only once even if the receive line remains idle for an extended period.
0 No idle line detected.
1 Idle line was detected.
3
OR
Receiver Overrun Flag — OR is set when a new serial character is ready to be transferred to the receive data
register (buffer), but the previously received character has not been read from SCIxD yet. In this case, the new
character (and all associated error information) is lost because there is no room to move it into SCIxD. To clear
OR, read SCIxS1 with OR = 1 and then read the SCI data register (SCIxD).
0 No overrun.
1 Receive overrun (new SCI data lost).
2
NF
Noise Flag — The advanced sampling technique used in the receiver takes seven samples during the start bit
and three samples in each data bit and the stop bit. If any of these samples disagrees with the rest of the samples
within any bit time in the frame, the flag NF will be set at the same time as the flag RDRF gets set for the
character. To clear NF, read SCIxS1 and then read the SCI data register (SCIxD).
0 No noise detected.
1 Noise detected in the received character in SCIxD.
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Table 13-5. SCIxS1 Field Descriptions (continued)
Field
Description
1
FE
Framing Error Flag — FE is set at the same time as RDRF when the receiver detects a logic 0 where the stop
bit was expected. This suggests the receiver was not properly aligned to a character frame. To clear FE, read
SCIxS1 with FE = 1 and then read the SCI data register (SCIxD).
0 No framing error detected. This does not guarantee the framing is correct.
1 Framing error.
0
PF
Parity Error Flag — PF is set at the same time as RDRF when parity is enabled (PE = 1) and the parity bit in
the received character does not agree with the expected parity value. To clear PF, read SCIxS1 and then read
the SCI data register (SCIxD).
0 No parity error.
1 Parity error.
13.2.5
SCI Status Register 2 (SCIxS2)
This register has one read-only status flag.
7
6
LBKDIF
RXEDGIF
0
0
R
5
4
3
2
1
RXINV
RWUID
BRK13
LBKDE
0
0
0
0
0
0
RAF
W
Reset
0
0
= Unimplemented or Reserved
Figure 13-9. SCI Status Register 2 (SCIxS2)
Table 13-6. SCIxS2 Field Descriptions
Field
Description
7
LBKDIF
LIN Break Detect Interrupt Flag — LBKDIF is set when the LIN break detect circuitry is enabled and a LIN break
character is detected. LBKDIF is cleared by writing a “1” to it.
0 No LIN break character has been detected.
1 LIN break character has been detected.
6
RXEDGIF
RxD Pin Active Edge Interrupt Flag — RXEDGIF is set when an active edge (falling if RXINV = 0, rising if
RXINV=1) on the RxD pin occurs. RXEDGIF is cleared by writing a “1” to it.
0 No active edge on the receive pin has occurred.
1 An active edge on the receive pin has occurred.
4
RXINV1
Receive Data Inversion — Setting this bit reverses the polarity of the received data input.
0 Receive data not inverted
1 Receive data inverted
3
RWUID
Receive Wake Up Idle Detect— RWUID controls whether the idle character that wakes up the receiver sets the
IDLE bit.
0 During receive standby state (RWU = 1), the IDLE bit does not get set upon detection of an idle character.
1 During receive standby state (RWU = 1), the IDLE bit gets set upon detection of an idle character.
2
BRK13
Break Character Generation Length — BRK13 is used to select a longer transmitted break character length.
Detection of a framing error is not affected by the state of this bit.
0 Break character is transmitted with length of 10 bit times (11 if M = 1)
1 Break character is transmitted with length of 13 bit times (14 if M = 1)
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Table 13-6. SCIxS2 Field Descriptions (continued)
Field
1
LBKDE
0
RAF
1
Description
LIN Break Detection Enable— LBKDE is used to select a longer break character detection length. While
LBKDE is set, framing error (FE) and receive data register full (RDRF) flags are prevented from setting.
0 Break character is detected at length of 10 bit times (11 if M = 1).
1 Break character is detected at length of 11 bit times (12 if M = 1).
Receiver Active Flag — RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is
cleared automatically when the receiver detects an idle line. This status flag can be used to check whether an
SCI character is being received before instructing the MCU to go to stop mode.
0 SCI receiver idle waiting for a start bit.
1 SCI receiver active (RxD input not idle).
Setting RXINV inverts the RxD input for all cases: data bits, start and stop bits, break, and idle.
When using an internal oscillator in a LIN system, it is necessary to raise the break detection threshold by
one bit time. Under the worst case timing conditions allowed in LIN, it is possible that a 0x00 data
character can appear to be 10.26 bit times long at a slave which is running 14% faster than the master. This
would trigger normal break detection circuitry which is designed to detect a 10 bit break symbol. When
the LBKDE bit is set, framing errors are inhibited and the break detection threshold changes from 10 bits
to 11 bits, preventing false detection of a 0x00 data character as a LIN break symbol.
13.2.6
SCI Control Register 3 (SCIxC3)
7
R
6
5
4
3
2
1
0
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
0
0
0
0
0
0
0
R8
W
Reset
0
= Unimplemented or Reserved
Figure 13-10. SCI Control Register 3 (SCIxC3)
Table 13-7. SCIxC3 Field Descriptions
Field
Description
7
R8
Ninth Data Bit for Receiver — When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a
ninth receive data bit to the left of the MSB of the buffered data in the SCIxD register. When reading 9-bit data,
read R8 before reading SCIxD because reading SCIxD completes automatic flag clearing sequences which
could allow R8 and SCIxD to be overwritten with new data.
6
T8
Ninth Data Bit for Transmitter — When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a
ninth transmit data bit to the left of the MSB of the data in the SCIxD register. When writing 9-bit data, the entire
9-bit value is transferred to the SCI shift register after SCIxD is written so T8 should be written (if it needs to
change from its previous value) before SCIxD is written. If T8 does not need to change in the new value (such
as when it is used to generate mark or space parity), it need not be written each time SCIxD is written.
5
TXDIR
TxD Pin Direction in Single-Wire Mode — When the SCI is configured for single-wire half-duplex operation
(LOOPS = RSRC = 1), this bit determines the direction of data at the TxD pin.
0 TxD pin is an input in single-wire mode.
1 TxD pin is an output in single-wire mode.
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Table 13-7. SCIxC3 Field Descriptions (continued)
Field
4
TXINV1
1
Description
Transmit Data Inversion — Setting this bit reverses the polarity of the transmitted data output.
0 Transmit data not inverted
1 Transmit data inverted
3
ORIE
Overrun Interrupt Enable — This bit enables the overrun flag (OR) to generate hardware interrupt requests.
0 OR interrupts disabled (use polling).
1 Hardware interrupt requested when OR = 1.
2
NEIE
Noise Error Interrupt Enable — This bit enables the noise flag (NF) to generate hardware interrupt requests.
0 NF interrupts disabled (use polling).
1 Hardware interrupt requested when NF = 1.
1
FEIE
Framing Error Interrupt Enable — This bit enables the framing error flag (FE) to generate hardware interrupt
requests.
0 FE interrupts disabled (use polling).
1 Hardware interrupt requested when FE = 1.
0
PEIE
Parity Error Interrupt Enable — This bit enables the parity error flag (PF) to generate hardware interrupt
requests.
0 PF interrupts disabled (use polling).
1 Hardware interrupt requested when PF = 1.
Setting TXINV inverts the TxD output for all cases: data bits, start and stop bits, break, and idle.
13.2.7
SCI Data Register (SCIxD)
This register is actually two separate registers. Reads return the contents of the read-only receive data
buffer and writes go to the write-only transmit data buffer. Reads and writes of this register are also
involved in the automatic flag clearing mechanisms for the SCI status flags.
7
6
5
4
3
2
1
0
R
R7
R6
R5
R4
R3
R2
R1
R0
W
T7
T6
T5
T4
T3
T2
T1
T0
0
0
0
0
0
0
0
0
Reset
Figure 13-11. SCI Data Register (SCIxD)
13.3
Functional Description
The SCI allows full-duplex, asynchronous, NRZ serial communication among the MCU and remote
devices, including other MCUs. The SCI comprises a baud rate generator, transmitter, and receiver block.
The transmitter and receiver operate independently, although they use the same baud rate generator. During
normal operation, the MCU monitors the status of the SCI, writes the data to be transmitted, and processes
received data. The following describes each of the blocks of the SCI.
13.3.1
Baud Rate Generation
As shown in Figure 13-12, the clock source for the SCI baud rate generator is the bus-rate clock.
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MODULO DIVIDE BY
(1 THROUGH 8191)
BUSCLK
SBR12:SBR0
BAUD RATE GENERATOR
OFF IF [SBR12:SBR0] = 0
DIVIDE BY
16
Tx BAUD RATE
Rx SAMPLING CLOCK
(16 × BAUD RATE)
BAUD RATE =
BUSCLK
[SBR12:SBR0] × 16
Figure 13-12. SCI Baud Rate Generation
SCI communications require the transmitter and receiver (which typically derive baud rates from
independent clock sources) to use the same baud rate. Allowed tolerance on this baud frequency depends
on the details of how the receiver synchronizes to the leading edge of the start bit and how bit sampling is
performed.
The MCU resynchronizes to bit boundaries on every high-to-low transition, but in the worst case, there are
no such transitions in the full 10- or 11-bit time character frame so any mismatch in baud rate is
accumulated for the whole character time. For a Freescale Semiconductor SCI system whose bus
frequency is driven by a crystal, the allowed baud rate mismatch is about 4.5percent for 8-bit data format
and about 4 percent for 9-bit data format. Although baud rate modulo divider settings do not always
produce baud rates that exactly match standard rates, it is normally possible to get within a few percent,
which is acceptable for reliable communications.
13.3.2
Transmitter Functional Description
This section describes the overall block diagram for the SCI transmitter, as well as specialized functions
for sending break and idle characters. The transmitter block diagram is shown in Figure 13-2.
The transmitter output (TxD) idle state defaults to logic high (TXINV = 0 following reset). The transmitter
output is inverted by setting TXINV = 1. The transmitter is enabled by setting the TE bit in SCIxC2. This
queues a preamble character that is one full character frame of the idle state. The transmitter then remains
idle until data is available in the transmit data buffer. Programs store data into the transmit data buffer by
writing to the SCI data register (SCIxD).
The central element of the SCI transmitter is the transmit shift register that is either 10 or 11 bits long
depending on the setting in the M control bit. For the remainder of this section, we will assume M = 0,
selecting the normal 8-bit data mode. In 8-bit data mode, the shift register holds a start bit, eight data bits,
and a stop bit. When the transmit shift register is available for a new SCI character, the value waiting in
the transmit data register is transferred to the shift register (synchronized with the baud rate clock) and the
transmit data register empty (TDRE) status flag is set to indicate another character may be written to the
transmit data buffer at SCIxD.
If no new character is waiting in the transmit data buffer after a stop bit is shifted out the TxD pin, the
transmitter sets the transmit complete flag and enters an idle mode, with TxD high, waiting for more
characters to transmit.
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Writing 0 to TE does not immediately release the pin to be a general-purpose I/O pin. Any transmit activity
that is in progress must first be completed. This includes data characters in progress, queued idle
characters, and queued break characters.
13.3.2.1
Send Break and Queued Idle
The SBK control bit in SCIxC2 is used to send break characters which were originally used to gain the
attention of old teletype receivers. Break characters are a full character time of logic 0 (10 bit times
including the start and stop bits). A longer break of 13 bit times can be enabled by setting BRK13 = 1.
Normally, a program would wait for TDRE to become set to indicate the last character of a message has
moved to the transmit shifter, then write 1 and then write 0 to the SBK bit. This action queues a break
character to be sent as soon as the shifter is available. If SBK is still 1 when the queued break moves into
the shifter (synchronized to the baud rate clock), an additional break character is queued. If the receiving
device is another Freescale Semiconductor SCI, the break characters will be received as 0s in all eight data
bits and a framing error (FE = 1) occurs.
When idle-line wakeup is used, a full character time of idle (logic 1) is needed between messages to wake
up any sleeping receivers. Normally, a program would wait for TDRE to become set to indicate the last
character of a message has moved to the transmit shifter, then write 0 and then write 1 to the TE bit. This
action queues an idle character to be sent as soon as the shifter is available. As long as the character in the
shifter does not finish while TE = 0, the SCI transmitter never actually releases control of the TxD pin. If
there is a possibility of the shifter finishing while TE = 0, set the general-purpose I/O controls so the pin
that is shared with TxD is an output driving a logic 1. This ensures that the TxD line will look like a normal
idle line even if the SCI loses control of the port pin between writing 0 and then 1 to TE.
The length of the break character is affected by the BRK13 and M bits as shown below.
Table 13-8. Break Character Length
13.3.3
BRK13
M
Break Character Length
0
0
10 bit times
0
1
11 bit times
1
0
13 bit times
1
1
14 bit times
Receiver Functional Description
In this section, the receiver block diagram (Figure 13-3) is used as a guide for the overall receiver
functional description. Next, the data sampling technique used to reconstruct receiver data is described in
more detail. Finally, two variations of the receiver wakeup function are explained.
The receiver input is inverted by setting RXINV = 1. The receiver is enabled by setting the RE bit in
SCIxC2. Character frames consist of a start bit of logic 0, eight (or nine) data bits (LSB first), and a stop
bit of logic 1. For information about 9-bit data mode, refer to Section 13.3.5.1, “8- and 9-Bit Data Modes.”
For the remainder of this discussion, we assume the SCI is configured for normal 8-bit data mode.
After receiving the stop bit into the receive shifter, and provided the receive data register is not already full,
the data character is transferred to the receive data register and the receive data register full (RDRF) status
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flag is set. If RDRF was already set indicating the receive data register (buffer) was already full, the overrun
(OR) status flag is set and the new data is lost. Because the SCI receiver is double-buffered, the program
has one full character time after RDRF is set before the data in the receive data buffer must be read to avoid
a receiver overrun.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCIxD. The RDRF flag is cleared automatically by a 2-step sequence which is
normally satisfied in the course of the user’s program that handles receive data. Refer to Section 13.3.4,
“Interrupts and Status Flags” for more details about flag clearing.
13.3.3.1
Data Sampling Technique
The SCI receiver uses a 16× baud rate clock for sampling. The receiver starts by taking logic level samples
at 16 times the baud rate to search for a falling edge on the RxD serial data input pin. A falling edge is
defined as a logic 0 sample after three consecutive logic 1 samples. The 16× baud rate clock is used to
divide the bit time into 16 segments labeled RT1 through RT16. When a falling edge is located, three more
samples are taken at RT3, RT5, and RT7 to make sure this was a real start bit and not merely noise. If at
least two of these three samples are 0, the receiver assumes it is synchronized to a receive character.
The receiver then samples each bit time, including the start and stop bits, at RT8, RT9, and RT10 to
determine the logic level for that bit. The logic level is interpreted to be that of the majority of the samples
taken during the bit time. In the case of the start bit, the bit is assumed to be 0 if at least two of the samples
at RT3, RT5, and RT7 are 0 even if one or all of the samples taken at RT8, RT9, and RT10 are 1s. If any
sample in any bit time (including the start and stop bits) in a character frame fails to agree with the logic
level for that bit, the noise flag (NF) will be set when the received character is transferred to the receive
data buffer.
The falling edge detection logic continuously looks for falling edges, and if an edge is detected, the sample
clock is resynchronized to bit times. This improves the reliability of the receiver in the presence of noise
or mismatched baud rates. It does not improve worst case analysis because some characters do not have
any extra falling edges anywhere in the character frame.
In the case of a framing error, provided the received character was not a break character, the sampling logic
that searches for a falling edge is filled with three logic 1 samples so that a new start bit can be detected
almost immediately.
In the case of a framing error, the receiver is inhibited from receiving any new characters until the framing
error flag is cleared. The receive shift register continues to function, but a complete character cannot
transfer to the receive data buffer if FE is still set.
13.3.3.2
Receiver Wakeup Operation
Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a
message that is intended for a different SCI receiver. In such a system, all receivers evaluate the first
character(s) of each message, and as soon as they determine the message is intended for a different
receiver, they write logic 1 to the receiver wake up (RWU) control bit in SCIxC2. When RWU bit is set,
the status flags associated with the receiver (with the exception of the idle bit, IDLE, when RWUID bit is
set) are inhibited from setting, thus eliminating the software overhead for handling the unimportant
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message characters. At the end of a message, or at the beginning of the next message, all receivers
automatically force RWU to 0 so all receivers wake up in time to look at the first character(s) of the next
message.
13.3.3.2.1
Idle-Line Wakeup
When WAKE = 0, the receiver is configured for idle-line wakeup. In this mode, RWU is cleared
automatically when the receiver detects a full character time of the idle-line level. The M control bit selects
8-bit or 9-bit data mode that determines how many bit times of idle are needed to constitute a full character
time (10 or 11 bit times because of the start and stop bits).
When RWU is one and RWUID is zero, the idle condition that wakes up the receiver does not set the IDLE
flag. The receiver wakes up and waits for the first data character of the next message which will set the
RDRF flag and generate an interrupt if enabled. When RWUID is one, any idle condition sets the IDLE
flag and generates an interrupt if enabled, regardless of whether RWU is zero or one.
The idle-line type (ILT) control bit selects one of two ways to detect an idle line. When ILT = 0, the idle
bit counter starts after the start bit so the stop bit and any logic 1s at the end of a character count toward
the full character time of idle. When ILT = 1, the idle bit counter does not start until after a stop bit time,
so the idle detection is not affected by the data in the last character of the previous message.
13.3.3.2.2
Address-Mark Wakeup
When WAKE = 1, the receiver is configured for address-mark wakeup. In this mode, RWU is cleared
automatically when the receiver detects a logic 1 in the most significant bit of a received character (eighth
bit in M = 0 mode and ninth bit in M = 1 mode).
Address-mark wakeup allows messages to contain idle characters but requires that the MSB be reserved
for use in address frames. The logic 1 MSB of an address frame clears the RWU bit before the stop bit is
received and sets the RDRF flag. In this case the character with the MSB set is received even though the
receiver was sleeping during most of this character time.
13.3.4
Interrupts and Status Flags
The SCI system has three separate interrupt vectors to reduce the amount of software needed to isolate the
cause of the interrupt. One interrupt vector is associated with the transmitter for TDRE and TC events.
Another interrupt vector is associated with the receiver for RDRF, IDLE, RXEDGIF and LBKDIF events,
and a third vector is used for OR, NF, FE, and PF error conditions. Each of these ten interrupt sources can
be separately masked by local interrupt enable masks. The flags can still be polled by software when the
local masks are cleared to disable generation of hardware interrupt requests.
The SCI transmitter has two status flags that optionally can generate hardware interrupt requests. Transmit
data register empty (TDRE) indicates when there is room in the transmit data buffer to write another
transmit character to SCIxD. If the transmit interrupt enable (TIE) bit is set, a hardware interrupt will be
requested whenever TDRE = 1. Transmit complete (TC) indicates that the transmitter is finished
transmitting all data, preamble, and break characters and is idle with TxD at the inactive level. This flag is
often used in systems with modems to determine when it is safe to turn off the modem. If the transmit
complete interrupt enable (TCIE) bit is set, a hardware interrupt will be requested whenever TC = 1.
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Instead of hardware interrupts, software polling may be used to monitor the TDRE and TC status flags if
the corresponding TIE or TCIE local interrupt masks are 0s.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCIxD. The RDRF flag is cleared by reading SCIxS1 while RDRF = 1 and then
reading SCIxD.
When polling is used, this sequence is naturally satisfied in the normal course of the user program. If
hardware interrupts are used, SCIxS1 must be read in the interrupt service routine (ISR). Normally, this is
done in the ISR anyway to check for receive errors, so the sequence is automatically satisfied.
The IDLE status flag includes logic that prevents it from getting set repeatedly when the RxD line remains
idle for an extended period of time. IDLE is cleared by reading SCIxS1 while IDLE = 1 and then reading
SCIxD. After IDLE has been cleared, it cannot become set again until the receiver has received at least one
new character and has set RDRF.
If the associated error was detected in the received character that caused RDRF to be set, the error flags —
noise flag (NF), framing error (FE), and parity error flag (PF) — get set at the same time as RDRF. These
flags are not set in overrun cases.
If RDRF was already set when a new character is ready to be transferred from the receive shifter to the
receive data buffer, the overrun (OR) flag gets set instead the data along with any associated NF, FE, or PF
condition is lost.
