MC9S08FL16 Reference Manual

MC9S08FL16
MC9S08FL8
Reference Manual
HCS08
Microcontrollers
Related Documentation:
• MC9S08FL16 (Data Sheet)
Contains pin assignments and diagrams, all electrical
specifications, and mechanical drawing outlines.
Find the most current versions of all documents at:
http://www.freescale.com
MC9S08FL16RM
Rev. 3
11/2010
freescale.com
MC9S08FL16 Features
8-Bit S08 Central Processor Unit (CPU)
•
•
•
Up to 20 MHz CPU at 4.5 V to 5.5 V across
temperature range –40 C to 85 C
HC08 instruction set with added BGND
instruction
Support for up to 32 interrupt/reset sources
On-Chip Memory
•
•
•
Up to 16 KB flash read/program/erase over
full operating voltage and temperature
Up to 1024-byte random-access memory
(RAM)
Security circuitry to prevent unauthorized
access to RAM and flash contents
•
•
•
Development Support
•
•
•
•
•
Two low power stop modes; reduced power
wait mode
Allowing clocks to remain enabled to
specific peripherals in stop3 mode
Clock Source Options
•
•
Oscillator (XOSC) — Loop-control Pierce
oscillator; crystal or ceramic resonator
range of 31.25 kHz to 39.0625 kHz or
1 MHz to 16 MHz
Internal Clock Source (ICS) — Internal
clock source module containing a
frequency-locked-loop (FLL) controlled by
internal or external reference; precision
trimming of internal reference allows 0.2%
resolution and 2% deviation over
temperature and voltage; supports bus
frequencies up to 10 MHz
•
•
•
•
Watchdog computer operating properly
(COP) reset with option to run from
dedicated 1 kHz internal clock source or
bus clock
Low-voltage detection with reset or
interrupt; selectable trip points
IPC — Interrupt priority controller to
provide hardware based nested interrupt
ADC — 12-channel, 8-bit resolution;
2.5 s conversion time; automatic compare
function; 1.7 mV/C temperature sensor;
internal bandgap reference channel;
operation in stop; optional hardware
trigger; fully functional from 4.5V to 5.5 V
TPM — One 4-channel and one 2-channel
timer/pulse-width modulators (TPM)
modules; selectable input capture, output
compare, or buffered edge- or
center-aligned PWM on each channel
MTIM16 — One 16-bit modulo timer with
optional prescaler
SCI — One serial communications
interface module with optional 13-bit
break; LIN extensions
Input/Output
•
System Protection
•
Single-wire background debug interface
Breakpoint capability to allow single
breakpoint setting during in-circuit
debugging (plus two more breakpoints)
On-chip in-circuit emulator (ICE) debug
module containing two comparators and
nine trigger modes
Peripherals
Power-Saving Modes
•
Illegal opcode detection with reset
Illegal address detection with reset
Flash block protection
30 GPIOs including one input-only pin and
one output-only pin
Package Options
•
•
32-pin LQFP
32-pin SDIP
MC9S08FL16 MCU Series Reference Manual
Covers:
MC9S08FL16
MC9S08FL8
MC9S08FL16
Rev. 3
11/2010
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.
Revision
Number
Revision
Date
1
3/20/2009
Initial public release.
2
4/27/2009
Reworded Chapter 9, “16-Bit Timer/PWM (S08TPMV3).”
Corrected Table 2-1.
3
11/23/2010
Updated Table 5-12.
Description of Changes
This product incorporates SuperFlash technology licensed from SST.
Freescale and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
 Freescale Semiconductor, Inc., 2009. All rights reserved.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
6
Freescale Semiconductor
List of Chapters
Chapter 1 Device Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 2 Pins and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Chapter 4 Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Chapter 5 Resets, Interrupts, and System Configuration . . . . . . . . . . . . . . . 57
Chapter 6 Parallel Input/Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Chapter 7 Central Processor Unit (S08CPUV3) . . . . . . . . . . . . . . . . . . . . . . . 85
Chapter 8 Internal Clock Source (S08ICSV3) . . . . . . . . . . . . . . . . . . . . . . . . 105
Chapter 9 16-Bit Timer/PWM (S08TPMV3). . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Chapter 10 Interrupt Priority Controller (S08IPCV1) . . . . . . . . . . . . . . . . . . 143
Chapter 11 16-Bit Modulo Timer (S08MTIM16V1) . . . . . . . . . . . . . . . . . . . . . 155
Chapter 12 Analog-to-Digital Converter (S08ADC12V1) . . . . . . . . . . . . . . . 167
Chapter 13 Serial Communications Interface (S08SCIV4) . . . . . . . . . . . . . . 195
Chapter 14 Development Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
MC9S08FL16 MCU Series Reference Manual, Rev. 3
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Contents
Section Number
Title
Page
Chapter 1
Device Overview
1.1
1.2
1.3
Introduction .....................................................................................................................................17
MCU Block Diagram ......................................................................................................................18
System Clock Distribution ..............................................................................................................19
Chapter 2
Pins and Connections
2.1
2.2
2.3
Introduction .....................................................................................................................................21
Device Pin Assignment ...................................................................................................................21
Recommended System Connections ...............................................................................................22
2.3.1 Power (VDD, VSS) .............................................................................................................23
2.3.2 Oscillator (XTAL, EXTAL) ..............................................................................................24
2.3.3 RESET and External Interrupt Pin (IRQ) .........................................................................24
2.3.4 Background/Mode Select (BKGD/MS) ............................................................................25
2.3.5 General-Purpose I/O and Peripheral Ports ........................................................................25
Chapter 3
Modes of Operation
3.1
3.2
3.3
3.4
3.5
3.6
Introduction .....................................................................................................................................29
Features ...........................................................................................................................................29
Run Mode ........................................................................................................................................29
Active Background Mode ...............................................................................................................29
Wait Mode .......................................................................................................................................30
Stop Modes ......................................................................................................................................31
3.6.1 Stop3 Mode .......................................................................................................................31
3.6.2 Stop2 Mode .......................................................................................................................32
3.6.3 On-Chip Peripheral Modules in Stop Modes ....................................................................32
Chapter 4
Memory
4.1
4.2
4.3
4.4
MC9S08FL16 Series Memory Map ................................................................................................35
4.1.1 Reset and Interrupt Vector Assignments ...........................................................................37
Register Addresses and Bit Assignments ........................................................................................37
RAM (System RAM) ......................................................................................................................42
Flash ................................................................................................................................................43
4.4.1 Features .............................................................................................................................43
4.4.2 Program and Erase Times .................................................................................................43
4.4.3 Program and Erase Command Execution .........................................................................44
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4.5
4.6
4.4.4 Burst Program Execution ..................................................................................................45
4.4.5 Access Errors ....................................................................................................................47
4.4.6 Flash Block Protection ......................................................................................................47
4.4.7 Vector Redirection ............................................................................................................48
Security ............................................................................................................................................48
Flash Registers and Control Bits .....................................................................................................49
4.6.1 Flash Clock Divider Register (FCDIV) ............................................................................50
4.6.2 Flash Options Register (FOPT and NVOPT) ....................................................................51
4.6.3 Flash Configuration Register (FCNFG) ...........................................................................52
4.6.4 Flash Protection Register (FPROT and NVPROT) ..........................................................53
4.6.5 Flash Status Register (FSTAT) ..........................................................................................53
4.6.6 Flash Command Register (FCMD) ...................................................................................55
Chapter 5
Resets, Interrupts, and System Configuration
5.1
5.2
5.3
5.4
5.5
5.6
5.7
Introduction .....................................................................................................................................57
Features ...........................................................................................................................................57
MCU Reset ......................................................................................................................................57
Computer Operating Properly (COP) Watchdog .............................................................................58
Interrupts .........................................................................................................................................59
5.5.1 Interrupt Stack Frame .......................................................................................................59
5.5.2 External Interrupt Request (IRQ) Pin ...............................................................................60
5.5.3 Interrupt Vectors, Sources, and Local Masks ...................................................................61
Low-Voltage Detect (LVD) System ................................................................................................62
5.6.1 Power-On Reset Operation ...............................................................................................63
5.6.2 LVD Reset Operation ........................................................................................................63
5.6.3 Low-Voltage Warning (LVW) Interrupt Operation ...........................................................63
Reset, Interrupt, and System Control Registers and Control Bits ...................................................63
5.7.1 Interrupt Pin Request Status and Control Register (IRQSC) ............................................63
5.7.2 System Reset Status Register (SRS) .................................................................................65
5.7.3 System Background Debug Force Reset Register (SBDFR) ............................................66
5.7.4 System Options Register 1 (SOPT1) ................................................................................66
5.7.5 System Options Register 2 (SOPT2) ................................................................................68
5.7.6 System Device Identification Register (SDIDH, SDIDL) ................................................69
5.7.7 System Power Management Status and Control 1 Register (SPMSC1) ...........................70
5.7.8 System Power Management Status and Control 2 Register (SPMSC2) ...........................71
Chapter 6
Parallel Input/Output
6.1
6.2
6.3
Introduction .....................................................................................................................................73
Port Data and Data Direction ..........................................................................................................73
Pin Control ......................................................................................................................................74
6.3.1 Internal Pullup Enable ......................................................................................................75
6.3.2 Output Slew Rate Control Enable .....................................................................................75
6.3.3 Output Drive Strength Select ............................................................................................75
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6.4
6.5
Pin Behavior in Stop Modes ............................................................................................................76
Parallel I/O and Pin Control Registers ............................................................................................76
6.5.1 Port A I/O Registers (PTAD and PTADD) ........................................................................76
6.5.2 Port A Pin Control Registers (PTAPE, PTASE, PTADS) .................................................77
6.5.3 Port B I/O Registers (PTBD and PTBDD) ........................................................................78
6.5.4 Port B Pin Control Registers (PTBPE, PTBSE, PTBDS) .................................................79
6.5.5 Port C I/O Registers (PTCD and PTCDD) ........................................................................80
6.5.6 Port C Pin Control Registers (PTCPE, PTCSE, PTCDS) .................................................81
6.5.7 Port D I/O Registers (PTDD and PTDDD) .......................................................................82
6.5.8 Port D Pin Control Registers (PTDPE, PTDSE, PTDDS) ................................................83
Chapter 7
Central Processor Unit (S08CPUV3)
7.1
7.2
7.3
7.4
7.5
Introduction .....................................................................................................................................85
7.1.1 Features .............................................................................................................................85
Programmer’s Model and CPU Registers .......................................................................................86
7.2.1 Accumulator (A) ...............................................................................................................86
7.2.2 Index Register (H:X) ........................................................................................................86
7.2.3 Stack Pointer (SP) .............................................................................................................87
7.2.4 Program Counter (PC) ......................................................................................................87
7.2.5 Condition Code Register (CCR) .......................................................................................87
Addressing Modes ...........................................................................................................................89
7.3.1 Inherent Addressing Mode (INH) .....................................................................................89
7.3.2 Relative Addressing Mode (REL) ....................................................................................89
7.3.3 Immediate Addressing Mode (IMM) ................................................................................89
7.3.4 Direct Addressing Mode (DIR) ........................................................................................89
7.3.5 Extended Addressing Mode (EXT) ..................................................................................90
7.3.6 Indexed Addressing Mode ................................................................................................90
Special Operations ...........................................................................................................................91
7.4.1 Reset Sequence .................................................................................................................91
7.4.2 Interrupt Sequence ............................................................................................................91
7.4.3 Wait Mode Operation ........................................................................................................92
7.4.4 Stop Mode Operation ........................................................................................................92
7.4.5 BGND Instruction .............................................................................................................93
HCS08 Instruction Set Summary ....................................................................................................94
Chapter 8
Internal Clock Source (S08ICSV3)
8.1
8.2
8.3
Introduction ...................................................................................................................................105
8.1.1 Features ...........................................................................................................................107
8.1.2 Block Diagram ................................................................................................................107
8.1.3 Modes of Operation ........................................................................................................108
External Signal Description ..........................................................................................................109
Register Definition ........................................................................................................................109
8.3.1 ICS Control Register 1 (ICSC1) .....................................................................................110
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8.4
8.3.2 ICS Control Register 2 (ICSC2) ..................................................................................... 111
8.3.3 ICS Trim Register (ICSTRM) .........................................................................................112
8.3.4 ICS Status and Control (ICSSC) .....................................................................................112
Functional Description ..................................................................................................................114
8.4.1 Operational Modes ..........................................................................................................114
8.4.2 Mode Switching ..............................................................................................................116
8.4.3 Bus Frequency Divider ...................................................................................................117
8.4.4 Low Power Bit Usage .....................................................................................................117
8.4.5 DCO Maximum Frequency with 32.768 kHz Oscillator ................................................117
8.4.6 Internal Reference Clock ................................................................................................117
8.4.7 External Reference Clock ...............................................................................................118
8.4.8 Fixed Frequency Clock ...................................................................................................118
8.4.9 Local Clock .....................................................................................................................118
Chapter 9
16-Bit Timer/PWM (S08TPMV3)
9.1
9.2
9.3
9.4
9.5
9.6
Introduction ...................................................................................................................................119
9.1.1 TPMV3 Differences from Previous Versions .................................................................120
9.1.2 Migrating from TPMV1 ..................................................................................................122
9.1.3 Features ...........................................................................................................................124
9.1.4 Modes of Operation ........................................................................................................124
9.1.5 Block Diagram ................................................................................................................125
Signal Description .........................................................................................................................127
9.2.1 Detailed Signal Descriptions ..........................................................................................127
Register Definition ........................................................................................................................130
9.3.1 TPM Status and Control Register (TPMxSC) ................................................................130
9.3.2 TPM-Counter Registers (TPMxCNTH:TPMxCNTL) ....................................................131
9.3.3 TPM Counter Modulo Registers (TPMxMODH:TPMxMODL) ....................................132
9.3.4 TPM Channel n Status and Control Register (TPMxCnSC) ..........................................133
9.3.5 TPM Channel Value Registers (TPMxCnVH:TPMxCnVL) ..........................................134
Functional Description ..................................................................................................................136
9.4.1 Counter ............................................................................................................................136
9.4.2 Channel Mode Selection .................................................................................................137
Reset Overview .............................................................................................................................140
9.5.1 General ............................................................................................................................140
9.5.2 Description of Reset Operation .......................................................................................141
Interrupts .......................................................................................................................................141
9.6.1 General ............................................................................................................................141
9.6.2 Description of Interrupt Operation .................................................................................141
Chapter 10
Interrupt Priority Controller (S08IPCV1)
10.1 Introduction ...................................................................................................................................143
10.1.1 Features ...........................................................................................................................145
10.1.2 Modes of Operation .......................................................................................................145
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10.2
10.3
10.4
10.5
10.6
10.1.3 Block Diagram ................................................................................................................145
External Signal Description ..........................................................................................................146
10.2.1 INTIN[47:0] — Interrupt Source Interrupt Request Input .............................................147
10.2.2 VFETCH — Vector Fetch Indicator from HCS08 CPU .................................................147
10.2.3 IADB[5:0] — Address Bus Input from HCS08 CPU .....................................................147
10.2.4 INTOUT[47:0] — Interrupt Request to HCS08 CPU ....................................................147
Register Definition ........................................................................................................................147
10.3.1 IPC Status and Control Register (IPCSC) ......................................................................147
10.3.2 Interrupt Priority Mask Pseudo Stack Register (IPMPS) ...............................................148
10.3.3 Interrupt Level Setting Registers (ILRS0–ILRS11) .......................................................149
Functional Description ..................................................................................................................150
10.4.1 Interrupt Priority Level Register ....................................................................................150
10.4.2 Interrupt Priority Level Comparator Set .........................................................................150
10.4.3 Interrupt Priority Mask Update and Restore Mechanism ...............................................150
10.4.4 The Integration and Application of the IPC ....................................................................151
Application Examples ...................................................................................................................152
Initialization/Application Information ..........................................................................................153
Chapter 11
16-Bit Modulo Timer (S08MTIM16V1)
11.1 Introduction ...................................................................................................................................155
11.2 Features .........................................................................................................................................157
11.2.1 Block Diagram ................................................................................................................157
11.2.2 Modes of Operation ........................................................................................................157
11.3 External Signal Description ..........................................................................................................158
11.3.1 TCLK — External Clock Source Input into MTIM16 ...................................................158
11.4 Register Definition ........................................................................................................................158
11.4.1 MTIM16 Status and Control Register (MTIMSC) .........................................................159
11.4.2 MTIM16 Clock Configuration Register (MTIMCLK) ...................................................160
11.4.3 MTIM16 Counter Register High/Low (MTIMCNTH:L) ...............................................161
11.4.4 MTIM16 Modulo Register High/Low (MTIMMODH/MTIMMODL) ..........................162
11.5 Functional Description ..................................................................................................................163
11.5.1 MTIM16 Operation Example .........................................................................................164
Chapter 12
Analog-to-Digital Converter (S08ADC12V1)
12.1 Introduction ...................................................................................................................................167
12.1.1 ADC Channel Assignments ............................................................................................167
12.1.2 Alternate Clock ...............................................................................................................168
12.1.3 Hardware Trigger ............................................................................................................168
12.1.4 Features ...........................................................................................................................170
12.1.5 ADC Module Block Diagram .........................................................................................170
12.2 External Signal Description ..........................................................................................................171
12.2.1 Analog Power (VDDA) ....................................................................................................172
12.2.2 Analog Ground (VSSA) ...................................................................................................172
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12.3
12.4
12.5
12.6
12.2.3 Voltage Reference High (VREFH) ...................................................................................172
12.2.4 Voltage Reference Low (VREFL) ....................................................................................172
12.2.5 Analog Channel Inputs (ADx) ........................................................................................172
Register Definition ........................................................................................................................172
12.3.1 Status and Control Register 1 (ADCSC1) ......................................................................172
12.3.2 Status and Control Register 2 (ADCSC2) ......................................................................174
12.3.3 Data Result High Register (ADCRH) .............................................................................175
12.3.4 Data Result Low Register (ADCRL) ..............................................................................175
12.3.5 Compare Value High Register (ADCCVH) ....................................................................176
12.3.6 Compare Value Low Register (ADCCVL) .....................................................................176
12.3.7 Configuration Register (ADCCFG) ................................................................................176
12.3.8 Pin Control 1 Register (APCTL1) ..................................................................................178
12.3.9 Pin Control 2 Register (APCTL2) ..................................................................................179
12.3.10Pin Control 3 Register (APCTL3) ..................................................................................180
Functional Description ..................................................................................................................181
12.4.1 Clock Select and Divide Control ....................................................................................181
12.4.2 Input Select and Pin Control ...........................................................................................182
12.4.3 Hardware Trigger ............................................................................................................182
12.4.4 Conversion Control .........................................................................................................182
12.4.5 Automatic Compare Function .........................................................................................185
12.4.6 MCU Wait Mode Operation ............................................................................................186
12.4.7 MCU Stop3 Mode Operation ..........................................................................................186
12.4.8 MCU Stop2 Mode Operation ..........................................................................................187
Initialization Information ..............................................................................................................187
12.5.1 ADC Module Initialization Example .............................................................................187
Application Information ................................................................................................................189
12.6.1 External Pins and Routing ..............................................................................................189
12.6.2 Sources of Error ..............................................................................................................191
Chapter 13
Serial Communications Interface (S08SCIV4)
13.1 Introduction ...................................................................................................................................195
13.1.1 Features ...........................................................................................................................197
13.1.2 Modes of Operation ........................................................................................................197
13.1.3 Block Diagram ................................................................................................................197
13.2 Register Definition ........................................................................................................................200
13.2.1 SCI Baud Rate Registers (SCIBDH, SCIBDL) ..............................................................200
13.2.2 SCI Control Register 1 (SCIC1) .....................................................................................201
13.2.3 SCI Control Register 2 (SCIC2) .....................................................................................202
13.2.4 SCI Status Register 1 (SCIS1) ........................................................................................203
13.2.5 SCI Status Register 2 (SCIS2) ........................................................................................205
13.2.6 SCI Control Register 3 (SCIC3) .....................................................................................206
13.2.7 SCI Data Register (SCID) ...............................................................................................207
13.3 Functional Description ..................................................................................................................207
13.3.1 Baud Rate Generation .....................................................................................................207
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13.3.2
13.3.3
13.3.4
13.3.5
Transmitter Functional Description ................................................................................208
Receiver Functional Description ....................................................................................209
Interrupts and Status Flags ..............................................................................................211
Additional SCI Functions ...............................................................................................212
Chapter 14
Development Support
14.1 Introduction ...................................................................................................................................215
14.1.1 Features ...........................................................................................................................216
14.2 Background Debug Controller (BDC) ..........................................................................................216
14.2.1 BKGD Pin Description ...................................................................................................217
14.2.2 Communication Details ..................................................................................................218
14.2.3 BDC Commands .............................................................................................................221
14.2.4 BDC Hardware Breakpoint .............................................................................................224
14.3 On-Chip Debug System (DBG) ....................................................................................................225
14.3.1 Comparators A and B .....................................................................................................225
14.3.2 Bus Capture Information and FIFO Operation ...............................................................225
14.3.3 Change-of-Flow Information ..........................................................................................226
14.3.4 Tag vs. Force Breakpoints and Triggers .........................................................................226
14.3.5 Trigger Modes .................................................................................................................227
14.3.6 Hardware Breakpoints ....................................................................................................229
14.4 Register Definition ........................................................................................................................229
14.4.1 BDC Registers and Control Bits .....................................................................................229
14.4.2 System Background Debug Force Reset Register (SBDFR) ..........................................231
14.4.3 DBG Registers and Control Bits .....................................................................................232
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Chapter 1
Device Overview
1.1
Introduction
MC9S08FL16 series MCUs 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 and package types.
Table 1-1 summarizes the peripheral availability per package type for the devices available in the
MC9S08FL16 series.
Table 1-1. Devices in the MC9S08FL16 Series
Device
Feature
MC9S08FL16
Package
MC9S08FL8
32-pin
Flash
16,384 bytes
8,192 bytes
RAM
1,024 bytes
768 bytes
IRQ
yes
IPC
yes
TPM1
4-ch 16-bit
TPM2
2-ch 16-bit
MTIM16
16-bit
ADC
12-ch 8-bit
SCI
yes
I/O pins
30
Package types
32-pin LQFP
32-pin SDIP
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Chapter 1 Device Overview
1.2
MCU Block Diagram
The block diagram in Figure 1-1 shows the structure of the MC9S08FL16 series MCUs.
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
INTERRUPT PRIORITY
CONTROLLER (IPC)
LVD
PTB0/RxD/ADP4
PTB1/TxD/ADP5
ON-CHIP ICE AND
DEBUG MODUE (DBG)
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 1-1. MC9S08FL16 Block Diagram
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Chapter 1 Device Overview
Table 1-2 lists the functional versions of the on-chip modules.
Table 1-2. Versions of On-Chip Modules
Module
1.3
Version
Analog-to-Digital Converter
(ADC)
1
Central Processing Unit
(CPU)
3
Debug Module
(DBG)
2
Interrupt Priority Controller
(IPC)
1
Internal Clock Source
(ICS)
3
16-Bit Modulo Timer
(MTIM16)
1
Serial Communications Interface
(SCI)
4
Timer and Pulse-Width Modulator
(TPM)
3
System Clock Distribution
MC9S08FL16 series use ICS module as clock sources. The ICS module can use internal or external clock
source as reference to provide up to 20 MHz CPU clock. The output of ICS module includes
• OSCOUT — XOSC output provides external reference clock to ADC.
• ICSFFCLK — ICS fixed frequency clock reference (around 32.768 kHz) provides double of the
fixed lock signal to TPMs and MTIM16.
• ICSOUT — ICS CPU clock provides double of the bus clock which is basic clock reference of
peripherals.
• ICSLCLK — Alternate BDC clock provides debug signal to BDC module.
The TCLK pin is an extra external clock source. When TCLK is enabled, it can provide alternate clock
source to TPMs and MTIM16. See Section 5.7.4, “System Options Register 1 (SOPT1)” for details.
The on-chip 1 kHz clock can provide clock source of COP module.
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Chapter 1 Device Overview
TCLK
1 kHz
COP
TPM1
TPM2
MTIM16
ADC
FLASH
RAM
IPC
OSCOUT
ICSFFCLK
2 FIXED CLOCK (XCLK)
ICS
ICSOUT
2
BUS CLOCK
ICSLCLK
XOSC
CPU
SCI
BDC
EXTAL XTAL
Figure 1-2. System Clock Distribution Diagram
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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 a detailed discussion of signals.
2.2
Device Pin Assignment
PTC5
PTC4
PTA5/TCLK/IRQ/RESET
PTD2/TPM1CH2
PTA4/BKGD/MS
PTD0
PTD1
VDD
VSS
PTB7/EXTAL
PTB6/XTAL
PTB5/TPM1CH1
PTD3/TPM1CH3
PTB4/TPM1CH0
PTC3/ADP11
PTC2/ADP10
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
PTC6
PTC7
PTA0/ADP0
PTD5
PTA1/ADP1
PTA2/ADP2
PTA3/ADP3
PTA6/TPM2CH0
PTA7/TPM2CH1
PTB0/RxD/ADP4
PTB1/TxD/ADP5
PTB2/ADP6
PTD4
PTB3/ADP7
PTC0/ADP8
PTC1/ADP9
Figure 2-1. MC9S08FL16 Series 32-Pin SDIP Package
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PTA5/IRQ/TCLK/RESET
PTC4
PTC5
PTC6
PTC7
PTA0/ADP0
31
30
29
28
27
26
25 PTD5
PTD2/TPM1CH2
32
Chapter 2 Pins and Connections
24
PTA1/ADP1
2
23
PTA2/ADP2
PTD1
3
22
PTA3/ADP3
VDD
4
21
PTA6/TPM2CH0
VSS
5
20
PTA7/TPM2CH1
PTB7/EXTAL
6
19
PTB0/RxD/ADP4
PTB6/XTAL
7
18
PTB1/TxD/ADP5
PTB5/TPM1CH1
8
PTA4/BKGD/MS 1
10
11
12
13
14
15
16
PTB4/TPM1CH0
PTC3/ADP11
PTC2/ADP10
PTC1/ADP9
PTC0/ADP8
PTB3/ADP7
PTD4
17 PTB2/ADP6
PTD3/TPM1CH3 9
PTD0
Figure 2-2. MC9S08FL16 Series 32-Pin LQFP Package
2.3
Recommended System Connections
Figure 2-3 shows pin connections that are common to almost all MC9S08FL16 series application systems.
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Chapter 2 Pins and Connections
MC9S08FL16
NOTE 5
PTA0/ADP0
VDD
PTA1/ADP1
PORT A
5V
CBLK +
CBY
0.1 F
10 F
VSS
PTA2/ADP2
PTA3/ADP3
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
PTA7/TPM2CH1
RF
NOTE 6
RS
PTB0/RxD/ADP4
XTAL
X1
PTB1/TxD/ADP5
C2
EXTAL
PORT B
C1
PTB3/ADP7
PTB4/TPM1CH0
VDD
PTB7/EXTAL
BKGD/MS
PERIPHERAL
INTERFACE TO
PTB5/TPM1CH1
PTB6/XTAL
NOTE 2
I/O AND
PTB2/ADP6
APPLICATION
SYSTEM
PTC0/ADP8
VDD
RESET
0.1 F VDD
PORT C
4.7 k–10 k
0.1F
NOTE 1, 3, 4
PTC3/ADP11
PTC4
PTC5
PTC7
4.7 k–
10 k
OPTIONAL
MANUAL ASYNCHRONOUS
INTERRUPT
RESET
INPUT
PTC2/ADP10
PTC6
PTD0
IRQ
PORT D
BACKGROUND HEADER
PTC1/ADP9
PTD1
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
NOTES:
1. RC filters on RESET and IRQ are recommended for EMC-sensitive applications.
2. The RESET pin can only be used to reset into user mode; you can not enter BDM using RESET pin. BDM can be entered by holding
MS low during POR or writing a 1 to BDFR in SBDFR with MS low after issuing the BDM command.
3. IRQ feature has optional internal pullup device.
4. IRQ and RESET are both multiplexed with PTA5. The recommended connection can be used for only one purpose.
5. The bulk and bypass capacitors must be placed close to MCU power supply as possible.
6. External crystal circuity is not required if using the ICS internal clock option.
Figure 2-3. Basic System Connections
2.3.1
Power (VDD, VSS)
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 a regulated
lower-voltage source to the CPU and to the MCU’s other internal circuitry.
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 F tantalum capacitor, that provides bulk charge
storage for the overall system and a 0.1 F ceramic bypass capacitor located as near to the paired VDD and
VSS power pins as practical to suppress high-frequency noise.
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Chapter 2 Pins and Connections
2.3.2
Oscillator (XTAL, EXTAL)
Immediately after reset, the MCU uses an internally generated clock provided by the internal clock
source (ICS) module. For more information on the ICS, see Chapter 8, “Internal Clock Source
(S08ICSV3).”
The oscillator (XOSC) in this MCU is a Pierce oscillator that can accommodate a crystal or ceramic resonator. Rather than a crystal or ceramic resonator, an external oscillator can be connected to the EXTAL
input pin.
RS (when used) and RF must 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
must 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; its
value is not generally critical. Typical systems use 1 M to 10 M. 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 selecting 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 and External Interrupt Pin (IRQ)
RESET shares an I/O pin with PTA5/IRQ/TCLK. The RESET pin function is disabled in default and
PTA5/IRQ/TCLK/RESET pin acts as PTA5 after POR reset, because internal power-on reset and
low-voltage reset circuitry typically make external reset circuitry unnecessary. This pin is normally
connected to the standard 6-pin background debug connector so that a development system can directly
reset the MCU system. If RESET function of PTA5/IRQ/TCLK/RESET pin is enabled, a manual external
reset can be added by supplying a simple switch to ground (pull reset pin low to force a reset). When the
RESET pin function is enabled, an internal pullup resistor is connected to this pin and a reset signal can
feed into MCU with an input hysteresis. This pin has no driving out function when it works as RESET pin
function. POR reset brings RESET pin into its default state, reset other than POR has no effect on the
RESET pin function configuration.
When PTA5/IRQ/TCLK/RESET is enabled as IRQ pin, it is the input source for the IRQ interrupt and is
also the input for the BIH and BIL instructions.
When PTA5/IRQ/TCLK/RESET is enabled as TCLK, it is the external clock source of TPMs and
MTIM16.
When PTA5/IRQ/TCLK/RESET is enabled as I/O pin, PTA5 can provide input operations only as normal
GPIO.
In EMC-sensitive applications, an external RC filter is recommended on the reset pin. See Figure 2-3 for
an example.
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Chapter 2 Pins and Connections
2.3.4
Background/Mode Select (BKGD/MS)
During a power-on-reset (POR) or background debug force reset (see Section 5.7.3, “System Background
Debug Force Reset Register (SBDFR)” for details), the PTA4/BKGD/MS pin functions as a mode select
pin. Immediately after internal reset rises the pin functions as the background pin and can be used for
background debug communication. While the pin functions as a background/mode selection pin, it
includes an internal pullup device, input hysteresis, a standard output driver, and has not output slew rate
control.
