Freescale MC68HC908JB16FA M68hc08 microcontroller Datasheet

MC68HC908JB16
Technical Data
M68HC08
Microcontrollers
Rev. 1.1
MC68HC908JB16/D
August 1, 2005
freescale.com
MC68HC908JB16
Technical Data
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disclaims any and all liability, including without limitation consequential or incidental
damages. "Typical" parameters which may be provided in FreescaleFreescale data
sheets and/or specifications can and do vary in different applications and actual
performance may vary over time. All operating parameters, including "Typicals" must
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© Freescale, Inc., 2002
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
3
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
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available, refer to:
http://freescale.com
The following revision history table summarizes changes contained in
this document. For your convenience, the page number designators
have been linked to the appropriate location.
Revision History
Date
Revision
Level
May
2002
1
Technical Data
4
Description
First general release.
Page
Number(s)
—
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data — MC68HC908JB16
List of Sections
Section 1. General Description . . . . . . . . . . . . . . . . . . . . . . . 29
Section 2. Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Section 3. Random-Access Memory (RAM) . . . . . . . . . . . . . 57
Section 4. FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Section 5. Configuration Register (CONFIG) . . . . . . . . . . . . 71
Section 6. Central Processor Unit (CPU). . . . . . . . . . . . . . . . 75
Section 7. Oscillator (OSC) . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Section 8. System Integration Module (SIM) . . . . . . . . . . . . . 97
Section 9. Monitor ROM (MON) . . . . . . . . . . . . . . . . . . . . . . 123
Section 10. Timer Interface Module (TIM) . . . . . . . . . . . . . . 137
Section 11. Universal Serial Bus Module (USB) . . . . . . . . . 161
Section 12. Serial Communications Interface
Module (SCI). . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Section 13. Clock Generator Module (CGM) . . . . . . . . . . . . 247
Section 14. Input/Output (I/O) Ports. . . . . . . . . . . . . . . . . . . 263
Section 15. External Interrupt (IRQ) . . . . . . . . . . . . . . . . . . . 281
Section 16. Keyboard Interrupt Module (KBI) . . . . . . . . . . . 289
Section 17. Computer Operating Properly (COP) . . . . . . . . 297
Section 18. Low-Voltage Inhibit (LVI) . . . . . . . . . . . . . . . . . 303
Section 19. Break Module (BRK) . . . . . . . . . . . . . . . . . . . . . 307
Section 20. Electrical Specifications . . . . . . . . . . . . . . . . . . 315
Section 21. Mechanical Specifications . . . . . . . . . . . . . . . . 325
Section 22. Ordering Information. . . . . . . . . . . . . . . . . . . . . 329
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Technical Data — MC68HC908JB16
Table of Contents
Section 1. General Description
1.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
1.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.4
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.5
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.6
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
1.6.1
Power Supply Pins (VDD, VSS) . . . . . . . . . . . . . . . . . . . . . . . 34
1.6.2
Voltage Regulator Output Pin (VREG). . . . . . . . . . . . . . . . . . 34
1.6.3
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . 35
1.6.4
External Reset Pin (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.6.5
External Interrupt Pins (IRQ, PTE4/D–) . . . . . . . . . . . . . . . . 35
1.6.6
CGM Power Supply Pins (VDDA, VSSA0, VSSA1) . . . . . . . . . 36
1.6.7
CGM Voltage Regulator Out (VREGA0) . . . . . . . . . . . . . . . . . 36
1.6.8
CGM Voltage Regulator In (VREGA1) . . . . . . . . . . . . . . . . . . 36
1.6.9
External Filter Capacitor Pins (CGMXFC1, CGMXFC2) . . . 36
1.6.10 CGM Clock Output Pins (CGMOUT1, CGMOUT2) . . . . . . . 36
1.6.11 Port A Input/Output (I/O) Pins (PTA7/KBA7–PTA0/KBA0). . 36
1.6.12 Port C I/O Pins (PTC1/RxD, PTC0/TxD) . . . . . . . . . . . . . . . 37
1.6.13 Port D I/O Pins (PTD5–PTD0) . . . . . . . . . . . . . . . . . . . . . . . 37
1.6.14 Port E I/O Pins (PTE4/D–, PTE3/D+, PTE2/T2CH01,
PTE1/T1CH01, PTE0/TCLK). . . . . . . . . . . . . . . . . . . . . . 37
Section 2. Memory Map
2.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
2.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . 41
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2.4
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.5
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Section 3. Random-Access Memory (RAM)
3.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
3.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
Section 4. FLASH Memory
4.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
4.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
4.4
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.5
FLASH Block Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.6
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.7
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .64
4.8
FLASH Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
4.8.1
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . . 66
4.9
ROM-Resident Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.9.1
Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.9.2
ERASE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.9.3
PROGRAM Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.9.4
VERIFY Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Section 5. Configuration Register (CONFIG)
5.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
5.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
5.4
Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
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Section 6. Central Processor Unit (CPU)
6.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
6.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.4.1
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.4.2
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.4.3
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.4.4
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.4.5
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
6.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.7
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.8
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.9
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Section 7. Oscillator (OSC)
7.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.3
Oscillator External Connections . . . . . . . . . . . . . . . . . . . . . . . .94
7.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.4.1
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . . 95
7.4.2
Crystal Amplifier Output Pin (OSC1) . . . . . . . . . . . . . . . . . . 95
7.4.3
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . . 95
7.4.4
Crystal Output Frequency Signal (OSCXCLK). . . . . . . . . . . 95
7.4.5
Clock Doubler Out (OSCDCLK) . . . . . . . . . . . . . . . . . . . . . . 95
7.4.6
Oscillator Out (OSCOUT). . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
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7.5.2
7.6
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . . 96
Section 8. System Integration Module (SIM)
8.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
8.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
8.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . . 100
8.3.1
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
8.3.2
Clock Startup from POR or LVI Reset . . . . . . . . . . . . . . . . 101
8.3.3
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . . 101
8.4
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . . 101
8.4.1
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
8.4.2
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . 103
8.4.2.1
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104
8.4.2.2
Computer Operating Properly (COP) Reset. . . . . . . . . . 105
8.4.2.3
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
8.4.2.4
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .105
8.4.2.5
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . 106
8.4.2.6
Universal Serial Bus (USB) Reset . . . . . . . . . . . . . . . . . 106
8.4.2.7
Registers Values After Different Resets. . . . . . . . . . . . . 106