At any time, an active edge on the RxD serial data input pin causes the RXEDGIF flag to set. The
RXEDGIF flag is cleared by writing a “1” to it. This function does depend on the receiver being enabled
(RE = 1).
13.3.5
Additional SCI Functions
The following sections describe additional SCI functions.
13.3.5.1
8- and 9-Bit Data Modes
The SCI system (transmitter and receiver) can be configured to operate in 9-bit data mode by setting the
M control bit in SCIxC1. In 9-bit mode, there is a ninth data bit to the left of the MSB of the SCI data
register. For the transmit data buffer, this bit is stored in T8 in SCIxC3. For the receiver, the ninth bit is
held in R8 in SCIxC3.
For coherent writes to the transmit data buffer, write to the T8 bit before writing to SCIxD.
If the bit value to be transmitted as the ninth bit of a new character is the same as for the previous character,
it is not necessary to write to T8 again. When data is transferred from the transmit data buffer to the
transmit shifter, the value in T8 is copied at the same time data is transferred from SCIxD to the shifter.
9-bit data mode typically is used in conjunction with parity to allow eight bits of data plus the parity in the
ninth bit. Or it is used with address-mark wakeup so the ninth data bit can serve as the wakeup bit. In
custom protocols, the ninth bit can also serve as a software-controlled marker.
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13.3.5.2
Stop Mode Operation
During all stop modes, clocks to the SCI module are halted.
In stop1 and stop2 modes, all SCI register data is lost and must be re-initialized upon recovery from these
two stop modes. No SCI module registers are affected in stop3 mode.
The receive input active edge detect circuit is still active in stop3 mode, but not in stop2. An active edge
on the receive input brings the CPU out of stop3 mode if the interrupt is not masked (RXEDGIE = 1).
Note, because the clocks are halted, the SCI module will resume operation upon exit from stop (only in
stop3 mode). Software should ensure stop mode is not entered while there is a character being transmitted
out of or received into the SCI module.
13.3.5.3
Loop Mode
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Loop mode is sometimes used to check software, independent of
connections in the external system, to help isolate system problems. In this mode, the transmitter output is
internally connected to the receiver input and the RxD pin is not used by the SCI, so it reverts to a
general-purpose port I/O pin.
13.3.5.4
Single-Wire Operation
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Single-wire mode is used to implement a half-duplex serial connection.
The receiver is internally connected to the transmitter output and to the TxD pin. The RxD pin is not used
and reverts to a general-purpose port I/O pin.
In single-wire mode, the TXDIR bit in SCIxC3 controls the direction of serial data on the TxD pin. When
TXDIR = 0, the TxD pin is an input to the SCI receiver and the transmitter is temporarily disconnected
from the TxD pin so an external device can send serial data to the receiver. When TXDIR = 1, the TxD pin
is an output driven by the transmitter. In single-wire mode, the internal loop back connection from the
transmitter to the receiver causes the receiver to receive characters that are sent out by the transmitter.
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Chapter 14
Serial Peripheral Interface (S08SPIV3)
14.1
Introduction
The MC9S08AC128 Series includes up to two serial peripheral interface (SPI) modules. See Chapter 3,
“Electrical Characteristics and Timing Specifications,” for SPI electrical parametric information.
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
HCS08 CORE
IRQ
LVD
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
VOLTAGE REGULATOR
VSS
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT H
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PORT J
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
PORT D
COP
EXTAL
XTAL
LOW-POWER OSC
PORT E
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
RESET
IRQ/TPMCLK
PORT A
HCS08 SYSTEM CONTROL
PORT B
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT C
CPU
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
TPM1CH0–TPM1CH5
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 14-1. Block Diagram Highlighting the SPI Module
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14.1.1
Features
Features of the SPI module include:
• Master or slave mode operation
• Full-duplex or single-wire bidirectional option
• Programmable transmit bit rate
• Double-buffered transmit and receive
• Serial clock phase and polarity options
• Slave select output
• Selectable MSB-first or LSB-first shifting
14.1.2
Block Diagrams
This section includes block diagrams showing SPI system connections, the internal organization of the SPI
module, and the SPI clock dividers that control the master mode bit rate.
14.1.2.1
SPI System Block Diagram
Figure 14-2 shows the SPI modules of two MCUs connected in a master-slave arrangement. The master
device initiates all SPI data transfers. During a transfer, the master shifts data out (on the MOSI pin) to the
slave while simultaneously shifting data in (on the MISO pin) from the slave. The transfer effectively
exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK signal is a clock
output from the master and an input to the slave. The slave device must be selected by a low level on the
slave select input (SS pin). In this system, the master device has configured its SS pin as an optional slave
select output.
SLAVE
MASTER
MOSI
MOSI
SPI SHIFTER
7
6
5
4
3
2
SPI SHIFTER
1
0
MISO
SPSCK
CLOCK
GENERATOR
SS
MISO
7
6
5
4
3
2
1
0
SPSCK
SS
Figure 14-2. SPI System Connections
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
The most common uses of the SPI system include connecting simple shift registers for adding input or
output ports or connecting small peripheral devices such as serial A/D or D/A converters. Although
Figure 14-2 shows a system where data is exchanged between two MCUs, many practical systems involve
simpler connections where data is unidirectionally transferred from the master MCU to a slave or from a
slave to the master MCU.
14.1.2.2
SPI Module Block Diagram
Figure 14-3 is a block diagram of the SPI module. The central element of the SPI is the SPI shift register.
Data is written to the double-buffered transmitter (write to SPIxD) and gets transferred to the SPI shift
register at the start of a data transfer. After shifting in a byte of data, the data is transferred into the
double-buffered receiver where it can be read (read from SPIxD). Pin multiplexing logic controls
connections between MCU pins and the SPI module.
When the SPI is configured as a master, the clock output is routed to the SPSCK pin, the shifter output is
routed to MOSI, and the shifter input is routed from the MISO pin.
When the SPI is configured as a slave, the SPSCK pin is routed to the clock input of the SPI, the shifter
output is routed to MISO, and the shifter input is routed from the MOSI pin.
In the external SPI system, simply connect all SPSCK pins to each other, all MISO pins together, and all
MOSI pins together. Peripheral devices often use slightly different names for these pins.
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PIN CONTROL
M
SPE
MOSI
(MOMI)
S
Tx BUFFER (WRITE SPIxD)
ENABLE
SPI SYSTEM
M
SHIFT
OUT
SPI SHIFT REGISTER
SHIFT
IN
MISO
(SISO)
S
SPC0
Rx BUFFER (READ SPIxD)
BIDIROE
SHIFT
DIRECTION
LSBFE
SHIFT
CLOCK
Rx BUFFER
FULL
Tx BUFFER
EMPTY
MASTER CLOCK
BUS RATE
CLOCK
SPIBR
CLOCK GENERATOR
MSTR
CLOCK
LOGIC
SLAVE CLOCK
MASTER/SLAVE
M
SPSCK
S
MASTER/
SLAVE
MODE SELECT
MODFEN
SSOE
MODE FAULT
DETECTION
SS
SPRF
SPTEF
SPTIE
MODF
SPIE
SPI
INTERRUPT
REQUEST
Figure 14-3. SPI Module Block Diagram
14.1.3
SPI Baud Rate Generation
As shown in Figure 14-4, the clock source for the SPI baud rate generator is the bus clock. The three
prescale bits (SPPR2:SPPR1:SPPR0) choose a prescale divisor of 1, 2, 3, 4, 5, 6, 7, or 8. The three rate
select bits (SPR2:SPR1:SPR0) divide the output of the prescaler stage by 2, 4, 8, 16, 32, 64, 128, or 256
to get the internal SPI master mode bit-rate clock.
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
BUS CLOCK
PRESCALER
CLOCK RATE DIVIDER
DIVIDE BY
1, 2, 3, 4, 5, 6, 7, or 8
DIVIDE BY
2, 4, 8, 16, 32, 64, 128, or 256
SPPR2:SPPR1:SPPR0
SPR2:SPR1:SPR0
MASTER
SPI
BIT RATE
Figure 14-4. SPI Baud Rate Generation
14.2
External Signal Description
The SPI optionally shares four port pins. The function of these pins depends on the settings of SPI control
bits. When the SPI is disabled (SPE = 0), these four pins revert to being general-purpose port I/O pins that
are not controlled by the SPI.
14.2.1
SPSCK — SPI Serial Clock
When the SPI is enabled as a slave, this pin is the serial clock input. When the SPI is enabled as a master,
this pin is the serial clock output.
14.2.2
MOSI — Master Data Out, Slave Data In
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data output. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
input. If SPC0 = 1 to select single-wire bidirectional mode, and master mode is selected, this pin becomes
the bidirectional data I/O pin (MOMI). Also, the bidirectional mode output enable bit determines whether
the pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and slave mode is
selected, this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
14.2.3
MISO — Master Data In, Slave Data Out
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data input. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
output. If SPC0 = 1 to select single-wire bidirectional mode, and slave mode is selected, this pin becomes
the bidirectional data I/O pin (SISO) and the bidirectional mode output enable bit determines whether the
pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and master mode is selected,
this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
14.2.4
SS — Slave Select
When the SPI is enabled as a slave, this pin is the low-true slave select input. When the SPI is enabled as
a master and mode fault enable is off (MODFEN = 0), this pin is not used by the SPI and reverts to being
a general-purpose port I/O pin. When the SPI is enabled as a master and MODFEN = 1, the slave select
output enable bit determines whether this pin acts as the mode fault input (SSOE = 0) or as the slave select
output (SSOE = 1).
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14.3
Modes of Operation
14.3.1
SPI in Stop Modes
The SPI is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
During either stop1 or stop2 mode, the SPI module will be fully powered down. Upon wake-up from stop1
or stop2 mode, the SPI module will be in the reset state. During stop3 mode, clocks to the SPI module are
halted. No registers are affected. If stop3 is exited with a reset, the SPI will be put into its reset state. If
stop3 is exited with an interrupt, the SPI continues from the state it was in when stop3 was entered.
14.4
Register Definition
The SPI has five 8-bit registers to select SPI options, control baud rate, report SPI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SPI registers. This section refers to registers and control bits only by their names, and
a Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
14.4.1
SPI Control Register 1 (SPIxC1)
This read/write register includes the SPI enable control, interrupt enables, and configuration options.
7
6
5
4
3
2
1
0
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
0
0
0
0
0
1
0
0
R
W
Reset
Figure 14-5. SPI Control Register 1 (SPIxC1)
Table 14-1. SPIxC1 Field Descriptions
Field
Description
7
SPIE
SPI Interrupt Enable (for SPRF and MODF) — This is the interrupt enable for SPI receive buffer full (SPRF)
and mode fault (MODF) events.
0 Interrupts from SPRF and MODF inhibited (use polling)
1 When SPRF or MODF is 1, request a hardware interrupt
6
SPE
SPI System Enable — Disabling the SPI halts any transfer that is in progress, clears data buffers, and initializes
internal state machines. SPRF is cleared and SPTEF is set to indicate the SPI transmit data buffer is empty.
0 SPI system inactive
1 SPI system enabled
5
SPTIE
SPI Transmit Interrupt Enable — This is the interrupt enable bit for SPI transmit buffer empty (SPTEF).
0 Interrupts from SPTEF inhibited (use polling)
1 When SPTEF is 1, hardware interrupt requested
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Table 14-1. SPIxC1 Field Descriptions (continued)
Field
Description
4
MSTR
Master/Slave Mode Select
0 SPI module configured as a slave SPI device
1 SPI module configured as a master SPI device
3
CPOL
Clock Polarity — This bit effectively places an inverter in series with the clock signal from a master SPI or to a
slave SPI device. Refer to Section 14.5.1, “SPI Clock Formats” for more details.
0 Active-high SPI clock (idles low)
1 Active-low SPI clock (idles high)
2
CPHA
Clock Phase — This bit selects one of two clock formats for different kinds of synchronous serial peripheral
devices. Refer to Section 14.5.1, “SPI Clock Formats” for more details.
0 First edge on SPSCK occurs at the middle of the first cycle of an 8-cycle data transfer
1 First edge on SPSCK occurs at the start of the first cycle of an 8-cycle data transfer
1
SSOE
Slave Select Output Enable — This bit is used in combination with the mode fault enable (MODFEN) bit in
SPCR2 and the master/slave (MSTR) control bit to determine the function of the SS pin as shown in Table 14-2.
0
LSBFE
LSB First (Shifter Direction)
0 SPI serial data transfers start with most significant bit
1 SPI serial data transfers start with least significant bit
Table 14-2. SS Pin Function
MODFEN
SSOE
Master Mode
Slave Mode
0
0
General-purpose I/O (not SPI)
Slave select input
0
1
General-purpose I/O (not SPI)
Slave select input
1
0
SS input for mode fault
Slave select input
1
1
Automatic SS output
Slave select input
NOTE
Ensure that the SPI should not be disabled (SPE=0) at the same time as a bit change to the CPHA bit. These
changes should be performed as separate operations or unexpected behavior may occur.
14.4.2
SPI Control Register 2 (SPIxC2)
This read/write register is used to control optional features of the SPI system. Bits 7, 6, 5, and 2 are not
implemented and always read 0.
R
7
6
5
0
0
0
4
3
MODFEN
BIDIROE
0
0
2
1
0
SPISWAI
SPC0
0
0
0
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 14-6. SPI Control Register 2 (SPIxC2)
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Table 14-3. SPIxC2 Register Field Descriptions
Field
Description
4
MODFEN
Master Mode-Fault Function Enable — When the SPI is configured for slave mode, this bit has no meaning or
effect. (The SS pin is the slave select input.) In master mode, this bit determines how the SS pin is used (refer
to Table 14-2 for more details).
0 Mode fault function disabled, master SS pin reverts to general-purpose I/O not controlled by SPI
1 Mode fault function enabled, master SS pin acts as the mode fault input or the slave select output
3
BIDIROE
Bidirectional Mode Output Enable — When bidirectional mode is enabled by SPI pin control 0 (SPC0) = 1,
BIDIROE determines whether the SPI data output driver is enabled to the single bidirectional SPI I/O pin.
Depending on whether the SPI is configured as a master or a slave, it uses either the MOSI (MOMI) or MISO
(SISO) pin, respectively, as the single SPI data I/O pin. When SPC0 = 0, BIDIROE has no meaning or effect.
0 Output driver disabled so SPI data I/O pin acts as an input
1 SPI I/O pin enabled as an output
1
SPISWAI
SPI Stop in Wait Mode
0 SPI clocks continue to operate in wait mode
1 SPI clocks stop when the MCU enters wait mode
0
SPC0
14.4.3
SPI Pin Control 0 — The SPC0 bit chooses single-wire bidirectional mode. If MSTR = 0 (slave mode), the SPI
uses the MISO (SISO) pin for bidirectional SPI data transfers. If MSTR = 1 (master mode), the SPI uses the
MOSI (MOMI) pin for bidirectional SPI data transfers. When SPC0 = 1, BIDIROE is used to enable or disable the
output driver for the single bidirectional SPI I/O pin.
0 SPI uses separate pins for data input and data output
1 SPI configured for single-wire bidirectional operation
SPI Baud Rate Register (SPIxBR)
This register is used to set the prescaler and bit rate divisor for an SPI master. This register may be read or
written at any time.
7
R
6
5
4
3
SPPR2
SPPR1
SPPR0
0
0
0
0
2
1
0
SPR2
SPR1
SPR0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 14-7. SPI Baud Rate Register (SPIxBR)
Table 14-4. SPIxBR Register Field Descriptions
Field
Description
6:4
SPPR[2:0]
SPI Baud Rate Prescale Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate prescaler
as shown in Table 14-5. The input to this prescaler is the bus rate clock (BUSCLK). The output of this prescaler
drives the input of the SPI baud rate divider (see Figure 14-4).
2:0
SPR[2:0]
SPI Baud Rate Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate divider as shown in
Table 14-6. The input to this divider comes from the SPI baud rate prescaler (see Figure 14-4). The output of this
divider is the SPI bit rate clock for master mode.
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Table 14-5. SPI Baud Rate Prescaler Divisor
SPPR2:SPPR1:SPPR0
Prescaler Divisor
0:0:0
1
0:0:1
2
0:1:0
3
0:1:1
4
1:0:0
5
1:0:1
6
1:1:0
7
1:1:1
8
Table 14-6. SPI Baud Rate Divisor
14.4.4
SPR2:SPR1:SPR0
Rate Divisor
0:0:0
2
0:0:1
4
0:1:0
8
0:1:1
16
1:0:0
32
1:0:1
64
1:1:0
128
1:1:1
256
SPI Status Register (SPIxS)
This register has three read-only status bits. Bits 6, 3, 2, 1, and 0 are not implemented and always read 0.
Writes have no meaning or effect.
R
7
6
5
4
3
2
1
0
SPRF
0
SPTEF
MODF
0
0
0
0
0
0
1
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 14-8. SPI Status Register (SPIxS)
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Table 14-7. SPIxS Register Field Descriptions
Field
Description
7
SPRF
SPI Read Buffer Full Flag — SPRF is set at the completion of an SPI transfer to indicate that received data may
be read from the SPI data register (SPIxD). SPRF is cleared by reading SPRF while it is set, then reading the
SPI data register.
0 No data available in the receive data buffer
1 Data available in the receive data buffer
5
SPTEF
SPI Transmit Buffer Empty Flag — This bit is set when there is room in the transmit data buffer. It is cleared by
reading SPIxS with SPTEF set, followed by writing a data value to the transmit buffer at SPIxD. SPIxS must be
read with SPTEF = 1 before writing data to SPIxD or the SPIxD write will be ignored. SPTEF generates an
SPTEF CPU interrupt request if the SPTIE bit in the SPIxC1 is also set. SPTEF is automatically set when a data
byte transfers from the transmit buffer into the transmit shift register. For an idle SPI (no data in the transmit buffer
or the shift register and no transfer in progress), data written to SPIxD is transferred to the shifter almost
immediately so SPTEF is set within two bus cycles allowing a second 8-bit data value to be queued into the
transmit buffer. After completion of the transfer of the value in the shift register, the queued value from the
transmit buffer will automatically move to the shifter and SPTEF will be set to indicate there is room for new data
in the transmit buffer. If no new data is waiting in the transmit buffer, SPTEF simply remains set and no data
moves from the buffer to the shifter.
0 SPI transmit buffer not empty
1 SPI transmit buffer empty
4
MODF
Master Mode Fault Flag — MODF is set if the SPI is configured as a master and the slave select input goes
low, indicating some other SPI device is also configured as a master. The SS pin acts as a mode fault error input
only when MSTR = 1, MODFEN = 1, and SSOE = 0; otherwise, MODF will never be set. MODF is cleared by
reading MODF while it is 1, then writing to SPI control register 1 (SPIxC1).
0 No mode fault error
1 Mode fault error detected
14.4.5
SPI Data Register (SPIxD)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 14-9. SPI Data Register (SPIxD)
Reads of this register return the data read from the receive data buffer. Writes to this register write data to
the transmit data buffer. When the SPI is configured as a master, writing data to the transmit data buffer
initiates an SPI transfer.
Data should not be written to the transmit data buffer unless the SPI transmit buffer empty flag (SPTEF)
is set, indicating there is room in the transmit buffer to queue a new transmit byte.
Data may be read from SPIxD any time after SPRF is set and before another transfer is finished. Failure
to read the data out of the receive data buffer before a new transfer ends causes a receive overrun condition
and the data from the new transfer is lost.
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
14.5
Functional Description
An SPI transfer is initiated by checking for the SPI transmit buffer empty flag (SPTEF = 1) and then
writing a byte of data to the SPI data register (SPIxD) in the master SPI device. When the SPI shift register
is available, this byte of data is moved from the transmit data buffer to the shifter, SPTEF is set to indicate
there is room in the buffer to queue another transmit character if desired, and the SPI serial transfer starts.
During the SPI transfer, data is sampled (read) on the MISO pin at one SPSCK edge and shifted, changing
the bit value on the MOSI pin, one-half SPSCK cycle later. After eight SPSCK cycles, the data that was in
the shift register of the master has been shifted out the MOSI pin to the slave while eight bits of data were
shifted in the MISO pin into the master’s shift register. At the end of this transfer, the received data byte is
moved from the shifter into the receive data buffer and SPRF is set to indicate the data can be read by
reading SPIxD. If another byte of data is waiting in the transmit buffer at the end of a transfer, it is moved
into the shifter, SPTEF is set, and a new transfer is started.
Normally, SPI data is transferred most significant bit (MSB) first. If the least significant bit first enable
(LSBFE) bit is set, SPI data is shifted LSB first.