The background debug communication function is enabled when BKGDPE bit in SOPT1 is set. BKGDPE
is set following any reset of the MCU and must be cleared to use the PTA4/BKGD/MS pin’s alternative
pin functions.
If this pin is floating, 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
POR or immediately after issuing a background debug force reset, which will force the MCU into 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 can run as fast as the bus clock, so there should never be any significant capacitance connected to
the BKGD/MS pin that interferes with background serial communications. When the pin performs output
only PTA4, it can only drive capacitance-limited MOSFET. Driving a bipolar transistor by PTA4 is
prohibited because this can cause mode entry fault and BKGD errors.
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
General-Purpose I/O and Peripheral Ports
The MC9S08FL16 series of MCUs support up to 30 general-purpose I/O pins, which are shared with
on-chip peripheral functions (TPM, ADC, SCI, etc.). These 30 general-purpose I/O pins include one
output-only pin (PTA4) and one input-only pin (PTA5).
When a port pin is configured as a general-purpose output or when a peripheral uses the port pin as an
output, software can select alternative drive strengths and slew rate controls. When a port pin is configured
as a general-purpose input, or when a peripheral uses the port pin as an input, the software can enable a
pullup device.
For information about controlling these pins as general-purpose I/O pins, see the Chapter 6, “Parallel
Input/Output.” For information about how and when on-chip peripheral systems use these pins, see the
appropriate module chapter.
Immediately after reset, all pins are configured as high-impedance general-purpose inputs with internal
pullup devices disabled.
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Chapter 2 Pins and Connections
Table 2-1. Pin Availability by Package Pin-Count
Pin Number
<-- Lowest
32-SDIP
32-LQFP
Port Pin
I/O
1
29
PTC5
I/O
2
30
PTC4
I/O
3
31
PTA5
I
4
32
PTD2
I/O
5
1
PTA4
O
6
2
PTD0
I/O
7
3
PTD1
I/O
8
4
Priority
--> Highest
Alt 1
I/O
Alt 2
I/O
Alt 3
I/O
IRQ
I
TCLK
I
RESET
I
MS
I
VDD
I
VSS
I
TPM1CH2 I/O
BKGD
I
9
5
10
6
PTB7
I/O
EXTAL
I
11
7
PTB6
I/O
XTAL
O
12
8
PTB5
I/O
TPM1CH1 I/O
13
9
PTD3
I/O
TPM1CH3 I/O
14
10
PTB4
I/O
TPM1CH0 I/O
15
11
PTC3
I/O
ADP11
I
16
12
PTC2
I/O
ADP10
I
17
13
PTC1
I/O
ADP9
I
18
14
PTC0
I/O
ADP8
I
19
15
PTB3
I/O
ADP7
I
20
16
PTD4
I/O
21
17
PTB2
I/O
ADP6
I
22
18
PTB1
I/O
TxD
I/O
ADP5
I
23
19
PTB0
I/O
RxD
I
ADP4
I
24
20
PTA7
I/O
TPM2CH1 I/O
TPM2CH0 I/O
25
21
PTA6
I/O
26
22
PTA3
I/O
ADP3
I
27
23
PTA2
I/O
ADP2
I
28
24
PTA1
I/O
ADP1
I
29
25
PTD5
I/O
30
26
PTA0
I/O
ADP0
I
31
27
PTC7
I/O
32
28
PTC6
I/O
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Chapter 2 Pins and Connections
NOTE
When an alternative function is first enabled, it is possible to get a spurious
edge to the module. User software must 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.
Disable all modules that share a pin before enabling another module.
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Chapter 2 Pins and Connections
MC9S08FL16 MCU Series Reference Manual, Rev. 3
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Chapter 3
Modes of Operation
3.1
Introduction
The operating modes of the MC9S08FL16 series are described in this chapter. Entry into each mode, exit
from each mode, and functionality while in each mode are described
3.2
•
•
•
•
3.3
Features
Run mode for normal operating
Active background mode for code development
Wait mode:
— CPU halts operation to conserve power
— System clocks continue running
— Full voltage regulation is maintained
Stop modes: CPU and bus clocks stopped
— Stop2: Partial power down of internal circuits; RAM contents retained
— Stop3: All internal circuits are powered for fast recovery; RAM and register contents are
retained
Run Mode
Run is the normal operating mode for the MC9S08FL16 series. This mode is selected upon the MCU
exiting reset if the PTA4/BKGD/MS pin is high. In this mode, the CPU executes code from internal
memory beginning at the address 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 provides the means for analyzing MCU operation during software
development.
Active background mode is entered in any of six ways:
• When PTA4/BKGD/MS is low during POR
• When PTA4/BKGD/MS is low immediately after issuing a background debug force reset when the
pin is configured to BKGD/MS function (see Section 5.7.3, “System Background Debug Force
Reset Register (SBDFR)”)
• When a BACKGROUND command is received through the BKGD pin
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Chapter 3 Modes of Operation
•
•
•
When a BGND instruction is executed
When encountering a BDC breakpoint
When encountering a DBG breakpoint
After entering active background mode, the CPU stays in a suspended state waiting for serial background
commands rather than executing instructions from the user 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: Commands that 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 application program (GO)
Active background mode is used to program bootloader or user application programs into the flash
program memory before the MCU operates in run mode for the first time. When the MC9S08FL16 series
are shipped from Freescale Semiconductor Inc., the flash program memory is erased by default unless
specifically noted, so there is no program that can execute in run mode until the flash memory is initially
programmed. The active background mode can also be used to erase and reprogram the flash memory after
it is programmed.
For additional information about the active background mode, refer to the Chapter 14, “Development
Support.”
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 the condition code register (CCR) is cleared
when the CPU enters wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits wait
mode and resumes processing, beginning with the stacking operations leading to the interrupt service
routine.
While the MCU is in wait mode, not all background debug commands can be used. Only the background
command and memory-access-with-status commands are available while 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.
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Chapter 3 Modes of Operation
3.6
Stop Modes
Stop modes is entered upon execution of a STOP instruction when the STOPE bit in the system option
register (SOPT1) is set. In stop mode, the bus and CPU clocks are halted. The ICS module can be
configured to keep the reference clocks running. See Chapter 8, “Internal Clock Source (S08ICSV3),” for
more information.
The MC9S08FL16 series of MCUs do not support stop1 mode.
Table 3-1 shows all of the control bits that affect stop mode selection and the mode selected under various
conditions. It enters the selected mode by executing a STOP instruction.
Table 3-1. Stop Mode Selection
STOPE
ENBDM 1
0
x
x
x
Stop modes disabled; illegal opcode reset if STOP
instruction executed
1
1
x
x
Stop3 with BDM enabled 2
1
0
Both bits must be 1
x
Stop3 with voltage regulator active
1
0
Either bit a 0
0
Stop3
1
0
Either bit a 0
1
Stop2
LVDE
LVDSE
PPDC
Stop Mode
1
ENBDM is located in the BDCSCR which is accessible through only the BDC commands, see
Section 14.4.1.1, “BDC Status and Control Register (BDCSCR).”
2 When in stop3 mode with BDM enabled, the SI
DD will be near RIDD levels because internal clocks are
enabled.
3.6.1
Stop3 Mode
Stop3 mode is entered by executing a STOP instruction under the conditions as shown in Table 3-1. The
states of all the internal registers and logic, as well as RAM contents, are maintained. The I/O pin states
are held.
Exit from stop3 by asserting RESET or any asynchronous interrupt. Asynchronous interrupts can come
from SCI, ADC, LVW, and IRQ.
If stop3 is exited by asserting of the RESET pin, then the MCU is reset and operation will resume after
taking the reset vector. If exited by asynchronous interrupt, the MCU will take the appropriate interrupt
vector.
3.6.1.1
LVD Enabled in Stop Mode
The LVD system can generate an interrupt or a reset when the supply voltage drops below the LVD
voltage. The LVD is enabled in stop (LVDE and LVDSE bits in SPMSC1 both set) at the time the CPU
executes a STOP instruction. The voltage regulator remains active during stop mode. If the user attempts
to enter stop2 with the LVD enabled for stop, the MCU will enter stop3 instead.
The LVD must be enabled to keep the ADC working in stop3.
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Chapter 3 Modes of Operation
3.6.1.2
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 14, “Development Support.” If ENBDM is set when the CPU
executes a STOP instruction, the system clocks for the background debug logic remain active when the
MCU enters stop mode. As a result, 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 enters stop3 instead.
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 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 background debug mode is entered, all background commands are available.
3.6.2
Stop2 Mode
Stop2 mode is entered by executing a STOP instruction under the conditions as shown in Table 3-1. Most
of the internal circuitry except for RAM in MCU is powered off in stop2. Upon entering stop2, all I/O pin
control signals are latched so that the pins retain their states during stop2.
Exit from stop2 is performed by asserting any wakeup pin. The wakeup pins include RESET or IRQ.
Upon wakeup from stop2 mode, the MCU starts up as from a power-on reset (POR):
• All module control and status registers are reset.
• The LVD reset function is enabled and the MCU remains in the reset state if VDD is below the LVD
trip point (low trip point selected due to POR).
• The CPU takes the reset vector.
In addition to the above, upon waking from stop2, the PPDF bit in SPMSC2 is set. This flag directs user
code to stop2 recovery routine. PPDF remains set and the I/O pin states remain latched until a 1 is written
to PPDACK bit in SPMSC2.
To maintain I/O states of general-purpose I/O, the user must restore the contents of the I/O port registers
saved in RAM before writing to the PPDACK bit. Otherwise, the pins will switch to their reset states when
PPDACK is written.
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.
3.6.3
On-Chip Peripheral Modules in Stop Modes
When MCU enters any stop mode, the system clocks for the internal peripheral modules stop. Even in the
exception case (ENBDM = 1), where clocks for the background debug logic continue to operate, clocks to
the peripheral systems are halted to reduce power consumption. Refer to Section 3.6.2, “Stop2 Mode,” and
Section 3.6.1, “Stop3 Mode,” for specific information on system behavior in stop modes.
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Chapter 3 Modes of Operation
Table 3-2. Stop Mode Behavior
Mode
Peripheral
Stop2
Stop3
CPU
Off
Standby
RAM
Standby
Standby
Flash
Off
Standby
Parallel Port Registers
Off
Standby
IPC
Off
Standby
ADC
Off
Optionally On1
ICS
Off
Optionally On2
SCI
Off
Standby
TPM
Off
Standby
MTIM16
Off
Standby
Standby
Standby
States Held
States Held
System Voltage Regulator
I/O Pins
1
2
Requires the asynchronous ADC clock and LVD to be enabled, else in standby.
IRCLKEN and IREFSTEN are set in ICSC1, else in standby.
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Chapter 3 Modes of Operation
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Chapter 4
Memory
4.1
MC9S08FL16 Series Memory Map
Figure 4-1 shows the memory map for the MC9S08FL16 series. On-chip memory in the MC9S08FL16
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 two groups:
• Direct-page registers (0x0000 through 0x003F)
• High-page registers (0x1800 through 0x187F)
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Chapter 4 Memory
0x0000
0x0000
DIRECT PAGE REGISTERS
0x003F
0x0040
0x033F
0x0340
RAM 768 BYTES
DIRECT PAGE REGISTERS
0x003F
0x0040
RAM 1024 BYTES
0x043F
0x0440
UNIMPLEMENTED
0x17FF
0x1800
HIGH PAGE REGISTERS
0x187F
0x1880
UNIMPLEMENTED
0x17FF
0x1800
HIGH PAGE REGISTERS
0x187F
0x1880
UNIMPLEMENTED
UNIMPLEMENTED
0xBFFF
0xC000
FLASH
16384 BYTES
0xDFFF
0xE000
FLASH
8192 BYTES
0xFFFF
0xFFFF
MC9S08FL8
MC9S08FL16
Figure 4-1. MC9S08FL16 Series Memory Map
MC9S08FL16 MCU Series Reference Manual, Rev. 3
36
Freescale Semiconductor
Chapter 4 Memory
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 MC9S08FL16 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
4.2
Address
(High/Low)
Vector
Vector Name
0xFFC0:0xFFC1
to
0xFFD0:FFD1
Unused Vector Space
—
0xFFD2:FFD3
SCI Transmit
Vscierr
0xFFD4:FFD5
SCI Receive
Vscirx
0xFFD6:FFD7
SCI Error
Vscitx
0xFFD8:FFD9
Unused
—
0xFFDA:FFDB
Unused
—
0xFFDC:FFDD
ADC Conversion
Vadc
0xFFDE:FFDF
TPM2 Overflow
Vtpm2ovf
0xFFE0:FFE1
TPM2 Channel 1
Vtpm2ch1
0xFFE2:FFE3
TPM2 Channel 0
Vtpm2ch0
0xFFE4:FFE5
TPM1 Overflow
Vtpm1ovf
0xFFE6:FFE7
Unused
—
0xFFE8:FFE9
Unused
—
0xFFEA:FFEB
TPM1 Channel 3
Vtpm1ch3
0xFFEC:FFED
TPM1 Channel 2
Vtpm1ch2
0xFFEE:FFEF
TPM1 Channel 1
Vtpm1ch1
0xFFF0:FFF1
TPM1 Channel 0
Vtpm1ch0
0xFFF2:FFF3
MTIM16
Vmtim
0xFFF4:FFF5
Unused
—
0xFFF6:FFF7
Unused
—
0xFFF8:FFF9
Low Voltage Warning
Vlvd
0xFFFA:FFFB
IRQ
Virq
0xFFFC:FFFD
SWI
Vswi
0xFFFE:FFFF
Reset
Vreset
Register Addresses and Bit Assignments
The registers in the MC9S08FL16 series are divided into two groups:
• Direct-page registers are located in the first 64 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 room in the direct page for more frequently used registers and variables.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
37
Chapter 4 Memory
Direct-page registers can be accessed with efficient direct addressing mode instructions. Bit manipulation
instructions can be used to access any bit in a 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 requires
only 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.
Table 4-2. Direct-Page Register Summary (Sheet 1 of 2)
Address
Register
Name
Bit 7
6
5
0x0000
ADCSC1
COCO
AIEN
ADCO
0x0001
ADCSC2
ADACT
ADTRG
ACFE
0x0002
Reserved
0x0003
ADCRL
4
3
ACFGT
0
2
1
Bit 0
R
R
ADCH
0
—
—
—
—
—
—
—
—
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
ADR0
0x0004
Reserved
—
—
—
—
—
—
—
—
0x0005
ADCCVL
ADCV7
ADCV6
ADCV5
ADCV4
ADCV3
ADCV2
ADCV1
ADCV0
0x0006
ADCCFG
ADLPC
0x0007
APCTL1
ADPC7
ADPC6
ADPC5
ADPC4
ADPC3
ADPC2
ADPC1
ADPC0
0x0008
APCTL2
ADIV
ADLSMP
MODE
ADICLK
—
—
—
—
ADPC11
ADPC10
ADPC9
ADPC8
0x0009– Reserved
0x000A
—
—
—
—
—
—
—
—
0x000B IRQSC
0
IRQPDD
IRQEDG
IRQPE
IRQF
IRQACK
IRQIE
IRQMOD
0x000C– Reserved
0x000F
—
—
—
—
—
—
—
—
PS1
PS0
0x0010
TPM2SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
0x0011
TPM2CNTH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0012
TPM2CNTL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0013
TPM2MODH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0014
TPM2MODL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0015
TPM2C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
0x0016
TPM2C0VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0017
TPM2C0VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0018
TPM2C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
0x0019
TPM2C1VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x001A TPM2C1VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
—
—
—
—
—
—
—
—
IPCE
0
PSE
PSF
PULIPM
0
0x001B– Reserved
0x001D
0x001E
IPCSC
IPM3
IPM2
IPM
0x001F
IPMPS
0x0020
TPM1SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
IPM1
PS2
PS1
IPM0
PS0
0x0021
TPM1CNTH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
MC9S08FL16 MCU Series Reference Manual, Rev. 3
38
Freescale Semiconductor
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 2 of 2) (continued)
Register
Name
Address
Bit 7
6
5
4
3
2
1
Bit 0
0x0022
TPM1CNTL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0023
TPM1MODH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0024
TPM1MODL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0025
TPM1C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
0x0026
TPM1C0VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0027
TPM1C0VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x0028
TPM1C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
0x0029
TPM1C1VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x002A TPM1C1VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x002B TPM1C2SC
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
0x002C TPM1C2VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x002D TPM1C2VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x002E
TPM1C3SC
CH3F
CH3IE
MS3B
MS3A
ELS3B
ELS3A
—
—
0x002F
TPM1C3VH
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0x0030
TPM1C3VL
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
—
—
—
—
—
—
—
—
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
PTADD7
PTADD6
—
—
PTADD3
PTADD2
PTADD1
PTADD0
PTBD7
PTBD6
PTBD5
PTBD4
PTBD3
PTBD2
PTBD1
PTBD0
PTBDD7
PTBDD6
PTBDD5
PTBDD4
PTBDD3
PTBDD2
PTBDD1
PTBDD0
PTCD7
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0x0031– Reserved
0x0037
0x0038
PTAD
0x0039
PTADD
0x003A PTBD
0x003B PTBDD
0x003C PTCD
PTCDD7
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0x003E
0x003D PTCDD
PTDD
—
—
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
0x003F
PTDDD
—
—
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
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
SBDFR
0x1802
SOPT1
0x1803
SOPT2
0x1804–
0x1805
Reserved
0x1806
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
ILAD
0
LVD
—
0
0
COPT
0
0
0
0
0
BDFR
STOPE
TCLKPEN
0
0
BKGDPE
RSTPE
COPCLKS
COPW
0
0
0
0
0
0
—
—
—
—
—
—
—
—
SDIDH
—
—
—
—
ID11
ID10
ID9
ID8
0x1807
SDIDL
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0x1808
Reserved
—
—
—
—
—
—
—
—
0x1809
SPMSC1
LVWF
LVWACK
LVWIE
LVDRE
LVDSE
LVDE
0
BGBE
0x180A
SPMSC2
0
0
LVDV
LVWV
PPDF
PPDACK
0
PPDC
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
39
Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 2 of 3) (continued)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x180B–
0x180F
Reserved
—
—
—
—
—
—
—
—
0x1810
DBGCAH
Bit 15
14
13
12
11
10
9
Bit 8
0x1811
DBGCAL
Bit 7
6
5
4
3
2
1
Bit 0
0x1812
DBGCBH
Bit 15
14
13
12
11
10
9
Bit 8
0x1813
DBGCBL
Bit 7
6
5
4
3
2
1
Bit 0
0x1814
DBGFH
Bit 15
14
13
12
11
10
9
Bit 8
0x1815
DBGFL
Bit 7
6
5
4
3
2
1
Bit 0
0x1816
DBGC
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
0x1817
DBGT
TRGSEL
BEGIN
0
0
TRG3
TRG2
TRG1
TRG0
0x1818
DBGS
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
0x1819–
0x181F
Reserved
—
—
—
—
—
—
—
—
0x1820
FCDIV
DIVLD
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
0x1821
FOPT
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
0x1822
Reserved
—
—
—
—
—
—
—
—
0x1823
FCNFG
0
0
KEYACC
0
0
0
0
0
0x1824
FPROT
FPS7
FPS6
FPS5
FPS4
FPS3
FPS2
FPS1
0
0x1825
FSTAT
FCBEF
FCCF
FPVIOL
FACCERR
0
FBLANK
0
0
0x1826
FCMD
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
0x1827–
0x183F
Reserved
—
—
—
—
—
—
—
—
0x1840
PTAPE
PTAPE7
PTAPE6
PTAPE5
—
PTAPE3
PTAPE2
PTAPE1
PTAPE0
0x1841
PTASE
PTASE7
PTASE6
—
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
0x1842
PTADS
PTADS7
PTADS6
—
PTADS4
PTADS3
PTADS2
PTADS1
PTADS0
0x1843
Reserved
—
—
—
—
—
—
—
—
0x1844
PTBPE
PTBPE7
PTBPE6
PTBPE5
PTBPE4
PTBPE3
PTBPE2
PTBPE1
PTBPE0
0x1845
PTBSE
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
PTBDS7
PTBDS6
PTBDS5
PTBDS4
PTBDS3
PTBDS2
PTBDS1
PTBDS0
—
—
—
—
—
—
—
—
0x1846
PTBDS
0x1847
Reserved
0x1848
PTCPE
PTCPE7
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0x1849
PTCSE
PTCSE7
PTCSE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0x184A
PTCDS
PTCDS7
PTCDS6
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
0x184B
Reserved
—
—
—
—
—
—
—
—
0x184C
PTDPE
—
—
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
0x184D
PTDSE
—
—
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
0x184E
PTDDS
—
—
PTDDS5
PTDDS4
PTDDS3
PTDDS2
PTDDS1
PTDDS0
0x184F
Reserved
—
—
—
—
—
—
—
—
0x1850
SCIBDH
LBKDIE
RXEDGIE
0
SBR12
SBR11
SBR10
SBR9
SBR8
0x1851
SCIBDL
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0x1852
SCIC1
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0x1853
SCIC2
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0x1854
SCIS1
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
MC9S08FL16 MCU Series Reference Manual, Rev. 3
40
Freescale Semiconductor
Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 3 of 3) (continued)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x1855
SCIS2
LBKDIF
RXEDGIF
0
RXINV
RWUID
BRK13
LBKDE
RAF
0x1856
SCIC3
R8
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
0x1857
SCID
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
IREFS
IRCLKEN IREFSTEN
LP
EREFS
ERCLKEN EREFSTEN
0x1858
ICSC1
CLKS
0x1859
ICSC2
BDIV
0x185A
ICSTRM
RDIV
RANGE
HGO
TRIM
DRST
0x185B
ICSSC
DMX32
IREFST
0x185C–
0x185F
Reserved
—
—
—
—
—
—
TOF
TOIE
TRST
TSTP
0
0
0
0
DRS
CLKST
OSCINIT
FTRIM
—
—
0
0
—
—
0x1860
MTIMSC
0x1861
MTIMCLK
0x1862
MTIMCNTH
CNTH
0x1863
MTIMCNTL
CNTL
0x1864
MTIMMODH
MODH
0x1865
MTIMMODL
MODL
0x1866–
0x1877
Reserved
0x1878
ILRS0
ILR3
ILR2
ILR1
ILR0
0x1879
ILRS1
ILR7
ILR6
ILR5
ILR4
0x187A
ILRS2
ILR11
ILR10
ILR9
ILR8
0x187B
ILRS3
ILR15
ILR14
ILR13
ILR12
0x187C
ILRS4
ILR19
ILR18
ILR17
ILR16
0x187D
ILRS5
ILR23
ILR22
ILR21
ILR20
0x187E
ILRS6
ILR27
ILR26
ILR25
ILR24
0x187F
ILRS7
ILR31
ILR30
ILR29
ILR28
—
—
CLKS
—
PS
—
—
—
Several reserved flash memory locations, shown in Table 4-4, are used for storing values used by several
registers. These registers include an 8-byte backdoor key, NVBACKKEY, which can be used to gain
access to secure memory resources. During reset events, the contents of NVPROT and NVOPT in the
reserved flash memory are transferred into corresponding FPROT and FOPT registers in the high-page
registers area to control security and block protection options.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
41
Chapter 4 Memory
Table 4-4. Reserved Flash Memory Addresses
Address
Register Name
0xFFAE
NV_FTRIM
0xFFAF
NV_ICSTRM
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
FTRIM
—
—
—
—
TRIM
0xFFB0– NVBACKKEY
0xFFB7
0xFFB8– Reserved
0xFFBC
0xFFBD
NVPROT
0xFFBE
Reserved
0xFFBF
NVOPT
8-Byte Comparison Key
—
—
—
—
—
—
—
—
—
—
—
—
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
0
FPS
Provided the key enable (KEYEN) bit is 1, 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 bit to 0. 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 (SEC) to the unsecured state (1:0).
4.3
RAM (System RAM)
The MC9S08FL16 series include static RAM. The locations in RAM below 0x0100 can be accessed using
the more efficient direct addressing mode. Any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET).
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
MC9S08FL16 series, it is best to re-initialize the stack pointer to the top of the RAM so that 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)
When security is enabled, the RAM is considered a secure memory resource and is not accessible through
BDM or code executing from non-secure memory. See Section 4.5, “Security” for a detailed description
of the security feature.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
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Freescale Semiconductor
Chapter 4 Memory
4.4
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. 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.
4.4.1
Features
Features of the flash memory include:
• flash size
— MC9S08FL16 — 16,384 bytes (32 pages of 512 bytes each)
— MC9S08FL8 — 8,192 bytes (16 pages of 512 bytes each)
• Single power supply program and erase
• Command interface for fast program and erase operation
• Up to 100,000 program/erase cycles at typical voltage and temperature
• Flexible block protection
• Security feature for flash and RAM
• Auto power-down for low-frequency read accesses
4.4.2
Program and Erase Times
Before any program or erase command can be accepted, the flash clock divider register (FCDIV) must be
written to set the internal clock for the flash module to a frequency (fFCLK) between 150 kHz and 200 kHz
(see Section 4.6.1, “Flash Clock Divider Register (FCDIV)”). This register can be written only once, so it
normally occurs 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 4-5 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 s. Program and erase times
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
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Table 4-5. Program and Erase Times
Parameter
1
4.4.3
Cycles of FCLK
Time if FCLK = 200 kHz
Byte program
9
45 s
Byte program (burst)
4
20 s1
Page erase
4000
20 ms
Mass erase
20,000
100 ms
Excluding start/end overhead
Program and Erase Command Execution
The FCDIV register must be initialized and any error flags cleared before beginning command execution.
The command execution steps are:
1. Write a data value to an address in the flash array. The address and data information from this write
is latched into the flash interface. This write is a required first step in any command sequence. For
erase and blank check commands, the value of the data is not important. For page erase commands,
the address may be any address in the 512 byte page of flash to be erased. For mass erase and blank
check commands, the address can be any address in the flash memory. Whole pages of 512 bytes
are the smallest block of flash that may be erased. In the 4 KB version, there are two instances
where the size of a block that is accessible to the user is less than 512 bytes: the first page following
RAM, and the first page following the high page registers. These pages are overlapped by the RAM
and high-page registers respectively.
NOTE
Do not program any byte in the flash more than once after a successful erase
operation. Reprogramming bits to a byte which is already programmed is
not allowed without first erasing the page in which the byte resides or mass
erasing the entire flash memory. Programming without first erasing may
disturb data stored in the flash.
2. Write the command code for the desired command to FCMD. The five valid commands are blank
check (0x05), byte program (0x20), burst program (0x25), page erase (0x40), and mass erase
(0x41). The command code is latched into the command buffer.
3. Write a 1 to the FCBEF bit in FSTAT to clear FCBEF and launch the command (including its
address and data information).
A partial command sequence can be aborted manually by writing a 0 to FCBEF any time after the write to
the memory array and before writing the 1 that clears FCBEF and launches the complete command.
Aborting a command in this way sets the FACCERR access error flag which must be cleared before
starting a new command.
A strictly monitored procedure must be obeyed or the command will not be accepted. This minimizes the
possibility of any unintended changes to the flash memory contents. The command complete flag (FCCF)
indicates when a command is complete. The command sequence must be completed by clearing FCBEF
to launch the command. Figure 4-2 is a flowchart for executing all of the commands except for burst
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programming. The FCDIV register must be initialized before using any flash commands. This must be
done only once following a reset.
(1) Required only once
WRITE TO FCDIV(1)
PROGRAM AND
ERASE FLOW
after reset.
START
0
FCBEF?
1
FACCERR OR FPVIOL?
0
1
CLEAR ERRORS
WRITE TO FLASH TO BUFFER
ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (2)
(3)During this time, avoid actions
that woudl result in an
FACCERR error.
Such as executing a
STOP instruction or writing
to the flash.
Reads of the flash during
program or erase are
ignored and invalid data
is returned.
FPVIOL OR
FACCERR?
(2) Wait at least four bus cycles
before checking FCBEF or FCCF.
YES
ERROR EXIT
NO
0
FCCF? (3)
1
DONE
Figure 4-2. Flash Program and Erase Flowchart
4.4.4
Burst Program Execution
The burst program command is used to program sequential bytes of data in less time than would be
required using the standard program command. This is possible because the high voltage to the flash array
does not need to be disabled between program operations. Ordinarily, when a program or erase command
is issued, an internal charge pump associated with the flash memory must be enabled to supply high
voltage to the array. Upon completion of the command, the charge pump is turned off. When a burst
program command is issued, the charge pump is enabled and then remains so after completion of the burst
program operation if these two conditions are met:
• The next burst program command has been queued before the current program operation has
completed.
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•
The next sequential address selects a byte on the same physical row as the current byte being
programmed. A row of flash memory consists of 64 bytes. A byte within a row is selected by
addresses A5 through A0. A new row begins when addresses A5 through A0 are all zero.
The first byte of a series of sequential bytes being programmed in burst mode will take the same amount
of time to program as a byte programmed in standard mode. Subsequent bytes will program in the burst
program time provided that the conditions above are met. If the next sequential address is the beginning
of a new row, the program time for that byte will be the standard time instead of the burst time. This is
because the high voltage of the array must be disabled and then enabled again. If a new burst command
has not been queued before the current command finishes, then the charge pump will be disabled and high
voltage removed from the array.
(1)
Required only once
after reset.
WRITE TO FCDIV(1)
START
BURST PROGRAM
FLOW
FACCERR OR FPVIOL?
0
1
CLEAR ERRORS
FCBEF?
0
1
WRITE TO Flash
TO BUFFER ADDRESS AND DATA
1
WRITE COMMAND
TO FCMD
(3)During this time, avoid actions
that woudl result in an
FACCERR error.
Such as executing a
STOP instruction or writing
to the flash.
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (2)
Reads of the flash during
program or erase are
ignored and invalid data
is returned.
FPVIOL OR
FACCERR?
(2)
Wait at least four bus cycles
before checking FCBEF or FCCF.
YES
ERROR EXIT
NO
YES
NEW BURST COMMAND?
NO
0
FCCF? (3)
1
DONE
Figure 4-3. Flash Burst Program Flowchart
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4.4.5
Access Errors
An access error occurs when the command execution protocol is violated.
Any of the following actions will set the access error flag (FACCERR) in FSTAT. FACCERR must be
cleared by writing a 1 to FACCERR in FSTAT before any command can be processed.
• Writing to a flash address before the internal flash clock frequency has been set by writing to the
FCDIV register
• Writing to a flash address while FCBEF is not set (A new command cannot be started until the
command buffer is empty.)
• Writing a second time to a flash address before launching the previous command (There is only
one write to flash for every command.)
• Writing a second time to FCMD before launching the previous command (There is only one write
to FCMD for every command.)