When the SPI is configured as a slave, its SS pin must be driven low before a transfer starts and SS must
stay low throughout the transfer. If a clock format where CPHA = 0 is selected, SS must be driven to a
logic 1 between successive transfers. If CPHA = 1, SS may remain low between successive transfers. See
Section 14.5.1, “SPI Clock Formats” for more details.
Because the transmitter and receiver are double buffered, a second byte, in addition to the byte currently
being shifted out, can be queued into the transmit data buffer, and a previously received character can be
in the receive data buffer while a new character is being shifted in. The SPTEF flag indicates when the
transmit buffer has room for a new character. The SPRF flag indicates when a received character is
available in the receive data buffer. The received character must be read out of the receive buffer (read
SPIxD) before the next transfer is finished or a receive overrun error results.
In the case of a receive overrun, the new data is lost because the receive buffer still held the previous
character and was not ready to accept the new data. There is no indication for such an overrun condition
so the application system designer must ensure that previous data has been read from the receive buffer
before a new transfer is initiated.
14.5.1
SPI Clock Formats
To accommodate a wide variety of synchronous serial peripherals from different manufacturers, the SPI
system has a clock polarity (CPOL) bit and a clock phase (CPHA) control bit to select one of four clock
formats for data transfers. CPOL selectively inserts an inverter in series with the clock. CPHA chooses
between two different clock phase relationships between the clock and data.
Figure 14-10 shows the clock formats when CPHA = 1. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting at the first SPSCK edge and bit 8 ending one-half SPSCK cycle after
the sixteenth SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending
on the setting in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms
applies for a specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the
MOSI input of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
pin from a master and the MISO waveform applies to the MISO output from a slave. The SS OUT
waveform applies to the slave select output from a master (provided MODFEN and SSOE = 1). The master
SS output goes to active low one-half SPSCK cycle before the start of the transfer and goes back high at
the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a
slave.
BIT TIME #
(REFERENCE)
1
2
...
6
7
8
BIT 7
BIT 0
BIT 6
BIT 1
...
...
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MSB FIRST
LSB FIRST
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
Figure 14-10. SPI Clock Formats (CPHA = 1)
When CPHA = 1, the slave begins to drive its MISO output when SS goes to active low, but the data is not
defined until the first SPSCK edge. The first SPSCK edge shifts the first bit of data from the shifter onto
the MOSI output of the master and the MISO output of the slave. The next SPSCK edge causes both the
master and the slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the
third SPSCK edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled,
and shifts the second data bit value out the other end of the shifter to the MOSI and MISO outputs of the
master and slave, respectively. When CHPA = 1, the slave’s SS input is not required to go to its inactive
high level between transfers.
Figure 14-11 shows the clock formats when CPHA = 0. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting as the slave is selected (SS IN goes low), and bit 8 ends at the last
SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending on the setting
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in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms applies for a
specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the MOSI input
of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output pin from a
master and the MISO waveform applies to the MISO output from a slave. The SS OUT waveform applies
to the slave select output from a master (provided MODFEN and SSOE = 1). The master SS output goes
to active low at the start of the first bit time of the transfer and goes back high one-half SPSCK cycle after
the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a
slave.
BIT TIME #
(REFERENCE)
1
2
BIT 7
BIT 0
BIT 6
BIT 1
...
6
7
8
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MSB FIRST
LSB FIRST
...
...
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
Figure 14-11. SPI Clock Formats (CPHA = 0)
When CPHA = 0, the slave begins to drive its MISO output with the first data bit value (MSB or LSB
depending on LSBFE) when SS goes to active low. The first SPSCK edge causes both the master and the
slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the second SPSCK
edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled and shifts the
second data bit value out the other end of the shifter to the MOSI and MISO outputs of the master and
slave, respectively. When CPHA = 0, the slave’s SS input must go to its inactive high level between
transfers.
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Chapter 14 Serial Peripheral Interface (S08SPIV3)
14.5.2
SPI Interrupts
There are three flag bits, two interrupt mask bits, and one interrupt vector associated with the SPI system.
The SPI interrupt enable mask (SPIE) enables interrupts from the SPI receiver full flag (SPRF) and mode
fault flag (MODF). The SPI transmit interrupt enable mask (SPTIE) enables interrupts from the SPI
transmit buffer empty flag (SPTEF). When one of the flag bits is set, and the associated interrupt mask bit
is set, a hardware interrupt request is sent to the CPU. If the interrupt mask bits are cleared, software can
poll the associated flag bits instead of using interrupts. The SPI interrupt service routine (ISR) should
check the flag bits to determine what event caused the interrupt. The service routine should also clear the
flag bit(s) before returning from the ISR (usually near the beginning of the ISR).
14.5.3
Mode Fault Detection
A mode fault occurs and the mode fault flag (MODF) becomes set when a master SPI device detects an
error on the SS pin (provided the SS pin is configured as the mode fault input signal). The SS pin is
configured to be the mode fault input signal when MSTR = 1, mode fault enable is set (MODFEN = 1),
and slave select output enable is clear (SSOE = 0).
The mode fault detection feature can be used in a system where more than one SPI device might become
a master at the same time. The error is detected when a master’s SS pin is low, indicating that some other
SPI device is trying to address this master as if it were a slave. This could indicate a harmful output driver
conflict, so the mode fault logic is designed to disable all SPI output drivers when such an error is detected.
When a mode fault is detected, MODF is set and MSTR is cleared to change the SPI configuration back
to slave mode. The output drivers on the SPSCK, MOSI, and MISO (if not bidirectional mode) are
disabled.
MODF is cleared by reading it while it is set, then writing to the SPI control register 1 (SPIxC1). User
software should verify the error condition has been corrected before changing the SPI back to master
mode.
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Chapter 15
Timer/PWM (S08TPMV3)
15.1
Introduction
The MC9S08AC128 Series includes three independent timer/PWM (TPM) modules which support
traditional input capture, output compare, or buffered edge-aligned pulse-width modulation (PWM) on
each channel. The timer system in the MC9S08AC128 Series includes a 6-channel TPM1, a separate
6-channel TPM2 and a separate 2-channel TPM3.
A control bit in each TPM configures all channels in that timer to operate as center-aligned PWM
functions. In each TPM, timing functions are based on a separate 16-bit counter with prescaler and modulo
features to control frequency and range (period between overflows) of the time reference.
The use of the fixed system clock, XCLK, as the clock source for any of the TPM modules allows the TPM
prescaler to run using the oscillator rate divided by two (ICGERCLK/2). This option is only available if
the ICG is configured in FEE mode and the proper conditions are met (see Section 10.4.11, “Fixed
Frequency Clock”). In all other ICG modes this selection is redundant because XCLK is the same as
BUSCLK.
An external clock source can be connected to the TPMxCLK pin. The maximum frequency for TPMxCLK
is the bus clock frequency divided by 4. For the MC9S08AC128 Series, TPMCLK, TPM1CLK, and
TPM2CLK options are configured via software using the TPMCCFG bit in the SOPT2 register; out of
reset, TPM1CLK, and TPM2CLK, and TPMCLK are connected to TPM1, TPM2, and TPM3 respectively.
(TPMCCFG = 1).
15.2
Features
Timer system features include:
• Clock source to prescaler for each TPM is independently selectable as bus clock, fixed system
clock, or an external pin.
• 16-bit free-running or up/down (CPWM) count operation
• 16-bit modulus register to control counter range
• Timer system enable
• One interrupt per channel plus a terminal count interrupt for each TPM module
• Each channel may be input capture, output compare, or buffered edge-aligned PWM
• Rising-edge, falling-edge, or any-edge input capture trigger
• Set, clear, or toggle output compare action
• Selectable polarity on PWM outputs
• Each TPM may be configured for buffered, center-aligned pulse-width modulation (CPWM) on all
channels
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Chapter 15 Timer/PWM (S08TPMV3)
HCS08 CORE
COP
IRQ
LVD
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
VDDAD
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
VSSAD
VREFL
VREFH
USERMEMORY
FLASH, RAM
(BYTES)
(AW128 = 128K, 8K)
(AW96 = 96K, 6K)
VDD
EXTAL
XTAL
LOW-POWER OSC
AD1P15–AD1P0
IIC MODULE (IIC1)
SCL
SDA
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
RXD1
TXD1
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
RXD2
TXD2
VOLTAGE REGULATOR
VSS
PTG6/EXTAL
PTG5/XTAL
PTG4/KBI1P4
PTG3/KBI1P3
PTG2/KBI1P2
PTG1/KBI1P1
PTG0/KBIP0
PORT H
PTC0/SCL1
SPSCK1
MOSI1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI2)
2-CHANNEL TIMER/PWM
MODULE (TPM3)
- Pin not connected in 64-pin and 48-pin packages
PTD7/KBI1P7/AD1P15
PTD6/TPM1CLK/AD1P14
PTD5/AD1P13
PTD4/TPM2CLK/AD1P12
PTD3/KBI1P6/AD1P11
PTD2/KBI1P5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
MISO1
PTE7/SPSCK1
SS1
PTE6/MOSI1
PTE5/MISO1
SPSCK2
MOSI2
MISO2
PTE4/SS1
TPM1CLK or TPMCLK
6-CHANNEL TIMER/PWM
MODULE (TPM1)
6-CHANNEL TIMER/PWM
MODULE (TPM2)
PORT G
PTH6/MISO2
PTH5/MOSI2
PTH4/SPSCK2
PTH3/TPM2CH5
PTH2/TPM2CH4
PTH1/TPM2CH3
PTH0/TPM2CH2
PORT J
PTJ7
PTJ6
PTJ5
PTJ4
PTJ3
PTJ2
PTJ1
PTJ0
PTC6
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
KBI1P7–KBI1P0
PORT D
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
RTI
PTB7/AD1P7
PTB6/AD1P6
PTB5/AD1P5
PTB4/AD1P4
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P1
PTB0/TPM3CH0/AD1P0
INTERNAL CLOCK
GENERATOR (ICG)
RESET
IRQ/TPMCLK
PORT A
HCS08 SYSTEM CONTROL
PORT B
CYCLIC REDUNDANCY
CHECK MODULE (CRC)
PORT C
CPU
PORT E
BDC
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
TPM1CH0–TPM1CH5
TPM2CLK or TPMCLK
TPM2CH0–TPM2CH5
TPMCLK
TPM3CH1
TPM3CH0
PORT F
BKGD/MS
DEBUG
MODULE (DBG)
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PTF7
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF3/TPM1CH5
PTF2/TPM1CH4
PTF1/TPM1CH3
PTF0/TPM1CH2
- Pin not connected in 48-pin package
Figure 15-1. Block Diagram Highlighting the TPM Module
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Chapter 15 Timer/PWM Module (S08TPMV3)
15.2.1
Features
The TPM includes these distinctive features:
• One to eight channels:
— Each channel may be input capture, output compare, or edge-aligned PWM
— Rising-Edge, falling-edge, or any-edge input capture trigger
— Set, clear, or toggle output compare action
— Selectable polarity on PWM outputs
• Module may be configured for buffered, center-aligned pulse-width-modulation (CPWM) on all
channels
• Timer clock source selectable as prescaled bus clock, fixed system clock, or an external clock pin
— Prescale taps for divide-by 1, 2, 4, 8, 16, 32, 64, or 128
— Fixed system clock source are synchronized to the bus clock by an on-chip synchronization
circuit
— External clock pin may be shared with any timer channel pin or a separated input pin
• 16-bit free-running or modulo up/down count operation
• Timer system enable
• One interrupt per channel plus terminal count interrupt
15.2.2
Modes of Operation
In general, TPM channels may be independently configured to operate in input capture, output compare,
or edge-aligned PWM modes. A control bit allows the whole TPM (all channels) to switch to
center-aligned PWM mode. When center-aligned PWM mode is selected, input capture, output compare,
and edge-aligned PWM functions are not available on any channels of this TPM module.
When the microcontroller is in active BDM background or BDM foreground mode, the TPM temporarily
suspends all counting until the microcontroller returns to normal user operating mode. During stop mode,
all system clocks, including the main oscillator, are stopped; therefore, the TPM is effectively disabled
until clocks resume. During wait mode, the TPM continues to operate normally. Provided the TPM does
not need to produce a real time reference or provide the interrupt source(s) needed to wake the MCU from
wait mode, the user can save power by disabling TPM functions before entering wait mode.
• Input capture mode
When a selected edge event occurs on the associated MCU pin, the current value of the 16-bit timer
counter is captured into the channel value register and an interrupt flag bit is set. Rising edges,
falling edges, any edge, or no edge (disable channel) may be selected as the active edge which
triggers the input capture.
• Output compare mode
When the value in the timer counter register matches the channel value register, an interrupt flag
bit is set, and a selected output action is forced on the associated MCU pin. The output compare
action may be selected to force the pin to zero, force the pin to one, toggle the pin, or ignore the
pin (used for software timing functions).
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Chapter 15 Timer/PWM Module (S08TPMV3)
•
•
Edge-aligned PWM mode
The value of a 16-bit modulo register plus 1 sets the period of the PWM output signal. The channel
value register sets the duty cycle of the PWM output signal. The user may also choose the polarity
of the PWM output signal. Interrupts are available at the end of the period and at the duty-cycle
transition point. This type of PWM signal is called edge-aligned because the leading edges of all
PWM signals are aligned with the beginning of the period, which is the same for all channels within
a TPM.
Center-aligned PWM mode
Twice the value of a 16-bit modulo register sets the period of the PWM output, and the
channel-value register sets the half-duty-cycle duration. The timer counter counts up until it
reaches the modulo value and then counts down until it reaches zero. As the count matches the
channel value register while counting down, the PWM output becomes active. When the count
matches the channel value register while counting up, the PWM output becomes inactive. This type
of PWM signal is called center-aligned because the centers of the active duty cycle periods for all
channels are aligned with a count value of zero. This type of PWM is required for types of motors
used in small appliances.
This is a high-level description only. Detailed descriptions of operating modes are in later sections.
15.2.3
Block Diagram
The TPM uses one input/output (I/O) pin per channel, TPMxCHn (timer channel n) where n is the channel
number (1-8). The TPM shares its I/O pins with general purpose I/O port pins (refer to I/O pin descriptions
in full-chip specification for the specific chip implementation).
Figure 15-2 shows the TPM structure. The central component of the TPM is the 16-bit counter that can
operate as a free-running counter or a modulo up/down counter. The TPM counter (when operating in
normal up-counting mode) provides the timing reference for the input capture, output compare, and
edge-aligned PWM functions. The timer counter modulo registers, TPMxMODH:TPMxMODL, control
the modulo value of the counter (the values 0x0000 or 0xFFFF effectively make the counter free running).
Software can read the counter value at any time without affecting the counting sequence. Any write to
either half of the TPMxCNT counter resets the counter, regardless of the data value written.
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Chapter 15 Timer/PWM Module (S08TPMV3)
BUS CLOCK
FIXED SYSTEM CLOCK
SYNC
EXTERNAL CLOCK
CLOCK SOURCE
SELECT
OFF, BUS, FIXED
SYSTEM CLOCK, EXT
PRESCALE AND SELECT
1, 2, 4, 8, 16, 32, 64,
or 128
CLKSB:CLKSA
PS2:PS1:PS0
CPWMS
16-BIT COUNTER
TOF
COUNTER RESET
TOIE
INTERRUPT
LOGIC
16-BIT COMPARATOR
TPMxMODH:TPMxMODL
ELS0B
CHANNEL 0
ELS0A
PORT
LOGIC
TPMxCH0
16-BIT COMPARATOR
TPMxC0VH:TPMxC0VL
CH0F
INTERNAL BUS
16-BIT LATCH
CHANNEL 1
MS0B
MS0A
ELS1B
ELS1A
CH0IE
INTERRUPT
LOGIC
PORT
LOGIC
TPMxCH1
16-BIT COMPARATOR
TPMxC1VH:TPMxC1VL
CH1F
16-BIT LATCH
MS1B
CH1IE
MS1A
INTERRUPT
LOGIC
Up to 8 channels
ELS7B
CHANNEL 7
ELS7A
PORT
LOGIC
TPMxCH7
16-BIT COMPARATOR
TPMxC7VH:TPMxC7VL
CH7F
16-BIT LATCH
MS7B
MS7A
CH7IE
INTERRUPT
LOGIC
Figure 15-2. TPM Block Diagram
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Chapter 15 Timer/PWM Module (S08TPMV3)
The TPM channels are programmable independently as input capture, output compare, or edge-aligned
PWM channels. Alternately, the TPM can be configured to produce CPWM outputs on all channels. When
the TPM is configured for CPWMs, the counter operates as an up/down counter; input capture, output
compare, and EPWM functions are not practical.
If a channel is configured as input capture, an internal pullup device may be enabled for that channel. The
details of how a module interacts with pin controls depends upon the chip implementation because the I/O
pins and associated general purpose I/O controls are not part of the module. Refer to the discussion of the
I/O port logic in a full-chip specification.
Because center-aligned PWMs are usually used to drive 3-phase AC-induction motors and brushless DC
motors, they are typically used in sets of three or six channels.
15.3
Signal Description
Table 15-1 shows the user-accessible signals for the TPM. The number of channels may be varied from
one to eight. When an external clock is included, it can be shared with the same pin as any TPM channel;
however, it could be connected to a separate input pin. Refer to the I/O pin descriptions in full-chip
specification for the specific chip implementation.
Table 15-1. Signal Properties
Name
Function
EXTCLK1
2
TPMxCHn
External clock source which may be selected to drive the TPM counter.
I/O pin associated with TPM channel n
1
When preset, this signal can share any channel pin; however depending upon full-chip
implementation, this signal could be connected to a separate external pin.
2 n=channel number (1 to 8)
Refer to documentation for the full-chip for details about reset states, port connections, and whether there
is any pullup device on these pins.
TPM channel pins can be associated with general purpose I/O pins and have passive pullup devices which
can be enabled with a control bit when the TPM or general purpose I/O controls have configured the
associated pin as an input. When no TPM function is enabled to use a corresponding pin, the pin reverts
to being controlled by general purpose I/O controls, including the port-data and data-direction registers.
Immediately after reset, no TPM functions are enabled, so all associated pins revert to general purpose I/O
control.
15.3.1
Detailed Signal Descriptions
This section describes each user-accessible pin signal in detail. Although Table 15-1 grouped all channel
pins together, any TPM pin can be shared with the external clock source signal. Since I/O pin logic is not
part of the TPM, refer to full-chip documentation for a specific derivative for more details about the
interaction of TPM pin functions and general purpose I/O controls including port data, data direction, and
pullup controls.
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Chapter 15 Timer/PWM Module (S08TPMV3)
15.3.1.1
EXTCLK — External Clock Source
Control bits in the timer status and control register allow the user to select nothing (timer disable), the
bus-rate clock (the normal default source), a crystal-related clock, or an external clock as the clock which
drives the TPM prescaler and subsequently the 16-bit TPM counter. The external clock source is
synchronized in the TPM. The bus clock clocks the synchronizer; the frequency of the external source must
be no more than one-fourth the frequency of the bus-rate clock, to meet Nyquist criteria and allowing for
jitter.
The external clock signal shares the same pin as a channel I/O pin, so the channel pin will not be usable
for channel I/O function when selected as the external clock source. It is the user’s responsibility to avoid
such settings. If this pin is used as an external clock source (CLKSB:CLKSA = 1:1), the channel can still
be used in output compare mode as a software timer (ELSnB:ELSnA = 0:0).
15.3.1.2
TPMxCHn — TPM Channel n I/O Pin(s)
Each TPM channel is associated with an I/O pin on the MCU. The function of this pin depends on the
channel configuration. The TPM pins share with general purpose I/O pins, where each pin has a port data
register bit, and a data direction control bit, and the port has optional passive pullups which may be enabled
whenever a port pin is acting as an input.
The TPM channel does not control the I/O pin when (ELSnB:ELSnA = 0:0) or when (CLKSB:CLKSA =
0:0) so it normally reverts to general purpose I/O control. When CPWMS = 1 (and ELSnB:ELSnA not =
0:0), all channels within the TPM are configured for center-aligned PWM and the TPMxCHn pins are all
controlled by the TPM system. When CPWMS=0, the MSnB:MSnA control bits determine whether the
channel is configured for input capture, output compare, or edge-aligned PWM.