• Writing to any flash control register other than FCMD after writing to a flash address
• Writing any command code other than the five allowed codes (0x05, 0x20, 0x25, 0x40, or 0x41)
to FCMD
• Accessing (read or write) any flash control register other than the write to FSTAT (to clear FCBEF
and launch the command) after writing the command to FCMD
• The MCU enters stop mode while a program or erase command is in progress (The command is
aborted.)
• Writing the byte program, burst program, or page erase command code (0x20, 0x25, or 0x40) with
a background debug command while the MCU is secured. (the background debug controller can
only do blank check and mass erase commands when the MCU is secure.)
• Writing 0 to FCBEF to cancel a partial command
4.4.6
Flash Block Protection
The block protection feature prevents the protected region of flash from program or erase changes. Block
protection is controlled through the flash protection register (FPROT). When enabled, block protection
begins at any 512 byte boundary below the last address of flash, 0xFFFF. (see Section 4.6.4, “Flash
Protection Register (FPROT and NVPROT)”)
After exit from reset, FPROT is loaded with the contents of the NVPROT location which is in the
nonvolatile register block of the flash memory. FPROT cannot be changed directly from application
software so a runaway program cannot alter the block protection settings. Since NVPROT is the last 512
bytes of flash, if any amount of memory is protected, NVPROT is protected and cannot be altered
(intentionally or unintentionally) by the application software. FPROT can be written through background
debug commands which allows a protected flash memory to be erased and reprogrammed.
The block protection mechanism is illustrated below. The FPS bits are used as the upper bits of the last
address of unprotected memory. This address is formed by concatenating FPS7:FPS1 with logic 1 bits as
shown. For example, in order to protect the last 8192 bytes of memory (addresses 0xE000 through
0xFFFF), the FPS bits must be set to 1101 111 which makes the value 0xDFFF the last address of
unprotected memory. In addition to programming the FPS bits to the appropriate value, FPDIS (bit 0 of
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NVPROT) must be programmed to logic 0 to enable block protection. Therefore the value 0xDE must be
programmed into NVPROT to protect addresses 0xE000 through 0xFFFF.
FPS7 FPS6 FPS5 FPS4 FPS3
A15
A14
A13
A12
A11
FPS2
FPS1
A10
A9
1
1
1
1
1
1
1
1
1
A8 A7 A6 A5 A4 A3 A2 A1 A0
Figure 4-4. Block Protection Mechanism
One use for block protection is to block protect an area of flash memory for a bootloader program. This
bootloader program can then be used to erase the rest of the flash memory and reprogram it. Because the
bootloader is protected, it remains intact even if MCU power is lost in the middle of an erase and
reprogram operation.
4.4.7
Vector Redirection
When block protection is enabled, the reset and interrupt vectors will be protected. Vector redirection
allows users to modify interrupt vector information without unprotecting the bootloader and reset vector
space. Vector redirection is enabled by programming the FNORED bit in the NVOPT register located at
address 0xFFBF to zero. For redirection to occur, at least some portion - but not all - of the flash memory
must be block protected by programming the NVPROT register located at address 0xFFBD. All of the
interrupt vectors (memory locations 0xFFC0–0xFFFD) are redirected, though the reset vector
(0xFFFE:FFFF) is not.
For example, if 512 bytes of flash are protected, the protected address region is from 0xFE00 through
0xFFFF. The interrupt vectors (0xFFC0–0xFFFD) are redirected to the locations 0xFDC0–0xFDFD. If a
TPM1 overflow interrupt is taken, for instance, the values in the locations 0xFDE0:FDE1 are used for the
vector instead of the values in the locations 0xFFE0:FFE1. This allows the user to reprogram the
unprotected portion of the flash with new program code including new interrupt vector values while
leaving the protected area, which includes the default vector locations, unchanged.
4.5
Security
The MC9S08FL16 series include circuitry that prevents 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).
Security is engaged or disengaged based on the state of two nonvolatile register bits (SEC01:SEC00) in
the FOPT register. During reset, the contents of the nonvolatile location NVOPT are copied from flash into
the working FOPT register in high-page register space. A user engages security by programming the
NVOPT location, which can be done at the same time the flash memory is programmed. The 1:0 state
disengages security and the other three combinations engage security. Notice the erased state (1:1) makes
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the MCU secure. When the flash is erased during development, you should immediately program the
SEC00 bit to 0 in NVOPT so SEC01:SEC00 = 1:0. This allows the MCU to remain unsecured after a
subsequent reset.
The on-chip debug module cannot be enabled while the MCU is secure. The separate background debug
controller can still be used for background memory access commands, but the MCU cannot enter active
background mode except by holding BKGD/MS low at the rising edge of reset.
A user can choose to allow or disallow a security unlocking mechanism through an 8-byte backdoor
security key. If the nonvolatile KEYEN bit in NVOPT/FOPT is 0, the backdoor key is disabled and there
is no way to disengage security without completely erasing all flash locations. If KEYEN is 1, a secure
user program can temporarily disengage security by:
1. Writing 1 to KEYACC in the FCNFG register. This makes the flash module interpret writes to the
backdoor comparison key locations (NVBACKKEY through NVBACKKEY+7) as values to be
compared against the key rather than as the first step in a flash program or erase command.
2. Writing the user-entered key values to the NVBACKKEY through NVBACKKEY+7 locations.
These writes must occur in order, starting with the value for NVBACKKEY and ending with
NVBACKKEY+7. STHX should not be used for these writes because they cannot be performed
on adjacent bus cycles. User software normally gets the key codes from outside the MCU system
through a communication interface such as a serial I/O.
3. Writing 0 to KEYACC in the FCNFG register. If the 8-byte key that was just written matches the
key stored in the flash locations, SEC01:SEC00 are automatically changed to 1:0 and security is
disengaged until the next reset.
The security key can be written only from secure memory (either RAM or flash), so it cannot be entered
through background commands without the cooperation of a secure user program.
The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in flash memory
locations in the nonvolatile register space so users can program these locations exactly as they would
program any other flash memory location. The nonvolatile registers are in the same 512-byte block of flash
as the reset and interrupt vectors, so block protecting that space also block protects the backdoor
comparison key. Block protects cannot be changed from user application programs, so if the vector space
is block protected, the backdoor security key mechanism cannot permanently change the block protect,
security settings, or the backdoor key.
Security can always be disengaged through the background debug interface by taking these steps:
1. Disabling any block protections by writing FPROT. FPROT can be written only with background
debug commands, not from application software.
2. Mass erase flash if necessary.
3. Blank check flash. Provided flash is completely erased, security is disengaged until the next reset.
To avoid returning to secure mode after the next reset, program NVOPT so SEC01:SEC00 = 1:0.
4.6
Flash Registers and Control Bits
The flash module has nine 8-bit registers in the high-page register space, three of which are in the
nonvolatile register space in flash memory which are copied into three corresponding high-page control
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Chapter 4 Memory
registers at reset. There is also an 8-byte comparison key in flash memory. Refer to Table 4-3 and Table 4-4
for the absolute address assignments for all flash registers. This section refers to registers and control bits
only by their names. A Freescale-provided equate or header file is normally used to translate these names
into the appropriate absolute addresses.
4.6.1
Flash Clock Divider Register (FCDIV)
Bit 7 of this register is a read-only status flag. Bits 6 through 0 may be read at any time but can be written
only once. Before any erase or programming operations are possible, write to this register to set the
frequency of the clock for the nonvolatile memory system within acceptable limits.
7
R
6
5
4
3
2
1
0
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
0
0
0
0
0
0
0
DIVLD
W
Reset
0
= Unimplemented or Reserved
Figure 4-5. Flash Clock Divider Register (FCDIV)
Table 4-6. FCDIV Register Field Descriptions
Field
Description
7
DIVLD
Divisor Loaded Status Flag — When set, this read-only status flag indicates that the FCDIV register has been
written since reset. Reset clears this bit and the first write to this register causes this bit to become set regardless
of the data written.
0 FCDIV has not been written since reset; erase and program operations disabled for flash.
1 FCDIV has been written since reset; erase and program operations enabled for flash.
6
PRDIV8
Prescale (Divide) Flash Clock by 8
0 Clock input to the flash clock divider is the bus rate clock.
1 Clock input to the flash clock divider is the bus rate clock divided by 8.
5:0
DIV[5:0]
Divisor for Flash Clock Divider — The flash clock divider divides the bus rate clock (or the bus rate clock
divided by 8 if PRDIV8 = 1) by the value in the 6-bit DIV5:DIV0 field plus one. The resulting frequency of the
internal flash clock must fall within the range of 200 kHz to 150 kHz for proper flash operations. Program/Erase
timing pulses are one cycle of this internal flash clock which corresponds to a range of 5 s to 6.7 s. The
automated programming logic uses an integer number of these pulses to complete an erase or program
operation. See Equation 4-1, Equation 4-2, and Table 4-6.
if PRDIV8 = 0, fFCLK = fBus  ([DIV5:DIV0] + 1)
Eqn. 4-1
if PRDIV8 = 1, fFCLK = fBus  (8  ([DIV5:DIV0] + 1))
Eqn. 4-2
Table 4-7 shows the appropriate values for PRDIV8 and DIV5:DIV0 for selected bus frequencies.
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Table 4-7. Flash Clock Divider Settings
fBus
PRDIV8
(Binary)
DIV5:DIV0
(Decimal)
fFCLK
Program/Erase Timing Pulse
(5 s Min, 6.7s Max)
10 MHz
0
49
200 kHz
5 s
8 MHz
0
39
200 kHz
5 s
4 MHz
0
19
200 kHz
5 s
2 MHz
0
9
200 kHz
5 s
1 MHz
0
4
200 kHz
5 s
200 kHz
0
0
200 kHz
5 s
150 kHz
0
0
150 kHz
6.7 s
4.6.2
Flash Options Register (FOPT and NVOPT)
During reset, the contents of the nonvolatile location NVOPT are copied from flash into FOPT. Bits 5
through 2 are not used and always read 0. This register may be read at any time, but writes have no meaning
or effect. To change the value in this register, erase and reprogram the NVOPT location in flash memory
as usual and issue a new MCU reset.
R
7
6
5
4
3
2
1
0
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
W
Reset
This register is loaded from nonvolatile location NVOPT during reset.
= Unimplemented or Reserved
Figure 4-6. Flash Options Register (FOPT)
Table 4-8. FOPT Register Field Descriptions
Field
Description
7
KEYEN
Backdoor Key Mechanism Enable — When this bit is 0, the backdoor key mechanism cannot be used to
disengage security. The backdoor key mechanism is accessible only from user (secured) firmware. BDM
commands cannot be used to write key comparison values that would unlock the backdoor key. For more detailed
information about the backdoor key mechanism, refer to Section 4.5, “Security.”
0 No backdoor key access allowed.
1 If user firmware writes an 8-byte value that matches the nonvolatile backdoor key (NVBACKKEY through
NVBACKKEY+7 in that order), security is temporarily disengaged until the next MCU reset.
6
FNORED
Vector Redirection Disable — When this bit is 1, then vector redirection is disabled.
0 Vector redirection enabled.
1 Vector redirection disabled.
1:0
SEC0[1:0]
Security State Code — This 2-bit field determines the security state of the MCU as shown in Table 4-9. When
the MCU is secure, the contents of RAM and flash memory cannot be accessed by instructions from any
unsecured source including the background debug interface. For more detailed information about security, refer
to Section 4.5, “Security.”
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Table 4-9. Security States
SEC01:SEC00
Description
0:0
secure
0:1
secure
1:0
unsecured
1:1
secure
SEC01:SEC00 changes to 1:0 after successful backdoor key entry or a successful blank check of flash.
4.6.3
Flash Configuration Register (FCNFG)
Bits 5 can be read or written at any time. Bits 7, 6 and 4 through 0 always read 0 and cannot be written.
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 4-7. Flash Configuration Register (FCNFG)
Table 4-10. FCNFG Register Field Descriptions
Field
Description
5
KEYACC
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to Section 4.5, “Security.”
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a flash programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
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4.6.4
Flash Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT are copied from flash into FPROT. Bits 0
is not used and always reads as 0. This register may be read at any time, but user program writes have no
meaning or effect. Background debug commands can write to FPROT.
7
6
5
4
3
2
1
0
R
FPS7
FPS6
FPS5
FPS4
FPS3
FPS2
FPS1
0
W
(1)
(1)
(1)
(1)
(1)
(1)
(1)
Reset
1
This register is loaded from nonvolatile location NVPROT during reset.
Background commands can be used to change the contents of these bits in FPROT.
Figure 4-8.
Table 4-11. FPROT Register Field Descriptions
Field
7:1
FPS[7:1]
4.6.5
Description
Flash Protect Select Bits — When FPDIS = 0, this 7-bit field determines the ending address of unprotected
flash locations at the high address end of the flash. Protected flash locations cannot be erased or programmed.
Flash Status Register (FSTAT)
Bits 3, 1, and 0 always read 0 and writes have no meaning or effect. The remaining five bits are status bits
that can be read at any time. Writes to these bits have special meanings that are discussed in the bit
descriptions.
7
6
R
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 4-9. Flash Status Register (FSTAT)
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Table 4-12. FSTAT Register Field Descriptions
Field
Description
7
FCBEF
Flash Command Buffer Empty Flag — The FCBEF bit is used to launch commands. It also indicates that the
6
FCCF
command buffer is empty so that a new command sequence can be executed when performing burst
programming. The FCBEF bit is cleared by writing a 1 to it or when a burst program command is transferred to
the array for programming. Only burst program commands can be buffered.
0 Command buffer is full (not ready for additional commands).
1 A new burst program command may be written to the command buffer.
Flash Command Complete Flag — FCCF is set automatically when the command buffer is empty and no
command is being processed. FCCF is cleared automatically when a new command is started (by writing 1 to
FCBEF to register a command). Writing to FCCF has no meaning or effect.
0 Command in progress
1 All commands complete
5
FPVIOL
Protection Violation Flag — FPVIOL is set automatically when FCBEF is cleared to register a command that
attempts to erase or program a location in a protected block (the erroneous command is ignored). FPVIOL is
cleared by writing a 1 to FPVIOL
0 No protection violation.
1 An attempt was made to erase or program a protected location.
4
FACCERR
Access Error Flag — FACCERR is set automatically when the proper command sequence is not obeyed exactly
(the erroneous command is ignored), if a program or erase operation is attempted before the FCDIV register has
been initialized, or if the MCU enters stop while a command was in progress. For a more detailed discussion of
the exact actions that are considered access errors, see Section 4.5.5, “Access Errors.” FACCERR is cleared by
writing a 1 to FACCERR. Writing a 0 to FACCERR has no meaning or effect.
0 No access error.
1 An access error has occurred.
2
FBLANK
Flash Verified as All Blank (erased) Flag — FBLANK is set automatically at the conclusion of a blank check
command if the entire flash array was verified as erased. FBLANK is cleared by clearing FCBEF to write a new
valid command. Writing to FBLANK has no meaning or effect.
0 After a blank check command is completed and FCCF = 1, FBLANK = 0 indicates the flash array is not
completely erased.
1 After a blank check command is completed and FCCF = 1, FBLANK = 1 indicates the flash array is completely
erased (all 0xFF).
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4.6.6
Flash Command Register (FCMD)
Only five command codes are recognized in normal user modes as shown in Table 4-14. Refer to
Section 4.6.3, “Flash Configuration Register (FCNFG)” for a detailed discussion of flash programming
and erase operations.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
0
0
0
0
0
0
0
0
Reset
Figure 4-10. Flash Command Register (FCMD)
Table 4-13. FCMD Register Field Descriptions
Field
FCMD[7:0]
Description
Flash Command Bits — See Table 4-14
Table 4-14. Flash Commands
Command
FCMD
Equate File Label
Blank check
0x05
mBlank
Byte program
0x20
mByteProg
Byte program — burst mode
0x25
mBurstProg
Page erase (512 bytes/page)
0x40
mPageErase
Mass erase (all flash)
0x41
mMassErase
All other command codes are illegal and generate an access error.
It is not necessary to perform a blank check command after a mass erase operation. Only blank check is
required as part of the security unlocking mechanism.
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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 MC9S08FL16 series. Some interrupt sources from peripheral modules are discussed in great detail
in other chapters of this reference 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, 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
• Reset status register (SRS) to indicate the source of the most recent reset
• Separate interrupt vectors for each module (reduces polling overhead) (see Table 5-1)
5.3
MCU Reset
Resetting the MCU provides a way to start processing from a set of known 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 disabled pullup devices. 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 MC9S08FL16 series have seven sources for reset:
• Power-on reset (POR)
• Low-voltage detect (LVD)
• Computer operating properly (COP) timer
• Illegal opcode detect (ILOP)
• Illegal address detect (ILAD)
• Background debug forced reset
• External reset pin (RESET)
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status (SRS) register.
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5.4
Computer Operating Properly (COP) Watchdog
The COP watchdog forces 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 an known starting point.
After any reset, the COP watchdog is enabled (see Section 5.7.4, “System Options Register 1 (SOPT1),”
for additional information). If the COP watchdog is not used in an application, it can be disabled by
clearing COPT bits in SOPT1.
The COP counter is reset by writing 0x55 and 0xAA (in this order) to the address of SRS during the
selected timeout period. Writes do not affect the data in the read-only SRS. As soon as the write sequence
is completed, the COP timeout period re-starts. If the program fails to do this during the time-out period,
the MCU will reset. Also, if any value other than 0x55 or 0xAA is written to SRS, the MCU immediately
resets.
The COPCLKS bit in SOPT2 (see Section 5.7.5, “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 are three associated time-outs
controlled by the COPT bits in SOPT1. Table 5-6 summarizes the control functions of the COPCLKS and
COPT bits. The COP watchdog defaults to operation from the 1 kHz clock source and the longest time-out
(210 cycles).
When the bus clock source is selected, windowed COP operation is available by setting COPW in the
SOPT2 register. In this mode, writes to the SRS register to clear the COP timer must occur in the last 25%
of the selected timeout period. A premature write immediately resets the MCU. When the 1 kHz clock
source is selected, windowed COP operation is not available.
The COP counter is initialized by the first writes to the SOPT1 and SOPT2 registers and after any system
reset. Subsequent writes to SOPT1 and SOPT2 have no effect on COP operation. Even if the application
uses the reset default settings of COPT, COPCLKS, and COPW bits, the user must write to the write-once
SOPT1 and SOPT2 registers during reset initialization to lock in the settings. This prevents accidental
changes if the application program gets lost.
The write to SRS that services (clears) the COP counter must not be placed in an interrupt service routine
(ISR) because the ISR can continue executing periodically even if the main application program fails.
If the bus clock source is selected, the COP counter does not increment while the MCU is in background
debug mode or while the system is in stop mode. The COP counter resumes when the MCU exits
background debug mode or stop mode.
If the 1 kHz clock source is selected, the COP counter is re-initialized to zero upon entry to either
background debug mode or stop mode and begins from zero upon exit from background debug mode or
stop mode.
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5.5
Interrupts
Interrupts 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 be set. The CPU
will not respond until and unless the local interrupt enable is a logic 1. 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 prevent another interrupt from
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 recommended for only the most
experienced programmers because it can lead to subtle program errors that are difficult to debug.
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. 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 5-1).
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
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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.
TOWARD LOWER ADDRESSES
UNSTACKING
ORDER
7
0
5
1
CONDITION CODE REGISTER
4
2
ACCUMULATOR
3
3
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
SP AFTER
INTERRUPT STACKING
INDEX REGISTER (LOW BYTE X)*
STACKING
ORDER
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 executes, 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 must be cleared at the beginning of the ISR so that if another interrupt is generated by
this source, it will be registered so it can be serviced after completion of the current ISR.
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 IRQSC must be 1 in order for the IRQ pin to act as the interrupt
request (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), or whether an event causes an interrupt or only sets
the IRQF flag which can be polled by software.
When enabled, the IRQ pin, defaults to use an internal pull device (IRQPDD = 0). The device is a pullup
or pulldown depending on the polarity chosen. If the user uses an external pullup or pulldown, the
IRQPDD can be written to a 1 to turn off the internal device.
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BIH and BIL instructions may be used to detect the level on the IRQ pin when it is configured to act as the
IRQ input.
NOTE
This pin does not contain a clamp diode to VDD and must not be driven
above VDD. The voltage measured on the internally 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.
When enabling the IRQ pin for use, the IRQF will be set, and must be
cleared prior to enabling the interrupt. When configuring the pin for falling
edge and level sensitivity in a 3V system, it is necessary to wait at least
cycles between clearing the flag and enabling the interrupt.
5.5.2.2
Edge and Level Sensitivity
The IRQMOD control bit reconfigures the detection logic so it can detect edge events and pin levels. In
this edge detection mode, the IRQF status flag is 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 5-1 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 is set. If the associated local interrupt enable is
1, an interrupt request is sent to the CPU. If the global interrupt mask (I bit in the CCR) is 0, the CPU
finishes the current instruction, stacks the PCL, PCH, X, A, and CCR CPU registers, sets the I bit, and then
fetches the interrupt vector for the highest priority pending interrupt. Processing then continues in the
interrupt service routine.
Table 5-1. Vector Summary (from Lowest to Highest Priority)
Vector
Number
Address
(High/Low)
23 to 31
0xFFC0:FFC1
0xFFD0:FFD1
22
0xFFD2:FFD3
21
0xFFD4:FFD5
Vector Name
Module
Source
Local
Enable
Description
Unused vector space (available for user program)
Vscitx
Vscirx
SCI
TRDE
TC
TIE
TCIE
SCI transmit
SCI
IDLE
RDRF
LBKDIF
RXEDGIF
ILIE
RIE
LBKDIE
RXEDGIE
SCI receive
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Table 5-1. Vector Summary (from Lowest to Highest Priority) (continued)
Vector
Number
5.6
Address
(High/Low)
Vector Name
Module
Source
Local
Enable
Description
ORIE
NEIE
FEIE
PEIE
SCI error
20
0xFFD6:FFD7
Vscierr
SCI
OR
NF
FE
PF
19
0xFFD8:FFD9
Unused
—
—
—
—
18
0xFFDA:FFDB
Unused
—
—
—
—
17
0xFFDC:FFDD
Vadc
ADC
COCO
AIEN
ADC
16
0xFFDE:FFDF
Vtpm2ovf
TPM2
TOF
TOIE
TPM2 overflow
15
0xFFE0:FFE1
Vtpm2ch1
TPM2CH1
CH1F
CH1IE
TPM2 channel 1
14
0xFFE2:FFE3
Vtpm2ch0
TPM2CH0
CH0F
CH0IE
TPM2 channel 0
13
0xFFE4:FFE5
Vtpm1ovf
TPM1
TOF
TOIE
TPM1 overflow
12
0xFFE6:FFE7
Unused
—
—
—
—
11
0xFFE8:FFE9
Unused
—
—
—
—
10
0xFFEA:FFEB
Vtpm1ch3
TPM1CH3
CH3F
CH3IE
TPM1 channel 3
9
0xFFEC:FFED
Vtpm1ch2
TPM1CH2
CH2F
CH2IE
TPM1 channel 2
8
0xFFEE:FFEF
Vtpm1ch1
TPM1CH1
CH1F
CH1IE
TPM1 channel 1
7
0xFFF0:FFF1
Vtpm1ch0
TPM1CH0
CH0F
CH0IE
TPM1 channel 0
6
0xFFF2:FFF3
Vmtim
MTIM16
TOF
TOIE
MTIM16 overflow
interrupt
5
0xFFF4:FFF5
Unused
—
—
—
—
4
0xFFF6:FFF7
Unused
—
—
—
—
3
0xFFF8:FFF9
Vlvd
System
control
LVWF
LVWIE
Low-voltage warning
2
0xFFFA:FFFB
Virq
IRQ
IRQF
IRQIE
IRQ pin
1
0xFFFC:FFFD
Vswi
Core
SWI Instruction
—
Software interrupt
0
0xFFFE:FFFF
Vreset
System
control
COP
LVD
RESET pin
Illegal opcode
Illegal address
POR
BDFR
COPE
LVDRE
RSTPE
—
—
—
Watchdog timer
Low-voltage detect
External pin
Illegal opcode
Illegal address
Power-on-reset
BDM force reset
Low-Voltage Detect (LVD) System
The MC9S08FL16 series include a system that protects against low voltage conditions 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.
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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 puts the system into reset. As the supply voltage rises, the LVD circuit holds 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 holds 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
Low-Voltage Warning (LVW) Interrupt Operation
The LVD system has a low voltage warning flag that indicates that the supply voltage is approaching, but
still above, the LVD voltage. When a low voltage warning condition is detected and is configured for
interrupt operation (LVWIE set to 1), LVWF in SPMSC1 is set and an LVW interrupt request occurs.
5.7
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.
Some control bits in the SOPT1 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.”
5.7.1
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)
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Table 5-2. 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.
0 IRQ pin function is disabled.
1 IRQ pin function is enabled.
3
IRQF
2
IRQACK
1
IRQIE
0
IRQMOD
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 0.If edge-and-level detection is selected (IRQMOD = 1),
IRQF cannot be cleared while the IRQ pin remains at its asserted level.
IRQ Interrupt Enable — This read/write control bit determines whether IRQ events generate an interrupt
request.
0 Interrupt request when IRQF set is disabled (use polling).
1 Interrupt requested whenever IRQF = 1.
IRQ Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. See Section 5.5.2.2, “Edge and Level Sensitivity,” for more details.
0 IRQ event on falling/rising edges only.
1 IRQ event on falling/rising edges and low/high levels.
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5.7.2
System Reset Status Register (SRS)
This register includes six 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
0
LVD
—
W
Writing 0x55 and then writing 0xAA to SRS 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
0
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 5-3. 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.
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.
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Table 5-3. SRS Register Field Descriptions (continued)
Field
Description
3
ILAD
Illegal Address— Reset was caused by an attempt to access a illegal address.
0 Reset not caused by an illegal address.
1 Reset caused by an illegal address.
1
LVD
Low Voltage Detect — If the LVDRE bit is set in run mode or both LVDRE and LVDSE bits are set in stop mode,
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.
5.7.3
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 5-4. 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.
5.7.4
System Options Register 1 (SOPT1)
This register may be read at any time. Bits 3 and 2 are unimplemented and always read 0. This is a
write-once register except for TCLKPEN so only the first write after reset is honored. Any subsequent
attempt to write to SOPT1 (intentionally or unintentionally) is ignored to avoid accidental changes to these
sensitive settings. SOPT1 must 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.
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7
6
5
4
STOPE
TCLKPEN
R
COPT
3
2
0
0
1
0
BKGDPE
RSTPE
W
Reset
1
1
0
0
0
0
1
U
POR
1
1
0
0
0
0
1
0
= Unimplemented or Reserved
1
User must not write 1 to bit 3 or bit 2.
Figure 5-5. System Options Register (SOPT1)
Table 5-5. SOPT1 Register Field Descriptions
Field
Description
7:6
COPT[1:0]
COP Watchdog Timeout — These write-once bits select the timeout period of the COP. COPT and COPCLKS
in SOPT2 define the COP timeout period. See Table 5-6.
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 occurs.
0 Stop mode disabled.
1 Stop mode enabled.
4
TCLKPEN
TCLK Pin Enable — This bit defaults to 0 after reset, which disables TCLK as TPM and MTIM16 as alternate
clock and ADC hardware trigger.
0 PTA5/IRQ/TCLK/RESET pin functions as PTA5, IRQ, or RESET
1 PTA5/IRQ/TCLK/RESET pin functions as TCLK
1
BKGDPE
Background Debug Mode Pin Enable — This write-once bit when set enables the PTA4/BKGD/MS pin to
function as BKGD/MS. When clear, the pin functions as output only PTA4. This pin defaults to the BKGD/MS
function following any MCU reset.
0 PTA4/BKGD/MS pin functions as PTA4.
1 PTA4/BKGD/MS pin functions as BKGD/MS.
0
RSTPE
RESET Pin Enable — This write-once bit can be written whenever after any reset. When RSTPE is set, the
PTA5/IRQ/TCLK/RESET pin functions as RESET. When clear, the pin functions as one of its alternative
functions. This pin defaults to PTA5 following an MCU POR. Other resets will not affect this bit. When RSTPE is
set, an internal pullup device on RESET is enabled.
0 PTA5/IRQ/TCLK/RESET pin functions as PTA5, IRQ, or TCLK.
1 PTA5/IRQ/TCLK/RESET pin functions as RESET.
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Table 5-6. COP Configuration Options
Control Bits
COPCLKS
Clock Source
COP Window1 Opens
(COPW = 1)
N/A
N/A
COPT[1:0]
COP Overflow Count
N/A
0:0
0
0:1
1 kHz
N/A
25
COP is disabled
0
1:0
1 kHz
N/A
28 cycles (256 ms1)
0
1:1
1 kHz
N/A
210 cycles (1.024 s1)
1
0:1
Bus
6144 cycles
213 cycles
1
1:0
Bus
49,152 cycles
216 cycles
1
1:1
Bus
196,608 cycles
218 cycles
cycles (32 ms2)
1
Windowed COP operation requires the user to clear the COP timer in the last 25% of the selected timeout period. This column
displays the minimum number of clock counts required before the COP timer can be reset when in windowed COP mode
(COPW = 1).
2
Values shown in milliseconds based on tLPO = 1 ms. See tLPO in the MC9S08FL16 Series Data Sheet for the tolerance of this
value.
5.7.5
R
System Options Register 2 (SOPT2)
7
6
COPCLKS1
COPW1
0
0
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
1
This bit can be written only once after reset. Additional writes are ignored.
Figure 5-6. System Options Register 2 (SOPT2)
Table 5-7. SOPT2 Register Field Descriptions
Field
7
COPCLKS
6
COPW
Description
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.
COP Window — This write-once bit selects the COP operation mode. When set, the 0x55-0xAA write sequence
to the SRS register must occur in the last 25% of the selected period. Any write to the SRS register during the
first 75% of the selected period will reset the MCU.
0 Normal COP operation.
1 Window COP operation.
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Chapter 5 Resets, Interrupts, and System Configuration
5.7.6
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]
R
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
MC9S08FL16 series are hard coded to the value 0x29. See also ID bits in Table 5-9.
7
6
5
4
3
2
1
0
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0
0
1
0
1
0
0
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]
Description
Part Identification Number — Each derivative in the HCS08 family has a unique identification number. The
MC9S08FL16 series are hard coded to the value 0x29. See also ID bits in Table 5-8.
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Chapter 5 Resets, Interrupts, and System Configuration
5.7.7
System Power Management Status and Control 1 Register
(SPMSC1)
This high-page register contains status and control bits to support the low-voltage detect function, and to
enable the bandgap voltage reference for use by the ADC module. This register 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
R
LVWF
W
Reset:
6
1
5
4
3
2
LVWIE
LVDRE2
LVDSE
LVDE2
0
1
1
1
0
1
0
0
BGBE
LVWACK
0
0
0
0
= Unimplemented or Reserved
1
2
LVWF will be set in the case when VSupply transitions below the trip point or after reset and VSupply is already below VLVW.
This bit can be written only once after reset. Additional writes are ignored.
Figure 5-9. System Power Management Status and Control 1 Register (SPMSC1)
Table 5-10. SPMSC1 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 is not present.
1 Low-voltage warning is present or was present.
Low-Voltage Warning Acknowledge — If LVWF = 1, a low-voltage condition has occurred. To acknowledge this
low-voltage warning, write 1 to LVWACK, which automatically clears LVWF to 0 if the low-voltage warning is no
longer present.
5
LVWIE
Low-Voltage Warning Interrupt Enable — This bit enables hardware interrupt requests for LVWF.
0 Hardware interrupt disabled (use polling).
1 Request a hardware interrupt when LVWF = 1.
4
LVDRE
Low-Voltage Detect Reset Enable — This write-once bit enables LVD events to generate a hardware reset
(provided LVDE = 1).
0 LVD events do not generate hardware resets.
1 Force an MCU reset when an enabled low-voltage detect event occurs.
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 write-once 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 — This bit enables 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.
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5.7.8
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. This register must 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.
R
7
6
0
0
5
4
LVDV
LVWV
3
2
1
PPDF
0
0
0
PPDC1
PPDACK
W
Power-on Reset:
0
0
0
0
0
0
0
0
LVD Reset:
0
0
u
u
0
0
0
0
Any other Reset:
0
0
u
u
0
0
0
0
= Unimplemented or Reserved
1
u = Unaffected by reset
This bit can be written only once after reset. Additional writes are ignored.
Figure 5-10. System Power Management Status and Control 2 Register (SPMSC2)
Table 5-11. SPMSC2 Register Field Descriptions
Field
Description
5
LVDV
Low-Voltage Detect Voltage Select — This write-once bit selects the low-voltage detect (LVD) trip point setting.
It also selects the warning voltage range. See Table 5-12.
4
LVWV
Low-Voltage Warning Voltage Select — This bit selects the low-voltage warning (LVW) trip point voltage. See
Table 5-12.
3
PPDF
Partial Power Down Flag — This read-only status bit indicates that the MCU has recovered from stop2 mode.
0 MCU has not recovered from stop2 mode.
1 MCU recovered from stop2 mode.
2
PPDACK
0
PPDC
Partial Power Down Acknowledge — Writing a 1 to PPDACK clears the PPDF bit.
Partial Power Down Control — This write-once bit controls whether stop2 or stop3 mode is selected.
0 Stop3 mode enabled.
1 Stop2, partial power down, mode enabled.
Table 5-12. LVD and LVW Trip Point Typical Values1
LVDV:LVWV
LVW Trip Point
0:0
LVD Trip Point
Reserved.
0:1
1
1:0
VLVW2 = 4.3 V
1:1
VLVW3 = 4.6 V
VLVD1 = 4.0 V
See MC9S08FL16 Series Data Sheet for minimum and maximum values.
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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 MC9S08FL16 series
have four I/O ports which include a total of 30 general-purpose I/O pins. See Chapter 2, “Pins and
Connections,” for more information about the logic and hardware aspects of these pins.
Not all pins are available on all devices. See Table 2-1 to determine which functions are available for a
specific device.
Many of the I/O pins are shared with on-chip peripheral functions, as shown in Table 2-1. The peripheral
modules have priority over the I/Os, so when a peripheral is enabled, the I/O functions are disabled.
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).
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
Port Data and Data Direction
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. They also control what
is read during 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.
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.
6.3
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
6.3.1
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.
6.3.2
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.
This reduces EMC emissions. Slew rate control has no effect on pins which are configured as inputs.
6.3.3
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 can source and sink 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 affects 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
6.4
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 from
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, before the STOP instruction was executed, peripherals may require
being initialized and restored I/O data previously stored in RAM 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 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.
6.5
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 on page zero of the memory map and the pin control
registers are located in the high-page register section of memory.
Refer to the 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 is normally used to translate these names into the appropriate
absolute addresses.
6.5.1
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
PTAD[7:0]
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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Chapter 6 Parallel Input/Output
7
6
5
PTADD7
PTADD6
0
0
4
3
2
1
0
PTADD3
PTADD2
PTADD1
PTADD0
0
0
0
0
R
W
Reset
0
0
Figure 6-3. Data Direction for Port A Register (PTADD)
Table 6-2. PTADD Register Field Descriptions
Field
Description
7:6,3:0
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read for
PTADD[7:6, PTAD reads.
3:0]
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.
6.5.2
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
PTAPE7
PTAPE6
PTAPE5
0
0
0
4
3
2
1
0
PTAPE3
PTAPE2
PTAPE1
PTAPE0
0
0
0
0
R
W
Reset
0
Figure 6-4. Internal Pullup Enable for Port A (PTAPE)
Table 6-3. PTAPE Register Field Descriptions
Field
Description
[7:5,3:0]
Internal Pullup Enable for Port A Bits — Each of these control bits determines if the internal pullup device is
PTAPE[7:5,3 enabled for the associated PTA pin. For port A pins that are configured as outputs, these bits have no effect and
:0]
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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Chapter 6 Parallel Input/Output
7
6
PTASE7
PTASE6
0
0
5
4
3
2
1
0
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
0
0
0
0
0
R
W
Reset
0
Figure 6-5. Output Slew Rate Control Enable for Port A (PTASE)
Table 6-4. PTASE Register Field Descriptions
Field
Description
7:6,4:0
Output Slew Rate Control Enable for Port A Bits — Each of these control bits determine whether output slew
PTASE[7:6,4 rate control is enabled for the associated PTA pin. For port A pins that are configured as inputs, these bits have
:0]
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
PTADS7
PTADS6
0
0
4
3
2
1
0
PTADS4
PTADS3
PTADS2
PTADS1
PTADS0
0
0
0
0
0
R
W
Reset
0
Figure 6-6. Output Drive Strength Selection for Port A (PTADS)
Table 6-5. PTADS Register Field Descriptions
Field
Description
7:6,4:0
Output Drive Strength Selection for Port A Bits — Each of these control bits selects between low and high
PTADS[7:6,4 output drive for the associated PTA pin.
:0]
0 Low output drive enabled for port A bit n.
1 High output drive enabled for port A bit n.
6.5.3
Port B I/O Registers (PTBD and PTBDD)
Port B parallel I/O function is controlled by the registers listed below.
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)
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Chapter 6 Parallel Input/Output
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 Register (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.
6.5.4
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.
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.
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Chapter 6 Parallel Input/Output
7
6
5
4
3
2
1
0
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-10. Output Slew Rate Control Enable for Port B (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. Output 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.
6.5.5
Port C I/O Registers (PTCD and PTCDD)
Port C parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTCD7
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-12. Port C Data Register (PTCD)
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Chapter 6 Parallel Input/Output
Table 6-11. PTCD Register Field Descriptions
Field
Description
7:0
PTCD[7:0]
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
6
5
4
3
2
1
0
PTCDD7
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-13. Data Direction for Port C Register (PTCDD)
Table 6-12. PTCDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port C Bits — These read/write bits control the direction of port C pins and what is read for
PTCDD[7:0] 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.
6.5.6
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.
7
6
5
4
3
2
1
0
PTCPE7
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-14. Internal Pullup Enable for Port C (PTCPE)
Table 6-13. PTCPE Register Field Descriptions
Field
Description
[7:0]
Internal Pullup Enable for Port C Bits — Each of these control bits determines if the internal pullup device is
PTCPE[7:0] 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.
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Chapter 6 Parallel Input/Output
7
6
5
4
3
2
1
0
PTCSE7
PTCSE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-15. Output Slew Rate Control Enable for Port C (PTCSE)
Table 6-14. PTCSE Register Field Descriptions
Field
Description
7:0
Output Slew Rate Control Enable for Port C Bits — Each of these control bits determine whether output slew
PTCSE[7:0] 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
6
5
4
3
2
1
0
PTCDS7
PTCDS6
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-16. Output Drive Strength Selection for Port C (PTCDS)
Table 6-15. PTCDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port C Bits — Each of these control bits selects between low and high
PTCDS[7:0] 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.
6.5.7
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
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
0
0
0
0
0
0
R
W
Reset
0
0
Figure 6-17. Port D Data Register (PTDD)
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Table 6-16. PTDD Register Field Descriptions
Field
Description
5:0
PTDD[5:0]
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
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
0
0
0
0
0
0
R
W
Reset
0
0
Figure 6-18. Data Direction for Port D Register (PTDDD)
Table 6-17. PTDDD Register Field Descriptions
Field
Description
5:0
Data Direction for Port D Bits — These read/write bits control the direction of port D pins and what is read for
PTDDD[5:0] 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.
6.5.8
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.
7
6
5
4
3
2
1
0
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
0
0
0
0
0
0
R
W
Reset
0
0
Figure 6-19. Internal Pullup Enable for Port D (PTDPE)
Table 6-18. PTDPE Register Field Descriptions
Field
Description
[5:0]
Internal Pullup Enable for Port D Bits — Each of these control bits determines if the internal pullup device is
PTDPE[5:0] 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.
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7
6
5
4
3
2
1
0
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
0
0
0
0
0
0
R
W
Reset
0
0
Figure 6-20. Output Slew Rate Control Enable for Port D (PTDSE)
Table 6-19. PTDSE Register Field Descriptions
Field
Description
5:0
Output Slew Rate Control Enable for Port D Bits — Each of these control bits determine whether output slew
PTDSE[5:0] 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
PTDDS5
PTDDS4
PTDDS3
PTDDS2
PTDDS1
PTDDS0
0
0
0
0
0
0
R
W
Reset
0
0
Figure 6-21. Output Drive Strength Selection for Port D (PTDDS)
Table 6-20. PTDDS Register Field Descriptions
Field
Description
5:0
Output Drive Strength Selection for Port D Bits — Each of these control bits selects between low and high
PTDDS[5:0] 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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Central Processor Unit (S08CPUV3)
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
• All registers and memory are mapped to a single 64-Kbyte address space
• 16-bit stack pointer (any size stack anywhere in 64-Kbyte 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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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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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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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, all memory, status
and control registers, and input/output (I/O) ports share a single 64-Kbyte linear address space so a 16-bit
binary address can uniquely identify any memory location. 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.
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,
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.
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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.
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.
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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.
3. Fetch the high-order half of the interrupt vector.
4. Fetch the low-order half of the interrupt vector.
5. Delay for one free bus cycle.
6. 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
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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
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.
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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.
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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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
94
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV3)
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 – – – – –
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
95
Chapter 7 Central Processor Unit (S08CPUV3)
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 – – – – –
5
4
4
5
5
6
rpppp
pppp
pppp
rpppp
rfppp
prpppp
– 1 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)
DIR
IMM
IMM
IX1+
IX+
SP1
dd
dd
dd
dd
dd
dd
dd
dd
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and...
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 –
M  $00
A  $00
X  $00
H  $00
M  $00
M  $00
M  $00
31
41
51
61
71
9E 61
dd
ii
ii
ff
rr
ff
rr
rr
rr
rr
rr
MC9S08FL16 MCU Series Reference Manual, Rev. 3
96
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV3)
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 –
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
0 1 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
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
–  –
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
97
Chapter 7 Central Processor Unit (S08CPUV3)
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
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
 1 1 –
dd
hh ll
ee ff
ff
3
4
4
3
3
ppp
pppp
pppp
ppp
ppp
– 1 1 – – – – –
DIR
INH
INH
IX1
IX
SP1
3C dd
4C
5C
6C ff
7C
9E 6C ff
BC
CC
DC
EC
FC
–  –
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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
98
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV3)
Operation
Object Code
Affect
on CCR
V11H INZC
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 – –  –
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
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Cyc-by-Cyc
Details
5
5
4
5
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 6 of 9)
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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
99
Chapter 7 Central Processor Unit (S08CPUV3)
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 – – – – –
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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
100
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV3)
Operation
Object Code
V11H INZC
 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 – –  –
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
Affect
on CCR
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
A0
B0
C0
D0
E0
F0
9E D0
9E E0
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Cyc-by-Cyc
Details
2
3
4
4
3
3
5
4
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
Cycles
Source
Form
Address
Mode
Table 7-2. Instruction Set Summary (Sheet 8 of 9)
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 – – – – –
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
101
Chapter 7 Central Processor Unit (S08CPUV3)
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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
102
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV3)
Table 7-3. Opcode Map (Sheet 1 of 2)
Bit-Manipulation
Branch
00
5 10
5 20
3 30
BRSET0
3
01
BRCLR0
3
02
BRSET2
3
05
BRSET3
3
07
BRCLR4
3
0A
BRSET5
3
0B
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
DBNZ
INC
REL 2
3 3D
TST
REL 2
3 3E
BIL
BIH
CLR
REL 2
REL
IX
IX1
IX2
IMD
DIX+
DIR 1
INH 1
Relative
Indexed, No Offset
Indexed, 8-Bit Offset
Indexed, 16-Bit Offset
IMM to DIR
DIR to IX+
ROL
INH 2
1 6A
DEC
DBNZ
DEC
DBNZ
IX1 2
5 7C
INC
IX1 1
4 7D
TST
INH 2
5 6E
MOV
CLRX
IX1 1
CLR
ADD
INH 2
1
Stack Pointer, 8-Bit Offset
Stack Pointer, 16-Bit Offset
Indexed, No Offset with
Post Increment
Indexed, 1-Byte Offset with
Post Increment
BSR
Page 2
WAIT
INH 1
2
5 BD
ADD
DIR 3
3 CC
LDX
2
1 AF
TXA
INH 2
LDX
IMM 2
2 BF
AIX
DIR 3
Opcode in
Hexadecimal F0
Number of Bytes 1
EXT 3
4 DF
STX
EXT 3
EOR
ADC
IX2 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
2
IX1 1
3 F9
IX2 2
4 EE
LDX
IX
3
LDA
IX1 1
3 F8
IX2 2
6 ED
JSR
EXT 3
4 DE
LDX
DIR 3
3 CF
STX
IMM 2
JSR
DIR 3
3 CE
BIT
STA
IX2 2
4 EC
JMP
EXT 3
6 DD
IX
3
IX1 1
3 F7
IX2 2
4 EB
ADD
EXT 3
4 DC
JMP
DIR 3
5 CD
JSR
REL 2
2 BE
EXT 3
4 DB
AND
LDA
IX2 2
4 EA
ORA
IX
3
IX1 1
3 F6
IX2 2
4 E9
ADC
CPX
BIT
IX2 2
4 E8
EOR
IX
3
IX1 1
3 F5
IX2 2
4 E7
EXT 3
4 DA
ORA
JMP
INH 2
AE
INH
2+ 9F
ADC
DIR 3
3 CB
ADD
IMM 2
BC
INH
1 AD
NOP
IX 1
IMM 2
2 BB
AND
LDA
EXT 3
4 D9
IX
3
SBC
IX1 1
3 F4
STA
EOR
DIR 3
3 CA
ORA
RSP
1
2+ 9E
STOP
ADC
CPX
IX2 2
4 E6
EXT 3
4 D8
CMP
IX1 1
3 F3
BIT
STA
DIR 3
3 C9
IMM 2
2 BA
ORA
SEI
INH 1
9D
IX
5 8E
MOV
ADC
INH 2
1 AB
INH 1
1 9C
CLRH
IX 1
3
IMD 2
IX+D 1
5 7F
4 8F
CLR
INH 2
INH 1
2 9B
EOR
SBC
IX2 2
4 E5
EXT 3
4 D7
DIR 3
3 C8
IMM 2
2 B9
INH 2
1 AA
CLI
TST
IX1 1
4 7E
MOV
SEC
INH 1
3 9A
PSHH
IX 1
4 8C
EOR
INH 2
1 A9
PULH
IX 1
6 8B
INC
INH 2
1 6D
PSHX
IX 1
4 8A
IX1 1
7 7B
INH 3
1 6C
IX1+
ROL
CLC
INH 1
2 99
AND
IX
3
IX1 1
3 F2
IX2 2
4 E4
EXT 3
4 D6
LDA
STA
IMM 2
2 B8
CPX
EXT 3
4 D5
DIR 3
3 C7
CMP
IX2 2
4 E3
BIT
LDA
AIS
INH 2
1 A8
AND
DIR 3
3 C6
IMM 2
2 B7
TAX
INH 1
3 98
PULX
IX 1
4 89
IX1 1
5 7A
INH 2
4 6B
SP1
SP2
IX+
LSL
IX1 1
5 79
LDA
SBC
3
SUB
IX1 1
3 F1
IX2 2
4 E2
EXT 3
4 D4
BIT
IMM 2
2 B6
EXT 2
1 A7
CPX
DIR 3
3 C5
BIT
STHX
INH 3
2 97
AND
CMP
EXT 3
4 D3
DIR 3
3 C4
IMM 2
2 B5
INH 2
5 A6
PSHA
IX 1
4 88
LSL
INH 2
1 69
DD 2
DIX+ 3
1 5F
1 6F
CLRA
ASR
IX1 1
5 78
TSTX
INH 1
5 5E
MOV
EXT 3
5 4F
ASR
INH 2
1 68
PULA
CPX
AND
TSX
INH 1
3 96
SBC
3 F0
SUB
IX2 2
4 E1
EXT 3
4 D2
DIR 3
3 C3
IMM 2
2 B4
INH 2
2 A5
TPA
IX 1
4 87
CPX
TXS
CMP
SBC
SUB
EXT 3
4 D1
DIR 3
3 C2
IMM 2
2 B3
REL 2
2 A4
INH 1
1 95
DIR 1
4 86
IX1 1
5 77
INCX
INH 1
1 5D
TSTA
DIR 1
6 4E
CPHX
REL 3
3 3F
INCA
DIR 1
4 4D
INH 2
1 67
DBNZX
INH 2
1 5C
CPHX
ROR
BLE
TAP
CMP
SBC
SUB
DIR 3
3 C1
IMM 2
2 B2
REL 2
3 A3
INH 2
1 94
IX 1
5 85
IMM 2
5 76
ROR
DECX
INH 1
4 5B
DBNZA
DIR 2
5 4C
CPHX
ROLX
INH 1
1 5A
DECA
DIR 1
7 4B
REL 3
3 3C
BMS
DIR 2
5 2E
DIR 2
DEC
BMC
DIR 2
5 2D
ROLA
DIR 1
5 4A
REL 2
3 3B
BMI
DIR 2
5 2C
BCLR7
DIR 2
ROL
LSR
CMP
BGT
SWI
SUB
IMM 2
2 B1
REL 2
3 A2
INH 2
11 93
IX 1
4 84
IX1 1
3 75
DIR 3
1 66
BGND
COM
SUB
BLT
INH 2
5+ 92
Register/Memory
3 C0
4 D0
4 E0
2 B0
REL 2
3 A1
RTS
INH 1
4 83
LSR
LSLX
INH 1
1 59
DAA
3 A0
BGE
INH 2
6 91
IX+ 1
1 82
IX1 1
5 74
INH 2
4 65
ASRX
INH 1
1 58
LSLA
DIR 1
5 49
REL 2
3 3A
DIR 2
5 2B
BSET7
DIR 2
5 1F
LSL
BHCS
BPL
ASRA
DIR 1
5 48
REL 2
3 39
DIR 2
5 2A
BCLR6
DIR 2
5 1E
ASR
COM
RORX
INH 1
1 57
CBEQ
INH 1
5 73
INH 2
1 64
LDHX
IMM 2
1 56
RORA
DIR 1
5 47
BHCC
DIR 2
5 29
BSET6
DIR 2
5 1D
ROR
INH 1
1 63
RTI
IX 1
5 81
IX1+ 2
1 72
LSRX
INH 1
3 55
NEG
NSA
COMX
INH 1
1 54
LDHX
DIR 3
5 46
REL 2
3 38
INH 1
1 53
LSRA
DIR 1
4 45
STHX
BEQ
DIR 2
5 28
BCLR5
DIR 2
5 1C
LSR
CBEQ
Control
9 90
4 80
IX1 1
5 71
IMM 3
6 62
DIV
COMA
DIR 1
5 44
REL 2
3 37
BSET5
DIR 2
5 1B
BRCLR5
3
0C
DIR 2
5 27
BCLR4
DIR 2
5 1A
COM
REL 2
3 36
BNE
MUL
5 70
NEG
INH 2
4 61
CBEQX
IMM 3
5 52
EXT 1
5 43
REL 2
3 35
BCS
CBEQA
LDHX
NEGX
INH 1
4 51
DIR 3
5 42
BCC
DIR 2
5 26
BSET4
DIR 2
5 19
CBEQ
REL 2
3 34
DIR 2
5 25
BCLR3
DIR 2
5 18
BRSET4
3
09
BLS
NEGA
DIR 1
5 41
REL 3
3 33
DIR 2
5 24
BSET3
DIR 2
5 17
BRCLR3
3
08
DIR 2
5 23
BCLR2
DIR 2
5 16
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 40
REL 2
3 31
BSET1
DIR 2
5 13
BRCLR1
3
04
BRA
DIR 2
5 21
BCLR0
DIR 2
5 12
BRSET1
3
03
BSET0
DIR 2
5 11
Read-Modify-Write
1 50
1 60
IX
3
LDX
IX
2
STX
IX
3 HCS08 Cycles
Instruction Mnemonic
IX Addressing Mode
SUB
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
103
Chapter 7 Central Processor Unit (S08CPUV3)
Table 7-3. Opcode Map (Sheet 2 of 2)
Bit-Manipulation
Branch
Read-Modify-Write
9E60
Control
Register/Memory
9ED0 5 9EE0
6
NEG
SUB
3
SP1
9E61
6
CBEQ
4
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
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
6 9ECE
LDHX
IX 4
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
MC9S08FL16 MCU Series Reference Manual, Rev. 3
104
Freescale Semiconductor
Chapter 8
Internal Clock Source (S08ICSV3)
8.1
Introduction
The internal clock source (ICS) module provides clock source choices for the MCU. The module contains
a frequency-locked loop (FLL) as a clock source that is controllable by an internal reference clock. The
module can provide this FLL clock or the internal reference clock as a source for the MCU system clock,
ICSOUT.
Whichever clock source is chosen, ICSOUT is passed through a bus clock divider (BDIV), which allows
a lower final output clock frequency to be derived. ICSOUT is twice the bus frequency.
The ICS on the MC9S08FL16 is configured to support only the low range DCO output. Therefore, the
DRS and DRST bits in ICSSC have no affect. The FLL will multiply the reference clock only by 512 or
608 depending on the state of the DMX32 bit.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
105
Chapter 8 Internal Clock Source (S08ICSV3)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 8-1. MC9S08FL16 Series Block Diagram Highlighting ICS Module and Pins
MC9S08FL16 MCU Series Reference Manual, Rev. 3
106
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
8.1.1
Features
Key features of the ICS module are:
• Frequency-locked loop (FLL) is trimmable for accuracy
• Internal or external reference clocks can be used to control the FLL
• Reference divider is provided for external clock
• Internal reference clock has 9 trim bits available
• Internal or external reference clocks can be selected as the clock source for the MCU
• Whichever clock is selected as the source can be divided down
— 2-bit select for clock divider is provided
– Allowable dividers are: 1, 2, 4, 8
• Control signals for a low power oscillator clock generator (OSCOUT) as the ICS external reference
clock are provided
— HGO, RANGE, EREFS, ERCLKEN, EREFSTEN
• FLL Engaged Internal mode is automatically selected out of reset
• BDC clock is provided as a constant divide by 2 of the low range DCO output
• Three selectable digitally-controlled oscillators (DCO) optimized for different frequency ranges.
• Option to maximize output frequency for a 32768 Hz external reference clock source.
8.1.2
Block Diagram
Figure 8-2 is the ICS block diagram.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
107
Internal Clock Source (S08ICSV3)
External Reference
Clock
STOP
OSCOUT
ICSERCLK
ERCLKEN
HGO
EREFS
IRCLKEN
ICSIRCLK
EREFSTEN
RANGE
CLKS
BDIV
IREFSTEN
/ 2n
Internal
Reference
Clock
DCOOUT
LP
ICSDCLK
FLL
n=0-10
RDIV
/2
ICSLCLK
DCOL
Filter DCOM
DCOH
/ 2n
FTRIM TRIM
ICSOUT
n=0-3
IREFS
DMX32
DRS
ICSFFCLK
DRST IREFST CLKST OSCINIT
Internal Clock Source Block
Figure 8-2. Internal Clock Source (ICS) Block Diagram
8.1.3
Modes of Operation
There are seven modes of operation for the ICS: FEI, FEE, FBI, FBILP, FBE, FBELP, and stop.
8.1.3.1
FLL Engaged Internal (FEI)
In FLL engaged internal mode, which is the default mode, the ICS supplies a clock derived from the FLL
which is controlled by the internal reference clock. The BDC clock is supplied from the FLL.
8.1.3.2
FLL Engaged External (FEE)
In FLL engaged external mode, the ICS supplies a clock derived from the FLL which is controlled by an
external reference clock source. The BDC clock is supplied from the FLL.
8.1.3.3
FLL Bypassed Internal (FBI)
In FLL bypassed internal mode, the FLL is enabled and controlled by the internal reference clock, but is
bypassed. The ICS supplies a clock derived from the internal reference clock. The BDC clock is supplied
from the FLL.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
108
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
FLL Bypassed Internal Low Power (FBILP)
8.1.3.4
In FLL bypassed internal low power mode, the FLL is disabled and bypassed, and the ICS supplies a clock
derived from the internal reference clock. The BDC clock is not available.
FLL Bypassed External (FBE)
8.1.3.5
In FLL bypassed external mode, the FLL is enabled and controlled by an external reference clock, but is
bypassed. The ICS supplies a clock derived from the external reference clock source. The BDC clock is
supplied from the FLL.
FLL Bypassed External Low Power (FBELP)
8.1.3.6
In FLL bypassed external low power mode, the FLL is disabled and bypassed, and the ICS supplies a clock
derived from the external reference clock. The BDC clock is not available.
8.1.3.7
Stop (STOP)
In stop mode, the FLL is disabled and the internal or the ICS external reference clocks source (OSCOUT)
can be selected to be enabled or disabled. The BDC clock is not available and the ICS does not provide an
MCU clock source.
NOTE
The DCO frequency changes from the pre-stop value to its reset value and
the FLL will need to re-acquire the lock before the frequency is stable.
Timing sensitive operations should wait for the FLL acquisition time before
executing.
8.2
External Signal Description
There are no ICS signals that connect off chip.
8.3
Register Definition
Figure 8-1 is a summary of ICS registers.
Table 8-1. ICS Register Summary
Name
7
6
5
4
3
2
1
0
IREFS
IRCLKEN
IREFSTEN
EREFS
ERCLKEN
EREFSTEN
R
ICSC1
CLKS
RDIV
W
R
ICSC2
BDIV
RANGE
HGO
LP
W
R
ICSTRM
TRIM
W
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
109
Internal Clock Source (S08ICSV3)
Table 8-1. ICS Register Summary (continued)
Name
7
R
6
5
DRST
3
IREFST
ICSSC
2
CLKST
1
0
OSCINIT
DMX32
W
8.3.1
4
FTRIM
DRS
ICS Control Register 1 (ICSC1)
7
6
5
4
3
2
1
0
IREFS
IRCLKEN
IREFSTEN
1
0
0
R
CLKS
RDIV
W
Reset:
0
0
0
0
0
Figure 8-3. ICS Control Register 1 (ICSC1)
Table 8-2. ICS Control Register 1 Field Descriptions
Field
Description
7:6
CLKS
Clock Source Select — Selects the clock source that controls the bus frequency. The actual bus frequency
depends on the value of the BDIV bits.
00 Output of FLL is selected.
01 Internal reference clock is selected.
10 External reference clock is selected.
11 Reserved, defaults to 00.
5:3
RDIV
Reference Divider — Selects the amount to divide down the external reference clock. Resulting frequency must
be in the range 31.25 kHz to 39.0625 kHz. See Table 8-3 for the divide-by factors.
2
IREFS
Internal Reference Select — The IREFS bit selects the reference clock source for the FLL.
1 Internal reference clock selected.
0 External reference clock selected.
1
IRCLKEN
0
IREFSTEN
Internal Reference Clock Enable — The IRCLKEN bit enables the internal reference clock for use as
ICSIRCLK.
1 ICSIRCLK active.
0 ICSIRCLK inactive.
Internal Reference Stop Enable — The IREFSTEN bit controls whether or not the internal reference clock
remains enabled when the ICS enters stop mode.
1 Internal reference clock stays enabled in stop if IRCLKEN is set before entering stop.
0 Internal reference clock is disabled in stop.
Table 8-3. Reference Divide Factor
RDIV
RANGE=0
RANGE=1
0
11
32
1
2
64
2
4
128
3
8
256
MC9S08FL16 MCU Series Reference Manual, Rev. 3
110
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
Table 8-3. Reference Divide Factor
1
8.3.2
RDIV
RANGE=0
RANGE=1
4
16
512
5
32
1024
6
64
Reserved
7
128
Reserved
Reset default
ICS Control Register 2 (ICSC2)
7
6
5
4
3
2
RANGE
HGO
LP
EREFS
0
0
0
0
1
0
R
BDIV
ERCLKEN EREFSTEN
W
Reset:
0
1
0
0
Figure 8-4. ICS Control Register 2 (ICSC2)
Table 8-4. ICS Control Register 2 Field Descriptions
Field
Description
7:6
BDIV
Bus Frequency Divider — Selects the amount to divide down the clock source selected by the CLKS bits. This
controls the bus frequency.
00 Encoding 0 — Divides selected clock by 1.
01 Encoding 1 — Divides selected clock by 2 (reset default).
10 Encoding 2 — Divides selected clock by 4.
11 Encoding 3 — Divides selected clock by 8.
5
RANGE
Frequency Range Select — Selects the frequency range for the external oscillator.
1 High frequency range selected for the external oscillator.
0 Low frequency range selected for the external oscillator.
4
HGO
High Gain Oscillator Select — The HGO bit controls the external oscillator mode of operation.
1 Configure external oscillator for high gain operation.
0 Configure external oscillator for low power operation.
3
LP
Low Power Select — The LP bit controls whether the FLL is disabled in FLL bypassed modes.
1 FLL is disabled in bypass modes unless BDM is active.
0 FLL is not disabled in bypass mode.
2
EREFS
1
ERCLKEN
External Reference Select — The EREFS bit selects the source for the external reference clock.
1 Oscillator requested.
0 External Clock Source requested.
External Reference Enable — The ERCLKEN bit enables the external reference clock for use as ICSERCLK.
1 ICSERCLK active.
0 ICSERCLK inactive.
0
External Reference Stop Enable — The EREFSTEN bit controls whether or not the external reference clock
EREFSTEN source (OSCOUT) remains enabled when the ICS enters stop mode.