When a channel is configured for input capture (CPWMS=0, MSnB:MSnA = 0:0 and ELSnB:ELSnA not
= 0:0), the TPMxCHn pin is forced to act as an edge-sensitive input to the TPM. ELSnB:ELSnA control
bits determine what polarity edge or edges will trigger input-capture events. A synchronizer based on the
bus clock is used to synchronize input edges to the bus clock. This implies the minimum pulse width—that
can be reliably detected—on an input capture pin is four bus clock periods (with ideal clock pulses as near
as two bus clocks can be detected). TPM uses this pin as an input capture input to override the port data
and data direction controls for the same pin.
When a channel is configured for output compare (CPWMS=0, MSnB:MSnA = 0:1 and ELSnB:ELSnA
not = 0:0), the associated data direction control is overridden, the TPMxCHn pin is considered an output
controlled by the TPM, and the ELSnB:ELSnA control bits determine how the pin is controlled. The
remaining three combinations of ELSnB:ELSnA determine whether the TPMxCHn pin is toggled, cleared,
or set each time the 16-bit channel value register matches the timer counter.
When the output compare toggle mode is initially selected, the previous value on the pin is driven out until
the next output compare event—then the pin is toggled.
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When a channel is configured for edge-aligned PWM (CPWMS=0, MSnB=1 and ELSnB:ELSnA not =
0:0), the data direction is overridden, the TPMxCHn pin is forced to be an output controlled by the TPM,
and ELSnA controls the polarity of the PWM output signal on the pin. When ELSnB:ELSnA=1:0, the
TPMxCHn pin is forced high at the start of each new period (TPMxCNT=0x0000), and the pin is forced
low when the channel value register matches the timer counter. When ELSnA=1, the TPMxCHn pin is
forced low at the start of each new period (TPMxCNT=0x0000), and the pin is forced high when the
channel value register matches the timer counter.
TPMxMODH:TPMxMODL = 0x0008
TPMxCnVH:TPMxCnVL = 0x0005
TPMxCNTH:TPMxCNTL
...
0
1
2
3
4
5
6
7
8
0
1
2
...
2
...
TPMxCHn
CHnF BIT
TOF BIT
Figure 15-3. High-True Pulse of an Edge-Aligned PWM
TPMxMODH:TPMxMODL = 0x0008
TPMxCnVH:TPMxCnVL = 0x0005
TPMxCNTH:TPMxCNTL
...
0
1
2
3
4
5
6
7
8
0
1
TPMxCHn
CHnF BIT
TOF BIT
Figure 15-4. Low-True Pulse of an Edge-Aligned PWM
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When the TPM is configured for center-aligned PWM (and ELSnB:ELSnA not = 0:0), the data direction
for all channels in this TPM are overridden, the TPMxCHn pins are forced to be outputs controlled by the
TPM, and the ELSnA bits control the polarity of each TPMxCHn output. If ELSnB:ELSnA=1:0, the
corresponding TPMxCHn pin is cleared when the timer counter is counting up, and the channel value
register matches the timer counter; the TPMxCHn pin is set when the timer counter is counting down, and
the channel value register matches the timer counter. If ELSnA=1, the corresponding TPMxCHn pin is set
when the timer counter is counting up and the channel value register matches the timer counter; the
TPMxCHn pin is cleared when the timer counter is counting down and the channel value register matches
the timer counter.
TPMxMODH:TPMxMODL = 0x0008
TPMxCnVH:TPMxCnVL = 0x0005
TPMxCNTH:TPMxCNTL
...
7
8
7
6
5
4
3
2
1
0
1
2
3
4
5
6
7
8
7
6
5
...
7
8
7
6
5
...
TPMxCHn
CHnF BIT
TOF BIT
Figure 15-5. High-True Pulse of a Center-Aligned PWM
TPMxMODH:TPMxMODL = 0x0008
TPMxCnVH:TPMxCnVL = 0x0005
TPMxCNTH:TPMxCNTL
...
7
8
7
6
5
4
3
2
1
0
1
2
3
4
5
6
TPMxCHn
CHnF BIT
TOF BIT
Figure 15-6. Low-True Pulse of a Center-Aligned PWM
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15.4
Register Definition
This section consists of register descriptions in address order. A typical MCU system may contain multiple
TPMs, and each TPM may have one to eight channels, so register names include placeholder characters to
identify which TPM and which channel is being referenced. For example, TPMxCnSC refers to timer
(TPM) x, channel n. TPM1C2SC would be the status and control register for channel 2 of timer 1.
15.4.1
TPM Status and Control Register (TPMxSC)
TPMxSC contains the overflow status flag and control bits used to configure the interrupt enable, TPM
configuration, clock source, and prescale factor. These controls relate to all channels within this timer
module.
7
R
TOF
W
0
Reset
0
6
5
4
3
2
1
0
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
0
0
0
0
0
0
0
Figure 15-7. TPM Status and Control Register (TPMxSC)
Table 15-2. TPMxSC Field Descriptions
Field
Description
7
TOF
Timer overflow flag. This read/write flag is set when the TPM counter resets to 0x0000 after reaching the modulo
value programmed in the TPM counter modulo registers. Clear TOF by reading the TPM status and control
register when TOF is set and then writing a logic 0 to TOF. If another TPM overflow occurs before the clearing
sequence is complete, the sequence is reset so TOF would remain set after the clear sequence was completed
for the earlier TOF. This is done so a TOF interrupt request cannot be lost during the clearing sequence for a
previous TOF. Reset clears TOF. Writing a logic 1 to TOF has no effect.
0 TPM counter has not reached modulo value or overflow
1 TPM counter has overflowed
6
TOIE
Timer overflow interrupt enable. This read/write bit enables TPM overflow interrupts. If TOIE is set, an interrupt is
generated when TOF equals one. Reset clears TOIE.
0 TOF interrupts inhibited (use for software polling)
1 TOF interrupts enabled
5
CPWMS
Center-aligned PWM select. When present, this read/write bit selects CPWM operating mode. By default, the
TPM operates in up-counting mode for input capture, output compare, and edge-aligned PWM functions. Setting
CPWMS reconfigures the TPM to operate in up/down counting mode for CPWM functions. Reset clears CPWMS.
0 All channels operate as input capture, output compare, or edge-aligned PWM mode as selected by the
MSnB:MSnA control bits in each channel’s status and control register.
1 All channels operate in center-aligned PWM mode.
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Table 15-2. TPMxSC Field Descriptions (continued)
Field
Description
4–3
Clock source selects. As shown in Table 15-3, this 2-bit field is used to disable the TPM system or select one of
CLKS[B:A] three clock sources to drive the counter prescaler. The fixed system clock source is only meaningful in systems
with a PLL-based or FLL-based system clock. When there is no PLL or FLL, the fixed-system clock source is the
same as the bus rate clock. The external source is synchronized to the bus clock by TPM module, and the fixed
system clock source (when a PLL or FLL is present) is synchronized to the bus clock by an on-chip
synchronization circuit. When a PLL or FLL is present but not enabled, the fixed-system clock source is the same
as the bus-rate clock.
2–0
PS[2:0]
Prescale factor select. This 3-bit field selects one of 8 division factors for the TPM clock input as shown in
Table 15-4. This prescaler is located after any clock source synchronization or clock source selection so it affects
the clock source selected to drive the TPM system. The new prescale factor will affect the clock source on the
next system clock cycle after the new value is updated into the register bits.
Table 15-3. TPM-Clock-Source Selection
CLKSB:CLKSA
TPM Clock Source to Prescaler Input
00
No clock selected (TPM counter disable)
01
Bus rate clock
10
Fixed system clock
11
External source
Table 15-4. Prescale Factor Selection
15.4.2
PS2:PS1:PS0
TPM Clock Source Divided-by
000
1
001
2
010
4
011
8
100
16
101
32
110
64
111
128
TPM-Counter Registers (TPMxCNTH:TPMxCNTL)
The two read-only TPM counter registers contain the high and low bytes of the value in the TPM counter.
Reading either byte (TPMxCNTH or TPMxCNTL) latches the contents of both bytes into a buffer where
they remain latched until the other half is read. This allows coherent 16-bit reads in either big-endian or
little-endian order which makes this more friendly to various compiler implementations. The coherency
mechanism is automatically restarted by an MCU reset or any write to the timer status/control register
(TPMxSC).
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Reset clears the TPM counter registers. Writing any value to TPMxCNTH or TPMxCNTL also clears the
TPM counter (TPMxCNTH:TPMxCNTL) and resets the coherency mechanism, regardless of the data
involved in the write.
R
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
W
Reset
Any write to TPMxCNTH clears the 16-bit counter
0
0
0
0
0
0
Figure 15-8. TPM Counter Register High (TPMxCNTH)
R
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
W
Reset
Any write to TPMxCNTL clears the 16-bit counter
0
0
0
0
0
0
Figure 15-9. TPM Counter Register Low (TPMxCNTL)
When BDM is active, the timer counter is frozen (this is the value that will be read by user); the coherency
mechanism is frozen such that the buffer latches remain in the state they were in when the BDM became
active, even if one or both counter halves are read while BDM is active. This assures that if the user was
in the middle of reading a 16-bit register when BDM became active, it will read the appropriate value from
the other half of the 16-bit value after returning to normal execution.
In BDM mode, writing any value to TPMxSC, TPMxCNTH or TPMxCNTL registers resets the read
coherency mechanism of the TPMxCNTH:L registers, regardless of the data involved in the write.
15.4.3
TPM Counter Modulo Registers (TPMxMODH:TPMxMODL)
The read/write TPM modulo registers contain the modulo value for the TPM counter. After the TPM
counter reaches the modulo value, the TPM counter resumes counting from 0x0000 at the next clock, and
the overflow flag (TOF) becomes set. Writing to TPMxMODH or TPMxMODL inhibits the TOF bit and
overflow interrupts until the other byte is written. Reset sets the TPM counter modulo registers to 0x0000
which results in a free running timer counter (modulo disabled).
Writing to either byte (TPMxMODH or TPMxMODL) latches the value into a buffer and the registers are
updated with the value of their write buffer according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), then the registers are updated after both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF
The latching mechanism may be manually reset by writing to the TPMxSC address (whether BDM is
active or not).
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When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the modulo register are written while BDM is active. Any write to the modulo registers
bypasses the buffer latches and directly writes to the modulo register while BDM is active.
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-10. TPM Counter Modulo Register High (TPMxMODH)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-11. TPM Counter Modulo Register Low (TPMxMODL)
Reset the TPM counter before writing to the TPM modulo registers to avoid confusion about when the first
counter overflow will occur.
15.4.4
TPM Channel n Status and Control Register (TPMxCnSC)
TPMxCnSC contains the channel-interrupt-status flag and control bits used to configure the interrupt
enable, channel configuration, and pin function.
7
R
6
5
4
3
2
CHnIE
MSnB
MSnA
ELSnB
ELSnA
0
0
0
0
0
CHnF
W
0
Reset
0
1
0
0
0
0
0
= Unimplemented or Reserved
Figure 15-12. TPM Channel n Status and Control Register (TPMxCnSC)
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Table 15-5. TPMxCnSC Field Descriptions
Field
Description
7
CHnF
Channel n flag. When channel n is an input-capture channel, this read/write bit is set when an active edge occurs
on the channel n pin. When channel n is an output compare or edge-aligned/center-aligned PWM channel, CHnF
is set when the value in the TPM counter registers matches the value in the TPM channel n value registers. When
channel n is an edge-aligned/center-aligned PWM channel and the duty cycle is set to 0% or 100%, CHnF will
not be set even when the value in the TPM counter registers matches the value in the TPM channel n value
registers.
A corresponding interrupt is requested when CHnF is set and interrupts are enabled (CHnIE = 1). Clear CHnF by
reading TPMxCnSC while CHnF is set and then writing a logic 0 to CHnF. If another interrupt request occurs
before the clearing sequence is complete, the sequence is reset so CHnF remains set after the clear sequence
completed for the earlier CHnF. This is done so a CHnF interrupt request cannot be lost due to clearing a previous
CHnF.
Reset clears the CHnF bit. Writing a logic 1 to CHnF has no effect.
0 No input capture or output compare event occurred on channel n
1 Input capture or output compare event on channel n
6
CHnIE
Channel n interrupt enable. This read/write bit enables interrupts from channel n. Reset clears CHnIE.
0 Channel n interrupt requests disabled (use for software polling)
1 Channel n interrupt requests enabled
5
MSnB
Mode select B for TPM channel n. When CPWMS=0, MSnB=1 configures TPM channel n for edge-aligned PWM
mode. Refer to the summary of channel mode and setup controls in Table 15-6.
4
MSnA
Mode select A for TPM channel n. When CPWMS=0 and MSnB=0, MSnA configures TPM channel n for
input-capture mode or output compare mode. Refer to Table 15-6 for a summary of channel mode and setup
controls.
Note: If the associated port pin is not stable for at least two bus clock cycles before changing to input capture
mode, it is possible to get an unexpected indication of an edge trigger.
3–2
ELSnB
ELSnA
Edge/level select bits. Depending upon the operating mode for the timer channel as set by CPWMS:MSnB:MSnA
and shown in Table 15-6, these bits select the polarity of the input edge that triggers an input capture event, select
the level that will be driven in response to an output compare match, or select the polarity of the PWM output.
Setting ELSnB:ELSnA to 0:0 configures the related timer pin as a general purpose I/O pin not related to any timer
functions. This function is typically used to temporarily disable an input capture channel or to make the timer pin
available as a general purpose I/O pin when the associated timer channel is set up as a software timer that does
not require the use of a pin.
Table 15-6. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
X
XX
00
Mode
Configuration
Pin not used for TPM - revert to general
purpose I/O or other peripheral control
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Table 15-6. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
Mode
Configuration
0
00
01
Input capture
Capture on rising edge
only
01
10
Capture on falling edge
only
11
Capture on rising or
falling edge
00
1X
Output compare
01
Toggle output on
compare
10
Clear output on
compare
11
Set output on compare
10
Edge-aligned
PWM
X1
1
XX
High-true pulses (clear
output on compare)
Low-true pulses (set
output on compare)
10
Center-aligned
PWM
X1
15.4.5
Software compare only
High-true pulses (clear
output on compare-up)
Low-true pulses (set
output on compare-up)
TPM Channel Value Registers (TPMxCnVH:TPMxCnVL)
These read/write registers contain the captured TPM counter value of the input capture function or the
output compare value for the output compare or PWM functions. The channel registers are cleared by
reset.
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-13. TPM Channel Value Register High (TPMxCnVH)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-14. TPM Channel Value Register Low (TPMxCnVL)
In input capture mode, reading either byte (TPMxCnVH or TPMxCnVL) latches the contents of both bytes
into a buffer where they remain latched until the other half is read. This latching mechanism also resets
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(becomes unlatched) when the TPMxCnSC register is written (whether BDM mode is active or not). Any
write to the channel registers will be ignored during the input capture mode.
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxCnSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the channel register are read while BDM is active. This assures that if the user was in the
middle of reading a 16-bit register when BDM became active, it will read the appropriate value from the
other half of the 16-bit value after returning to normal execution. The value read from the TPMxCnVH
and TPMxCnVL registers in BDM mode is the value of these registers and not the value of their read
buffer.
In output compare or PWM modes, writing to either byte (TPMxCnVH or TPMxCnVL) latches the value
into a buffer. After both bytes are written, they are transferred as a coherent 16-bit value into the
timer-channel registers according to the value of CLKSB:CLKSA bits and the selected mode, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written.
• If (CLKSB:CLKSA not = 0:0 and in output compare mode) then the registers are updated after the
second byte is written and on the next change of the TPM counter (end of the prescaler counting).
• If (CLKSB:CLKSA not = 0:0 and in EPWM or CPWM modes), then the registers are updated after
the both bytes were written, and the TPM counter changes from (TPMxMODH:TPMxMODL - 1)
to (TPMxMODH:TPMxMODL). If the TPM counter is a free-running counter then the update is
made when the TPM counter changes from 0xFFFE to 0xFFFF.
The latching mechanism may be manually reset by writing to the TPMxCnSC register (whether BDM
mode is active or not). This latching mechanism allows coherent 16-bit writes in either big-endian or
little-endian order which is friendly to various compiler implementations.
When BDM is active, the coherency mechanism is frozen such that the buffer latches remain in the state
they were in when the BDM became active even if one or both halves of the channel register are written
while BDM is active. Any write to the channel registers bypasses the buffer latches and directly write to
the channel register while BDM is active. The values written to the channel register while BDM is active
are used for PWM & output compare operation once normal execution resumes. Writes to the channel
registers while BDM is active do not interfere with partial completion of a coherency sequence. After the
coherency mechanism has been fully exercised, the channel registers are updated using the buffered values
written (while BDM was not active) by the user.
15.5
Functional Description
All TPM functions are associated with a central 16-bit counter which allows flexible selection of the clock
source and prescale factor. There is also a 16-bit modulo register associated with the main counter.
The CPWMS control bit chooses between center-aligned PWM operation for all channels in the TPM
(CPWMS=1) or general purpose timing functions (CPWMS=0) where each channel can independently be
configured to operate in input capture, output compare, or edge-aligned PWM mode. The CPWMS control
bit is located in the main TPM status and control register because it affects all channels within the TPM
and influences the way the main counter operates. (In CPWM mode, the counter changes to an up/down
mode rather than the up-counting mode used for general purpose timer functions.)
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The following sections describe the main counter and each of the timer operating modes (input capture,
output compare, edge-aligned PWM, and center-aligned PWM). Because details of pin operation and
interrupt activity depend upon the operating mode, these topics will be covered in the associated mode
explanation sections.
15.5.1
Counter
All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section
discusses selection of the clock source, end-of-count overflow, up-counting vs. up/down counting, and
manual counter reset.
15.5.1.1
Counter Clock Source
The 2-bit field, CLKSB:CLKSA, in the timer status and control register (TPMxSC) selects one of three
possible clock sources or OFF (which effectively disables the TPM). See Table 15-3. After any MCU reset,
CLKSB:CLKSA=0:0 so no clock source is selected, and the TPM is in a very low power state. These
control bits may be read or written at any time and disabling the timer (writing 00 to the CLKSB:CLKSA
field) does not affect the values in the counter or other timer registers.
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Table 15-7. TPM Clock Source Selection
CLKSB:CLKSA
TPM Clock Source to Prescaler Input
00
No clock selected (TPM counter disabled)
01
Bus rate clock
10
Fixed system clock
11
External source
The bus rate clock is the main system bus clock for the MCU. This clock source requires no
synchronization because it is the clock that is used for all internal MCU activities including operation of
the CPU and buses.
In MCUs that have no PLL and FLL or the PLL and FLL are not engaged, the fixed system clock source
is the same as the bus-rate-clock source, and it does not go through a synchronizer. When a PLL or FLL
is present and engaged, a synchronizer is required between the crystal divided-by two clock source and the
timer counter so counter transitions will be properly aligned to bus-clock transitions. A synchronizer will
be used at chip level to synchronize the crystal-related source clock to the bus clock.
The external clock source may be connected to any TPM channel pin. This clock source always has to pass
through a synchronizer to assure that counter transitions are properly aligned to bus clock transitions. The
bus-rate clock drives the synchronizer; therefore, to meet Nyquist criteria even with jitter, the frequency of
the external clock source must not be faster than the bus rate divided-by four. With ideal clocks the external
clock can be as fast as bus clock divided by four.
When the external clock source shares the TPM channel pin, this pin should not be used for other channel
timing functions. For example, it would be ambiguous to configure channel 0 for input capture when the
TPM channel 0 pin was also being used as the timer external clock source. (It is the user’s responsibility
to avoid such settings.) The TPM channel could still be used in output compare mode for software timing
functions (pin controls set not to affect the TPM channel pin).
15.5.1.2
Counter Overflow and Modulo Reset
An interrupt flag and enable are associated with the 16-bit main counter. The flag (TOF) is a
software-accessible indication that the timer counter has overflowed. The enable signal selects between
software polling (TOIE=0) where no hardware interrupt is generated, or interrupt-driven operation
(TOIE=1) where a static hardware interrupt is generated whenever the TOF flag is equal to one.
The conditions causing TOF to become set depend on whether the TPM is configured for center-aligned
PWM (CPWMS=1). In the simplest mode, there is no modulus limit and the TPM is not in CPWMS=1
mode. In this case, the 16-bit timer counter counts from 0x0000 through 0xFFFF and overflows to 0x0000
on the next counting clock. TOF becomes set at the transition from 0xFFFF to 0x0000. When a modulus
limit is set, TOF becomes set at the transition from the value set in the modulus register to 0x0000. When
the TPM is in center-aligned PWM mode (CPWMS=1), the TOF flag gets set as the counter changes
direction at the end of the count value set in the modulus register (that is, at the transition from the value
set in the modulus register to the next lower count value). This corresponds to the end of a PWM period
(the 0x0000 count value corresponds to the center of a period).
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15.5.1.3
Counting Modes
The main timer counter has two counting modes. When center-aligned PWM is selected (CPWMS=1), the
counter operates in up/down counting mode. Otherwise, the counter operates as a simple up counter. As
an up counter, the timer counter counts from 0x0000 through its terminal count and then continues with
0x0000. The terminal count is 0xFFFF or a modulus value in TPMxMODH:TPMxMODL.
When center-aligned PWM operation is specified, the counter counts up from 0x0000 through its terminal
count and then down to 0x0000 where it changes back to up counting. Both 0x0000 and the terminal count
value are normal length counts (one timer clock period long). In this mode, the timer overflow flag (TOF)
becomes set at the end of the terminal-count period (as the count changes to the next lower count value).
15.5.1.4
Manual Counter Reset
The main timer counter can be manually reset at any time by writing any value to either half of
TPMxCNTH or TPMxCNTL. Resetting the counter in this manner also resets the coherency mechanism
in case only half of the counter was read before resetting the count.
15.5.2
Channel Mode Selection
Provided CPWMS=0, the MSnB and MSnA control bits in the channel n status and control registers
determine the basic mode of operation for the corresponding channel. Choices include input capture,
output compare, and edge-aligned PWM.
15.5.2.1
Input Capture Mode
With the input-capture function, the TPM can capture the time at which an external event occurs. When an
active edge occurs on the pin of an input-capture channel, the TPM latches the contents of the TPM counter
into the channel-value registers (TPMxCnVH:TPMxCnVL). Rising edges, falling edges, or any edge may
be chosen as the active edge that triggers an input capture.
In input capture mode, the TPMxCnVH and TPMxCnVL registers are read only.
When either half of the 16-bit capture register is read, the other half is latched into a buffer to support
coherent 16-bit accesses in big-endian or little-endian order. The coherency sequence can be manually
reset by writing to the channel status/control register (TPMxCnSC).
An input capture event sets a flag bit (CHnF) which may optionally generate a CPU interrupt request.
While in BDM, the input capture function works as configured by the user. When an external event occurs,
the TPM latches the contents of the TPM counter (which is frozen because of the BDM mode) into the
channel value registers and sets the flag bit.
15.5.2.2
Output Compare Mode
With the output-compare function, the TPM can generate timed pulses with programmable position,
polarity, duration, and frequency. When the counter reaches the value in the channel-value registers of an
output-compare channel, the TPM can set, clear, or toggle the channel pin.
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In output compare mode, values are transferred to the corresponding timer channel registers only after both
8-bit halves of a 16-bit register have been written and according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated at the next change of the TPM counter
(end of the prescaler counting) after the second byte is written.
The coherency sequence can be manually reset by writing to the channel status/control register
(TPMxCnSC).
An output compare event sets a flag bit (CHnF) which may optionally generate a CPU-interrupt request.
15.5.2.3
Edge-Aligned PWM Mode
This type of PWM output uses the normal up-counting mode of the timer counter (CPWMS=0) and can
be used when other channels in the same TPM are configured for input capture or output compare
functions. The period of this PWM signal is determined by the value of the modulus register
(TPMxMODH:TPMxMODL) plus 1. The duty cycle is determined by the setting in the timer channel
register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by the setting in the
ELSnA control bit. 0% and 100% duty cycle cases are possible.
The output compare value in the TPM channel registers determines the pulse width (duty cycle) of the
PWM signal (Figure 15-15). The time between the modulus overflow and the output compare is the pulse
width. If ELSnA=0, the counter overflow forces the PWM signal high, and the output compare forces the
PWM signal low. If ELSnA=1, the counter overflow forces the PWM signal low, and the output compare
forces the PWM signal high.
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PULSE
WIDTH
TPMxCHn
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 15-15. PWM Period and Pulse Width (ELSnA=0)
When the channel value register is set to 0x0000, the duty cycle is 0%. 100% duty cycle can be achieved
by setting the timer-channel register (TPMxCnVH:TPMxCnVL) to a value greater than the modulus
setting. This implies that the modulus setting must be less than 0xFFFF in order to get 100% duty cycle.
Because the TPM may be used in an 8-bit MCU, the settings in the timer channel registers are buffered to
ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxCnVH and TPMxCnVL, actually write to buffer registers. In edge-aligned PWM mode, values are
transferred to the corresponding timer-channel registers according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
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the TPM counter is a free-running counter then the update is made when the TPM counter changes
from 0xFFFE to 0xFFFF.
15.5.2.4
Center-Aligned PWM Mode
This type of PWM output uses the up/down counting mode of the timer counter (CPWMS=1). The output
compare value in TPMxCnVH:TPMxCnVL determines the pulse width (duty cycle) of the PWM signal
while the period is determined by the value in TPMxMODH:TPMxMODL. TPMxMODH:TPMxMODL
should be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous
results. ELSnA will determine the polarity of the CPWM output.
pulse width = 2 x (TPMxCnVH:TPMxCnVL)
period = 2 x (TPMxMODH:TPMxMODL); TPMxMODH:TPMxMODL=0x0001-0x7FFF
If the channel-value register TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle will
be 0%. If TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the (non-zero)
modulus setting, the duty cycle will be 100% because the duty cycle compare will never occur. This
implies the usable range of periods set by the modulus register is 0x0001 through 0x7FFE (0x7FFF if you
do not need to generate 100% duty cycle). This is not a significant limitation. The resulting period would
be much longer than required for normal applications.
TPMxMODH:TPMxMODL=0x0000 is a special case that should not be used with center-aligned PWM
mode. When CPWMS=0, this case corresponds to the counter running free from 0x0000 through 0xFFFF,
but when CPWMS=1 the counter needs a valid match to the modulus register somewhere other than at
0x0000 in order to change directions from up-counting to down-counting.
The output compare value in the TPM channel registers (times 2) determines the pulse width (duty cycle)
of the CPWM signal (Figure 15-16). If ELSnA=0, a compare occurred while counting up forces the
CPWM output signal low and a compare occurred while counting down forces the output high. The
counter counts up until it reaches the modulo setting in TPMxMODH:TPMxMODL, then counts down
until it reaches zero. This sets the period equal to two times TPMxMODH:TPMxMODL.
COUNT= 0
OUTPUT
COUNT=
COMPARE
TPMxMODH:TPMxMODL (COUNT DOWN)
OUTPUT
COMPARE
(COUNT UP)
COUNT=
TPMxMODH:TPMxMODL
TPMxCHn
PULSE WIDTH
2 x TPMxCnVH:TPMxCnVL
PERIOD
2 x TPMxMODH:TPMxMODL
Figure 15-16. CPWM Period and Pulse Width (ELSnA=0)
Center-aligned PWM outputs typically produce less noise than edge-aligned PWMs because fewer I/O pin
transitions are lined up at the same system clock edge. This type of PWM is also required for some types
of motor drives.
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Input capture, output compare, and edge-aligned PWM functions do not make sense when the counter is
operating in up/down counting mode so this implies that all active channels within a TPM must be used in
CPWM mode when CPWMS=1.
The TPM may be used in an 8-bit MCU. The settings in the timer channel registers are buffered to ensure
coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxMODH, TPMxMODL, TPMxCnVH, and TPMxCnVL, actually write to buffer registers.
In center-aligned PWM mode, the TPMxCnVH:L registers are updated with the value of their write buffer
according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF.
When TPMxCNTH:TPMxCNTL=TPMxMODH:TPMxMODL, the TPM can optionally generate a TOF
interrupt (at the end of this count).
Writing to TPMxSC cancels any values written to TPMxMODH and/or TPMxMODL and resets the
coherency mechanism for the modulo registers. Writing to TPMxCnSC cancels any values written to the
channel value registers and resets the coherency mechanism for TPMxCnVH:TPMxCnVL.
15.6
15.6.1
Reset Overview
General
The TPM is reset whenever any MCU reset occurs.
15.6.2
Description of Reset Operation
Reset clears the TPMxSC register which disables clocks to the TPM and disables timer overflow interrupts
(TOIE=0). CPWMS, MSnB, MSnA, ELSnB, and ELSnA are all cleared which configures all TPM
channels for input-capture operation with the associated pins disconnected from I/O pin logic (so all MCU
pins related to the TPM revert to general purpose I/O pins).
15.7
15.7.1
Interrupts
General
The TPM generates an optional interrupt for the main counter overflow and an interrupt for each channel.
The meaning of channel interrupts depends on each channel’s mode of operation. If the channel is
configured for input capture, the interrupt flag is set each time the selected input capture edge is
recognized. If the channel is configured for output compare or PWM modes, the interrupt flag is set each
time the main timer counter matches the value in the 16-bit channel value register.
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All TPM interrupts are listed in Table 15-8 which shows the interrupt name, the name of any local enable
that can block the interrupt request from leaving the TPM and getting recognized by the separate interrupt
processing logic.
Table 15-8. Interrupt Summary
Interrupt
Local
Enable
Source
Description
TOF
TOIE
Counter overflow
Set each time the timer counter reaches its terminal
count (at transition to next count value which is
usually 0x0000)
CHnF
CHnIE
Channel event
An input capture or output compare event took
place on channel n
The TPM module will provide a high-true interrupt signal. Vectors and priorities are determined at chip
integration time in the interrupt module so refer to the user’s guide for the interrupt module or to the chip’s
complete documentation for details.
15.7.2
Description of Interrupt Operation
For each interrupt source in the TPM, a flag bit is set upon recognition of the interrupt condition such as
timer overflow, channel-input capture, or output-compare events. This flag may be read (polled) by
software to determine that the action has occurred, or an associated enable bit (TOIE or CHnIE) can be set
to enable hardware interrupt generation. While the interrupt enable bit is set, a static interrupt will generate
whenever the associated interrupt flag equals one. The user’s software must perform a sequence of steps
to clear the interrupt flag before returning from the interrupt-service routine.
TPM interrupt flags are cleared by a two-step process including a read of the flag bit while it is set (1)
followed by a write of zero (0) to the bit. If a new event is detected between these two steps, the sequence
is reset and the interrupt flag remains set after the second step to avoid the possibility of missing the new
event.
15.7.2.1
Timer Overflow Interrupt (TOF) Description
The meaning and details of operation for TOF interrupts varies slightly depending upon the mode of
operation of the TPM system (general purpose timing functions versus center-aligned PWM operation).
The flag is cleared by the two step sequence described above.
15.7.2.1.1
Normal Case
Normally TOF is set when the timer counter changes from 0xFFFF to 0x0000. When the TPM is not
configured for center-aligned PWM (CPWMS=0), TOF gets set when the timer counter changes from the
terminal count (the value in the modulo register) to 0x0000. This case corresponds to the normal meaning
of counter overflow.
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15.7.2.1.2
Center-Aligned PWM Case
When CPWMS=1, TOF gets set when the timer counter changes direction from up-counting to
down-counting at the end of the terminal count (the value in the modulo register). In this case the TOF
corresponds to the end of a PWM period.
15.7.2.2
Channel Event Interrupt Description
The meaning of channel interrupts depends on the channel’s current mode (input-capture, output-compare,
edge-aligned PWM, or center-aligned PWM).
15.7.2.2.1
Input Capture Events
When a channel is configured as an input capture channel, the ELSnB:ELSnA control bits select no edge
(off), rising edges, falling edges or any edge as the edge which triggers an input capture event. When the
selected edge is detected, the interrupt flag is set. The flag is cleared by the two-step sequence described
in Section 15.7.2, “Description of Interrupt Operation.”
15.7.2.2.2
Output Compare Events
When a channel is configured as an output compare channel, the interrupt flag is set each time the main
timer counter matches the 16-bit value in the channel value register. The flag is cleared by the two-step
sequence described Section 15.7.2, “Description of Interrupt Operation.”
15.7.2.2.3
PWM End-of-Duty-Cycle Events
For channels configured for PWM operation there are two possibilities. When the channel is configured
for edge-aligned PWM, the channel flag gets set when the timer counter matches the channel value register
which marks the end of the active duty cycle period. When the channel is configured for center-aligned
PWM, the timer count matches the channel value register twice during each PWM cycle. In this CPWM
case, the channel flag is set at the start and at the end of the active duty cycle period which are the times
when the timer counter matches the channel value register. The flag is cleared by the two-step sequence
described Section 15.7.2, “Description of Interrupt Operation.”
15.8
The Differences from TPM v2 to TPM v3
1. Write to TPMxCNTH:L registers (Section 15.4.2, “TPM-Counter Registers
(TPMxCNTH:TPMxCNTL)) [SE110-TPM case 7]
Any write to TPMxCNTH or TPMxCNTL registers in TPM v3 clears the TPM counter
(TPMxCNTH:L) and the prescaler counter. Instead, in the TPM v2 only the TPM counter is cleared
in this case.
2. Read of TPMxCNTH:L registers (Section 15.4.2, “TPM-Counter Registers
(TPMxCNTH:TPMxCNTL))
— In TPM v3, any read of TPMxCNTH:L registers during BDM mode returns the value of the
TPM counter that is frozen. In TPM v2, if only one byte of the TPMxCNTH:L registers was
read before the BDM mode became active, then any read of TPMxCNTH:L registers during
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BDM mode returns the latched value of TPMxCNTH:L from the read buffer instead of the
frozen TPM counter value.
— This read coherency mechanism is cleared in TPM v3 in BDM mode if there is a write to
TPMxSC, TPMxCNTH or TPMxCNTL. Instead, in these conditions the TPM v2 does not clear
this read coherency mechanism.
3. Read of TPMxCnVH:L registers (Section 15.4.5, “TPM Channel Value Registers
(TPMxCnVH:TPMxCnVL))
— In TPM v3, any read of TPMxCnVH:L registers during BDM mode returns the value of the
TPMxCnVH:L register. In TPM v2, if only one byte of the TPMxCnVH:L registers was read
before the BDM mode became active, then any read of TPMxCnVH:L registers during BDM
mode returns the latched value of TPMxCNTH:L from the read buffer instead of the value in
the TPMxCnVH:L registers.
— This read coherency mechanism is cleared in TPM v3 in BDM mode if there is a write to
TPMxCnSC. Instead, in this condition the TPM v2 does not clear this read coherency
mechanism.
4. Write to TPMxCnVH:L registers
— Input Capture Mode (Section 15.5.2.1, “Input Capture Mode)
In this mode the TPM v3 does not allow the writes to TPMxCnVH:L registers. Instead, the
TPM v2 allows these writes.
— Output Compare Mode (Section 15.5.2.2, “Output Compare Mode)
In this mode and if (CLKSB:CLKSA not = 0:0), the TPM v3 updates the TPMxCnVH:L
registers with the value of their write buffer at the next change of the TPM counter (end of the
prescaler counting) after the second byte is written. Instead, the TPM v2 always updates these
registers when their second byte is written.
The following procedure can be used in the TPM v3 to verify if the TPMxCnVH:L registers
were updated with the new value that was written to these registers (value in their write buffer).
...
write the new value to TPMxCnVH:L;
read TPMxCnVH and TPMxCnVL registers;
while (the read value of TPMxCnVH:L is different from the new value written to
TPMxCnVH:L)
begin
read again TPMxCnVH and TPMxCnVL;
end
...
In this point, the TPMxCnVH:L registers were updated, so the program can continue and, for
example, write to TPMxC0SC without cancelling the previous write to TPMxCnVH:L
registers.
— Edge-Aligned PWM (Section 15.5.2.3, “Edge-Aligned PWM Mode)
In this mode and if (CLKSB:CLKSA not = 00), the TPM v3 updates the TPMxCnVH:L
registers with the value of their write buffer after that the both bytes were written and when the
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TPM counter changes from (TPMxMODH:L - 1) to (TPMxMODH:L). If the TPM counter is
a free-running counter, then this update is made when the TPM counter changes from $FFFE
to $FFFF. Instead, the TPM v2 makes this update after that the both bytes were written and
when the TPM counter changes from TPMxMODH:L to $0000.
— Center-Aligned PWM (Section 15.5.2.4, “Center-Aligned PWM Mode)
In this mode and if (CLKSB:CLKSA not = 00), the TPM v3 updates the TPMxCnVH:L
registers with the value of their write buffer after that the both bytes were written and when the
TPM counter changes from (TPMxMODH:L - 1) to (TPMxMODH:L). If the TPM counter is
a free-running counter, then this update is made when the TPM counter changes from $FFFE
to $FFFF. Instead, the TPM v2 makes this update after that the both bytes were written and
when the TPM counter changes from TPMxMODH:L to (TPMxMODH:L - 1).
5. Center-Aligned PWM (Section 15.5.2.4, “Center-Aligned PWM Mode)
— TPMxCnVH:L = TPMxMODH:L [SE110-TPM case 1]
In this case, the TPM v3 produces 100% duty cycle. Instead, the TPM v2 produces 0% duty
cycle.
— TPMxCnVH:L = (TPMxMODH:L - 1) [SE110-TPM case 2]
In this case, the TPM v3 produces almost 100% duty cycle. Instead, the TPM v2 produces 0%
duty cycle.
— TPMxCnVH:L is changed from 0x0000 to a non-zero value [SE110-TPM case 3 and 5]
In this case, the TPM v3 waits for the start of a new PWM period to begin using the new duty
cycle setting. Instead, the TPM v2 changes the channel output at the middle of the current
PWM period (when the count reaches 0x0000).
— TPMxCnVH:L is changed from a non-zero value to 0x0000 [SE110-TPM case 4]
In this case, the TPM v3 finishes the current PWM period using the old duty cycle setting.
Instead, the TPM v2 finishes the current PWM period using the new duty cycle setting.
6. Write to TPMxMODH:L registers in BDM mode (Section 15.4.3, “TPM Counter Modulo
Registers (TPMxMODH:TPMxMODL))
In the TPM v3 a write to TPMxSC register in BDM mode clears the write coherency mechanism
of TPMxMODH:L registers. Instead, in the TPM v2 this coherency mechanism is not cleared when
there is a write to TPMxSC register.
7. Update of EPWM signal when CLKSB:CLKSA = 00
In the TPM v3 if CLKSB:CLKSA = 00, then the EPWM signal in the channel output is not update
(it is frozen while CLKSB:CLKSA = 00). Instead, in the TPM v2 the EPWM signal is updated at
the next rising edge of bus clock after a write to TPMxCnSC register.
The Figure 0-1 and Figure 0-2 show when the EPWM signals generated by TPM v2 and TPM v3
after the reset (CLKSB:CLKSA = 00) and if there is a write to TPMxCnSC register.
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EPWM mode
TPMxMODH:TPMxMODL = 0x0007
TPMxCnVH:TPMxCnVL = 0x0005
RESET (active low)
BUS CLOCK
TPMxCNTH:TPMxCNTL
0
1
2
3 4
5
00
CLKSB:CLKSA BITS
6
7
0 1
2 ...
01
MSnB:MSnA BITS
00
10
ELSnB:ELSnA BITS
00
10
TPMv2 TPMxCHn
TPMv3 TPMxCHn
CHnF BIT
(in TPMv2 and TPMv3)
Figure 15-17. Generation of high-true EPWM signal by TPM v2 and v3 after the reset
EPWM mode
TPMxMODH:TPMxMODL = 0x0007
TPMxCnVH:TPMxCnVL = 0x0005
RESET (active low)
BUS CLOCK
TPMxCNTH:TPMxCNTL
0
1
3 4
5
6
7
0 1
2 ...
01
00
CLKSB:CLKSA BITS
2
MSnB:MSnA BITS
00
10
ELSnB:ELSnA BITS
00
01
TPMv2 TPMxCHn
TPMv3 TPMxCHn
CHnF BIT
(in TPMv2 and TPMv3)
Figure 15-18. Generation of low-true EPWM signal by TPM v2 and v3 after the reset
The following procedure can be used in TPM v3 (when the channel pin is also a port pin) to emulate
the high-true EPWM generated by TPM v2 after the reset.