1 External reference clock source stays enabled in stop if ERCLKEN is set before entering stop.
0 External reference clock source is disabled in stop.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
111
Internal Clock Source (S08ICSV3)
8.3.3
ICS Trim Register (ICSTRM)
7
6
5
4
3
2
1
0
R
TRIM
W
Reset: Note: TRIM is loaded during reset from a factory programmed location when not in BDM mode. If in a BDM
mode, a default value of 0x80 is loaded.
Figure 8-5. ICS Trim Register (ICSTRM)
Table 8-5. ICS Trim Register Field Descriptions
Field
Description
7:0
TRIM
ICS Trim Setting — The TRIM bits control the internal reference clock frequency by controlling the internal
reference clock period. The bits’ effect are binary weighted (in other words, bit 1 adjusts twice as much as bit 0).
Increasing the binary value in TRIM will increase the period, and decreasing the value will decrease the period.
An additional fine trim bit is available in ICSSC as the FTRIM bit.
8.3.4
ICS Status and Control (ICSSC)
7
R
6
5
DRST
4
3
IREFST
2
CLKST
1
OSCINIT
DMX32
W
Reset:
0
FTRIM1
DRS
0
0
0
1
0
0
0
Figure 8-6. ICS Status and Control Register (ICSSC)
1
FTRIM is loaded during reset from a factory programmed location when not in any BDM mode. If in a BDM mode, FTRIM
gets loaded with a value of 1’b0.
Table 8-6. ICS Status and Control Register Field Descriptions
Field
Description
7-6
DRST
DRS
DCO Range Status — The DRST read field indicates the current frequency range for the FLL output, DCOOUT.
See Table 8-7. The DRST field does not update immediately after a write to the DRS field due to internal
synchronization between clock domains. Writing the DRS bits to 2’b11 is ignored and the DRST bits remain with
the current setting.
DCO Range Select — The DRS field selects the frequency range for the FLL output, DCOOUT. Writes to the
DRS field while the LP bit is set are ignored.
00 Low range.
01 Mid range.
10 High range.
11 Reserved.
5
DMX32
DCO Maximum frequency with 32.768 kHz reference — The DMX32 bit controls whether or not the DCO
frequency range is narrowed to its maximum frequency with a 32.768 kHz reference. See Table 8-7.
0 DCO has default range of 25%.
1 DCO is fined tuned for maximum frequency with 32.768 kHz reference.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
112
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
Table 8-6. ICS Status and Control Register Field Descriptions (continued)
Field
Description
4
IREFST
Internal Reference Status — The IREFST bit indicates the current source for the reference clock. The IREFST
bit does not update immediately after a write to the IREFS bit due to internal synchronization between clock
domains.
0 Source of reference clock is external clock.
1 Source of reference clock is internal clock.
3-2
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 Output of FLL is selected.
01 FLL Bypassed, Internal reference clock is selected.
10 FLL Bypassed, External reference clock is selected.
11
Reserved.
1
OSCINIT
0
FTRIM
OSC Initialization — If the external reference clock is selected by ERCLKEN or by the ICS being in FEE, FBE,
or FBELP mode, and if EREFS is set, then this bit is set after the initialization cycles of the external oscillator
clock have completed. This bit is only cleared when either ERCLKEN or EREFS are cleared.
ICS Fine Trim — The FTRIM bit controls the smallest adjustment of the internal reference clock frequency.
Setting FTRIM will increase the period and clearing FTRIM will decrease the period by the smallest amount
possible.
Table 8-7. DCO frequency range1
DRS
00
01
10
11
1
DMX32
Reference range
FLL factor
DCO range
0
31.25 - 39.0625 kHz
512
16 - 20 MHz
1
32.768 kHz
608
19.92 MHz
0
31.25 - 39.0625 kHz
1024
32 - 40 MHz
1
32.768 kHz
1216
39.85 MHz
0
31.25 - 39.0625 kHz
1536
48 - 60 MHz
1
32.768 kHz
1824
59.77 MHz
Reserved
The resulting bus clock frequency should not exceed the maximum specified bus
clock frequency of the device.
r
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
113
Internal Clock Source (S08ICSV3)
8.4
Functional Description
8.4.1
Operational Modes
IREFS=1
CLKS=00
FLL Engaged
Internal (FEI)
IREFS=0
CLKS=10
BDM Enabled
or LP =0
FLL Bypassed
External Low
Power(FBELP)
FLL Bypassed
External (FBE)
IREFS=0
CLKS=10
BDM Disabled
and LP=1
IREFS=1
CLKS=01
BDM Enabled
or LP=0
FLL Bypassed
Internal (FBI)
FLL Bypassed
Internal Low
Power(FBILP)
IREFS=1
CLKS=01
BDM Disabled
and LP=1
FLL Engaged
External (FEE)
IREFS=0
CLKS=00
Entered from any state
when MCU enters stop
Stop
Returns to state that was active
before MCU entered stop, unless
RESET occurs while in stop.
Figure 8-7. Clock Switching Modes
The seven states of the ICS are shown as a state diagram and are described below. The arrows indicate the
allowed movements between the states.
8.4.1.1
FLL Engaged Internal (FEI)
FLL engaged internal (FEI) is the default mode of operation and is entered when all the following
conditions occur:
• CLKS bits are written to 00.
• IREFS bit is written to 1.
In FLL engaged internal mode, the ICSOUT clock is derived from the FLL clock, which is controlled by
the internal reference clock. The FLL loop locks the frequency to the FLL factor times the internal
reference frequency. The ICSLCLK is available for BDC communications, and the internal reference
clock is enabled.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
114
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
8.4.1.2
FLL Engaged External (FEE)
The FLL engaged external (FEE) mode is entered when all the following conditions occur:
•
•
•
CLKS bits are written to 00.
IREFS bit is written to 0.
RDIV bits are written to divide external reference clock to be within the range of 31.25 kHz to
39.0625 kHz.
In FLL engaged external mode, the ICSOUT clock is derived from the FLL clock which is controlled by
the external reference clock source.The FLL loop locks the frequency to the FLL factor times the external
reference frequency, as selected by the RDIV bits. The ICSLCLK is available for BDC communications,
and the external reference clock is enabled.
8.4.1.3
FLL Bypassed Internal (FBI)
The FLL bypassed internal (FBI) mode is entered when all the following conditions occur:
• CLKS bits are written to 01.
• IREFS bit is written to 1.
• BDM mode is active or LP bit is written to 0.
In FLL bypassed internal mode, the ICSOUT clock is derived from the internal reference clock. The FLL
clock is controlled by the internal reference clock, and the FLL loop locks the FLL frequency to the FLL
factor times the internal reference frequency. The ICSLCLK will be available for BDC communications,
and the internal reference clock is enabled.
8.4.1.4
FLL Bypassed Internal Low Power (FBILP)
The FLL bypassed internal low power (FBILP) mode is entered when all the following conditions occur:
• CLKS bits are written to 01.
• IREFS bit is written to 1.
• BDM mode is not active and LP bit is written to 1.
In FLL bypassed internal low power mode, the ICSOUT clock is derived from the internal reference clock
and the FLL is disabled. The ICSLCLK will be not be available for BDC communications, and the internal
reference clock is enabled.
8.4.1.5
FLL Bypassed External (FBE)
The FLL bypassed external (FBE) mode is entered when all the following conditions occur:
• CLKS bits are written to 10.
• IREFS bit is written to 0.
• RDIV bits are written to divide external reference clock to be within the range of 31.25 kHz to
39.0625 kHz.
• BDM mode is active or LP bit is written to 0.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
Freescale Semiconductor
115
Internal Clock Source (S08ICSV3)
In FLL bypassed external mode, the ICSOUT clock is derived from the external reference clock source.
The FLL clock is controlled by the external reference clock, and the FLL loop locks the FLL frequency to
the FLL factor times the external reference frequency, as selected by the RDIV bits, so that the ICSLCLK
will be available for BDC communications, and the external reference clock is enabled.
8.4.1.6
FLL Bypassed External Low Power (FBELP)
The FLL bypassed external low power (FBELP) mode is entered when all the following conditions occur:
• CLKS bits are written to 10.
• IREFS bit is written to 0.
• BDM mode is not active and LP bit is written to 1.
In FLL bypassed external low power mode, the ICSOUT clock is derived from the external reference clock
source and the FLL is disabled. The ICSLCLK will be not be available for BDC communications. The
external reference clock source is enabled.
8.4.1.7
Stop
Stop mode is entered whenever the MCU enters a STOP state. In this mode, all ICS clock signals are static
except in the following cases:
ICSIRCLK will be active in stop mode when all the following conditions occur:
• IRCLKEN bit is written to 1.
• IREFSTEN bit is written to 1.
OSCOUT will be active in stop mode when all the following conditions occur:
• ERCLKEN bit is written to 1.
• EREFSTEN bit is written to 1.
8.4.2
Mode Switching
The IREF bit can be changed at anytime, but the actual switch to the newly selected clock is shown by the
IREFST bit. When switching between FLL engaged internal (FEI) and FLL engaged external (FEE)
modes, the FLL begins locking again after the switch is completed.
The CLKS bits can also be changed at anytime, but the actual switch to the newly selected clock is shown
by the CLKST bits. If the newly selected clock is not available, the previous clock remains selected.
The DRS bits can be changed at anytime except when LP bit is 1. If the DRS bits are changed while in
FLL engaged internal (FEI) or FLL engaged external (FEE), the bus clock remains at the previous DCO
range until the new DCO starts. When the new DCO starts the bus clock switches to it. After switching to
the new DCO the FLL remains unlocked for several reference cycles. Once the selected DCO startup time
is over, the FLL is locked. The completion of the switch is shown by the DRST bits.
MC9S08FL16 MCU Series Reference Manual, Rev. 3
116
Freescale Semiconductor
Internal Clock Source (S08ICSV3)
8.4.3
Bus Frequency Divider
The BDIV bits can be changed at anytime and the actual switch to the new frequency occurs immediately.
8.4.4
Low Power Bit Usage
The low power bit (LP) is provided to allow the FLL to be disabled and thus conserve power when it is
not being used. The DRS bits can not be written while LP bit is 1.
However, in some applications it may be desirable to allow the FLL to be enabled and to lock for maximum
accuracy before switching to an FLL engaged mode. To do this, write the LP bit to 0.
8.4.5
DCO Maximum Frequency with 32.768 kHz Oscillator
The FLL has an option to change the clock multiplier for the selected DCO range such that it results in the
maximum bus frequency with a common 32.768 kHz crystal reference clock.
8.4.6
Internal Reference Clock
When IRCLKEN is set the internal reference clock signal is presented as ICSIRCLK, which can be used
as an additional clock source. To re-target the ICSIRCLK frequency, write a new value to the TRIM bits
in the ICSTRM register to trim the period of the internal reference clock:
• Writing a larger value slows down the ICSIRCLK frequency.
• Writing a smaller value to the ICSTRM register speeds up the ICSIRCLK frequency.
The TRIM bits effect the ICSOUT frequency if the ICS is in FLL engaged internal (FEI), FLL bypassed
internal (FBI), or FLL bypassed internal low power (FBILP) mode.
Until ICSIRCLK is trimmed, programming low reference divider (RDIV) factors may result in ICSOUT
frequencies that exceed the maximum chip-level frequency and violate the chip-level clock timing
specifications (see the Device Overview chapter).
If IREFSTEN is set and the IRCLKEN bit is written to 1, the internal reference clock keeps running during
stop mode in order to provide a fast recovery upon exiting stop.
All MCU devices are factory programmed with a trim value in a reserved memory location. This value is
uploaded to the ICSTRM register and ICS FTRIM register during any reset initialization. For finer
precision, trim the internal oscillator in the application and set the FTRIM bit accordingly.
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117
Internal Clock Source (S08ICSV3)
8.4.7
External Reference Clock
The ICS module supports an external reference clock with frequencies between 31.25 kHz to 40 MHz in
all modes. When the ERCLKEN is set, the external reference clock signal is presented as ICSERCLK,
which can be used as an additional clock source in run mode. When IREFS = 1, the external reference
clock is not used by the FLL and will only be used as ICSERCLK. In these modes, the frequency can be
equal to the maximum frequency the chip-level timing specifications support (see the Device Overview
chapter).
If EREFSTEN is set and the ERCLKEN bit is written to 1, the external reference clock source (OSCOUT)
keeps running during stop mode in order to provide a fast recovery upon exiting stop.
8.4.8
Fixed Frequency Clock
The ICS presents the divided FLL reference clock as ICSFFCLK for use as an additional clock source.
ICSFFCLK frequency must be no more than 1/4 of the ICSOUT frequency to be valid.
8.4.9
Local Clock
The ICS presents the low range DCO output clock divided by two as ICSLCLK for use as a clock source
for BDC communications. ICSLCLK is not available in FLL bypassed internal low power (FBILP) and
FLL bypassed external low power (FBELP) modes.
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Chapter 9
16-Bit Timer/PWM (S08TPMV3)
9.1
Introduction
MC9S08FL16 series contain two multi-channel TPM modules. TPM1 contains four 16-bit channels and
TPM2 contains two 16-bit channels. Each channel can operate as input capture, output compare, or
buffered edge- or center-aligned PWM functions.
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119
Chapter 9 16-Bit Timer/PWM (S08TPMV3)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
VSS
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 9-1. MC9S08FL16 Series Block Diagram Highlighting TPM Modules and Pins
9.1.1
TPMV3 Differences from Previous Versions
The TPMV3 is the latest version of the Timer/PWM module that addresses errata found in previous
versions. The following section outlines the differences between TPMV3 and TPMV2 modules, and any
considerations that should be taken when porting code.
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Chapter 9 16-Bit Timer/PWM (S08TPMV3)
Table 9-1. TPMV2 and TPMV3 Porting Considerations
Action
TPMV3
TPMV2
Write to TPMxCnTH:L registers1
Any write to TPMxCNTH or TPMxCNTL registers
Clears the TPM counter
(TPMxCNTH:L) and the
prescaler counter.
Clears the TPM counter
(TPMxCNTH:L) only.
Read of TPMxCNTH:L registers1
In BDM mode, any read of TPMxCNTH:L registers
Returns the value of the TPM If only one byte of the
counter that is frozen.
TPMxCNTH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the frozen TPM counter value).
In BDM mode, a write to TPMxSC, TPMxCNTH or TPMxCNTL Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
Read of TPMxCnVH:L registers2
In BDM mode, any read of TPMxCnVH:L registers
Returns the value of the
TPMxCnVH:L register.
If only one byte of the
TPMxCnVH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the value in the TPMxCnVH:L
registers).
In BDM mode, a write to TPMxCnSC
Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
In Input Capture mode, writes to TPMxCnVH:L registers3
Not allowed.
Allowed.
In Output Compare mode, when (CLKSB:CLKSA not = 0:0),
writes to TPMxCnVH:L registers3
Update 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.
Always update these registers
when their second byte is
written.
Write to TPMxCnVH:L registers
In Edge-Aligned PWM mode when (CLKSB:CLKSA not = 00), Update the TPMxCnVH:L
writes to TPMxCnVH:L registers
registers with the value of
their write buffer after both
bytes were written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
0xFFFE to 0xFFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to 0x0000.
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Chapter 9 16-Bit Timer/PWM (S08TPMV3)
Table 9-1. TPMV2 and TPMV3 Porting Considerations (continued)
Action
TPMV3
In Center-Aligned PWM mode when (CLKSB:CLKSA not =
00), writes to TPMxCnVH:L registers4
TPMV2
Update the TPMxCnVH:L
registers with the value of
their write buffer after both
bytes are written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
0xFFFE to 0xFFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to
(TPMxMODH:L - 1).
Produces 100% duty cycle.
Produces 0% duty cycle.
Produces a near 100% duty
cycle.
Produces 0% duty cycle.
TPMxCnVH:L is changed from 0x0000 to a non-zero value7
Waits for the start of a new
PWM period to begin using
the new duty cycle setting.
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 0x00008
Finishes the current PWM
period using the old duty
cycle setting.
Finishes the current PWM
period using the new duty
cycle setting.
Clears the write coherency
mechanism of
TPMxMODH:L registers.
Does not clear the write
coherency mechanism.
Center-Aligned PWM
When TPMxCnVH:L = TPMxMODH:L5
When TPMxCnVH:L = (TPMxMODH:L -
1)6
Write to TPMxMODH:L registers in BDM mode
In BDM mode, a write to TPMxSC register
1
2
3
4
5
6
7
8
For more information, refer to Section 9.3.2, “TPM-Counter Registers (TPMxCNTH:TPMxCNTL).” [SE110-TPM case 7]
For more information, refer to Section 9.3.5, “TPM Channel Value Registers (TPMxCnVH:TPMxCnVL).”
For more information, refer to Section 9.4.2.1, “Input Capture Mode .”
For more information, refer to Section 9.4.2.4, “Center-Aligned PWM Mode.”
For more information, refer to Section 9.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 1]
For more information, refer to Section 9.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 2]
For more information, refer to Section 9.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 3 and 5]
For more information, refer to Section 9.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 4]
9.1.2
Migrating from TPMV1
In addition to Section 9.1.1, “TPMV3 Differences from Previous Versions,” keep in mind the following
considerations when migrating from a device that uses TPMV1.
• You can write to the Channel Value register (TPMxCnV) when the timer is not in input capture
mode for TPMV2, not TPMV3.
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Chapter 9 16-Bit Timer/PWM (S08TPMV3)
•
•
In edge- or center- aligned modes, the Channel Value register (TPMxCnV) registers only update
when the timer changes from TPMMOD-1 to TPMMOD, or in the case of a free running timer
from 0xFFFE to 0xFFFF.
Also, when configuring the TPM modules, it is best to write to TPMxSC before TPMxCnV as a
write to TPMxSC resets the coherency mechanism on the TPMxCnV registers.
Table 9-2. Migrating to TPMV3 Considerations
When...
Writing to the Channel Value Register (TPMxCnV)
register...
Action / Best Practice
Timer must be in Input Capture mode.
Updating the Channel Value Register (TPMxCnV) Only occurs when the timer changes from
register in edge-aligned or center-aligned modes... TPMMOD-1 to TPMMOD (or in the case of a free
running timer, from 0xFFFE to 0xFFFF).
Reseting the coherency mechanism for the
Channel Value Register (TPMxCnV) register...
Write to TPMxSC.
Configuring the TPM modules...
Write first to TPMxSC and then to TPMxCnV
register.
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16-Bit Timer/PWM (S08TPMV3)
9.1.3
Features
The TPM includes these distinctive features:
• One to eight channels:
— Each channel is 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 is configured for buffered, center-aligned pulse-width-modulation (CPWM) on all
channels
• Timer clock source selectable as bus clock, fixed frequency clock, or an external clock
— Prescale taps for divide-by 1, 2, 4, 8, 16, 32, 64, or 128 used for any clock input selection
— Fixed frequency clock is an additional clock input to allow the selection of an on chip clock
source other than bus clock
— Selecting external clock connects TPM clock to a chip level input pin therefore allowing to
synchronize the TPM counter with an off chip clock source
• 16-bit free-running or modulus count with up/down selection
• One interrupt per channel and one interrupt for TPM counter overflow
9.1.4
Modes of Operation
In general, TPM channels are 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 MCU is in active BDM background or BDM foreground mode, the TPM temporarily suspends
all counting until the MCU returns to normal user operating mode. During stop mode, all TPM input clocks
are stopped, so the TPM is effectively disabled until clocks resume. During wait mode, the TPM continues
to operate normally. If the TPM does not need to produce a real time reference or provide the interrupt
sources needed to wake the MCU from wait mode, the power can then be saved 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) are selected as the active edge that 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 is selected to force the pin to zero, force the pin to one, toggle the pin, or ignore the pin (used
for software timing functions).
• Edge-aligned PWM mode
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Freescale Semiconductor
16-Bit Timer/PWM (S08TPMV3)
•
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. You can 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 that is 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.
9.1.5
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 9-2 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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16-Bit Timer/PWM (S08TPMV3)
no clock selected
(TPM counter disable)
bus clock
Prescaler
³(1, 2, 4, 8, 16, 32, 64 or 128)
fixed frequency clock
external clock
synchronizer
PS[2:0]
CLKSB:CLKSA
CPWMS
TPM counter
(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
Interrupt
logic
16-bit latch
TPM counter
channel 1
MS0B
MS0A
ELS1B
ELS1A
CH0IE
Port
logic
TPMxCH1
16-bit comparator
TPMxC1VH:TPMxC1VL
CH1F
Interrupt
logic
16-bit latch
MS1B
CH1IE
MS1A
up to 8 channels
ELS7B
channel 7
ELS7A
Port
logic
TPMxCH7
16-bit comparator
TPMxC7VH:TPMxC7VL
CH7F
Interrupt
logic
16-bit latch
MS7B
MS7A
CH7IE
Figure 9-2. TPM Block Diagram
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16-Bit Timer/PWM (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.
9.2
Signal Description
Table 9-3 shows the user-accessible signals for the TPM. The number of channels are 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 9-3. Signal Properties
Name
EXTCLK1
TPMxCHn2
Function
External clock source that is selected to drive the TPM counter.
I/O pin associated with TPM channel n.
1
The external clock pin can be shared with any channel pin. However, depending upon full-chip
implementation, this signal could be connected to a separate external pin.
2 n = channel number (1–8)
9.2.1
9.2.1.1
Detailed Signal Descriptions
EXTCLK — External Clock Source
The external clock signal can share the same pin as a channel pin, however the channel pin can not be used
for channel I/O function when external clock is selected. If this pin is used as an external clock
(CLKSB:CLKSA = 1:1), the channel can still be configured to output compare mode therefore allowing
its use as a timer (ELSnB:ELSnA = 0:0).
For proper TPM operation, the external clock frequency must not exceed one-fourth of the bus clock
frequency.
9.2.1.2
TPMxCHn — TPM Channel n I/O Pins
The TPM channel does not control the I/O pin when ELSnB:ELSnA or CLKSB:CLKSA are cleared so it
normally reverts to general purpose I/O control. When CPWMS is set and ELSnB:ELSnA are not cleared,
all TPM channels are configured for center-aligned PWM and the TPMxCHn pins are all controlled by
TPM. When CPWMS is cleared, 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  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 trigger input capture events. The
channel input signal is synchronized on the bus clock. This implies the minimum pulse width—that can
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127
16-Bit Timer/PWM (S08TPMV3)
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).
When a channel is configured for output compare (CPWMS = 0, MSnB:MSnA = 0:1, and
ELSnB:ELSnA  0:0), the TPMxCHn pin is an output controlled by the TPM. The ELSnB:ELSnA bits
determine whether the TPMxCHn pin is toggled, cleared, or set each time the 16-bit channel value register
matches the TPM 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, the pin is then toggled.
When a channel is configured for edge-aligned PWM (CPWMS = 0, MSnB = 1, and
ELSnB:ELSnA  0:0), the TPMxCHn pin is an output controlled by the TPM, and ELSnB:ELSnA bits
control the polarity of the PWM output signal. When ELSnB is set and ELSnA is cleared, the TPMxCHn
pin is forced high at the start of each new period (TPMxCNT=0x0000), and it is forced low when the
channel value register matches the TPM counter. When ELSnA is set, the TPMxCHn pin is forced low at
the start of each new period (TPMxCNT=0x0000), and it is forced high when the channel value register
matches the TPM counter.
TPMxMODH:TPMxMODL = 0x0008
TPMxCnVH:TPMxCnVL = 0x0005
TPMxCNTH:TPMxCNTL
...
0
1
2
3
4
5
6
7
8
0
1
2
...
1
2
...
TPMxCHn
CHnF bit
TOF bit
Figure 9-3. 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
TPMxCHn
CHnF bit
TOF bit
Figure 9-4. Low-true pulse of an edge-aligned PWM
When the TPM is configured for center-aligned PWM (CPWMS = 1 and ELSnB:ELSnA  0:0), the
TPMxCHn pins are outputs controlled by the TPM, and ELSnB:ELSnA bits control the polarity of the
PWM output signal. If ELSnB is set and ELSnA is cleared, the corresponding TPMxCHn pin is cleared
when the TPM counter is counting up, and the channel value register matches the TPM counter; and it is
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16-Bit Timer/PWM (S08TPMV3)
set when the TPM counter is counting down, and the channel value register matches the TPM counter. If
ELSnA is set, the corresponding TPMxCHn pin is set when the TPM counter is counting up and the
channel value register matches the TPM counter; and it is cleared when the TPM counter is counting down
and the channel value register matches the TPM 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
...
6
7
8
7
6
5
...
TPMxCHn
CHnF bit
TOF bit
Figure 9-5. 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
TPMxCHn
CHnF bit
TOF bit
Figure 9-6. Low-true pulse of a center-aligned PWM
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16-Bit Timer/PWM (S08TPMV3)
9.3
Register Definition
9.3.1
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 9-7. TPM Status and Control Register (TPMxSC)
Table 9-4. 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 completed, the sequence is reset so TOF remains 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. 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.
4–3
Clock source selection bits. As shown in Table 9-5, this 2-bit field is used to disable the TPM counter or select one
CLKS[B:A] of three clock sources to TPM counter and counter prescaler.
2–0
PS[2:0]
Prescale factor select. This 3-bit field selects one of eight division factors for the TPM clock as shown in Table 9-6.
This prescaler is located after any clock synchronization or clock selection so it affects the clock selected to drive
the TPM counter. The new prescale factor affects the selected clock on the next bus clock cycle after the new
value is updated into the register bits.
Table 9-5. TPM Clock Selection
CLKSB:CLKSA
TPM Clock to Prescaler Input
00
No clock selected (TPM counter disable)
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16-Bit Timer/PWM (S08TPMV3)
Table 9-5. TPM Clock Selection
CLKSB:CLKSA
TPM Clock to Prescaler Input
01
Bus clock
10
Fixed frequency clock
11
External clock
Table 9-6. Prescale Factor Selection
9.3.2
PS[2:0]
TPM Clock 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 big-endian or
little-endian order that 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).
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.
7
6
5
4
3
2
R
TPMxCNT[15:8]
W
Any write to TPMxCNTH clears the 16-bit counter
Reset
0
0
0
0
0
0
1
0
0
0
Figure 9-8. TPM Counter Register High (TPMxCNTH)
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16-Bit Timer/PWM (S08TPMV3)
7
6
5
4
3
2
R
TPMxCNT[7:0]
W
Any write to TPMxCNTL clears the 16-bit counter
Reset
0
0
0
0
0
0
1
0
0
0
Figure 9-9. TPM Counter Register Low (TPMxCNTL)
When BDM is active, the timer counter is frozen (this is the value you read). The coherency mechanism
is frozen so 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 you were in the middle of reading
a 16-bit register when BDM became active, it reads 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:TPMxCNTL registers, regardless of the data involved in the
write.
9.3.3
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
that results in a free running timer counter (modulo disabled).
Writes to any of the registers TPMxMODH and TPMxMODL actually writes to buffer registers and the
registers are updated with the value of their write buffer according to the value of CLKSB:CLKSA bits:
• If CLKSB and CLKSA are cleared, the registers are updated when the second byte is written
• If CLKSB and CLKSA are not cleared, 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 is manually reset by writing to the TPMxSC address (whether BDM is active or
not).
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxSC register) so
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
0
0
0
R
TPMxMOD[15:8]
W
Reset
0
0
0
0
0
Figure 9-10. TPM Counter Modulo Register High (TPMxMODH)
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16-Bit Timer/PWM (S08TPMV3)
7
6
5
4
3
2
1
0
0
0
0
R
TPMxMOD[7:0]
W
Reset
0
0
0
0
0
Reset the TPM counter before writing to the TPM modulo registers to avoid confusion about when the first
counter overflow occurs.
9.3.4
TPM Channel n Status and Control Register (TPMxCnSC)
TPMxCnSC contains the channel-interrupt-status flag and control bits that configure the interrupt enable,
channel configuration, and pin function.
7
R
CHnF
W
0
Reset
0
6
5
4
3
2
CHnIE
MSnB
MSnA
ELSnB
ELSnA
0
0
0
0
0
1
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-12. TPM Channel n Status and Control Register (TPMxCnSC)
Table 9-7. 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 input. 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
is not 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 this bit is set and channel n interrupt is enabled (CHnIE = 1). Clear
CHnF by reading TPMxCnSC while this bit is set and then writing a logic 0 to it. If another interrupt request occurs
before the clearing sequence is completed CHnF remains set. This is done so a CHnF interrupt request is not lost
due to clearing a previous CHnF.
Reset clears this 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 this bit.
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 is cleared, setting the MSnB bit configures TPM channel n for
edge-aligned PWM mode. Refer to the summary of channel mode and setup controls in Table 9-8.
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16-Bit Timer/PWM (S08TPMV3)
Table 9-7. TPMxCnSC Field Descriptions (continued)
Field
Description
4
MSnA
Mode select A for TPM channel n. When CPWMS and MSnB are cleared, the MSnA bit configures TPM channel
n for input capture mode or output compare mode. Refer to Table 9-8 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 9-8, these bits select the polarity of the input edge that triggers an input capture event, select
the level that is driven in response to an output compare match, or select the polarity of the PWM output.
If ELSnB and ELSnA bits are cleared, the channel pin is not controlled by TPM. This configuration can be used
by software compare only, because it does not require the use of a pin for the channel.
Table 9-8. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
X
XX
00
Pin is not controlled by TPM. It is reverted to general purpose I/O or
other peripheral control
0
00
01
Input capture
01
11
Capture on rising or falling edge
Output compare
Toggle output on channel match
10
Clear output on channel match
11
Set output on channel match
10
Edge-aligned
PWM
High-true pulses (clear output on channel match)
Center-aligned
PWM
High-true pulses (clear output on channel match
when TPM counter is counting up)
X1
9.3.5
Software compare only
01
10
XX
Capture on rising edge only
Capture on falling edge only
X1
1
Configuration
10
00
1X
Mode
Low-true pulses (set output on channel match)
Low-true pulses (set output on channel match when
TPM counter is counting 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
0
0
0
R
TPMxCnV[15:8]
W
Reset
0
0
0
0
0
Figure 9-13. TPM Channel Value Register High (TPMxCnVH)
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16-Bit Timer/PWM (S08TPMV3)
7
6
5
4
3
2
1
0
0
0
0
R
TPMxCnV[7:0]
W
Reset
0
0
0
0
0
Figure 9-14. 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
(becomes unlatched) when the TPMxCnSC register is written (whether BDM mode is active or not). Any
write to the channel registers is ignored during the input capture mode.
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxCnSC register)
so 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 you were in the middle of
reading a 16-bit register when BDM became active, it reads 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 were 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:
• If CLKSB and CLKSA are cleared, the registers are updated when the second byte is written.
• If CLKSB and CLKSA are not cleared and in output compare mode, 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 and CLKSA are not cleared and in EPWM or CPWM modes, 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 is 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 that is friendly to various compiler implementations.
When BDM is active, the coherency mechanism is frozen so 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 and output compare operation after 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 is fully exercised, the channel registers are updated using the buffered values (while
BDM was not active).
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16-Bit Timer/PWM (S08TPMV3)
9.4
Functional Description
All TPM functions are associated with a central 16-bit counter that allows flexible selection of the clock
and prescale factor. There is also a 16-bit modulo register associated with this 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 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.)
The following sections describe TPM 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 are covered in the associated mode explanation
sections.
9.4.1
Counter
All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section
discusses selection of the clock, end-of-count overflow, up-counting vs. up/down counting, and manual
counter reset.
9.4.1.1
Counter Clock Source
The 2-bit field, CLKSB:CLKSA, in the timer status and control register (TPMxSC) disables the TPM
counter or selects one of three clock sources to TPM counter (Table 9-5). After any MCU reset, CLKSB
and CLKSA are cleared so no clock is selected and the TPM counter is disabled (TPM is in a very low
power state). You can read or write these control bits at any time. Disabling the TPM counter by writing
00 to CLKSB:CLKSA bits, does not affect the values in the TPM counter or other registers.
The fixed frequency clock is an alternative clock source for the TPM counter that allows the selection of
a clock other than the bus clock or external clock. This clock input is defined by chip integration. You can
refer chip specific documentation for further information. Due to TPM hardware implementation
limitations, the frequency of the fixed frequency clock must not exceed the bus clock frequency. The fixed
frequency clock has no limitations for low frequency operation.
The external clock passes through a synchronizer clocked by the bus clock to assure that counter
transitions are properly aligned to bus clock transitions.Therefore, in order to meet Nyquist criteria
considering also jitter, the frequency of the external clock source must not exceed 1/4 of the bus clock
frequency.
When the external clock source is shared with a TPM channel pin, this pin must not be used in input
capture mode. However, this channel can be used in output compare mode with ELSnB:ELSnA = 0:0 for
software timing functions. In this case, the channel output is disabled, but the channel match events
continue to set the appropriate flag.
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9.4.1.2
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 interrupt is generated, or interrupt-driven operation (TOIE = 1)
where the interrupt is generated whenever the TOF is set.
The conditions causing TOF to become set depend on whether the TPM is configured for center-aligned
PWM (CPWMS = 1). If CPWMS is cleared and there is no modulus limit, the 16-bit timer counter counts
from 0x0000 through 0xFFFF and overflows to 0x0000 on the next counting clock. TOF is set at the
transition from 0xFFFF to 0x0000. When a modulus limit is set, TOF is 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 is set as the counter changes direction at the end of the count value set in the modulus register
(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).
9.4.1.3
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 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. The terminal count value and
0x0000 are normal length counts (one timer clock period long). In this mode, the timer overflow flag
(TOF) is set at the end of the terminal-count period (as the count changes to the next lower count value).
9.4.1.4
Manual Counter Reset
The main timer counter can be manually reset at any time by writing any value to 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.
9.4.2
Channel Mode Selection
If CPWMS is cleared, MSnB and MSnA bits determine the basic mode of operation for the corresponding
channel. Choices include input capture, output compare, and edge-aligned PWM.
9.4.2.1
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 is
chosen as the active edge that triggers an input capture.
In input capture mode, the TPMxCnVH and TPMxCnVL registers are read only.
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16-Bit Timer/PWM (S08TPMV3)
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 TPMxCnSC.
An input capture event sets a flag bit (CHnF) that optionally generates a CPU interrupt request.
While in BDM, the input capture function works as configured. When an external event occurs, the TPM
latches the contents of the TPM counter (frozen because of the BDM mode) into the channel value registers
and sets the flag bit.
9.4.2.2
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 TPMxCnVH:TPMxCnVL
registers of an output compare channel, the TPM can set, clear, or toggle the channel pin.
Writes to any of TPMxCnVH and TPMxCnVL registers actually write to buffer registers. In output
compare mode, the TPMxCnVH:TPMxCnVL registers are updated with the value of their write buffer
only after both bytes were written and according to the value of CLKSB:CLKSA bits:
• If CLKSB and CLKSA are cleared, the registers are updated when the second byte is written
• If CLKSB and CLKSA are not cleared, 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) that optionally generates a CPU interrupt request.
9.4.2.3
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 value of the timer channel
register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by ELSnA bit. 0% and
100% duty cycle cases are possible.
The time between the modulus overflow and the channel match value (TPMxCnVH:TPMxCnVL) is the
pulse width or duty cycle (Figure 9-15). If ELSnA is cleared, the counter overflow forces the PWM signal
high, and the channel match forces the PWM signal low. If ELSnA is set, the counter overflow forces the
PWM signal low, and the channel match forces the PWM signal high.
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16-Bit Timer/PWM (S08TPMV3)
overflow
overflow
overflow
period
pulse width
TPMxCHn
channel
match
channel
match
channel
match
Figure 9-15. EPWM period and pulse width (ELSnA=0)
When the channel value register is set to 0x0000, the duty cycle is 0%. A 100% duty cycle is 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.
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, the TPMxCnVH:TPMxCnVL registers are updated with the value of their
write buffer according to the value of CLKSB:CLKSA bits:
• If CLKSB and CLKSA are cleared, the registers are updated when the second byte is written
• If CLKSB and CLKSA are not cleared, 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.
9.4.2.4
Center-Aligned PWM Mode
This type of PWM output uses the up/down counting mode of the timer counter (CPWMS=1). The channel
match 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
must be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous
results. ELSnA determines the polarity of the CPWM signal.
pulse width = 2  (TPMxCnVH:TPMxCnVL)
period = 2  (TPMxMODH:TPMxMODL); TPMxMODH:TPMxMODL = 0x0001–0x7FFF
If TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle is 0%. If
TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the non-zero modulus
setting, the duty cycle is 100% because the channel match never occurs. 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 is much longer than required
for normal applications.
All zeros in TPMxMODH:TPMxMODL is a special case that must not be used with center-aligned PWM
mode. When CPWMS is cleared, this case corresponds to the counter running free from 0x0000 through
0xFFFF. When CPWMS is set, 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.
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The channel match value in the TPM channel registers (times two) determines the pulse width (duty cycle)
of the CPWM signal (Figure 9-16). If ELSnA is cleared, a channel match occurring while counting up
clears the CPWM output signal and a channel match occurring while counting down sets the output. 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.
TPM counter =
TPMxMODH:TPMxMODL
TPM counter = 0
channel match
channel match
(count up)
(count down)
TPM counter =
TPMxMODH:TPMxMODL
TPMxCHn
pulse width
2  TPMxCnVH:TPMxCnVL
period
2  TPMxMODH:TPMxMODL
Figure 9-16. 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.
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 is set.
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 center-aligned PWM mode, the TPMxCnVH:TPMxCnVL registers are updated with the value of their
write buffer according to the value of CLKSB:CLKSA bits:
• If CLKSB and CLKSA are cleared, the registers are updated when the second byte is written
• If CLKSB and CLKSA are not cleared, 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.
When TPMxCNTH:TPMxCNTL equals TPMxMODH:TPMxMODL, the TPM can optionally generate a
TOF interrupt (at the end of this count).
9.5
9.5.1
Reset Overview
General
The TPM is reset whenever any MCU reset occurs.
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16-Bit Timer/PWM (S08TPMV3)
9.5.2
Description of Reset Operation
Reset clears TPMxSC that disables TPM counter clock and overflow interrupt (TOIE=0). CPWMS,
MSnB, MSnA, ELSnB, and ELSnA are all cleared. This configures all TPM channels for input capture
operation and the associated pins are not controlled by TPM.
9.6
9.6.1
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.
All TPM interrupts are listed in Table 9-9.
Table 9-9. Interrupt Summary
Interrupt
Local
Enable
Source
Description
TOF
TOIE
Counter overflow
Set each time the TPM counter reaches its terminal
count (at transition to its next count value)
CHnF
CHnIE
Channel event
An input capture event or channel match took place
on channel n
The TPM module provides high-true interrupt signals.
9.6.2
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 is read (polled) by software to
determine that the action has occurred, or an associated enable bit (TOIE or CHnIE) can be set to enable
the interrupt generation. While the interrupt enable bit is set, the interrupt is generated whenever the
associated interrupt flag is set. 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 followed
by a write of zero 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.
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9.6.2.1
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.
9.6.2.1.1
Normal Case
When CPWMS is cleared, TOF is set when the timer counter changes from the terminal count (the value
in the modulo register) to 0x0000. If the TPM counter is a free-running counter, the update is made when
the TPM counter changes from 0xFFFF to 0x0000.
9.6.2.1.2
Center-Aligned PWM Case
When CPWMS is set, TOF is 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).
9.6.2.2
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).
9.6.2.2.1
Input Capture Events
When a channel is configured as an input capture channel, the ELSnB:ELSnA bits select if channel pin is
not controlled by TPM, rising edges, falling edges, or any edge as the edge that 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 9.6.2, “Description of Interrupt Operation.”
9.6.2.2.2
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 in Section 9.6.2, “Description of Interrupt Operation.”
9.6.2.2.3
PWM End-of-Duty-Cycle Events
When the channel is configured for edge-aligned PWM, the channel flag is set when the timer counter
matches the channel value register that 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 when the timer counter matches the channel value register. The flag is cleared by the two-step
sequence described in Section 9.6.2, “Description of Interrupt Operation.”
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Chapter 10
Interrupt Priority Controller (S08IPCV1)
10.1
Introduction
The interrupt priority controller (IPC) provides hardware based nested interrupt mechanism in HCS08
MCUs. It allows all prioritized interrupt being interrupted except software interrupt.
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Chapter 10 Interrupt Priority Controller (S08IPCV1)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 10-1. MC9S08FL16 Series Block Diagram Highlighting IPC Module
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Interrupt Priority Controller (S08IPCV1)
10.1.1
Features
The interrupt priority controller (IPC) includes the following features:
• Four-level programmable interrupt priority for each interrupt source
• Support for prioritized preemptive interrupt service routines
— Lower priority interrupt requests are blocked when higher priority interrupts are being serviced
— Higher or equal priority level interrupt requests can preempt lower priority interrupts being
serviced
• Automatic update of interrupt priority mask with being serviced interrupt source priority level
when the interrupt vector is being fetched
• Interrupt priority mask can be modified during main flow or interrupt service execution
• Previous interrupt mask level is automatically stored when interrupt vector is fetched (four levels
of previous values accommodated)
10.1.2
10.1.2.1
Modes of Operation
Run Mode
In run mode, if the IPC is enabled, interrupt requests are qualified against interrupt mask register and
unique interrupt level register before being sent to the CPU. If the IPC is disabled, the module is inactive
and is transparently allowing interrupt requests to pass to HCS08 CPU, no programmable priority or
priority preemptive interrupt is supported.
10.1.2.2
Wait Mode
In wait mode, the IPC module acts as it does in run mode.
10.1.2.3
Stop Mode
In stop3 mode, the interrupt mask is set to 0 and the IPC module is bypassed. The IPC interrupt mask value
upon the stop3 entry is automatically restored when exiting stop3. This ensures that asynchronous interrupt
can still wake up CPU from stop3 mode.
If the stop3 exits with an interrupt, the IPC will continues to working with previous setting; If the stop3
exits with a reset, the IPC will return to its reset state.
In stop2 and stop1 mode, the IPC module is powered off, the MCU works as the module is not there. Upon
the exiting of stop2 and stop1, the IPC module is reset.
10.1.3
Block Diagram
Figure 10-2 is the block diagram of the interrupt priority controller module (IPC).
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Interrupt Priority Controller (S08IPCV1)
Inputs
Outputs
INTIN0
INTOUT0
+

–
ILR0[1:0]
INTI1
INTOUT1
ILR1[1:0]
.
.
.
+

–
.
.
.
.
.
.
.
.
.
INTOUT47
INTIN47
ILR Register Content
ILR0
.
.
.
ILR47
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
ILR47[1:0]
Stop
1
CPU
+

–
0
00
IPCE
(IPC Enable)
DECODE
AND SHIFT
LOGIC
IPM
[1 : 0]
IPMPS
(Interrupt Priority Mask Pseudo Stack Register)
[1:0]
[1:0]
[1:0]
[1:0]
Two bits are pushed during vector fetch
Two bits are pulled by
software (PULIPM = 1)
6
ADDRESS[5:0]
VFETCH
Figure 10-2. Interrupt Priority Controller (IPC) Block Diagram
10.2
External Signal Description
Table 10-1. Signal Properties
Name
Port
Function
Reset State
Pull Up
INTIN[47:2]
N/A
Interrupt source interrupt request input
Input
N/A
VFETCH
N/A
Vector fetch indicator from HCS08 CPU
Input
N/A
IADB[5:0]
N/A
Address bus input from HCS08 CPU
Input
N/A
INTOUT[47:2]
N/A
Interrupt request to HCS08 CPU
Output
N/A
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10.2.1
INTIN[47:0] — Interrupt Source Interrupt Request Input
Input from interrupt sources.
10.2.2
VFETCH — Vector Fetch Indicator from HCS08 CPU
Vector fetch signal generated from HCS08 CPU.
10.2.3
IADB[5:0] — Address Bus Input from HCS08 CPU
Internal address bus used to decode the IPC registers.
10.2.4
INTOUT[47:0] — Interrupt Request to HCS08 CPU
Interrupt output signals to HCS08 CPU.
10.3
10.3.1
Register Definition
IPC Status and Control Register (IPCSC)
This register contains status and control bits for the IPC.
7
R
6
5
4
3
2
0
PSE
PSF
0
0
1
IPCE
IPM
W
Reset
0
PULIPM
0
0
1
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-3. IPC Status and Control Register (IPCSC)
Table 10-2. IPCSC Field Descriptions
Field
Description
7
IPCE
Interrupt Priority Controller Enable — This bit enables/disables the interrupt priority controller module.
0 Disables IPCE. Interrupt generated from the interrupt source is passed directly to CPU without processing.
(Bypass mode) The IPMPS register is not updated when the module is disabled.
1 Enables IPCE and interrupt generated from the interrupt source is processed by IPC before passing to CPU.
5
PSE
Pseudo Stack Empty — This bit indicates that the pseudo stack has no valid information. This bit is automatically
updated after each IPMPS register push or pull operation.
4
PSF
Pseudo Stack Full — This bit indicates that the pseudo stack register IPMPS register is full. It is automatically
updated after each IPMPS register push or pull operation. If additional interrupt is nested after this bit is set, the
earliest interrupt mask value(IPM0[1:0]) stacked in IPMPS will be lost.
0 IPMPS register is not full.
1 IPMPS register is full.
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Table 10-2. IPCSC Field Descriptions (continued)
Field
Description
3
PULIPM
Pull IPM from IPMPS— This bit pulls stacked IPM value from IPMPS register to IPM bits of IPCSC. Zeros are
shifted into bit positions 1 and 0 of IPMPS.
0 No operation.
1 Writing 1 to this bit causes a 2-bit value from the interrupt priority mask pseudo stack register to be pulled to the
IPM bits of IPCSC to restore the previous IPM value.
1:0
IPM
Interrupt Priority Mask — This field sets the mask for the interrupt priority control. If the interrupt priority controller
is enabled, the interrupt source with interrupt level (ILRxx) value which is greater than or equal to the value of IPM
will be presented to the CPU. Writes to this field are allowed, but doing this will not push information to the IPMPS
register. Writing IPM with PULIPM setting when IPCE is already set, the IPM will restore the value pulled from the
IPMPS register, not the value written to the IPM register
10.3.2
Interrupt Priority Mask Pseudo Stack Register (IPMPS)
This register is used to store the previous interrupt priority mask level temporarily while the currently
active interrupt is executed.
7
R
6
5
IPM3
4
3
IPM2
2
1
IPM1
0
IPM0
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-4. Interrupt Priority Mask Pseudo Stack Register (IPMR)
Table 10-3. IPMPS Positions 0–3 Field Descriptions
Field
Description
7:6
IPM3
Interrupt Priority Mask pseudo stack position 3 — This field is the pseudo stack register for IPM3. The most
recent information is stored in IPM3.
5:4
IPM2
Interrupt Priority Mask pseudo stack position 2 — This field is the pseudo stack register for IPM2.
3:2
IPM1
Interrupt Priority Mask pseudo stack position 1 — This field is the pseudo stack register for IPM1.
1:0
IPM0
Interrupt Priority Mask pseudo stack position 0 — This field is the pseudo stack register for IPM0.
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10.3.3
Interrupt Level Setting Registers (ILRS0–ILRS11)
This set of registers (ILRS0–ILRS11) contains the user specified interrupt level for each interrupt source.
In Figure 10-5, x indicates the number of the register (ILRSx is ILRS0 through ILRS11). Also, n is the
field number (ILRn is ILR0 through ILR47). Refer to Table 10-4.
Table 10-4. Interrupt Level Register Fields
7
6
5
4
3
2
1
0
ILRS0
ILR3
ILR2
ILR1
ILR0
ILRS1
ILR7
ILR6
ILR5
ILR4
ILRS2
ILR11
ILR10
ILR9
ILR8
ILRS3
ILR15
ILR14
ILR13
ILR12
ILRS4
ILR19
ILR18
ILR17
ILR16
ILRS5
ILR23
ILR22
ILR21
ILR20
ILRS6
ILR27
ILR26
ILR25
ILR24
ILRS7
ILR31
ILR30
ILR29
ILR28
ILRS8
ILR34
ILR34
ILR33
ILR32
ILRS9
ILR39
ILR38
ILR37
ILR36
ILRS10
ILR43
ILR42
ILR41
ILR40
ILRS11
ILR47
ILR46
ILR45
ILR44
7
6
5
4
3
2
1
0
R
ILRn+3
ILRn+2
ILRn+1
ILRn
W
Reset:
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-5. Interrupt Level Register Set ILRx (ILRS0–ILRS11)
Table 10-5. Interrupt Level Registers
Field
Description
7:6
ILRn+3
Interrupt Level Register for Source n+3 — This field sets the interrupt level for interrupt source n+3.
5:4
ILRn+2
Interrupt Level Register for Source n+2 — This field sets the interrupt level for interrupt source n+2.
3:2
ILRn+1
Interrupt Level Register for Source n+1 — This field sets the interrupt level for interrupt source n+1.
1:0
ILRn
Interrupt Level Register for Source n— This field sets the interrupt level for interrupt source n.
The number of ILRS registers is parameterized in the design, the number can be 4, 6, 8, 10 and 12 based
on the actual interrupt number in the design. The corresponding interrupt number is 16, 24, 32, 40 and 48
separately.
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Interrupt Priority Controller (S08IPCV1)
10.4
Functional Description
The IPC works with the existing HCS08 interrupt mechanism to allow nestable interrupts with
programmable priority levels. This module also allows implementation of preemptive interrupt according
to the programmed interrupt priority with minimal software overhead. The IPC consists of three major
functional blocks.
• The interrupt priority level registers
• The interrupt priority level comparator set
• The interrupt mask register update and restore mechanism
10.4.1
Interrupt Priority Level Register
This set of registers is associated with the interrupt sources to the HCS08 CPU. Each interrupt priority
level is a 2-bit value such that a user can program the interrupt priority level of each source to priority 0,
1, 2, or 3. Level 3 has the highest priority while level 0 has the lowest. Software can read or write to these
registers at any time. The interrupt priority level comparator set, interrupt mask register update, and restore
mechanism use this information.
10.4.2
Interrupt Priority Level Comparator Set
When the module is enabled, an active interrupt request forces a comparison between the corresponding
ILR and the 2-bit interrupt mask IPM[1:0](in stop3 mode, the IPM[1:0] is substituted by value 0x00). If
the ILR value is greater than or equal to the value of the interrupt priority mask (IPM bits in IPCSC), the
corresponding interrupt out (INTOUT) signal will be asserted and will signal an interrupt request to the
HCS08 CPU.
When the module is disabled, the interrupt request signal from the source is directly passed to the CPU.
Because the IPC is an external module, the interrupt priority level programmed in the interrupt priority
register will not affect the inherent interrupt priority arbitration as defined by the HCS08 CPU. Therefore,
if two (or more) interrupts are present in the HCS08 CPU at the same time, the inherent priority in HCS08
CPU will perform arbitration by the inherent interrupt priority.
10.4.3
Interrupt Priority Mask Update and Restore Mechanism
The interrupt priority mask (IPM) is 2-bits located in the least significant end of IPCSC register. This two
bits controls which interrupt is allowed to be presented to the HCS08 CPU. During vector fetch, the
interrupt priority mask is updated automatically with the value of the ILR corresponding to that interrupt
source. The original value of the IPM will be saved onto IPMPS for restoration after the interrupt service
routine completes execution. When the interrupt service routine completes execution, the user restore the
original value of IPM by writing 1 to the PULIPM bit. In both cases, the IPMPS is a shift register
functioning as a pseudo stack register for storing the IPM. When the IPM is updated, the original value is
shifted into IPMPS. The IPMPS can store four levels of IPM. If the last position of IPMPS is written, the
PSF flag indicates that the IPMPS is full. If all the values in the IPMPS were read, the PSE flag indicates
that the IPMPS is empty.
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Interrupt Priority Controller (S08IPCV1)
10.4.4
The Integration and Application of the IPC
All the interrupt inputs coming from peripheral modules are synchronous signals. None of asynchronous
signals of the interrupts are routed to IPC. The asynchronous signals of the interrupts are routed directly
to SIM module to wake up system clocks in stop3 mode.
Additional care should be exercised when IRQ is re-prioritized by IPC. CPU instructions BIL and BIH
need input from IRQ pin. If IRQ interrupt is masked, BIL and BIH still work but the IRQ interrupt will not
occur.
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Interrupt Priority Controller (S08IPCV1)
10.5
Application Examples
Figure 10-6 and Figure 10-7 are the examples of the IPC operation at interrupt entry and exitting.
Bus Clock
IntA
PC+1 PC+2 PCL PCH
Address bus
X
A
ISR
CCR VECLVECH
ISR
ISR
ISR
Vector Fetch
ILR[1:0](intA)
2’b11
Push IPMPS
IPMPS[7:0]
8’b0000 0000
8’b1000 0000
Update IPM with ILR value of intA
2’b10
IPM[1:0]
2’b11
Figure 10-6. IPC Operation at Interrupt Entry
Bus Clock
IntA
Write 1 to PULIPM bit in ISR
Address bus
Vector Fetch
RTI
ISR
CCR
A
X
PCH
PCL
PC
PC+1
0
ILR[1:0](intA)
2’b11
Pull IPMPS
IPMPS[7:0]
8’b1000 0000
8’b0000 0000
Restore IPM previous value
IPM[1:0]
2’b11
2’b10
Figure 10-7. IPC Operation at Interrupt Exiting
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Interrupt Priority Controller (S08IPCV1)
10.6
•
Initialization/Application Information
The interrupt priority controller must be enabled to function. While inside an interrupt service
routine, some work has to be done to enable other higher priority interrupts. The following is a
pseudo code per example written in assembly language:
INT_SER :
BCLR
.
.
.
.
.
CLI
.
.
.
.
BSET
RTI
•
•
•
•
INTFLAG,INTFLAG_R ; clear flag that generate interrupt
; do the most critical part that
; which it cannot be interrupted
; global interrupt enable and nested interrupt enabled
; continue the less critical
PULIPM, PULIPM_R
; restore the old IPM value before leaving
; then you can return
A minimum overhead of six bus clock cycles is added inside an interrupt services routine to enable
preemptive interrupts.
As interrupt of same priority level is allowed to pass through IPC to HCS08 CPU thus the flag
generating the interrupt should be cleared before doing CLI to enable preemptive interrupts.
The IPM is automatically updated to the level the interrupt is servicing and the original level is kept
in IPMPS. Watch out for the full (PSF) bit if nesting for more than 4 level is expected.
Before leaving the interrupt service routine, the previous levels should be restored manually by
setting PULIPM bit. Watch out for the full (PSF) bit and empty (PSE) bit.
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Chapter 11
16-Bit Modulo Timer (S08MTIM16V1)
11.1
Introduction
MC9S08FL16 series contain a 16-bit modulo timer (MTIM16), which is an extended of 8-bit MTIM in
previous S08 families. The 16-bit MTIM counts and overflows when the counter value matches the
modulo value. By software configuration, an interrupt is triggered when overflow occurs.
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Chapter 11 16-Bit Modulo Timer (S08MTIM16V1)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 11-1. MC9S08FL16 Series Block Diagram Highlighting MTIM16 Module and Pin
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Modulo Timer (S08MTIM16V1)
11.2
Features
Timer system features include:
• 16-bit up-counter
— Free-running or 16-bit modulo limit
— Software controllable interrupt on overflow
— Counter reset bit (TRST)
— Counter stop bit (TSTP)
• Four software selectable clock sources for input to prescaler:
— System bus clock — rising edge
— Fixed frequency clock (XCLK) — rising edge
— External clock source on the TCLK pin — rising edge
— External clock source on the TCLK pin — falling edge
• Nine selectable clock prescale values:
— Clock source divide by 1, 2, 4, 8, 16, 32, 64, 128, or 256
• Modulo compare matched can be an output
11.2.1
Block Diagram
The block diagram for the modulo timer module is shown Figure 11-2.
BUSCLK
XCLK
TCLK
MTIM16
INTERRUPT
REQUEST
SYNC
CLOCK
SOURCE
SELECT
PRESCALE
AND SELECT
DIVIDE BY
CLKS
PS
16-BIT COUNTER
(MTIMxCNT)
TRST
TSTP
16-BIT COMPARATOR
TOF
16-BIT MODULO
(MTIMxMOD)
TOIE
Figure 11-2. Modulo Timer (S08MTIM16) Block Diagram
11.2.2
Modes of Operation
This section defines MTIM16 operation in stop, wait, and background debug modes.
11.2.2.1
MTIM16 in Wait Mode
The MTIM16 continues to run in wait mode if enabled prior to the execution of the WAIT instruction. The
timer overflow interrupt brings the MCU out of wait mode if it is enabled. For lowest possible current
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Modulo Timer (S08MTIM16V1)
consumption, the MTIM16 should be stopped by software if it is not needed as an interrupt source during
wait mode.
11.2.2.2
MTIM16 in Stop Modes
The MTIM16 is disabled in all stop modes, regardless of the settings before executing the STOP
instruction. Therefore, the MTIM16 cannot be used as a wake up source from stop mode.
Upon waking from stop2 mode, the MTIM16 will enter its reset state. If stop3 is exited with a reset, the
MTIM16 will enter its reset state. If stop3 is exited with an interrupt, the MTIM16 continues from the state
it was in stop3. If the counter was active upon entering stop3, the count will resume from the current value.
11.2.2.3
MTIM16 in Active Background Mode
The MTIM16 stops all counting until the microcontroller returns to normal user operating mode. Counting
resumes from the suspended value as long as an MTIM16 reset did not occur (TRST written to a 1).
11.3
11.3.1
External Signal Description
TCLK — External Clock Source Input into MTIM16
The MTIM16 includes one external signal, TCLK, used to input an external clock when selected as the
MTIM16 clock source.The signal properties of TCLK are shown in Table 11-1.
Table 11-1. Signal Properties
Signal
TCLK
Function
External clock source input into MTIM16
I/O
I
The TCLK input must be synchronized by the bus clock. Also, variations in duty cycle and clock jitter
must be accommodated. As a result, the TCLK signal must be limited to one-fourth of the bus frequency.
The TCLK pin can be muxed with a general-purpose port pin. See Chapter 2, “Pins and Connections” for
the pin location and priority of this function.
11.4
Register Definition
Each MTIM16 includes four registers:
• An 8-bit status and control register
• An 8-bit clock configuration register
• A 16-bit counter register
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Modulo Timer (S08MTIM16V1)
A 16-bit modulo register. Figure 11-3 is a summary of MTIM16 registers.
Figure 11-3. MTIM16 Register Summary
Name
7
6
TOF
TOIE
5
R
MTIMSC
0
3
2
1
0
0
0
0
0
TSTP
W
R
4
TRST
0
0
MTIMCLK
CLKS
PS
W
R
CNTH
MTIMCNTH
W
R
CNTL
MTIMCNTL
W
R
MTIMMODH
MODH
W
R
MTIMMODL
MODL
W
Refer to the direct-page register summary in the Memory chapter for the absolute address assignments for
all MTIM16 registers.This section refers to registers and control bits only by their names and relative
address offsets.
Some MCUs may have more than one MTIM16, so register names include placeholder characters to
identify the correct MTIM16.
11.4.1
MTIM16 Status and Control Register (MTIMSC)
MTIMSC contains the overflow status flag and control bits. These are used to configure the interrupt
enable, reset the counter, and stop the counter.
7
6
TOF
TOIE
Reset:
4
0
R
W
5
3
2
1
0
0
0
0
0
0
0
0
0
TSTP
TRST
0
0
0
1
Figure 11-4. MTIM16 Status and Control Register (MTIMSC)
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Modulo Timer (S08MTIM16V1)
Table 11-2. MTIMSC Register Field Descriptions
Field
Description
7
TOF
MTIM16 Overflow Flag — This bit is set when the MTIM16 counter register overflows to 0x0000 after reaching the
value in the MTIM16 modulo register. Clear TOF by reading the MTIMSC register while TOF is set, then writing a
0 to TOF. Writing a 1 has not effect. TOF is also cleared when TRST is written to a 1.
0 MTIM16 counter has not reached the overflow value in the MTIM16 modulo register.
1 MTIM16 counter has reached the overflow value in the MTIM16 modulo register.
6
TOIE
MTIM16 Overflow Interrupt Enable — This read/write bit enables MTIM16 overflow interrupts. If TOIE is set, then
an interrupt is generated when TOF = 1. Reset clears TOIE. Do not set TOIE if TOF = 1. Clear TOF first, then set
TOIE.
0 TOF interrupts are disabled. Use software polling.
1 TOF interrupts are enabled.
5
TRST
MTIM16 Counter Reset — When an 1 is written to this write-only bit, the MTIM16 counter register resets to 0x0000
and TOF is cleared. Writing an 1 to this bit also makes the modulo value to take effect at once. Reading this bit
always returns 0.
0 No effect. MTIM16 counter remains in its current state.
1 MTIM16 counter is reset to 0x0000.
4
TSTP
MTIM16 Counter Stop — When set, this read/write bit stops the MTIM16 counter at its current value.Counting
resumes from the current value when TSTP is cleared.Reset sets TSTP to prevent the MTIM16 from counting.
0 MTIM16 counter is active.
1 MTIM16 counter is stopped.
3:0
Unused register bits, always read 0.
11.4.2
MTIM16 Clock Configuration Register (MTIMCLK)
MTIMCLK contains the clock select bits (CLKS) and the prescaler select bits (PS).
R
7
6
0
0
5
4
3
2
CLKS
1
0
0
0
PS
W
Reset:
0
0
0
0
0
0
Figure 11-5. MTIM16 Clock Configuration Register (MTIMCLK)
Table 11-3. MTIMCLK Register Field Description
Field
7:6
Description
Unused register bits, always read 0.
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Table 11-3. MTIMCLK Register Field Description (continued)
Field
5:4
CLKS
3:0
PS
Description
Clock Source Select — These two read/write bits select one of four different clock sources as the input to the
MTIM16 prescaler. Changing the clock source while the counter is active does not clear the counter. The count
continues with the new clock source. Reset clears CLKS to 00.