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...
configure the channel pin as output port pin and set the output pin;
configure the channel to generate the EPWM signal but keep ELSnB:ELSnA as 00;
configure the other registers (TPMxMODH, TPMxMODL, TPMxCnVH, TPMxCnVL, ...);
configure CLKSB:CLKSA bits (TPM v3 starts to generate the high-true EPWM signal, however
TPM does not control the channel pin, so the EPWM signal is not available);
wait until the TOF is set (or use the TOF interrupt);
enable the channel output by configuring ELSnB:ELSnA bits (now EPWM signal is available);
...
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Chapter 16
Development Support
16.1
Introduction
Development support systems in the HCS08 include the background debug controller (BDC) and the
on-chip debug module (DBG). The BDC provides a single-wire debug interface to the target MCU that
provides a convenient interface for programming the on-chip FLASH and other nonvolatile memories. The
BDC is also the primary debug interface for development and allows non-intrusive access to memory data
and traditional debug features such as CPU register modify, breakpoints, and single instruction trace
commands.
In the HCS08 Family, address and data bus signals are not available on external pins (not even in test
modes). Debug is done through commands fed into the target MCU via the single-wire background debug
interface. The debug module provides a means to selectively trigger and capture bus information so an
external development system can reconstruct what happened inside the MCU on a cycle-by-cycle basis
without having external access to the address and data signals.
The alternate BDC clock source for MC9S08AC128 Series is the ICGLCLK. See Chapter 10, “Internal
Clock Generator (S08ICGV4)” for more information about ICGCLK and how to select clock sources.
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16.1.1
Features
Features of the BDC module include:
• Single pin for mode selection and background communications
• BDC registers are not located in the memory map
• SYNC command to determine target communications rate
• Non-intrusive commands for memory access
• Active background mode commands for CPU register access
• GO and TRACE1 commands
• BACKGROUND command can wake CPU from stop or wait modes
• One hardware address breakpoint built into BDC
• Oscillator runs in stop mode, if BDC enabled
• COP watchdog disabled while in active background mode
16.2
Background Debug Controller (BDC)
All MCUs in the HCS08 Family contain a single-wire background debug interface that supports in-circuit
programming of on-chip nonvolatile memory and sophisticated non-intrusive debug capabilities. Unlike
debug interfaces on earlier 8-bit MCUs, this system does not interfere with normal application resources.
It does not use any user memory or locations in the memory map and does not share any on-chip
peripherals.
BDC commands are divided into two groups:
• Active background mode commands require that the target MCU is in active background mode (the
user program is not running). Active background mode commands allow the CPU registers to be
read or written, and allow the user to trace one user instruction at a time, or GO to the user program
from active background mode.
• Non-intrusive commands can be executed at any time even while the user’s program is running.
Non-intrusive commands allow a user to read or write MCU memory locations or access status and
control registers within the background debug controller.
Typically, a relatively simple interface pod is used to translate commands from a host computer into
commands for the custom serial interface to the single-wire background debug system. Depending on the
development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port,
or some other type of communications such as a universal serial bus (USB) to communicate between the
host PC and the pod. The pod typically connects to the target system with ground, the BKGD pin, RESET,
and sometimes VDD. An open-drain connection to reset allows the host to force a target system reset,
which is useful to regain control of a lost target system or to control startup of a target system before the
on-chip nonvolatile memory has been programmed. Sometimes VDD can be used to allow the pod to use
power from the target system to avoid the need for a separate power supply. However, if the pod is powered
separately, it can be connected to a running target system without forcing a target system reset or otherwise
disturbing the running application program.
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BKGD 1
2 GND
NO CONNECT 3
4 RESET
NO CONNECT 5
6 VDD
Figure 16-1. BDM Tool Connector
16.2.1
BKGD Pin Description
BKGD is the single-wire background debug interface pin. The primary function of this pin is for
bidirectional serial communication of active background mode commands and data. During reset, this pin
is used to select between starting in active background mode or starting the user’s application program.
This pin is also used to request a timed sync response pulse to allow a host development tool to determine
the correct clock frequency for background debug serial communications.
BDC serial communications use a custom serial protocol first introduced on the M68HC12 Family of
microcontrollers. This protocol assumes the host knows the communication clock rate that is determined
by the target BDC clock rate. All communication is initiated and controlled by the host that drives a
high-to-low edge to signal the beginning of each bit time. Commands and data are sent most significant bit
first (MSB first). For a detailed description of the communications protocol, refer to Section 16.2.2,
“Communication Details.”
If a host is attempting to communicate with a target MCU that has an unknown BDC clock rate, a SYNC
command may be sent to the target MCU to request a timed sync response signal from which the host can
determine the correct communication speed.
BKGD is a pseudo-open-drain pin and there is an on-chip pullup so no external pullup resistor is required.
Unlike typical open-drain pins, the external RC time constant on this pin, which is influenced by external
capacitance, plays almost no role in signal rise time. The custom protocol provides for brief, actively
driven speedup pulses to force rapid rise times on this pin without risking harmful drive level conflicts.
Refer to Section 16.2.2, “Communication Details,” for more detail.
When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
chooses normal operating mode. When a debug pod is connected to BKGD it is possible to force the MCU
into active background mode after reset. The specific conditions for forcing active background depend
upon the HCS08 derivative (refer to the introduction to this Development Support section). It is not
necessary to reset the target MCU to communicate with it through the background debug interface.
16.2.2
Communication Details
The BDC serial interface requires the external controller to generate a falling edge on the BKGD pin to
indicate the start of each bit time. The external controller provides this falling edge whether data is
transmitted or received.
BKGD is a pseudo-open-drain pin that can be driven either by an external controller or by the MCU. Data
is transferred MSB first at 16 BDC clock cycles per bit (nominal speed). The interface times out if
512 BDC clock cycles occur between falling edges from the host. Any BDC command that was in progress
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when this timeout occurs is aborted without affecting the memory or operating mode of the target MCU
system.
The custom serial protocol requires the debug pod to know the target BDC communication clock speed.
The clock switch (CLKSW) control bit in the BDC status and control register allows the user to select the
BDC clock source. The BDC clock source can either be the bus or the alternate BDC clock source.
The BKGD pin can receive a high or low level or transmit a high or low level. The following diagrams
show timing for each of these cases. Interface timing is synchronous to clocks in the target BDC, but
asynchronous to the external host. The internal BDC clock signal is shown for reference in counting cycles.
Figure 16-2 shows an external host transmitting a logic 1 or 0 to the BKGD pin of a target HCS08 MCU.
The host is asynchronous to the target so there is a 0-to-1 cycle delay from the host-generated falling edge
to where the target perceives the beginning of the bit time. Ten target BDC clock cycles later, the target
senses the bit level on the BKGD pin. Typically, the host actively drives the pseudo-open-drain BKGD pin
during host-to-target transmissions to speed up rising edges. Because the target does not drive the BKGD
pin during the host-to-target transmission period, there is no need to treat the line as an open-drain signal
during this period.
BDC CLOCK
(TARGET MCU)
HOST
TRANSMIT 1
HOST
TRANSMIT 0
10 CYCLES
SYNCHRONIZATION
UNCERTAINTY
EARLIEST START
OF NEXT BIT
TARGET SENSES BIT LEVEL
PERCEIVED START
OF BIT TIME
Figure 16-2. BDC Host-to-Target Serial Bit Timing
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Figure 16-3 shows the host receiving a logic 1 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the perceived start of the bit time in the target MCU. The host holds the BKGD pin low long
enough for the target to recognize it (at least two target BDC cycles). The host must release the low drive
before the target MCU drives a brief active-high speedup pulse seven cycles after the perceived start of the
bit time. The host should sample the bit level about 10 cycles after it started the bit time.
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
HIGH-IMPEDANCE
TARGET MCU
SPEEDUP PULSE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
PERCEIVED START
OF BIT TIME
R-C RISE
BKGD PIN
10 CYCLES
10 CYCLES
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Figure 16-3. BDC Target-to-Host Serial Bit Timing (Logic 1)
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Figure 16-4 shows the host receiving a logic 0 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the start of the bit time as perceived by the target MCU. The host initiates the bit time but the
target HCS08 finishes it. Because the target wants the host to receive a logic 0, it drives the BKGD pin low
for 13 BDC clock cycles, then briefly drives it high to speed up the rising edge. The host samples the bit
level about 10 cycles after starting the bit time.
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
HIGH-IMPEDANCE
SPEEDUP
PULSE
TARGET MCU
DRIVE AND
SPEED-UP PULSE
PERCEIVED START
OF BIT TIME
BKGD PIN
10 CYCLES
10 CYCLES
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Figure 16-4. BDM Target-to-Host Serial Bit Timing (Logic 0)
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16.2.3
BDC Commands
BDC commands are sent serially from a host computer to the BKGD pin of the target HCS08 MCU. All
commands and data are sent MSB-first using a custom BDC communications protocol. Active background
mode commands require that the target MCU is currently in the active background mode while
non-intrusive commands may be issued at any time whether the target MCU is in active background mode
or running a user application program.
Table 16-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command.
Coding Structure Nomenclature
This nomenclature is used in Table 16-1 to describe the coding structure of the BDC commands.
Commands begin with an 8-bit hexadecimal command code in the host-to-target
direction (most significant bit first)
/ = separates parts of the command
d = delay 16 target BDC clock cycles
AAAA = a 16-bit address in the host-to-target direction
RD = 8 bits of read data in the target-to-host direction
WD = 8 bits of write data in the host-to-target direction
RD16 = 16 bits of read data in the target-to-host direction
WD16 = 16 bits of write data in the host-to-target direction
SS = the contents of BDCSCR in the target-to-host direction (STATUS)
CC = 8 bits of write data for BDCSCR in the host-to-target direction (CONTROL)
RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)
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Table 16-1. BDC Command Summary
Command
Mnemonic
1
Active BDM/
Non-intrusive
Coding
Structure
Description
SYNC
Non-intrusive
n/a1
Request a timed reference pulse to determine
target BDC communication speed
ACK_ENABLE
Non-intrusive
D5/d
Enable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
ACK_DISABLE
Non-intrusive
D6/d
Disable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
BACKGROUND
Non-intrusive
90/d
Enter active background mode if enabled
(ignore if ENBDM bit equals 0)
READ_STATUS
Non-intrusive
E4/SS
Read BDC status from BDCSCR
WRITE_CONTROL
Non-intrusive
C4/CC
Write BDC controls in BDCSCR
READ_BYTE
Non-intrusive
E0/AAAA/d/RD
Read a byte from target memory
READ_BYTE_WS
Non-intrusive
E1/AAAA/d/SS/RD
Read a byte and report status
READ_LAST
Non-intrusive
E8/SS/RD
Re-read byte from address just read and
report status
WRITE_BYTE
Non-intrusive
C0/AAAA/WD/d
Write a byte to target memory
WRITE_BYTE_WS
Non-intrusive
C1/AAAA/WD/d/SS
Write a byte and report status
READ_BKPT
Non-intrusive
E2/RBKP
Read BDCBKPT breakpoint register
WRITE_BKPT
Non-intrusive
C2/WBKP
Write BDCBKPT breakpoint register
GO
Active BDM
08/d
Go to execute the user application program
starting at the address currently in the PC
TRACE1
Active BDM
10/d
Trace 1 user instruction at the address in the
PC, then return to active background mode
TAGGO
Active BDM
18/d
Same as GO but enable external tagging
(HCS08 devices have no external tagging pin)
READ_A
Active BDM
68/d/RD
Read accumulator (A)
READ_CCR
Active BDM
69/d/RD
Read condition code register (CCR)
READ_PC
Active BDM
6B/d/RD16
Read program counter (PC)
READ_HX
Active BDM
6C/d/RD16
Read H and X register pair (H:X)
READ_SP
Active BDM
6F/d/RD16
Read stack pointer (SP)
READ_NEXT
Active BDM
70/d/RD
Increment H:X by one then read memory byte
located at H:X
READ_NEXT_WS
Active BDM
71/d/SS/RD
Increment H:X by one then read memory byte
located at H:X. Report status and data.
WRITE_A
Active BDM
48/WD/d
Write accumulator (A)
WRITE_CCR
Active BDM
49/WD/d
Write condition code register (CCR)
WRITE_PC
Active BDM
4B/WD16/d
Write program counter (PC)
WRITE_HX
Active BDM
4C/WD16/d
Write H and X register pair (H:X)
WRITE_SP
Active BDM
4F/WD16/d
Write stack pointer (SP)
WRITE_NEXT
Active BDM
50/WD/d
Increment H:X by one, then write memory byte
located at H:X
WRITE_NEXT_WS
Active BDM
51/WD/d/SS
Increment H:X by one, then write memory byte
located at H:X. Also report status.
The SYNC command is a special operation that does not have a command code.
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The SYNC command is unlike other BDC commands because the host does not necessarily know the
correct communications speed to use for BDC communications until after it has analyzed the response to
the SYNC command.
To issue a SYNC command, the host:
• Drives the BKGD pin low for at least 128 cycles of the slowest possible BDC clock (The slowest
clock is normally the reference oscillator/64 or the self-clocked rate/64.)
• Drives BKGD high for a brief speedup pulse to get a fast rise time (This speedup pulse is typically
one cycle of the fastest clock in the system.)
• Removes all drive to the BKGD pin so it reverts to high impedance
• Monitors the BKGD pin for the sync response pulse
The target, upon detecting the SYNC request from the host (which is a much longer low time than would
ever occur during normal BDC communications):
• Waits for BKGD to return to a logic high
• Delays 16 cycles to allow the host to stop driving the high speedup pulse
• Drives BKGD low for 128 BDC clock cycles
• Drives a 1-cycle high speedup pulse to force a fast rise time on BKGD
• Removes all drive to the BKGD pin so it reverts to high impedance
The host measures the low time of this 128-cycle sync response pulse and determines the correct speed for
subsequent BDC communications. Typically, the host can determine the correct communication speed
within a few percent of the actual target speed and the communication protocol can easily tolerate speed
errors of several percent.
16.2.4
BDC Hardware Breakpoint
The BDC includes one relatively simple hardware breakpoint that compares the CPU address bus to a
16-bit match value in the BDCBKPT register. This breakpoint can generate a forced breakpoint or a tagged
breakpoint. A forced breakpoint causes the CPU to enter active background mode at the first instruction
boundary following any access to the breakpoint address. The tagged breakpoint causes the instruction
opcode at the breakpoint address to be tagged so that the CPU will enter active background mode rather
than executing that instruction if and when it reaches the end of the instruction queue. This implies that
tagged breakpoints can only be placed at the address of an instruction opcode while forced breakpoints can
be set at any address.
The breakpoint enable (BKPTEN) control bit in the BDC status and control register (BDCSCR) is used to
enable the breakpoint logic (BKPTEN = 1). When BKPTEN = 0, its default value after reset, the
breakpoint logic is disabled and no BDC breakpoints are requested regardless of the values in other BDC
breakpoint registers and control bits. The force/tag select (FTS) control bit in BDCSCR is used to select
forced (FTS = 1) or tagged (FTS = 0) type breakpoints.
16.3
Register Definition
This section contains the descriptions of the BDC registers and control bits.
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This section refers to registers and control bits only by their names. A Freescale-provided equate or header
file is used to translate these names into the appropriate absolute addresses.
16.3.1
BDC Registers and Control Bits
The BDC has two registers:
• The BDC status and control register (BDCSCR) is an 8-bit register containing control and status
bits for the background debug controller.
• The BDC breakpoint match register (BDCBKPT) holds a 16-bit breakpoint match address.
These registers are accessed with dedicated serial BDC commands and are not located in the memory
space of the target MCU (so they do not have addresses and cannot be accessed by user programs).
Some of the bits in the BDCSCR have write limitations; otherwise, these registers may be read or written
at any time. For example, the ENBDM control bit may not be written while the MCU is in active
background mode. (This prevents the ambiguous condition of the control bit forbidding active background
mode while the MCU is already in active background mode.) Also, the four status bits (BDMACT, WS,
WSF, and DVF) are read-only status indicators and can never be written by the WRITE_CONTROL serial
BDC command. The clock switch (CLKSW) control bit may be read or written at any time.
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16.3.1.1
BDC Status and Control Register (BDCSCR)
This register can be read or written by serial BDC commands (READ_STATUS and WRITE_CONTROL)
but is not accessible to user programs because it is not located in the normal memory map of the MCU.
7
6
R
5
4
3
BKPTEN
FTS
CLKSW
BDMACT
ENBDM
2
1
0
WS
WSF
DVF
W
Normal
Reset
0
0
0
0
0
0
0
0
Reset in
Active BDM:
1
1
0
0
1
0
0
0
= Unimplemented or Reserved
Figure 16-5. BDC Status and Control Register (BDCSCR)
Table 16-2. BDCSCR Register Field Descriptions
Field
Description
7
ENBDM
Enable BDM (Permit Active Background Mode) — Typically, this bit is written to 1 by the debug host shortly
after the beginning of a debug session or whenever the debug host resets the target and remains 1 until a normal
reset clears it.
0 BDM cannot be made active (non-intrusive commands still allowed)
1 BDM can be made active to allow active background mode commands
6
BDMACT
Background Mode Active Status — This is a read-only status bit.
0 BDM not active (user application program running)
1 BDM active and waiting for serial commands
5
BKPTEN
BDC Breakpoint Enable — If this bit is clear, the BDC breakpoint is disabled and the FTS (force tag select)
control bit and BDCBKPT match register are ignored.
0 BDC breakpoint disabled
1 BDC breakpoint enabled
4
FTS
3
CLKSW
Force/Tag Select — When FTS = 1, a breakpoint is requested whenever the CPU address bus matches the
BDCBKPT match register. When FTS = 0, a match between the CPU address bus and the BDCBKPT register
causes the fetched opcode to be tagged. If this tagged opcode ever reaches the end of the instruction queue,
the CPU enters active background mode rather than executing the tagged opcode.
0 Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute that
instruction
1 Breakpoint match forces active background mode at next instruction boundary (address need not be an
opcode)
Select Source for BDC Communications Clock — CLKSW defaults to 0, which selects the alternate BDC
clock source.
0 Alternate BDC clock source
1 MCU bus clock
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Table 16-2. BDCSCR Register Field Descriptions (continued)
Field
Description
2
WS
Wait or Stop Status — When the target CPU is in wait or stop mode, most BDC commands cannot function.
However, the BACKGROUND command can be used to force the target CPU out of wait or stop and into active
background mode where all BDC commands work. Whenever the host forces the target MCU into active
background mode, the host should issue a READ_STATUS command to check that BDMACT = 1 before
attempting other BDC commands.
0 Target CPU is running user application code or in active background mode (was not in wait or stop mode when
background became active)
1 Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from wait or stop to
active background mode
1
WSF
Wait or Stop Failure Status — This status bit is set if a memory access command failed due to the target CPU
executing a wait or stop instruction at or about the same time. The usual recovery strategy is to issue a
BACKGROUND command to get out of wait or stop mode into active background mode, repeat the command
that failed, then return to the user program. (Typically, the host would restore CPU registers and stack values and
re-execute the wait or stop instruction.)
0 Memory access did not conflict with a wait or stop instruction
1 Memory access command failed because the CPU entered wait or stop mode
0
DVF
Data Valid Failure Status — This status bit is not used in the MC9S08AC128 Series because it does not have
any slow access memory.
0 Memory access did not conflict with a slow memory access
1 Memory access command failed because CPU was not finished with a slow memory access
16.3.1.2
BDC Breakpoint Match Register (BDCBKPT)
This 16-bit register holds the address for the hardware breakpoint in the BDC. The BKPTEN and FTS
control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC
commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register but is
not accessible to user programs because it is not located in the normal memory map of the MCU.
Breakpoints are normally set while the target MCU is in active background mode before running the user
application program. For additional information about setup and use of the hardware breakpoint logic in
the BDC, refer to Section 16.2.4, “BDC Hardware Breakpoint.”
16.3.2
System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial background mode command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
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R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
BDFR1
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
1
BDFR is writable only through serial background mode debug commands, not from user programs.
Figure 16-6. System Background Debug Force Reset Register (SBDFR)
Table 16-3. SBDFR Register Field Description
Field
Description
0
BDFR
Background Debug Force Reset — A serial active background mode command such as WRITE_BYTE allows
an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot
be written from a user program.
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Chapter 17
Debug Module (S08DBGV3) (128K)
17.1
Introduction
The DBG module implements an on-chip ICE (in-circuit emulation) system and allows non-intrusive
debug of application software by providing an on-chip trace buffer with flexible triggering capability. The
trigger also can provide extended breakpoint capacity. The on-chip ICE system is optimized for the HCS08
8-bit architecture and supports 64K bytes or 128K bytes of memory space.