00
Encoding 0. Bus clock (BUSCLK)
01
Encoding 1. Fixed-frequency clock (XCLK)
10
Encoding 3. External source (TCLK pin), falling edge
11
Encoding 4. External source (TCLK pin), rising edge
Clock Source Prescaler — These four read/write bits select one of nine outputs from the 8-bit prescaler. Changing
the prescaler value while the counter is active does not clear the counter. The count continues with the new
prescaler value. Reset clears PS to 0000.
0000 Encoding 0. MTIM16 clock source  1
0001 Encoding 1. MTIM 16clock source  2
0010 Encoding 2. MTIM16 clock source  4
0011 Encoding 3. MTIM16 clock source  8
0100 Encoding 4. MTIM16 clock source  16
0101 Encoding 5. MTIM16 clock source  32
0110 Encoding 6. MTIM16 clock source  64
0111 Encoding 7. MTIM16 clock source  128
1000 Encoding 8. MTIM16 clock source  256
All other encodings default to MTIM16 clock source  256.
11.4.3
MTIM16 Counter Register High/Low (MTIMCNTH:L)
MTIMCNTH is the read-only value of the high byte of current MTIM16 16-bit counter.
7
6
5
4
R
3
2
1
0
0
0
0
0
CNTH
W
Reset:
0
0
0
0
Figure 11-6. MTIM16 Counter Register High (MTIMCNTH)
Table 11-4. MTIMCNTH Register Field Description
Field
Description
7:0
CNTH
MTIM16 Count (High Byte)— These eight read-only bits contain the current high byte value of the 16-bit counter.
Writing has no effect to this register. Reset clears the register to 0x00.
MTIMCNTL is the read-only value of the low byte of current MTIM16 16-bit counter.
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Modulo Timer (S08MTIM16V1)
7
6
5
4
R
3
2
1
0
0
0
0
0
CNTL
W
Reset:
0
0
0
0
Figure 11-7. MTIM16 Counter Register Low (MTIMCNTL)
Table 11-5. MTIMCNTL Register Field Description
Field
Description
7:0
CNTL
MTIM16 Count (Low Byte) — These eight read-only bits contain the current low byte value of the 16-bit counter.
writing has no effect to this register. Reset clears the register to 0x00.
When either MTIMCNTH or MTIMCNTL is read, the content of the two registers is latched into a buffer
where they remain latched until the other register is read.This allows the coherent 16-bit to be read in both
big-endian and little-endian compile environments and ensures the 16-bit counter is unaffected by the read
operation. The coherency mechanism is automatically restarted by an MCU reset or setting of TRST bit
of MTIMSC register (whether BDM mode is active or not).
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 counter 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, the appropriate value from the other half of the 16-bit value will be read after returning to
normal execution.The value read from the MTIMCNTH and MTIMCNTL registers in BDM mode is the
value of these registers and not the value of their read buffer.
11.4.4
MTIM16 Modulo Register High/Low (MTIMMODH/MTIMMODL)
7
6
5
4
3
2
1
0
0
0
0
0
R
MODH
W
Reset:
0
0
0
0
Figure 11-8. MTIM16 Modulo Register High (MTIMMODH)
Table 11-6. MTIMMODH Register Field Descriptions
Field
Description
7:0
MODH
MTIM16 Modulo (High Byte) — These eight read/write bits contain the modulo high byte value used to reset the
counter and set TOF.Reset sets the register to 0x00.
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Modulo Timer (S08MTIM16V1)
7
6
5
4
3
2
1
0
0
0
0
0
R
MODL
W
Reset:
0
0
0
0
Figure 11-9. MTIM16 Modulo Register Low (MTIMMODL)
Table 11-7. MTIMMODL Register Field Descriptions
Field
7:0
MODL
Description
MTIM16 Modulo (Low Byte) — These eight read/write bits contain the modulo low byte value used to reset the
counter and set TOF. Reset sets the register to 0x00.
A value of 0x0000 in MTIMMODH:L puts the MTIM16 in free-running mode. Writing to either
MTIMMODH or MTIMMODL latches the value into a buffer and the registers are updated with the value
of their write buffer after the second byte writing, the updated MTIMMODH:L will take effect in the next
MITIM16 counter cycle except for the first writing of modulo after a chip reset or in BDM mode. But after
a software reset, the MTIMMODH:L takes effect at once even if it didn’t take effect before the reset. On
the first writing of MTIMMODH:L after chip reset, the counter is reset and the modulo takes effect
immediately. The latching mechanism may be manually reset by setting the TRST bit of MTIMSC register
(whether BDM is active or not).
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 modulo register are written
while BDM is active. Any writing to the modulo registers bypasses the buffer latches and writes directly
to the modulo register while BDM is active, and also the counter is cleared at the same time.The reading
of MTIMMODH:L returns the modulo value which is taking effect whenever in normal run mode or in
BDM mode.
11.5
Functional Description
The MTIM16 is composed of a main 16-bit up-counter with 16-bit modulo register, a clock source selector,
and a prescaler block with nine selectable values. The module also contains software selectable interrupt
logic.
The MTIM16 counter (MTIMCNTH:L) has three modes of operation: stopped, free-running, and modulo.
The counter is stopped out of reset. If the counter starts without writing a new value to the modulo
registers, it will be in free-running mode. The counter is in modulo mode when a value other than 0x0000
is in the modulo registers.
After an MCU reset, the counter stops and resets to 0x0000, and the modulo is also reseted to 0x0000. The
bus clock functions as the default clock source and the prescale value is divided by 1. To start the MTIM16
in free-running mode, write to the MTIM16 status and control register (MTIMSC) and clear the MTIM16
stop bit (TSTP).
Four clock sources are software selectable: the internal bus clock, the fixed frequency clock (XCLK), and
an external clock on the TCLK pin, selectable as incrementing on either rising or falling edges. The
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Modulo Timer (S08MTIM16V1)
MTIM16 clock select bits (CLKS1:CLKS0) in MTIMSC are used to select the desired clock source. If the
counter is active (TSTP = 0) when a new clock source is selected, the counter continues counting from the
previous value using the new clock source.
Nine prescale values are software selectable: clock source divided by 1, 2, 4, 8, 16, 32, 64, 128, or 256.
The prescaler select bits (PS[3:0]) in MTIMxSC select the desired prescale value. If the counter is active
(TSTP = 0) when a new prescaler value is selected, the counter continues counting from the previous value
using the new prescaler value.
The MTIM16 modulo register (MTIMMODH:L) allows the overflow compare value to be set to any value
from 0x0001 to 0xFFFF. Reset clears the modulo value to 0x0000, which results in a free running counter.
When the counter is active (TSTP = 0), it increases at the selected rate until the count matches the modulo
value. When these values match, the counter overflows to 0x0000 and continues counting. The MTIM16
overflow flag (TOF) is set whenever the counter overflows. The flag sets on the transition from the modulo
value to 0x0000.
Clearing TOF is a two-step process. The first step is to read the MTIMxSC register while TOF is set. The
second step is to write a 0 to TOF. If another overflow occurs between the first and second steps, the
clearing process is reset and TOF stays set after the second step is performed. This will prevent the second
occurrence from being missed. TOF is also cleared when a 1 is written to TRST.
The MTIM16 allows for an optional interrupt to be generated whenever TOF is set. To enable the MTIM16
overflow interrupt, set the MTIM16 overflow interrupt enable bit (TOIE) in MTIMSC. TOIE should never
be written to a 1 while TOF = 1. Instead, TOF should be cleared first, then the TOIE can be set to 1.
11.5.1
MTIM16 Operation Example
This section shows an example of the MTIM16 operation as the counter reaches a matching value from
the modulo register.
selected
clock source
MTIM16 clock
(PS=%0010)
MTIMCNT
0x01A7
0x01A8
0x01A9
0x01AA
0x0000
0x0001
TOF
MTIMMOD:
0x01AA
Figure 11-10. MTIM16 Counter Overflow Example
In the example of Figure 11-10, the selected clock source could be any of the four possible choices. The
prescaler is set to PS = %0010 or divide-by-4. The modulo value in the MTIMMODH:L register is set to
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Modulo Timer (S08MTIM16V1)
0x01AA. When the counter, MTIMCNTH:L, reaches the modulo value of 0x01AA, the counter overflows
to 0x0000 and continues counting. The timer overflow flag, TOF, sets when the counter value changes
from 0x01AA to 0x0000. An MTIM16 overflow interrupt is generated when TOF is set, if TOIE = 1.
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Modulo Timer (S08MTIM16V1)
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Chapter 12
Analog-to-Digital Converter (S08ADC12V1)
12.1
Introduction
The 8-bit 12-ch analog-to-digital converter (ADC) is a successive approximation ADC designed for
operation within an integrated microcontroller system-on-chip.
NOTE
The ADC in MC9S08FL16 series MCUs supports only the 8-bit conversion,
ignore the 10-bit and 12-bit information in this chapter.
12.1.1
ADC Channel Assignments
Figure 12-1 shows the ADC channel assignments. Reserved channels convert to an unknown value.
Table 12-1. ADC Channel Assignment
1
2
ADCH
Input Select
ADCH
Input Select
00000
AD0
10000
Reserved
00001
AD1
10001
Reserved
00010
AD2
10010
Reserved
00011
AD3
10011
Reserved
00100
AD4
10100
Reserved
00101
AD5
10101
Reserved
00110
AD6
10110
Reserved
00111
AD7
10111
Reserved
01000
AD8
11000
Reserved
01001
AD9
11001
Reserved
01010
AD10
11010
Temperature Sensor
01011
AD11
11011
Bandgap
01100
Reserved
11100
Reserved
01101
Reserved
11101
VREFH1
01110
Reserved
11110
VREFL2
01111
Reserved
11111
Module disabled
VREFH, VDDA and VDD are connected together.
VREFL, VSSA and VSS are connected together.
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Chapter 12 Analog-to-Digital Converter (S08ADC12V1)
12.1.2
Alternate Clock
The ADC 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
ALTCLK on the MC9S08FL16 series are connected to the OSCOUT.
12.1.3
Hardware Trigger
In MC9S08FL16 series MCUs, the ADC hardware trigger is associated with TCLK. The TCLKPEN bit
in SOPT1 register must be enabled to use TCLK as hardware trigger.
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Chapter 12 Analog-to-Digital Converter (S08ADC12V1)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 12-1. MC9S08FL16 Series Block Diagram Highlighting ADC Module and Pins.
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Analog-to-Digital Converter (S08ADC12V1)
12.1.4
Features
Features of the ADC module include:
• Linear successive approximation algorithm with 12-bit resolution
• Up to 28 analog inputs
• Output formatted in 12-, 10-, or 8-bit right-justified unsigned 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
• Temperature sensor
12.1.5
ADC Module Block Diagram
Figure 12-2 provides a block diagram of the ADC module.
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Analog-to-Digital Converter (S08ADC12V1)
ADIV
ADLPC
MODE
ADLSMP
ADTRG
2
ADCO
ADCH
1
ADCCFG
complete
COCO
ADCSC1
ADICLK
Compare true
AIEN
3
Async
Clock Gen
ADACK
MCU STOP
ADCK

ALTCLK
abort
transfer
sample
initialize
•••
AD0
convert
Control Sequencer
ADHWT
Bus Clock
Clock
Divide
AIEN 1
COCO 2
ADVIN
Interrupt
SAR Converter
AD27
VREFH
Data Registers
Sum
VREFL
Compare true
3
Compare Value Registers
ACFGT
Value
Compare
Logic
ADCSC2
Figure 12-2. ADC Block Diagram
12.2
External Signal Description
The ADC module supports up to 28 separate analog inputs. It also requires four supply/reference/ground
connections.
Table 12-2. Signal Properties
Name
Function
AD27–AD0
Analog Channel inputs
VREFH
High reference voltage
VREFL
Low reference voltage
VDDA
Analog power supply
VSSA
Analog ground
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12.2.1
Analog Power (VDDA)
The ADC analog portion uses VDDA as its power connection. In some packages, VDDA is connected
internally to VDD. If externally available, connect the VDDA pin to the same voltage potential as VDD.
External filtering may be necessary to ensure clean VDDA for good results.
12.2.2
Analog Ground (VSSA)
The ADC analog portion uses VSSA as its ground connection. In some packages, VSSA is connected
internally to VSS. If externally available, connect the VSSA pin to the same voltage potential as VSS.
12.2.3
Voltage Reference High (VREFH)
VREFH is the high reference voltage for the converter. In some packages, VREFH is connected internally to
VDDA. If externally available, VREFH may be connected to the same potential as VDDA or may be driven
by an external source between the minimum VDDA spec and the VDDA potential (VREFH must never
exceed VDDA).
12.2.4
Voltage Reference Low (VREFL)
VREFL is the low-reference voltage for the converter. In some packages, VREFL is connected internally to
VSSA. If externally available, connect the VREFL pin to the same voltage potential as VSSA.
12.2.5
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.
12.3
Register Definition
These memory-mapped registers control and monitor operation of the ADC:
•
•
•
•
•
•
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 control registers, APCTL1, APCTL2, APCTL3
12.3.1
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
AIEN
ADCO
0
0
4
3
2
1
0
1
1
COCO
ADCH
W
Reset:
0
1
1
1
Figure 12-3. Status and Control Register (ADCSC1)
Table 12-3. ADCSC1 Field Descriptions
Field
Description
7
COCO
Conversion Complete Flag. The COCO flag is a read-only bit 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 when ADCSC1 is written
or when ADCRL is read.
0 Conversion not completed
1 Conversion completed
6
AIEN
Interrupt Enable AIEN enables 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 enables 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 that selects one of the input channels. The input channels
are detailed in Table 12-4.
The successive approximation converter subsystem is turned off when the channel select bits are all set. This
feature allows for explicit disabling of the ADC and isolation of the input channel from all sources. Terminating
continuous conversions this way prevents an additional, single conversion from being performed. It is not
necessary to set the channel select bits to all ones 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.
Table 12-4. Input Channel Select
ADCH
Input Select
00000–01111
AD0–15
10000–11011
AD16–27
11100
Reserved
11101
VREFH
11110
VREFL
11111
Module disabled
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12.3.2
Status and Control Register 2 (ADCSC2)
The ADCSC2 register controls 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
Figure 12-4. Status and Control Register 2 (ADCSC2)
1
Bits 1 and 0 are reserved bits that must always be written to 0.
Table 12-5. ADCSC2 Register Field Descriptions
Field
Description
7
ADACT
Conversion Active. 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. Selects the type of trigger used for initiating a conversion. Two types of triggers 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
5
ACFE
4
ACFGT
Compare Function Enable. Enables the compare function.
0 Compare function disabled
1 Compare function enabled
Compare Function Greater Than Enable. Configures 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 value
1 Compare triggers when input is greater than or equal to compare value
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12.3.3
Data Result High Register (ADCRH)
In 12-bit operation, ADCRH contains the upper four bits of 12-bit conversion data. In 10-bit operation,
ADCRH contains the upper two bits of 10-bit conversion data. In 12-bit and 10-bit mode, ADCRH is
updated each time a conversion completes except when automatic compare is enabled and the compare
condition is not met. When configured for 10-bit mode, ADR[11:10] are cleared. When configured for
8-bit mode, ADR[11:8] are cleared.
When automatic compare is not enabled, the value stored in ADCRH are the upper bits of the conversion
result. When automatic compare is enabled, the conversion result is manipulated as described in
Section 12.4.5, “Automatic Compare Function” prior to storage in ADCRH:ADCRL registers.
In 12-bit and 10-bit mode, reading ADCRH prevents the ADC from transferring subsequent conversion
data into the result registers until ADCRL is read. If ADCRL is not read until after the next conversion is
completed, the intermediate conversion data is lost. In 8-bit mode, there is no interlocking with ADCRL.
If the MODE bits are changed, any data in ADCRH becomes invalid.
R
7
6
5
4
3
2
1
0
0
0
0
0
ADR11
ADR10
ADR9
ADR8
0
0
0
0
0
0
0
0
W
Reset:
Figure 12-5. Data Result High Register (ADCRH)
12.3.4
Data Result Low Register (ADCRL)
ADCRL contains the lower eight bits of a 12-bit or 10-bit conversion data, and all eight bits of 8-bit
conversion data. ADCRL is updated each time a conversion completes except when automatic compare is
enabled and the compare condition is not met.
When automatic compare is not enabled, the value stored in ADCRL is the lower eight bits of the
conversion result. When automatic compare is enabled, the conversion result is manipulated as described
in Section 12.4.5, “Automatic Compare Function” prior to storage in ADCRH:ADCRL registers.
In 12-bit and 10-bit mode, reading ADCRH prevents the ADC from transferring subsequent conversion
data into the result registers until ADCRL is read. If ADCRL is not read until the after next conversion is
completed, the intermediate conversion data is lost. In 8-bit mode, there is no interlocking with ADCRH.
If the MODE bits are changed, any data in ADCRL becomes invalid.
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:
Figure 12-6. Data Result Low Register (ADCRL)
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12.3.5
Compare Value High Register (ADCCVH)
In 12-bit mode, the ADCCVH register holds the upper four bits of the 12-bit compare value. When the
compare function is enabled, these bits are compared to the upper four bits of the result following a
conversion in 12-bit mode.
R
7
6
5
4
0
0
0
0
3
2
1
0
ADCV11
ADCV10
ADCV9
ADCV8
0
0
0
0
W
Reset:
0
0
0
0
Figure 12-7. Compare Value High Register (ADCCVH)
In 10-bit mode, the ADCCVH register holds the upper two bits of the 10-bit compare value (ADCV[9:8]).
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 mode, ADCCVH is not used during compare.
12.3.6
Compare Value Low Register (ADCCVL)
This register holds the lower eight bits of the 12-bit or 10-bit compare value or all eight bits of the 8-bit
compare value. When the compare function is enabled, bits ADCV[7:0] are compared to the lower eight
bits of the result following a conversion in 12-bit, 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 12-8. Compare Value Low Register (ADCCVL)
12.3.7
Configuration Register (ADCCFG)
ADCCFG selects the mode of operation, clock source, clock divide, and configures for low power and
long sample time.
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 12-9. Configuration Register (ADCCFG)
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Table 12-6. ADCCFG Register Field Descriptions
Field
Description
7
ADLPC
Low-Power Configuration. ADLPC controls the speed and power configuration of the successive approximation
converter. This optimizes power consumption when higher sample rates are not required.
0 High speed configuration
1 Low power configuration: The power is reduced at the expense of maximum clock speed.
6:5
ADIV
Clock Divide Select. ADIV selects the divide ratio used by the ADC to generate the internal clock ADCK.
Table 12-7 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 12-, 10-, or 8-bit operation. See Table 12-8.
1:0
ADICLK
Input Clock Select. ADICLK bits select the input clock source to generate the internal clock ADCK. See
Table 12-9.
Table 12-7. 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 12-8. Conversion Modes
MODE
Mode Description
00
8-bit conversion (N=8)
01
12-bit conversion (N=12)
10
10-bit conversion (N=10)
11
Reserved
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Table 12-9. Input Clock Select
ADICLK
00
12.3.8
Selected Clock Source
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 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 12-10. Pin Control 1 Register (APCTL1)
Table 12-10. APCTL1 Register Field Descriptions
Field
Description
7
ADPC7
ADC Pin Control 7. ADPC7 controls 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 controls 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 controls 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 controls 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 controls 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 controls 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 12-10. APCTL1 Register Field Descriptions (continued)
Field
Description
1
ADPC1
ADC Pin Control 1. ADPC1 controls 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 controls the pin associated with channel AD0.
0 AD0 pin I/O control enabled
1 AD0 pin I/O control disabled
12.3.9
Pin Control 2 Register (APCTL2)
APCTL2 controls 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 12-11. Pin Control 2 Register (APCTL2)
Table 12-11. APCTL2 Register Field Descriptions
Field
Description
7
ADPC15
ADC Pin Control 15. ADPC15 controls 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 controls 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 controls 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 controls 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 controls 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 controls 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 12-11. APCTL2 Register Field Descriptions (continued)
Field
Description
1
ADPC9
ADC Pin Control 9. ADPC9 controls 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 controls the pin associated with channel AD8.
0 AD8 pin I/O control enabled
1 AD8 pin I/O control disabled
12.3.10 Pin Control 3 Register (APCTL3)
APCTL3 controls 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 12-12. Pin Control 3 Register (APCTL3)
Table 12-12. APCTL3 Register Field Descriptions
Field
Description
7
ADPC23
ADC Pin Control 23. ADPC23 controls 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 controls 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 controls 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 controls 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 controls 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 controls 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 12-12. APCTL3 Register Field Descriptions (continued)
Field
Description
1
ADPC17
ADC Pin Control 17. ADPC17 controls 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 controls the pin associated with channel AD16.
0 AD16 pin I/O control enabled
1 AD16 pin I/O control disabled
12.4
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. In 12-bit
and 10-bit mode, the selected channel voltage is converted by a successive approximation algorithm into
a 12-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 the data registers (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
with any of the conversion modes and configurations.
12.4.1
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 two. 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 do not perform according to specifications. If the available clocks
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are too fast, 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.
12.4.2
Input Select and Pin Control
The pin control registers (APCTL3, APCTL2, and APCTL1) 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.
12.4.3
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.
12.4.4
Conversion Control
Conversions can be performed in 12-bit mode, 10-bit mode, or 8-bit mode as determined by the MODE
bits. Conversions can be initiated by 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.
12.4.4.1
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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12.4.4.2
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 12-bit or 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.
12.4.4.3
Aborting Conversions
Any conversion in progress is 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.
However, they continue to be the values transferred after the completion of the last successful conversion.
If the conversion was aborted by a reset, ADCRH and ADCRL return to their reset states.
12.4.4.4
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).
12.4.4.5
Sample Time and 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, 10-bit or 12-bit), and the frequency of the conversion clock (fADCK).
After the module becomes active, sampling of the input begins. ADLSMP selects between short (3.5
ADCK cycles) and long (23.5 ADCK cycles) sample times.When sampling is complete, the converter is
isolated from the input channel and a successive approximation algorithm is performed to determine the
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digital value of the analog signal. The 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 12-13.
Table 12-13. 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 or 12-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 or 12-bit
0x, 10
1
43 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit
11
0
5 s + 20 ADCK + 5 bus clock cycles
Single or first continuous 10-bit or 12-bit
11
0
5 s + 23 ADCK + 5 bus clock cycles
Single or first continuous 8-bit
11
1
5 s + 40 ADCK + 5 bus clock cycles
Single or first continuous 10-bit or 12-bit
11
1
5 s + 43 ADCK + 5 bus clock cycles
Subsequent continuous 8-bit;
fBUS fADCK
xx
0
17 ADCK cycles
Subsequent continuous 10-bit or 12-bit;
fBUS fADCK
xx
0
20 ADCK cycles
Subsequent continuous 8-bit;
fBUS  fADCK/11
xx
1
37 ADCK cycles
Subsequent continuous 10-bit or 12-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 s
Number of bus cycles = 3.5 s 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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12.4.5
Automatic Compare Function
The compare function is enabled by the ACFE bit. The compare function can be configured to check for
an upper or lower limit. After the input is sampled and converted, the compare value (ADCCVH and
ADCCVL) is subtracted from the conversion result. When comparing to an upper limit (ACFGT = 1), if
the conversion 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. An ADC interrupt is
generated upon the setting of COCO if the ADC interrupt is enabled (AIEN = 1).
The subtract operation of two positive values (the conversion result less the compare value) results in a
signed value that is 1-bit wider than the bit-width of the two terms. The final value transferred to the
ADCRH and ADCRL registers is the result of the subtraction operation, excluding the sign bit. The value
of the sign bit can be derived based on ACFGT control setting. When ACFGT=1, the sign bit of any value
stored in ADCRH and ADCRL is always 0, indicating a positive result for the subtract operation. When
ACFGT = 1, the sign bit of any result is always 1, indicating a negative result for the subtract operation.
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.
NOTE
The compare function can monitor the voltage on a channel while the MCU
is in wait or stop3 mode. The ADC interrupt wakes the MCU when the
compare condition is met.
An example of compare operation eases understanding of the compare feature. If the ADC is configured
for 10-bit operation, ACFGT=0, and ADCCVH:ADCCVL= 0x200, then a conversion result of 0x080
causes the compare condition to be met and the COCO bit is set. A value of 0x280 is stored in
ADCRH:ADCRL. This is signed data without the sign bit and must be combined with a derived sign bit
to have meaning. The value stored in ADCRH:ADCRL is calculated as follows.
The value to interpret from the data is (Result – Compare Value) = (0x080 – 0x200) = –0x180. A standard
method for handling subtraction is to convert the second term to its 2’s complement, and then add the two
terms. First calculate the 2’s complement of 0x200 by complementing each bit and adding 1. Note that
prior to complementing, a sign bit of 0 is added so that the 10-bit compare value becomes a 11-bit signed
value that is always positive.
%101 1111 1111
+
<= 1’s complement of 0x200 compare value
%1
--------------%110 0000 0000
<= 2’s complement of 0x200 compare value
Then the conversion result of 0x080 is added to 2’s complement of 0x200:
%000 1000 0000
+
%110 0000 0000
--------------%110 1000 0000
<= Subtraction result is –0x180 in signed 11-bit data
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Analog-to-Digital Converter (S08ADC12V1)
The subtraction result is an 11-bit signed value. The lower 10 bits (0x280) are stored in ADCRH:ADCRL.
The sign bit is known to be 1 (negative) because the ACFGT=0, the COCO bit was set, and conversion
data was updated in ADCRH:ADCRL.
A simpler way to use the data stored in ADCRH:ADCRL is to apply the following rules. When comparing
for upper limit (ACFGT=1), the value in ADCRH:ADCRL is a positive value and does not need to be
manipulated. This value is the difference between the conversion result and the compare value. When
comparing for lower limit (ACFGT=0), ADCRH:ADCRL is a negative value without the sign bit. If the
value from these registers is complemented and then a value of 1 is added, then the calculated value is the
unsigned (i.e., absolute) difference between the conversion result and the compare value. In the previous
example, 0x280 is stored in ADCRH:ADCRL. The following example shows how the absolute value of
the difference is calculated.
<= Complement of 10-bit value stored in ADCRH:ADCRL
%01 0111 1111
+
%1
--------------%01 1000 0000<= Unsigned value 0x180 is the absolute value of (Result - Compare Value)
12.4.6
MCU Wait Mode Operation
Wait mode is a lower power-consumption standby mode from which recovery is 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).
12.4.7
MCU Stop3 Mode Operation
Stop mode is a low power-consumption standby mode during which most or all clock sources on the MCU
are disabled.
12.4.7.1
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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12.4.7.2
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
The ADC module can 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 the data
transfer blocking mechanism (discussed in Section 12.4.4.2, “Completing
Conversions) is cleared when entering stop3 and continuing ADC
conversions.
12.4.8
MCU Stop2 Mode Operation
The ADC module is automatically disabled when the MCU enters stop2 mode. All module registers
contain their reset values following exit from stop2. Therefore, the module must be re-enabled and
re-configured following exit from stop2.
12.5
Initialization Information
This section gives an example that provides some basic direction on how to initialize and configure the
ADC module. You can configure the module for 8-, 10-, or 12-bit resolution, single or continuous
conversion, and a polled or interrupt approach, among many other options. Refer to Table 12-7,
Table 12-8, and Table 12-9 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.
12.5.1
12.5.1.1
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.
12.5.1.2
Pseudo-Code Example
In this example, the ADC module is 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 is derived from
the bus clock divided by 1.
ADCCFG = 0x98 (%10011000)
Bit
Bit
Bit
Bit
Bit
7
6:5
4
3:2
1:0
ADLPC
ADIV
ADLSMP
MODE
ADICLK
1
00
1
10
00
Configures for low power (lowers maximum clock speed)
Sets the ADCK to the input clock  1
Configures for long sample time
Sets mode at 10-bit conversions
Selects bus clock as input clock source
ADCSC2 = 0x00 (%00000000)
Bit
Bit
Bit
Bit
Bit
Bit
7
6
5
4
3:2
1:0
ADACT
ADTRG
ACFE
ACFGT
0
0
0
0
00
00
Flag indicates if a conversion is in progress
Software trigger selected
Compare function disabled
Not used in this example
Reserved, always reads zero
Reserved for Freescale’s internal use; always write zero
ADCSC1 = 0x41 (%01000001)
Bit
Bit
Bit
Bit
7
6
5
4:0
COCO
AIEN
ADCO
ADCH
0
1
0
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 = 0x98
ADCSC2 = 0x00
ADCSC1 = 0x41
Check
COCO=1?
No
Yes
Read ADCRH
Then ADCRL To
Clear COCO Bit
Continue
Figure 12-13. Initialization Flowchart for Example
12.6
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.
12.6.1
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.
12.6.1.1
Analog Supply Pins
The ADC module has analog power and ground supplies (VDDA and VSSA) available as separate pins on
some devices. VSSA is shared on the same pin as the MCU digital VSS on some devices. On other devices,
VSSA and VDDA are shared with the MCU digital supply pins. In these cases, there are separate pads for
the analog supplies bonded to the same pin as the corresponding digital supply so that some degree of
isolation between the supplies is maintained.
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When available on a separate pin, both VDDA and VSSA 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.
If separate power supplies are used for analog and digital power, the ground connection between these
supplies must be at the VSSA pin. This should be the only ground connection between these supplies if
possible. The VSSA pin makes a good single point ground location.
12.6.1.2
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 VDDA on some devices. The low
reference is VREFL, which may be shared on the same pin as VSSA on some devices.
When available on a separate pin, VREFH may be connected to the same potential as VDDA, or may be
driven by an external source between the minimum VDDA spec and the VDDA potential (VREFH must never
exceed VDDA). When available on a separate pin, VREFL must be connected to the same voltage potential
as VSSA. 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 F 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 causes a voltage drop that could result in conversion errors.
Inductance in this path must be minimum (parasitic only).
12.6.1.3
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 is in its high impedance state and the pullup is disabled. Also, the input buffer
draws DC current when its input is not at 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 F 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 0xFFF (full scale 12-bit representation), 0x3FF
(full scale 10-bit representation) or 0xFF (full scale 8-bit representation). If the input is equal to or less
than VREFL, the converter circuit converts it to 0x000. Input voltages between VREFH and VREFL are
straight-line linear conversions. There is a brief current associated with VREFL when the sampling
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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.
12.6.2
Sources of Error
Several sources of error exist for A/D conversions. These are discussed in the following sections.
12.6.2.1
Sampling Error
For proper conversions, the input must be sampled long enough to achieve the proper accuracy. Given the
maximum input resistance of approximately 7k and input capacitance of approximately 5.5 pF, sampling
to within 1/4LSB (at 12-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 2 k.
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.
12.6.2.2
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 VDDA / (2N*ILEAK) for less than
1/4LSB leakage error (N = 8 in 8-bit, 10 in 10-bit or 12 in 12-bit mode).
12.6.2.3
Noise-Induced Errors
System noise that 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 F low-ESR capacitor from VREFH to VREFL.
• There is a 0.1 F low-ESR capacitor from VDDA to VSSA.
• If inductive isolation is used from the primary supply, an additional 1 F capacitor is placed from
VDDA to VSSA.
• VSSA (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 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.
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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 F capacitor (CAS) on the selected input channel to VREFL or VSSA (this improves
noise issues, but affects the sample rate based on the external analog source resistance).
• 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.
12.6.2.4
Code Width and Quantization Error
The ADC quantizes the ideal straight-line transfer function into 4096 steps (in 12-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, 10 or
12), defined as 1LSB, is:
1 lsb = (VREFH - VREFL) / 2N
Eqn. 12-1
There is an inherent quantization error due to the digitization of the result. For 8-bit or 10-bit conversions
the code transitions 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 
1/2 lsb in 8- or 10-bit mode. As a consequence, however, the code width of the first (0x000) conversion is
only 1/2 lsb and the code width of the last (0xFF or 0x3FF) is 1.5 lsb.
For 12-bit conversions the code transitions only after the full code width is present, so the quantization
error is 1 lsb to 0 lsb and the code width of each step is 1 lsb.
12.6.2.5
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 (1/2 lsb in 8-bit or 10-bit
modes and 1 lsb in 12-bit mode). If the first conversion is 0x001, the difference between the actual
0x001 code width and its ideal (1 lsb) 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 (1.5 lsb in 8-bit or 10-bit modes and 1LSB in 12-bit
mode). If the last conversion is 0x3FE, the difference between the actual 0x3FE 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.
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•
•
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 includes all forms of error.
12.6.2.6
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
converter yields the lower code (and vice-versa). However, even 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 ±1/2 lsb in 8-bit or 10-bit mode, or around 2 lsb in 12-bit mode,
and increases with noise.
This error may be reduced by repeatedly sampling the input and averaging the result. Additionally the
techniques discussed in Section 12.6.2.3 reduces 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 never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and have no missing codes.
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Chapter 13
Serial Communications Interface (S08SCIV4)
13.1
Introduction
MC9S08FL16 series contain a serial communications interface module (SCI) that behavior as a UART.
The SCI module supports single-wire mode and LIN-extension.
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Chapter 13 Serial Communications Interface (S08SCIV4)
PTA0/ADP0
16-BIT MODULO TIMER
HCS08 CORE
TCLK
PTA1/ADP1
(MTIM16)
BDC
2-CH TIMER/PWM
TPM2CH[1:0]
MODULE (TPM2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
PTA2/ADP2
CPU
PTA4/BKGD/MS
PTA5/IRQ/TCLK/RESET
PTA6/TPM2CH0
RESET
PTA7/TPM2CH1
IRQ
IRQ
LVD
ON-CHIP ICE AND
DEBUG MODUE (DBG)
INTERRUPT PRIORITY
CONTROLLER (IPC)
PTB0/RxD/ADP4
PTB1/TxD/ADP5
SERIAL COMMUNICATIONS
INTERFACE (SCI)
TxD
RxD
USER FLASH
MC9S08FL16 — 16,384 BYTES
MC9S08FL8 — 8,192 BYTES
4-CH TIMER/PWM
USER RAM
MC9S08FL16 — 1,024 BYTES
MC9S08FL8 — 768 BYTES
PTB2/ADP6
PORT B
COP
PTA3/ADP3
PTB3/ADP7
PTB4/TPM1CH0
PTB5/TPM1CH1
TPM1CH[3:0]
MODULE (TPM1)
PTB6/XTAL
PTB7/EXTAL
PTC0/ADP8
20 MHz INTERNAL CLOCK
SOURCE (ICS)
PTC1/ADP9
PORT C
PTC2/ADP10
EXTAL
XTAL
EXTERNAL OSCILLATOR
SOURCE (XOSC)
VDD
VSS
PTC3/ADP11
PTC4
PTC5
VOLTAGE REGULATOR
PTC6
PTC7
VREFH
VREFL
VDDA
VSSA
12-CH 8-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
ADP[11:0]
PTD0
PORT D
PTD1
NOTE
1. PTA4 is output only when used as port pin.
2. PTA5 is input only when used as port pin.
PTD2/TPM1CH2
PTD3/TPM1CH3
PTD4
PTD5
Figure 13-1. MC9S08FL16 Series Block Diagram Highlighting SCI Module and Pins
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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
13.1.3
Block Diagram
Figure 13-2 shows the transmitter portion of the SCI.
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Serial Communications Interface (S08SCIV4)
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
BREAK (ALL 0s)
PARITY
GENERATION
PT
PREAMBLE (ALL 1s)
PE
SHIFT ENABLE
T8
LOAD FROM SCID
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
Figure 13-3 shows the receiver portion of the SCI.
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Serial Communications Interface (S08SCIV4)
INTERNAL BUS
(READ-ONLY)
16  BAUD
RATE CLOCK
DIVIDE
BY 16
SCID – Rx BUFFER
LBKDE
H
DATA RECOVERY
WAKE
ILT
8
7
6
5
4
3
2
1
START
FROM RxD PIN
RXINV
11-BIT RECEIVE SHIFT REGISTER
LSB
RSRC
M
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
NF
ERROR INTERRUPT
REQUEST
NEIE
PE
PT
PARITY
CHECKING
PF
PEIE
Figure 13-3. SCI Receiver Block Diagram
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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 (SCIBDH, SCIBDL)
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 SCIBDH to buffer the high half of the new value and then write
to SCIBDL. The working value in SCIBDH does not change until SCIBDL is written.
SCIBDL 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 SCIC2 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 (SCIBDH)
Table 13-1. SCIBDH 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.
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 (SCIBDL)
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Table 13-2. SCIBDL 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 (SCIC1)
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 (SCIC1)
Table 13-3. SCIC1 Field Descriptions
Field
Description
7
LOOPS
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.
6
SCISWAI
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.
5
RSRC
4
M
3
WAKE
2
ILT
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.
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.
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.
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Table 13-3. SCIC1 Field Descriptions (continued)
Field
Description
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 (SCIC2)
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 (SCIC2)
Table 13-4. SCIC2 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.
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.
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Table 13-4. SCIC2 Field Descriptions (continued)
Field
Description
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 (SCIS1)
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 (SCIS1)
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Table 13-5. SCIS1 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
SCIS1 with TDRE = 1 and then write to the SCI data register (SCID).
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 SCIS1 with TC = 1 and then doing one of the following three things:
• Write to the SCI data register (SCID) to transmit new data
• Queue a preamble by changing TE from 0 to 1
• Queue a break character by writing 1 to SBK in SCIC2
5
RDRF
Receive Data Register Full Flag — RDRF becomes set when a character transfers from the receive shifter into
the receive data register (SCID). To clear RDRF, read SCIS1 with RDRF = 1 and then read the SCI data register
(SCID).
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 SCIS1 with IDLE = 1 and then read the SCI data register (SCID). 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 SCID yet. In this case, the new
character (and all associated error information) is lost because there is no room to move it into SCID. To clear
OR, read SCIS1 with OR = 1 and then read the SCI data register (SCID).
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 SCIS1 and then read the SCI data register (SCID).
0 No noise detected.
1 Noise detected in the received character in SCID.
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Table 13-5. SCIS1 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
SCIS1 with FE = 1 and then read the SCI data register (SCID).
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 SCIS1 and then read the
SCI data register (SCID).
0 No parity error.
1 Parity error.
13.2.5
SCI Status Register 2 (SCIS2)
This register has one read-only status flag.
7
6
5
LBKDIF
RXEDGIF
0
0
R
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 (SCIS2)
Table 13-6. SCIS2 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. SCIS2 Field Descriptions (continued)
1
Field
Description
1
LBKDE
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).
0
RAF
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 (SCIC3)
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 (SCIC3)
Table 13-7. SCIC3 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 SCID register. When reading 9-bit data, read R8
before reading SCID because reading SCID completes automatic flag clearing sequences which could allow R8
and SCID 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 SCID register. When writing 9-bit data, the entire
9-bit value is transferred to the SCI shift register after SCID is written so T8 should be written (if it needs to change
from its previous value) before SCID 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 SCID 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. SCIC3 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 (SCID)
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 (SCID)
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 ±4.5 percent 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 SCIC2. 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 (SCID).
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 SCID.
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 SCIC2 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
SCIC2. 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)
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status 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 SCID. 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 SCIC2. 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 message
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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 SCID. 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 SCID. The RDRF flag is cleared by reading SCIS1 while RDRF = 1 and then
reading SCID.
When polling is used, this sequence is naturally satisfied in the normal course of the user program. If
hardware interrupts are used, SCIS1 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 SCIS1 while IDLE = 1 and then reading
SCID. 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 SCIC1. 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 SCIC3. For the receiver, the ninth bit is held
in R8 in SCIC3.
For coherent writes to the transmit data buffer, write to the T8 bit before writing to SCID.
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 SCID 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 SCIC3 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
Development Support
14.1
Introduction
Development support systems in the S08 family include the S08 background debug controller (BDC).
The BDC provides a single-wire debug interface to the target MCU. This interface provides a convenient
means for programming the on-chip flash and other nonvolatile memories. Also, the BDC is the primary
debug interface for development and allows non-intrusive access to memory data and traditional debug
features such as CPU register modify, breakpoint, and single-instruction trace commands.
In the S08 family, address and data bus signals are not available on external pins. Debug is done through
commands fed into the target MCU via the single-wire background debug interface, including resetting the
device without using a reset pin.
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14.1.1
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
Features of the ICE system include:
• Two trigger comparators: Two address + read/write (R/W) or one full address + data + R/W
• Flexible 8-word by 16-bit FIFO (first-in, first-out) buffer for capture information:
— Change-of-flow addresses or
— Event-only data
• Two types of breakpoints:
— Tag breakpoints for instruction opcodes
— Force breakpoints for any address access
• Nine trigger modes:
— Basic: A-only, A OR B
— Sequence: A then B
— Full: A AND B data, A AND NOT B data
— Event (store data): Event-only B, A then event-only B
— Range: Inside range (A  address  B), outside range (address < A or address > B)
14.2
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
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•
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.
BKGD 1
2 GND
NO CONNECT 3
4 RESET
NO CONNECT 5
6 VDD
Figure 14-1. BDM Tool Connector
14.2.1
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 14.2.2,
“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
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driven speedup pulses to force rapid rise times on this pin without risking harmful drive level conflicts.
Refer to Section 14.2.2, “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.
14.2.2
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
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 14-2 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.
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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 14-2. BDC Host-to-Target Serial Bit Timing
Figure 14-3 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.
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BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
TARGET MCU
SPEEDUP PULSE
HIGH-IMPEDANCE
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 14-3. BDC Target-to-Host Serial Bit Timing (Logic 1)
Figure 14-4 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.
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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 14-4. BDM Target-to-Host Serial Bit Timing (Logic 0)
14.2.3
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 14-1 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 14-1 to describe the coding structure of the BDC commands.
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/
d
AAAA
RD
WD
RD16
WD16
SS
CC
RBKP
=
=
=
=
=
=
=
=
=
=
WBKP
=
Commands begin with an 8-bit hexadecimal command code in the host-to-target
direction (most significant bit first)
separates parts of the command
delay 16 target BDC clock cycles
a 16-bit address in the host-to-target direction
8 bits of read data in the target-to-host direction
8 bits of write data in the host-to-target direction
16 bits of read data in the target-to-host direction
16 bits of write data in the host-to-target direction
the contents of BDCSCR in the target-to-host direction (STATUS)
8 bits of write data for BDCSCR in the host-to-target direction (CONTROL)
16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)
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Table 14-1. 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.
14.2.4
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.
The on-chip debug module (DBG) includes circuitry for two additional hardware breakpoints that are more
flexible than the simple breakpoint in the BDC module.
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14.3
On-Chip Debug System (DBG)
Because HCS08 devices do not have external address and data buses, the most important functions of an
in-circuit emulator have been built onto the chip with the MCU. The debug system consists of an 8-stage
FIFO that can store address or data bus information, and a flexible trigger system to decide when to capture
bus information and what information to capture. The system relies on the single-wire background debug
system to access debug control registers and to read results out of the eight stage FIFO.
The debug module includes control and status registers that are accessible in the user’s memory map.
These registers are located in the high register space to avoid using valuable direct page memory space.
Most of the debug module’s functions are used during development, and user programs rarely access any
of the control and status registers for the debug module. The one exception is that the debug system can
provide the means to implement a form of ROM patching. This topic is discussed in greater detail in
Section 14.3.6, “Hardware Breakpoints.”
14.3.1
Comparators A and B
Two 16-bit comparators (A and B) can optionally be qualified with the R/W signal and an opcode tracking
circuit. Separate control bits allow you to ignore R/W for each comparator. The opcode tracking circuitry
optionally allows you to specify that a trigger will occur only if the opcode at the specified address is
actually executed as opposed to only being read from memory into the instruction queue. The comparators
are also capable of magnitude comparisons to support the inside range and outside range trigger modes.
Comparators are disabled temporarily during all BDC accesses.
The A comparator is always associated with the 16-bit CPU address. The B comparator compares to the
CPU address or the 8-bit CPU data bus, depending on the trigger mode selected. Because the CPU data
bus is separated into a read data bus and a write data bus, the RWAEN and RWA control bits have an
additional purpose, in full address plus data comparisons they are used to decide which of these buses to
use in the comparator B data bus comparisons. If RWAEN = 1 (enabled) and RWA = 0 (write), the CPU’s
write data bus is used. Otherwise, the CPU’s read data bus is used.
The currently selected trigger mode determines what the debugger logic does when a comparator detects
a qualified match condition. A match can cause:
• Generation of a breakpoint to the CPU
• Storage of data bus values into the FIFO
• Starting to store change-of-flow addresses into the FIFO (begin type trace)
• Stopping the storage of change-of-flow addresses into the FIFO (end type trace)
14.3.2
Bus Capture Information and FIFO Operation
The usual way to use the FIFO is to setup the trigger mode and other control options, then arm the
debugger. When the FIFO has filled or the debugger has stopped storing data into the FIFO, you would
read the information out of it in the order it was stored into the FIFO. Status bits indicate the number of
words of valid information that are in the FIFO as data is stored into it. If a trace run is manually halted by
writing 0 to ARM before the FIFO is full (CNT = 1:0:0:0), the information is shifted by one position and
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the host must perform ((8 – CNT) – 1) dummy reads of the FIFO to advance it to the first significant entry
in the FIFO.
In most trigger modes, the information stored in the FIFO consists of 16-bit change-of-flow addresses. In
these cases, read DBGFH then DBGFL to get one coherent word of information out of the FIFO. Reading
DBGFL (the low-order byte of the FIFO data port) causes the FIFO to shift so the next word of information
is available at the FIFO data port. In the event-only trigger modes (see Section 14.3.5, “Trigger Modes”),
8-bit data information is stored into the FIFO. In these cases, the high-order half of the FIFO (DBGFH) is
not used and data is read out of the FIFO by simply reading DBGFL. Each time DBGFL is read, the FIFO
is shifted so the next data value is available through the FIFO data port at DBGFL.
In trigger modes where the FIFO is storing change-of-flow addresses, there is a delay between CPU
addresses and the input side of the FIFO. Because of this delay, if the trigger event itself is a
change-of-flow address or a change-of-flow address appears during the next two bus cycles after a trigger
event starts the FIFO, it will not be saved into the FIFO. In the case of an end-trace, if the trigger event is
a change-of-flow, it will be saved as the last change-of-flow entry for that debug run.
The FIFO can also be used to generate a profile of executed instruction addresses when the debugger is
not armed. When ARM = 0, reading DBGFL causes the address of the most-recently fetched opcode to be
saved in the FIFO. To use the profiling feature, a host debugger would read addresses out of the FIFO by
reading DBGFH then DBGFL at regular periodic intervals. The first eight values would be discarded
because they correspond to the eight DBGFL reads needed to initially fill the FIFO. Additional periodic
reads of DBGFH and DBGFL return delayed information about executed instructions so the host debugger
can develop a profile of executed instruction addresses.
14.3.3
Change-of-Flow Information
To minimize the amount of information stored in the FIFO, only information related to instructions that
cause a change to the normal sequential execution of instructions is stored. With knowledge of the source
and object code program stored in the target system, an external debugger system can reconstruct the path
of execution through many instructions from the change-of-flow information stored in the FIFO.
For conditional branch instructions where the branch is taken (branch condition was true), the source
address is stored (the address of the conditional branch opcode). Because BRA and BRN instructions are
not conditional, these events do not cause change-of-flow information to be stored in the FIFO.
Indirect JMP and JSR instructions use the current contents of the H:X index register pair to determine the
destination address, so the debug system stores the run-time destination address for any indirect JMP or
JSR. For interrupts, RTI, or RTS, the destination address is stored in the FIFO as change-of-flow
information.
14.3.4
Tag vs. Force Breakpoints and Triggers
Tagging is a term that refers to identifying an instruction opcode as it is fetched into the instruction queue,
but not taking any other action until and unless that instruction is actually executed by the CPU. This
distinction is important because any change-of-flow from a jump, branch, subroutine call, or interrupt
causes some instructions that have been fetched into the instruction queue to be thrown away without being
executed.
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A force-type breakpoint waits for the current instruction to finish and then acts upon the breakpoint
request. The usual action in response to a breakpoint is to go to active background mode rather than
continuing to the next instruction in the user application program.
The tag vs. force terminology is used in two contexts within the debug module. The first context refers to
breakpoint requests from the debug module to the CPU. The second refers to match signals from the
comparators to the debugger control logic. When a tag-type break request is sent to the CPU, a signal is
entered into the instruction queue along with the opcode so that if/when this opcode ever executes, the
CPU will effectively replace the tagged opcode with a BGND opcode so the CPU goes to active
background mode rather than executing the tagged instruction. When the TRGSEL control bit in the DBGT
register is set to select tag-type operation, the output from comparator A or B is qualified by a block of
logic in the debug module that tracks opcodes and only produces a trigger to the debugger if the opcode at
the compare address is actually executed. There is separate opcode tracking logic for each comparator so
more than one compare event can be tracked through the instruction queue at a time.
14.3.5
Trigger Modes
The trigger mode controls the overall behavior of a debug run. The 4-bit TRG field in the DBGT register
selects one of nine trigger modes. When TRGSEL = 1 in the DBGT register, the output of the comparator
must propagate through an opcode tracking circuit before triggering FIFO actions. The BEGIN bit in
DBGT chooses whether the FIFO begins storing data when the qualified trigger is detected (begin trace),
or the FIFO stores data in a circular fashion from the time it is armed until the qualified trigger is detected
(end trigger).
A debug run is started by writing a 1 to the ARM bit in the DBGC register, which sets the ARMF flag and
clears the AF and BF flags and the CNT bits in DBGS. A begin-trace debug run ends when the FIFO gets
full. An end-trace run ends when the selected trigger event occurs. Any debug run can be stopped manually
by writing a 0 to ARM or DBGEN in DBGC.
In all trigger modes except event-only modes, the FIFO stores change-of-flow addresses. In event-only
trigger modes, the FIFO stores data in the low-order eight bits of the FIFO.
The BEGIN control bit is ignored in event-only trigger modes and all such debug runs are begin type
traces. When TRGSEL = 1 to select opcode fetch triggers, it is not necessary to use R/W in comparisons
because opcode tags would only apply to opcode fetches that are always read cycles. It would also be
unusual to specify TRGSEL = 1 while using a full mode trigger because the opcode value is normally
known at a particular address.
The following trigger mode descriptions only state the primary comparator conditions that lead to a trigger.
Either comparator can usually be further qualified with R/W by setting RWAEN (RWBEN) and the
corresponding RWA (RWB) value to be matched against R/W. The signal from the comparator with
optional R/W qualification is used to request a CPU breakpoint if BRKEN = 1 and TAG determines
whether the CPU request will be a tag request or a force request.
A-Only — Trigger when the address matches the value in comparator A
A OR B — Trigger when the address matches either the value in comparator A or the value in
comparator B
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A Then B — Trigger when the address matches the value in comparator B but only after the address for
another cycle matched the value in comparator A. There can be any number of cycles after the A match
and before the B match.
A AND B Data (Full Mode) — This is called a full mode because address, data, and R/W (optionally)
must match within the same bus cycle to cause a trigger event. Comparator A checks address, the low byte
of comparator B checks data, and R/W is checked against RWA if RWAEN = 1. The high-order half of
comparator B is not used.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
A AND NOT B Data (Full Mode) — Address must match comparator A, data must not match the low
half of comparator B, and R/W must match RWA if RWAEN = 1. All three conditions must be met within
the same bus cycle to cause a trigger.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
Event-Only B (Store Data) — Trigger events occur each time the address matches the value in
comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the
FIFO becomes full.
A Then Event-Only B (Store Data) — After the address has matched the value in comparator A, a trigger
event occurs each time the address matches the value in comparator B. Trigger events cause the data to be
captured into the FIFO. The debug run ends when the FIFO becomes full.
Inside Range (A  Address  B) — A trigger occurs when the address is greater than or equal to the value
in comparator A and less than or equal to the value in comparator B at the same time.
Outside Range (Address < A or Address > B) — A trigger occurs when the address is either less than
the value in comparator A or greater than the value in comparator B.
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14.3.6
Hardware Breakpoints
The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions
described in Section 14.3.5, “Trigger Modes,” to be used to generate a hardware breakpoint request to the
CPU. TAG in DBGC controls whether the breakpoint request will be treated as a tag-type breakpoint or a
force-type breakpoint. A tag breakpoint causes the current opcode to be marked as it enters the instruction
queue. If a tagged opcode reaches the end of the pipe, the CPU executes a BGND instruction to go to active
background mode rather than executing the tagged opcode. A force-type breakpoint causes the CPU to
finish the current instruction and then go to active background mode.
If the background mode has not been enabled (ENBDM = 1) by a serial WRITE_CONTROL command
through the BKGD pin, the CPU will execute an SWI instruction instead of going to active background
mode.
14.4
Register Definition
This section contains the descriptions of the BDC and DBG registers and control bits.
Refer to the high-page register summary in the device overview chapter of this data sheet for the absolute
address assignments for all DBG 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.
14.4.1
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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14.4.1.1
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
R
6
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 14-5. BDC Status and Control Register (BDCSCR)
Table 14-2. 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
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)
3
CLKSW
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 14-2. 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 MC9S08FL16 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
14.4.1.2
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 14.2.4, “BDC Hardware Breakpoint.”
14.4.2
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 14-6. System Background Debug Force Reset Register (SBDFR)
Table 14-3. 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.
14.4.3
DBG Registers and Control Bits
The debug module includes nine bytes of register space for three 16-bit registers and three 8-bit control
and status registers. These registers are located in the high register space of the normal memory map so
they are accessible to normal application programs. These registers are rarely if ever accessed by normal
user application programs with the possible exception of a ROM patching mechanism that uses the
breakpoint logic.
14.4.3.1
Debug Comparator A High Register (DBGCAH)
This register contains compare value bits for the high-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
14.4.3.2
Debug Comparator A Low Register (DBGCAL)
This register contains compare value bits for the low-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
14.4.3.3
Debug Comparator B High Register (DBGCBH)
This register contains compare value bits for the high-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
14.4.3.4
Debug Comparator B Low Register (DBGCBL)
This register contains compare value bits for the low-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
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14.4.3.5
Debug FIFO High Register (DBGFH)
This register provides read-only access to the high-order eight bits of the FIFO. Writes to this register have
no meaning or effect. In the event-only trigger modes, the FIFO only stores data into the low-order byte
of each FIFO word, so this register is not used and will read 0x00.
Reading DBGFH does not cause the FIFO to shift to the next word. When reading 16-bit words out of the
FIFO, read DBGFH before reading DBGFL because reading DBGFL causes the FIFO to advance to the
next word of information.
14.4.3.6
Debug FIFO Low Register (DBGFL)
This register provides read-only access to the low-order eight bits of the FIFO. Writes to this register have
no meaning or effect.
Reading DBGFL causes the FIFO to shift to the next available word of information. When the debug
module is operating in event-only modes, only 8-bit data is stored into the FIFO (high-order half of each
FIFO word is unused). When reading 8-bit words out of the FIFO, simply read DBGFL repeatedly to get
successive bytes of data from the FIFO. It isn’t necessary to read DBGFH in this case.
Do not attempt to read data from the FIFO while it is still armed (after arming but before the FIFO is filled
or ARMF is cleared) because the FIFO is prevented from advancing during reads of DBGFL. This can
interfere with normal sequencing of reads from the FIFO.
Reading DBGFL while the debugger is not armed causes the address of the most-recently fetched opcode
to be stored to the last location in the FIFO. By reading DBGFH then DBGFL periodically, external host
software can develop a profile of program execution. After eight reads from the FIFO, the ninth read will
return the information that was stored as a result of the first read. To use the profiling feature, read the FIFO
eight times without using the data to prime the sequence and then begin using the data to get a delayed
picture of what addresses were being executed. The information stored into the FIFO on reads of DBGFL
(while the FIFO is not armed) is the address of the most-recently fetched opcode.
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14.4.3.7
Debug Control Register (DBGC)
This register can be read or written at any time.
7
6
5
4
3
2
1
0
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 14-7. Debug Control Register (DBGC)
Table 14-4. DBGC Register Field Descriptions
Field
Description
7
DBGEN
Debug Module Enable — Used to enable the debug module. DBGEN cannot be set to 1 if the MCU is secure.
0 DBG disabled
1 DBG enabled
6
ARM
Arm Control — Controls whether the debugger is comparing and storing information in the FIFO. A write is used
to set this bit (and ARMF) and completion of a debug run automatically clears it. Any debug run can be manually
stopped by writing 0 to ARM or to DBGEN.
0 Debugger not armed
1 Debugger armed
5
TAG
Tag/Force Select — Controls whether break requests to the CPU will be tag or force type requests. If
BRKEN = 0, this bit has no meaning or effect.
0 CPU breaks requested as force type requests
1 CPU breaks requested as tag type requests
4
BRKEN
Break Enable — Controls whether a trigger event will generate a break request to the CPU. Trigger events can
cause information to be stored in the FIFO without generating a break request to the CPU. For an end trace, CPU
break requests are issued to the CPU when the comparator(s) and R/W meet the trigger requirements. For a
begin trace, CPU break requests are issued when the FIFO becomes full. TRGSEL does not affect the timing of
CPU break requests.
0 CPU break requests not enabled
1 Triggers cause a break request to the CPU
3
RWA
R/W Comparison Value for Comparator A — When RWAEN = 1, this bit determines whether a read or a write
access qualifies comparator A. When RWAEN = 0, RWA and the R/W signal do not affect comparator A.
0 Comparator A can only match on a write cycle
1 Comparator A can only match on a read cycle
2
RWAEN
Enable R/W for Comparator A — Controls whether the level of R/W is considered for a comparator A match.
0 R/W is not used in comparison A
1 R/W is used in comparison A
1
RWB
R/W Comparison Value for Comparator B — When RWBEN = 1, this bit determines whether a read or a write
access qualifies comparator B. When RWBEN = 0, RWB and the R/W signal do not affect comparator B.
0 Comparator B can match only on a write cycle
1 Comparator B can match only on a read cycle
0
RWBEN
Enable R/W for Comparator B — Controls whether the level of R/W is considered for a comparator B match.
0 R/W is not used in comparison B
1 R/W is used in comparison B
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14.4.3.8
Debug Trigger Register (DBGT)
This register can be read any time, but may be written only if ARM = 0, except bits 4 and 5 are hard-wired
to 0s.
7
6
TRGSEL
BEGIN
0
0
R
5
4
0
0
3
2
1
0
TRG3
TRG2
TRG1
TRG0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 14-8. Debug Trigger Register (DBGT)
Table 14-5. DBGT Register Field Descriptions
Field
Description
7
TRGSEL
Trigger Type — Controls whether the match outputs from comparators A and B are qualified with the opcode
tracking logic in the debug module. If TRGSEL is set, a match signal from comparator A or B must propagate
through the opcode tracking logic and a trigger event is only signalled to the FIFO logic if the opcode at the match
address is actually executed.
0 Trigger on access to compare address (force)
1 Trigger if opcode at compare address is executed (tag)
6
BEGIN
Begin/End Trigger Select — Controls whether the FIFO starts filling at a trigger or fills in a circular manner until
a trigger ends the capture of information. In event-only trigger modes, this bit is ignored and all debug runs are
assumed to be begin traces.
0 Data stored in FIFO until trigger (end trace)
1 Trigger initiates data storage (begin trace)
3:0
TRG[3:0]
14.4.3.9
Select Trigger Mode — Selects one of nine triggering modes, as described below.
0000 A-only
0001 A OR B
0010 A Then B
0011 Event-only B (store data)
0100 A then event-only B (store data)
0101 A AND B data (full mode)
0110 A AND NOT B data (full mode)
0111 Inside range: A  address  B
1000 Outside range: address < A or address > B
1001 – 1111 (No trigger)
Debug Status Register (DBGS)
This is a read-only status register.
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R
7
6
5
4
3
2
1
0
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 14-9. Debug Status Register (DBGS)
Table 14-6. DBGS Register Field Descriptions
Field
Description
7
AF
Trigger Match A Flag — AF is cleared at the start of a debug run and indicates whether a trigger match A
condition was met since arming.
0 Comparator A has not matched
1 Comparator A match
6
BF
Trigger Match B Flag — BF is cleared at the start of a debug run and indicates whether a trigger match B
condition was met since arming.
0 Comparator B has not matched
1 Comparator B match
5
ARMF
Arm Flag — While DBGEN = 1, this status bit is a read-only image of ARM in DBGC. This bit is set by writing 1
to the ARM control bit in DBGC (while DBGEN = 1) and is automatically cleared at the end of a debug run. A
debug run is completed when the FIFO is full (begin trace) or when a trigger event is detected (end trace). A
debug run can also be ended manually by writing 0 to ARM or DBGEN in DBGC.
0 Debugger not armed
1 Debugger armed
3:0
CNT[3:0]
FIFO Valid Count — These bits are cleared at the start of a debug run and indicate the number of words of valid
data in the FIFO at the end of a debug run. The value in CNT does not decrement as data is read out of the FIFO.
The external debug host is responsible for keeping track of the count as information is read out of the FIFO.
0000 Number of valid words in FIFO = No valid data
0001 Number of valid words in FIFO = 1
0010 Number of valid words in FIFO = 2
0011 Number of valid words in FIFO = 3
0100 Number of valid words in FIFO = 4
0101 Number of valid words in FIFO = 5
0110 Number of valid words in FIFO = 6
0111 Number of valid words in FIFO = 7
1000 Number of valid words in FIFO = 8
MC9S08FL16 MCU Series Reference Manual, Rev. 3
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MC9S08FL16RM
Rev. 3
11/2010