17.1.1
Features
The on-chip ICE system includes these distinctive features:
• Three comparators (A, B, and C) with ability to match addresses in 128K space
— Dual mode, Comparators A and B used to compare addresses
— Full mode, Comparator A compares address and Comparator B compares data
— Can be used as triggers and/or breakpoints
— Comparator C can be used as a normal hardware breakpoint
— Loop1 capture mode, Comparator C is used to track most recent COF event captured into FIFO
• Tag and Force type breakpoints
• Nine trigger modes
— A
— A Or B
— A Then B
— A And B, where B is data (Full mode)
— A And Not B, where B is data (Full mode)
— Event Only B, store data
— A Then Event Only B, store data
— Inside Range, A ≤ Address ≤ B
— Outside Range, Address < Α or Address > B
• FIFO for storing change of flow information and event only data
— Source address of conditional branches taken
— Destination address of indirect JMP and JSR instruction
— Destination address of interrupts, RTI, RTC, and RTS instruction
— Data associated with Event B trigger modes
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•
Ability to End-trace until reset and Begin-trace from reset
17.1.2
Modes of Operation
The on-chip ICE system can be enabled in all MCU functional modes. The DBG module is disabled if the
MCU is secure. The DBG module comparators are disabled when executing a Background Debug Mode
(BDM) command.
17.1.3
Block Diagram
Figure 17-1 shows the structure of the DBG module.
core_cpu_aob_14_t2 1
core_cpu_aob_15_t2 1
core_ppage_t2[2:0] 1
DBG Read Data Bus
FIFO Data
Address Bus[16:0]1
c
o
n
t
r
o
l
Write Data Bus
Read Data Bus
Read/Write
DBG Module Enable
mmu_ppage_sel1
core_cof[1:0]
Address/Data/Control Registers
control
Trigger
Break
Control
Logic
match_A
Comparator A
match_B
Comparator B
Tag
Force
match_C
Comparator C
Change of Flow Indicators
MCU in BDM
MCU reset
event only
store
Read DBGFL
Read DBGFH
Read DBGFX
Instr. Lastcycle
Bus Clk
register
m
u
x
subtract 2
ppage_sel1
m
u
x
m
u
x
8 deep
FIFO
FIFO Data
addr[16:0]1
Write Data Bus
Read Data Bus
m
u
x
Read/Write
1. In 64K versions of this module there are only 16 address lines [15:0], there are no core_cpu_aob_14_t2,
core_cpu_aob_15_t2, core_ppage_t2[2:0], and ppage_sel signals.
Figure 17-1. DBG Block Diagram
17.2
Signal Description
The DBG module contains no external signals.
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17.3
Memory Map and Registers
This section provides a detailed description of all DBG registers accessible to the end user.
17.3.1
Module Memory Map
Table 17-1 shows the registers contained in the DBG module.
Table 17-1. Module Memory Map
Address
Use
Access
Base + $0000
Debug Comparator A High Register (DBGCAH)
Read/write
Base + $0001
Debug Comparator A Low Register (DBGCAL)
Read/write
Base + $0002
Debug Comparator B High Register (DBGCBH)
Read/write
Base + $0003
Debug Comparator B Low Register (DBGCBL)
Read/write
Base + $0004
Debug Comparator C High Register (DBGCCH)
Read/write
Base + $0005
Debug Comparator C Low Register (DBGCCL)
Read/write
Base + $0006
Debug FIFO High Register (DBGFH)
Read only
Base + $0007
Debug FIFO Low Register (DBGFL)
Read only
Base + $0008
Debug Comparator A Extension Register (DBGCAX)
Read/write
Base + $0009
Debug Comparator B Extension Register (DBGCBX)
Read/write
Base + $000A
Debug Comparator C Extension Register (DBGCCX)
Read/write
Base + $000B
Debug FIFO Extended Information Register (DBGFX)
Read only
Base + $000C
Debug Control Register (DBGC)
Read/write
Base + $000D
Debug Trigger Register (DBGT)
Read/write
Base + $000E
Debug Status Register (DBGS)
Read only
Base + $000F
Debug FIFO Count Register (DBGCNT)
Read only
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17.3.2
Table 17-2. Register Bit Summary
7
6
5
4
3
2
1
0
DBGCAH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
DBGCAL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
DBGCBH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
DBGCBL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
DBGCCH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
DBGCCL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
DBGFH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
DBGFL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
DBGCAX
RWAEN
RWA
PAGSEL
0
0
0
0
bit-16
DBGCBX
RWBEN
RWB
PAGSEL
0
0
0
0
bit-16
DBGCCX
RWCEN
RWC
PAGSEL
0
0
0
0
bit-16
DBGFX
PPACC
0
0
0
0
0
0
bit-16
DBGC
DBGEN
ARM
TAG
BRKEN
-
-
-
LOOP1
DBGT
TRGSEL
BEGIN
0
0
DBGS
AF
BF
CF
0
0
ARMF
0
0
0
0
DBGCNT
TRG[3:0]
0
0
CNT[3:0]
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17.3.3
Register Descriptions
This section consists of the DBG register descriptions in address order.
Note: For all registers below, consider: U = Unchanged, bit maintain its value after reset.
17.3.3.1
Debug Comparator A High Register (DBGCAH)
Module Base + 0x0000
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
POR
or nonend-run
1
1
1
1
1
1
1
1
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-2. Debug Comparator A High Register (DBGCAH)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-3. DBGCAH Field Descriptions
Field
Description
Bits 15–8
Comparator A High Compare Bits — The Comparator A High compare bits control whether Comparator A will
compare the address bus bits [15:8] to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
17.3.3.2
Debug Comparator A Low Register (DBGCAL)
Module Base + 0x0001
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
or nonend-run
1
1
1
1
1
1
1
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-3. Debug Comparator A Low Register (DBGCAL)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
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Table 17-4. DBGCAL Field Descriptions
Field
Description
Bits 7–0
Comparator A Low Compare Bits — The Comparator A Low compare bits control whether Comparator A will
compare the address bus bits [7:0] to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
17.3.3.3
Debug Comparator B High Register (DBGCBH)
Module Base + 0x0002
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-4. Debug Comparator B High Register (DBGCBH)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-5. DBGCBH Field Descriptions
Field
Description
Bits 15–8
Comparator B High Compare Bits — The Comparator B High compare bits control whether Comparator B will
compare the address bus bits [15:8] to a logic 1 or logic 0. Not used in Full mode.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
17.3.3.4
Debug Comparator B Low Register (DBGCBL)
Module Base + 0x0003
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-5. Debug Comparator B Low Register (DBGCBL)
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1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-6. DBGCBL Field Descriptions
Field
Description
Bits 7–0
Comparator B Low Compare Bits — The Comparator B Low compare bits control whether Comparator B will
compare the address bus or data bus bits [7:0] to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0, compares to data if in Full mode
1 Compare corresponding address bit to a logic 1, compares to data if in Full mode
17.3.3.5
Debug Comparator C High Register (DBGCCH)
Module Base + 0x0004
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-6. Debug Comparator C High Register (DBGCCH)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-7. DBGCCH Field Descriptions
Field
Description
Bits 15–8
Comparator C High Compare Bits — The Comparator C High compare bits control whether Comparator C will
compare the address bus bits [15:8] to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
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17.3.3.6
Debug Comparator C Low Register (DBGCCL)
Module Base + 0x0005
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
Figure 17-7. Debug Comparator C Low Register (DBGCCL)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-8. DBGCCL Field Descriptions
Field
Description
Bits 7–0
Comparator C Low Compare Bits — The Comparator C Low compare bits control whether Comparator C will
compare the address bus bits [7:0] to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
17.3.3.7
Debug FIFO High Register (DBGFH)
Module Base + 0x0006
7
6
5
4
3
2
1
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
= Unimplemented or Reserved
Figure 17-8. Debug FIFO High Register (DBGFH)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
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Table 17-9. DBGFH Field Descriptions
Field
Description
Bits 15–8
FIFO High Data Bits — The FIFO High data bits provide access to bits [15:8] of data in the FIFO. This register
is not used in event only modes and will read a $00 for valid FIFO words.
17.3.3.8
Debug FIFO Low Register (DBGFL)
Module Base + 0x0007
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
U
U
U
U
U
R
W
= Unimplemented or Reserved
Figure 17-9. Debug FIFO Low Register (DBGFL)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-10. DBGFL Field Descriptions
Field
Description
Bits 7–0
FIFO Low Data Bits — The FIFO Low data bits contain the least significant byte of data in the FIFO. When
reading FIFO words, read DBGFX and DBGFH before reading DBGFL because reading DBGFL causes the
FIFO pointers to advance to the next FIFO location. In event-only modes, there is no useful information in DBGFX
and DBGFH so it is not necessary to read them before reading DBGFL.
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17.3.3.9
Debug Comparator A Extension Register (DBGCAX)
Module Base + 0x0008
7
6
5
RWAEN
RWA
PAGSEL
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
0
0
0
0
U
R
4
3
2
1
0
0
0
0
0
Bit 16
W
= Unimplemented or Reserved
Figure 17-10. Debug Comparator A Extension Register (DBGCAX)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-11. DBGCAX Field Descriptions
Field
Description
7
RWAEN
Read/Write Comparator A Enable Bit — The RWAEN bit controls whether read or write comparison is enabled
for Comparator A.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
6
RWA
5
PAGSEL
0
Bit 16
Read/Write Comparator A Value Bit — The RWA bit controls whether read or write is used in compare for
Comparator A. The RWA bit is not used if RWAEN = 0.
0 Write cycle will be matched
1 Read cycle will be matched
Comparator A Page Select Bit — This PAGSEL bit controls whether Comparator A will be qualified with the
internal signal (mmu_ppage_sel) that indicates an extended access through the PPAGE mechanism. When
mmu_ppage_sel = 1, the 17-bit core address is a paged program access, and the 17-bit core address is made
up of PPAGE[2:0]:addr[13:0]. When mmu_ppage_sel = 0, the 17-bit core address is either a 16-bit CPU address
with a leading 0 in bit 16, or a 17-bit linear address pointer value.
0 Match qualified by mmu_ppage_sel = 0 so address bits [16:0] correspond to a 17-bit CPU address with a
leading zero at bit 16, or a 17-bit linear address pointer address
1 Match qualified by mmu_ppage_sel = 1 so address bits [16:0] compare to flash memory address made up of
PPAGE[2:0]:addr[13:0]
Comparator A Extended Address Bit 16 Compare Bit — The Comparator A bit 16 compare bit controls
whether Comparator A will compare the core address bus bit 16 to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
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17.3.3.10 Debug Comparator B Extension Register (DBGCBX)
Module Base + 0x0009
7
6
5
RWBEN
RWB
PAGSEL
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
0
0
0
0
U
R
4
3
2
1
0
0
0
0
0
Bit 16
W
= Unimplemented or Reserved
Figure 17-11. Debug Comparator B Extension Register (DBGCBX)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-12. DBGCBX Field Descriptions
Field
Description
7
RWBEN
Read/Write Comparator B Enable Bit — The RWBEN bit controls whether read or write comparison is enabled
for Comparator B. In full modes, RWAEN and RWA are used to control comparison of R/W and RWBEN is
ignored.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
6
RWB
Read/Write Comparator B Value Bit — The RWB bit controls whether read or write is used in compare for
Comparator B. The RWB bit is not used if RWBEN = 0. In full modes, RWAEN and RWA are used to control
comparison of R/W and RWB is ignored.
0 Write cycle will be matched
1 Read cycle will be matched
5
PAGSEL
Comparator B Page Select Bit — This PAGSEL bit controls whether Comparator B will be qualified with the
internal signal (mmu_papge_sel) that indicates an extended access through the PPAGE mechanism. When
mmu_ppage_sel = 1, the 17-bit core address is a paged program access, and the 17-bit core address is made
up of PPAGE[2:0]:addr[13:0]. When mmu_papge_sel = 0, the 17-bit core address is either a 16-bit CPU address
with a leading 0 in bit 16, or a 17-bit linear address pointer value. This bit is not used in full modes where
comparator B is used to match the data value.
0 Match qualified by mmu_ppage_sel = 0 so address bits [16:0] correspond to a 17-bit CPU address with a
leading zero at bit 16, or a 17-bit linear address pointer address
1 Match qualified by mmu_ppage_sel = 1 so address bits [16:0] compare to flash memory address made up of
PPAGE[2:0]:addr[13:0]
0
Bit 16
Comparator B Extended Address Bit 16 Compare Bit — The Comparator B bit 16 compare bit controls
whether Comparator B will compare the core address bus bit 16 to a logic 1 or logic 0. This bit is not used in full
modes where comparator B is used to match the data value.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
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17.3.3.11 Debug Comparator C Extension Register (DBGCCX)
Module Base + 0x000A
7
6
5
RWCEN
RWC
PAGSEL
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
U
U
0
0
0
0
U
R
4
3
2
1
0
0
0
0
0
Bit 16
W
= Unimplemented or Reserved
Figure 17-12. Debug Comparator C Extension Register (DBGCCX)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-13. DBGCCX Field Descriptions
Field
Description
7
RWCEN
Read/Write Comparator C Enable Bit — The RWCEN bit controls whether read or write comparison is enabled
for Comparator C.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
6
RWC
5
PAGSEL
0
Bit 16
Read/Write Comparator C Value Bit — The RWC bit controls whether read or write is used in compare for
Comparator C. The RWC bit is not used if RWCEN = 0.
0 Write cycle will be matched
1 Read cycle will be matched
Comparator C Page Select Bit — This PAGSEL bit controls whether Comparator C will be qualified with the
internal signal (mmu_papge_sel) that indicates an extended access through the PPAGE mechanism. When
mmu_ppage_sel = 1, the 17-bit core address is a paged program access, and the 17-bit core address is made
up of PPAGE[2:0]:addr[13:0]. When mmu_papge_sel = 0, the 17-bit core address is either a 16-bit CPU address
with a leading 0 in bit 16, or a 17-bit linear address pointer value.
0 Match qualified by mmu_ppage_sel = 0 so address bits [16:0] correspond to a 17-bit CPU address with a
leading zero at bit 16, or a 17-bit linear address pointer address
1 Match qualified by mmu_ppage_sel = 1 so address bits [16:0] compare to flash memory address made up of
PPAGE[2:0]:addr[13:0]
Comparator C Extended Address Bit 16 Compare Bit — The Comparator C bit 16 compare bit controls
whether Comparator C will compare the core address bus bit 16 to a logic 1 or logic 0.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
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17.3.3.12 Debug FIFO Extended Information Register (DBGFX)
Module Base + 0x000B
7
6
5
4
3
2
1
0
PPACC
0
0
0
0
0
0
Bit 16
POR
or nonend-run
0
0
0
0
0
0
0
0
Reset
end-run1
U
0
0
0
0
0
0
U
R
W
= Unimplemented or Reserved
Figure 17-13. Debug FIFO Extended Information Register (DBGFX)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the bits in this register do not change after reset.
Table 17-14. DBGFX Field Descriptions
Field
Description
7
PPACC
PPAGE Access Indicator Bit — This bit indicates whether the captured information in the current FIFO word is
associated with an extended access through the PPAGE mechanism or not. This is indicated by the internal
signal mmu_ppage_sel which is 1 when the access is through the PPAGE mechanism.
0 The information in the corresponding FIFO word is event-only data or an unpaged 17-bit CPU address with
bit-16 = 0
1 The information in the corresponding FIFO word is a 17-bit flash address with PPAGE[2:0] in the three most
significant bits and CPU address[13:0] in the 14 least significant bits
0
Bit 16
Extended Address Bit 16 — This bit is the most significant bit of the 17-bit core address.
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17.3.3.13 Debug Control Register (DBGC)
Module Base + 0x000C
7
6
5
4
DBGEN
ARM
TAG
BRKEN
POR
or nonend-run
1
1
0
0
0
0
0
0
Reset
end-run1
U
0
U
0
0
0
0
U
R
3
2
1
0
0
0
0
LOOP1
W
= Unimplemented or Reserved
Figure 17-14. Debug Control Register (DBGC)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the ARM and BRKEN bits are cleared but the remaining
control bits in this register do not change after reset.
Table 17-15. DBGC Field Descriptions
Field
7
DBGEN
Description
DBG Module Enable Bit — The DBGEN bit enables the DBG module. The DBGEN bit is forced to zero and
cannot be set if the MCU is secure.
0 DBG not enabled
1 DBG enabled
6
ARM
Arm Bit — The ARM bit controls whether the debugger is comparing and storing data in FIFO. See
Section 17.4.4.2, “Arming the DBG Module” for more information.
0 Debugger not armed
1 Debugger armed
5
TAG
Tag or Force Bit — The TAG bit controls whether a debugger or comparator C breakpoint will be requested as
a tag or force breakpoint to the CPU. The TAG bit is not used if BRKEN = 0.
0 Force request selected
1 Tag request selected
4
BRKEN
Break Enable Bit — The BRKEN bit controls whether the debugger will request a breakpoint to the CPU at the
end of a trace run, and whether comparator C will request a breakpoint to the CPU.
0 CPU break request not enabled
1 CPU break request enabled
0
LOOP1
Select LOOP1 Capture Mode — This bit selects either normal capture mode or LOOP1 capture mode. LOOP1
is not used in event-only modes.
0 Normal operation - capture COF events into the capture buffer FIFO
1 LOOP1 capture mode enabled. When the conditions are met to store a COF value into the FIFO, compare the
current COF address with the address in comparator C. If these addresses match, override the FIFO capture
and do not increment the FIFO count. If the address does not match comparator C, capture the COF address,
including the PPACC indicator, into the FIFO and into comparator C.
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17.3.3.14 Debug Trigger Register (DBGT)
Module Base + 0x000D
7
6
TRGSEL
BEGIN
POR
or nonend-run
0
1
0
0
0
Reset
end-run1
U
U
0
0
U
R
W2
5
4
0
0
3
2
1
0
0
0
0
U
U
U
TRG
= Unimplemented or Reserved
Figure 17-15. Debug Trigger Register (DBGT)
1
2
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the control bits in this register do not change after reset.
The DBG trigger register (DBGT) can not be changed unless ARM=0.
Table 17-16. DBGT Field Descriptions
Field
7
TRGSEL
6
BEGIN
3–0
TRG
Description
Trigger Selection Bit — The TRGSEL bit controls the triggering condition for the comparators. See
Section 17.4.4, “Trigger Break Control (TBC)” for more information.
0 Trigger on any compare address access
1 Trigger if opcode at compare address is executed
Begin/End Trigger Bit — The BEGIN bit controls whether the trigger begins or ends storing of data in FIFO.
0 Trigger at end of stored data
1 Trigger before storing data
Trigger Mode Bits — The TRG bits select the trigger mode of the DBG module as shown in Table 17-17.
Table 17-17. Trigger Mode Encoding
TRG Value
Meaning
0000
A Only
0001
A Or B
0010
A Then B
0011
Event Only B
0100
A Then Event Only B
0101
A And B (Full Mode)
0110
A And Not B (Full mode)
0111
Inside Range
1000
Outside Range
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Table 17-17. Trigger Mode Encoding
TRG Value
Meaning
1001
↓
1111
No Trigger
NOTE
The DBG trigger register (DBGT) can not be changed unless ARM=0.
17.3.3.15 Debug Status Register (DBGS)
Module Base + 0x000E
7
6
5
4
3
2
1
0
AF
BF
CF
0
0
0
0
ARMF
POR
or nonend-run
0
0
0
0
0
0
0
1
Reset
end-run1
U
U
U
0
0
0
0
0
R
W
= Unimplemented or Reserved
Figure 17-16. Debug Status Register (DBGS)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, ARMF gets cleared by reset but AF, BF, and CF do not
change after reset.
Table 17-18. DBGS Field Descriptions
Field
Description
7
AF
Trigger A Match Bit — The AF bit indicates if Trigger A match condition was met since arming.
0 Comparator A did not match
1 Comparator A match
6
BF
Trigger B Match Bit — The BF bit indicates if Trigger B match condition was met since arming.
0 Comparator B did not match
1 Comparator B match
5
CF
Trigger C Match Bit — The CF bit indicates if Trigger C match condition was met since arming.
0 Comparator C did not match
1 Comparator C match
0
ARMF
Arm Flag Bit — The ARMF bit indicates whether the debugger is waiting for trigger or waiting for the FIFO to fill.
While DBGEN = 1, this status bit is a read-only image of the ARM bit in DBGC. See Section 17.4.4.2, “Arming
the DBG Module” for more information.
0 Debugger not armed
1 Debugger armed
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17.3.3.16 Debug Count Status Register (DBGCNT)
Module Base + 0x000F
7
6
5
4
0
0
0
0
POR
or nonend-run
0
0
0
0
0
Reset
end-run1
0
0
0
0
U
R
3
2
1
0
0
0
0
U
U
U
CNT
W
= Unimplemented or Reserved
Figure 17-17. Debug Count Status Register (DBGCNT)
1
In the case of an end-trace to reset where DBGEN=1 and BEGIN=0, the CNT[3:0] bits do not change after reset.
Table 17-19. DBGS Field Descriptions
Field
Description
3–0
CNT
FIFO Valid Count Bits — The CNT bits indicate the amount of valid data stored in the FIFO. Table 17-20 shows
the correlation between the CNT bits and the amount of valid data in FIFO. The CNT will stop after a count to
eight even if more data is being stored in the FIFO. The CNT bits are cleared when the DBG module is armed,
and the count is incremented each time a new word is captured into the FIFO. The host development system is
responsible for checking the value in CNT[3:0] and reading the correct number of words from the FIFO because
the count does not decrement as data is read out of the FIFO at the end of a trace run.
Table 17-20. CNT Bits
CNT Value
Meaning
0000
No data valid
0001
1 word valid
0010
2 words valid
0011
3 words valid
0100
4 words valid
0101
5 words valid
0110
6 words valid
0111
7 words valid
1000
8 words valid
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17.4
Functional Description
This section provides a complete functional description of the on-chip ICE system. The DBG module is
enabled by setting the DBGEN bit in the DBGC register. Enabling the module allows the arming,
triggering and storing of data in the FIFO. The DBG module is made up of three main blocks, the
Comparators, Trigger Break Control logic and the FIFO.
17.4.1
Comparator
The DBG module contains three comparators, A, B, and C. Comparator A compares the core address bus
with the address stored in the DBGCAX, DBGCAH, and DBGCAL registers. Comparator B compares the
core address bus with the address stored in the DBGCBX, DBGCBH, and DBGCBL registers except in
full mode, where it compares the data buses to the data stored in the DBGCBL register. Comparator C
compares the core address bus with the address stored in the DBGCCX, DBGCCH, and DBGCCL
registers. Matches on Comparators A, B, and C are signaled to the Trigger Break Control (TBC) block.
17.4.1.1
RWA and RWAEN in Full Modes
In full modes (“A And B” and “A And Not B”) RWAEN and RWA are used to select read or write
comparisons for both comparators A and B. To select write comparisons and the write data bus in Full
Modes set RWAEN=1 and RWA=0, otherwise read comparisons and the read data bus will be selected.
The RWBEN and RWB bits are not used and will be ignored in Full Modes.
17.4.1.2
Comparator C in LOOP1 Capture Mode
Normally comparator C is used as a third hardware breakpoint and is not involved in the trigger logic for
the on-chip ICE system. In this mode, it compares the core address bus with the address stored in the
DBGCCX, DBGCCH, and DBGCCL registers. However, in LOOP1 capture mode, comparator C is
managed by logic in the DBG module to track the address of the most recent change-of-flow event that
was captured into the FIFO buffer. In LOOP1 capture mode, comparator C is not available for use as a
normal hardware breakpoint.
When the ARM and DBGEN bits are set to one in LOOP1 capture mode, comparator C value registers are
cleared to prevent the previous contents of these registers from interfering with the LOOP1 capture mode
operation. When a COF event is detected, the address of the event is compared to the contents of the
DBGCCX, DBGCCH, and DBGCCL registers to determine whether it is the same as the previous COF
entry in the capture FIFO. If the values match, the capture is inhibited to prevent the FIFO from filling up
with duplicate entries. If the values do not match, the COF event is captured into the FIFO and the
DBGCCX, DBGCCH, and DBGCCL registers are updated to reflect the address of the captured COF
event. When comparator C is updated, the PAGSEL bit (bit-7 of DBGCCX) is updated with the PPACC
value that is captured into the FIFO. This bit indicates whether the COF address was a paged 17-bit
program address using the PPAGE mechanism (PPACC=1) or a 17-bit CPU address that resulted from an
unpaged CPU access.
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17.4.2
Breakpoints
A breakpoint request to the CPU at the end of a trace run can be created if the BRKEN bit in the DBGC
register is set. The value of the BEGIN bit in DBGT register determines when the breakpoint request to
the CPU will occur. If the BEGIN bit is set, begin-trigger is selected and the breakpoint request will not
occur until the FIFO is filled with 8 words. If the BEGIN bit is cleared, end-trigger is selected and the
breakpoint request will occur immediately at the trigger cycle.
When traditional hardware breakpoints from comparators A or B are desired, set BEGIN=0 to select an
end-trace run and set the trigger mode to either 0x0 (A-only) or 0x1 (A OR B) mode.
There are two types of breakpoint requests supported by the DBG module, tag-type and force-type. Tagged
breakpoints are associated with opcode addresses and allow breaking just before a specific instruction
executes. Force breakpoints are not associated with opcode addresses and allow breaking at the next
instruction boundary. The TAG bit in the DBGC register determines whether CPU breakpoint requests will
be a tag-type or force-type breakpoints. When TAG=0, a force-type breakpoint is requested and it will take
effect at the next instruction boundary after the request. When TAG=1, a tag-type breakpoint is registered
into the instruction queue and the CPU will break if/when this tag reaches the head of the instruction queue
and the tagged instruction is about to be executed.
17.4.2.1
Hardware Breakpoints
Comparators A, B, and C can be used as three traditional hardware breakpoints whether the on-chip ICE
real-time capture function is required or not. To use any breakpoint or trace run capture functions set
DBGEN=1. BRKEN and TAG affect all three comparators. When BRKEN=0, no CPU breakpoints are
enabled. When BRKEN=1, CPU breakpoints are enabled and the TAG bit determines whether the
breakpoints will be tag-type or force-type breakpoints. To use comparators A and B as hardware
breakpoints, set DBGT=0x81 for tag-type breakpoints and 0x01 for force-type breakpoints. This sets up
an end-type trace with trigger mode “A OR B”.
Comparator C is not involved in the trigger logic for the on-chip ICE system.
17.4.3
Trigger Selection
The TRGSEL bit in the DBGT register is used to determine the triggering condition of the on-chip ICE
system. TRGSEL applies to both trigger A and B except in the event only trigger modes. By setting the
TRGSEL bit, the comparators will qualify a match with the output of opcode tracking logic. The opcode
tracking logic is internal to each comparator and determines whether the CPU executed the opcode at the
compare address. With the TRGSEL bit cleared a comparator match is all that is necessary for a trigger
condition to be met.
NOTE
If the TRGSEL is set, the address stored in the comparator match address
registers must be an opcode address for the trigger to occur.
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17.4.4
Trigger Break Control (TBC)
The TBC is the main controller for the DBG module. Its function is to decide whether data should be stored
in the FIFO based on the trigger mode and the match signals from the comparator. The TBC also
determines whether a request to break the CPU should occur.
The TAG bit in DBGC controls whether CPU breakpoints are treated as tag-type or force-type breakpoints.
The TRGSEL bit in DBGT controls whether a comparator A or B match is further qualified by opcode
tracking logic. Each comparator has a separate circuit to track opcodes because the comparators could
correspond to separate instructions that could be propagating through the instruction queue at the same
time.
In end-type trace runs (BEGIN=0), when the comparator registers match, including the optional R/W
match, this signal goes to the CPU break logic where BRKEN determines whether a CPU break is
requested and the TAG control bit determines whether the CPU break will be a tag-type or force-type
breakpoint. When TRGSEL is set, the R/W qualified comparator match signal also passes through the
opcode tracking logic. If/when it propagates through this logic, it will cause a trigger to the ICE logic to
begin or end capturing information into the FIFO. In the case of an end-type (BEGIN=0) trace run, the
qualified comparator signal stops the FIFO from capturing any more information.
If a CPU breakpoint is also enabled, you would want TAG and TRGSEL to agree so that the CPU break
occurs at the same place in the application program as the FIFO stopped capturing information. If
TRGSEL was 0 and TAG was 1 in an end-type trace run, the FIFO would stop capturing as soon as the
comparator address matched, but the CPU would continue running until a TAG signal could propagate
through the CPUs instruction queue which could take a long time in the case where changes of flow caused
the instruction queue to be flushed. If TRGSEL was one and TAG was zero in an end-type trace run, the
CPU would break before the comparator match signal could propagate through the opcode tracking logic
to end the trace run.
In begin-type trace runs (BEGIN=1), the start of FIFO capturing is triggered by the qualified comparator
signals, and the CPU breakpoint (if enabled by BRKEN=1) is triggered when the FIFO becomes full. Since
this FIFO full condition does not correspond to the execution of a tagged instruction, it would not make
sense to use TAG=1 for a begin-type trace run.
17.4.4.1
Begin- and End-Trigger
The definition of begin- and end-trigger as used in the DBG module are as follows:
• Begin-trigger: Storage in FIFO occurs after the trigger and continues until 8 locations are filled.
• End-trigger: Storage in FIFO occurs until the trigger with the least recent data falling out of the
FIFO if more than 8 words are collected.
17.4.4.2
Arming the DBG Module
Arming occurs by enabling the DBG module by setting the DBGEN bit and by setting the ARM bit in the
DBGC register. The ARM bit in the DBGC register and the ARMF bit in the DBGS register are cleared
when the trigger condition is met in end-trigger mode or when the FIFO is filled in begin-trigger mode. In
the case of an end-trace where DBGEN=1 and BEGIN=0, ARM and ARMF are cleared by any reset to
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end the trace run that was in progress. The ARMF bit is also cleared if ARM is written to zero or when the
DBGEN bit is low. The TBC logic determines whether a trigger condition has been met based on the
trigger mode and the trigger selection.
17.4.4.3
Trigger Modes
The on-chip ICE system supports nine trigger modes. The trigger modes are encoded as shown in
Table 17-17. The trigger mode is used as a qualifier for either starting or ending the storing of data in the
FIFO. When the match condition is met, the appropriate flag AF or BF is set in DBGS register. Arming
the DBG module clears the AF, BF, and CF flags in the DBGS register. In all trigger modes except for the
event only modes change of flow addresses are stored in the FIFO. In the event only modes only the value
on the data bus at the trigger event B comparator match address will be stored.
17.4.4.3.1
A Only
In the A Only trigger mode, if the match condition for A is met, the AF flag in the DBGS register is set.
17.4.4.3.2
A Or B
In the A Or B trigger mode, if the match condition for A or B is met, the corresponding flag(s) in the DBGS
register are set.
17.4.4.3.3
A Then B
In the A Then B trigger mode, the match condition for A must be met before the match condition for B is
compared. When the match condition for A or B is met, the corresponding flag in the DBGS register is set.
17.4.4.3.4
Event Only B
In the Event Only B trigger mode, if the match condition for B is met, the BF flag in the DBGS register is
set. The Event Only B trigger mode is considered a begin-trigger type and the BEGIN bit in the DBGT
register is ignored.
17.4.4.3.5
A Then Event Only B
In the A Then Event Only B trigger mode, the match condition for A must be met before the match
condition for B is compared. When the match condition for A or B is met, the corresponding flag in the
DBGS register is set. The A Then Event Only B trigger mode is considered a begin-trigger type and the
BEGIN bit in the DBGT register is ignored.
17.4.4.3.6
A And B (Full Mode)
In the A And B trigger mode, Comparator A compares to the address bus and Comparator B compares to
the data bus. In the A and B trigger mode, if the match condition for A and B happen on the same bus cycle,
both the AF and BF flags in the DBGS register are set. If a match condition on only A or only B happens,
no flags are set.
For Breakpoint tagging operation with an end-trigger type trace, only matches from Comparator A will be
used to determine if the Breakpoint conditions are met and Comparator B matches will be ignored.
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17.4.4.3.7
A And Not B (Full Mode)
In the A And Not B trigger mode, comparator A compares to the address bus and comparator B compares
to the data bus. In the A And Not B trigger mode, if the match condition for A and Not B happen on the
same bus cycle, both the AF and BF flags in the DBGS register are set. If a match condition on only A or
only Not B occur no flags are set.
For Breakpoint tagging operation with an end-trigger type trace, only matches from Comparator A will be
used to determine if the Breakpoint conditions are met and Comparator B matches will be ignored.
17.4.4.3.8
Inside Range, A ≤ address ≤ B
In the Inside Range trigger mode, if the match condition for A and B happen on the same bus cycle, both
the AF and BF flags in the DBGS register are set. If a match condition on only A or only B occur no flags
are set.
17.4.4.3.9
Outside Range, address < A or address > B
In the Outside Range trigger mode, if the match condition for A or B is met, the corresponding flag in the
DBGS register is set.
The four control bits BEGIN and TRGSEL in DBGT, and BRKEN and TAG in DBGC, determine the basic
type of debug run as shown in Table 1.21. Some of the 16 possible combinations are not used (refer to the
notes at the end of the table).
Table 17-21. Basic Types of Debug Runs
BEGIN
TRGSEL
BRKEN
TAG
Type of Debug Run
(1)
Fill FIFO until trigger address (No CPU breakpoint - keep
running)
0
0
0
x
0
0
1
0
Fill FIFO until trigger address, then force CPU breakpoint
0
0
1
1
Do not use(2)
0
1
0
0
1
1
0
0
1
1
1
Fill FIFO until trigger opcode about to execute (trigger causes
CPU breakpoint)
1
0
0
(1)
Start FIFO at trigger address (No CPU breakpoint - keep
running)
1
0
1
0
Start FIFO at trigger address, force CPU breakpoint when
FIFO full
1
0
1
1
1
1
0
1
1
1
1
(1)
x
x
Fill FIFO until trigger opcode about to execute (No CPU
breakpoint - keep running)
Do not use(3)
Do not use(4)
(1)
Start FIFO at trigger opcode (No CPU breakpoint - keep
running)
1
0
Start FIFO at trigger opcode, force CPU breakpoint when FIFO
full
1
1
x
Do not use(4)
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1
When BRKEN = 0, TAG is do not care (x in the table).
2
In end trace configurations (BEGIN = 0) where a CPU breakpoint is enabled (BRKEN = 1), TRGSEL should agree with TAG. In this case, where
TRGSEL = 0 to select no opcode tracking qualification and TAG = 1 to specify a tag-type CPU breakpoint, the CPU breakpoint would not take
effect until sometime after the FIFO stopped storing values. Depending on program loops or interrupts, the delay could be very long.
3
In end trace configurations (BEGIN = 0) where a CPU breakpoint is enabled (BRKEN = 1), TRGSEL should agree with TAG. In this case, where
TRGSEL = 1 to select opcode tracking qualification and TAG = 0 to specify a force-type CPU breakpoint, the CPU breakpoint would erroneously
take effect before the FIFO stopped storing values and the debug run would not complete normally.
4 In begin trace configurations (BEGIN = 1) where a CPU breakpoint is enabled (BRKEN = 1), TAG should not be set to 1. In begin trace debug
runs, the CPU breakpoint corresponds to the FIFO full condition which does not correspond to a taggable instruction fetch.
17.4.5
FIFO
The FIFO is an eight word deep FIFO. In all trigger modes except for event only, the data stored in the
FIFO will be change of flow addresses. In the event only trigger modes only the data bus value
corresponding to the event is stored. In event only trigger modes, the high byte of the valid data from the
FIFO will always read a 0x00 and the extended information byte in DBGFX will always read 0x00.
17.4.5.1
Storing Data in FIFO
In all trigger modes except for the event only modes, the address stored in the FIFO will be determined by
the change of flow indicators from the core. The signal core_cof[1] indicates the current core address is
the destination address of an indirect JSR or JMP instruction, or a RTS, RTC, or RTI instruction or interrupt
vector and the destination address should be stored. The signal core_cof[0] indicates that a conditional
branch was taken and that the source address of the conditional branch should be stored.
17.4.5.2
Storing with Begin-Trigger
Storing with Begin-Trigger can be used in all trigger modes. Once the DBG module is enabled and armed
in the begin-trigger mode, data is not stored in the FIFO until the trigger condition is met. Once the trigger
condition is met the DBG module will remain armed until 8 words are stored in the FIFO. If the
core_cof[1] signal becomes asserted, the current address is stored in the FIFO. If the core_cof[0] signal
becomes asserted, the address registered during the previous last cycle is decremented by two and stored
in the FIFO.
17.4.5.3
Storing with End-Trigger
Storing with End-Trigger cannot be used in event-only trigger modes. Once the DBG module is enabled
and armed in the end-trigger mode, data is stored in the FIFO until the trigger condition is met. If the
core_cof[1] signal becomes asserted, the current address is stored in the FIFO. If the core_cof[0] signal
becomes asserted, the address registered during the previous last cycle is decremented by two and stored
in the FIFO. When the trigger condition is met, the ARM and ARMF will be cleared and no more data will
be stored. In non-event only end-trigger modes, if the trigger is at a change of flow address the trigger event
will be stored in the FIFO.
17.4.5.4
Reading Data from FIFO
The data stored in the FIFO can be read using BDM commands provided the DBG module is enabled and
not armed (DBGEN=1 and ARM=0). The FIFO data is read out first-in-first-out. By reading the CNT bits
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in the DBGCNT register at the end of a trace run, the number of valid words can be determined. The FIFO
data is read by optionally reading the DBGFX and DBGFH registers followed by the DBGFL register.
Each time the DBGFL register is read the FIFO is shifted to allow reading of the next word however the
count does not decrement. In event-only trigger modes where the FIFO will contain only the data bus
values stored, to read the FIFO only DBGFL needs to be accessed.
The FIFO is normally only read while ARM and ARMF=0, however reading the FIFO while the DBG
module is armed will return the data value in the oldest location of the FIFO and the TBC will not allow
the FIFO to shift. This action could cause a valid entry to be lost because the unexpected read blocked the
FIFO advance.
If the DBG module is not armed and the DBGFL register is read, the TBC will store the current opcode
address. Through periodic reads of the DBGFX, DBGFH, and DBGFL registers while the DBG module
is not armed, host software can provide a histogram of program execution. This is called profile mode.
Since the full 17-bit address and the signal that indicates whether an address is in paged extended memory
are captured on each FIFO store, profile mode works correctly over the entire extended memory map.
17.4.6
Interrupt Priority
When TRGSEL is set and the DBG module is armed to trigger on begin- or end-trigger types, a trigger is
not detected in the condition where a pending interrupt occurs at the same time that a target address reaches
the top of the instruction pipe. In these conditions, the pending interrupt has higher priority and code
execution switches to the interrupt service routine.
When TRGSEL is clear and the DBG module is armed to trigger on end-trigger types, the trigger event is
detected on a program fetch of the target address, even when an interrupt becomes pending on the same
cycle. In these conditions, the pending interrupt has higher priority, the exception is processed by the core
and the interrupt vector is fetched. Code execution is halted before the first instruction of the interrupt
service routine is executed. In this scenario, the DBG module will have cleared ARM without having
recorded the change-of-flow that occurred as part of the interrupt exception. Note that the stack will hold
the return addresses and can be used to reconstruct execution flow in this scenario.
When TRGSEL is clear and the DBG module is armed to trigger on begin-trigger types, the trigger event
is detected on a program fetch of the target address, even when an interrupt becomes pending on the same
cycle. In this scenario, the FIFO captures the change of flow event. Because the system is configured for
begin-trigger, the DBG remains armed and does not break until the FIFO has been filled by subsequent
change of flow events.
17.5
Resets
The DBG module cannot cause an MCU reset.
There are two different ways this module will respond to reset depending upon the conditions before the
reset event. If the DBG module was setup for an end trace run with DBGEN=1 and BEGIN=0, ARM,
ARMF, and BRKEN are cleared but the reset function on most DBG control and status bits is overridden
so a host development system can read out the results of the trace run after the MCU has been reset. In all
other cases including POR, the DBG module controls are initialized to start a begin trace run starting from
when the reset vector is fetched. The conditions for the default begin trace run are:
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•
•
•
17.6
DBGCAX=0x00, DBGCAH=0xFF, DBGCAL=0xFE so comparator A is set to match when the
16-bit CPU address 0xFFFE appears during the reset vector fetch
DBGC=0xC0 to enable and arm the DBG module
DBGT=0x40 to select a force-type trigger, a BEGIN trigger, and A-only trigger mode
Interrupts
The DBG contains no interrupt source.
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