8.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
8.5.1
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . 107
8.5.2
SIM Counter During Stop Mode Recovery . . . . . . . . . . . . . 108
8.5.3
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . . 108
8.6
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108
8.6.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.6.1.1
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.6.1.2
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2
Interrupt Status Registers. . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2.1
Interrupt Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2.2
Interrupt Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . 114
8.6.3
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8.6.4
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8.6.5
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . 114
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8.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
8.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
8.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116
8.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
8.8.1
SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . 118
8.8.2
SIM Reset Status Register (SRSR) . . . . . . . . . . . . . . . . . . 119
8.8.3
SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . 120
Section 9. Monitor ROM (MON)
9.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
9.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
9.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
9.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124
9.4.1
Entering Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
9.4.2
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9.4.3
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9.4.4
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
9.4.5
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
9.5
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
9.5.1
Extended Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Section 10. Timer Interface Module (TIM)
10.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
10.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
10.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
10.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
10.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
10.5.1 TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10.5.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10.5.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
10.5.3.1
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . 144
10.5.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . .145
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10.5.4 Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . 145
10.5.4.1
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . 146
10.5.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . 147
10.5.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
10.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149
10.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
10.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
10.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
10.8
TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 150
10.9 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
10.9.1 TIM Clock Pin (PTE0/TCLK) . . . . . . . . . . . . . . . . . . . . . . .151
10.9.2 TIM Channel I/O Pins (PTE1/T1CH01:PTE2/T2CH01) . . . 151
10.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
10.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . . 152
10.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
10.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . 155
10.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . . 156
10.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Section 11. Universal Serial Bus Module (USB)
11.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
11.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
11.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
11.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
11.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168
11.5.1 USB Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
11.5.1.1
Sync Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
11.5.1.2
Packet Identifier Field . . . . . . . . . . . . . . . . . . . . . . . . . . 171
11.5.1.3
Address Field (ADDR) . . . . . . . . . . . . . . . . . . . . . . . . . . 172
11.5.1.4
Endpoint Field (ENDP). . . . . . . . . . . . . . . . . . . . . . . . . . 172
11.5.1.5
Cyclic Redundancy Check (CRC) . . . . . . . . . . . . . . . . . 172
11.5.1.6
End-of-Packet (EOP) . . . . . . . . . . . . . . . . . . . . . . . . . . .172
11.5.2 Reset Signaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
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11.5.3 Suspend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
11.5.4 Resume After Suspend . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
11.5.4.1
Host Initiated Resume . . . . . . . . . . . . . . . . . . . . . . . . . . 175
11.5.4.2
USB Reset Signalling. . . . . . . . . . . . . . . . . . . . . . . . . . .175
11.5.4.3
Remote Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175
11.5.5 Low-Speed Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
11.6
Clock Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
11.7 Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.1 Voltage Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.2 USB Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.2.1
Output Driver Characteristics . . . . . . . . . . . . . . . . . . . . . 178
11.7.2.2
Low Speed (1.5 Mbps) Driver Characteristics . . . . . . . . 178
11.7.2.3
Receiver Data Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11.7.2.4
Data Source Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11.7.2.5
Data Signal Rise and Fall Time . . . . . . . . . . . . . . . . . . . 180
11.7.3 USB Control Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
11.8 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
11.8.1 USB Address Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.8.2 USB Interrupt Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.8.3 USB Interrupt Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 185
11.8.4 USB Interrupt Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.8.5 USB Control Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
11.8.6 USB Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.8.7 USB Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
11.8.8 USB Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.8.9 USB Control Register 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.8.10 USB Status Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
11.8.11 USB Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
11.8.12 USB Endpoint 0 Data Registers . . . . . . . . . . . . . . . . . . . . . 198
11.8.13 USB Endpoint 1 Data Registers . . . . . . . . . . . . . . . . . . . . . 199
11.8.14 USB Endpoint 2 Data Registers . . . . . . . . . . . . . . . . . . . . . 200
11.9 USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.9.1 USB End-of-Transaction Interrupt . . . . . . . . . . . . . . . . . . . 201
11.9.1.1
Receive Control Endpoint 0 . . . . . . . . . . . . . . . . . . . . . . 202
11.9.1.2
Transmit Control Endpoint 0 . . . . . . . . . . . . . . . . . . . . . 204
11.9.1.3
Transmit Endpoint 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
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11.9.1.4
Transmit Endpoint 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.1.5
Receive Endpoint 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.2 Resume Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.3 End-of-Packet Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Section 12. Serial Communications Interface Module
(SCI)
12.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
12.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
12.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
12.5.1 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.5.2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.5.2.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
12.5.2.2
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . 215
12.5.2.3
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
12.5.2.4
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
12.5.2.5
Inversion of Transmitted Output. . . . . . . . . . . . . . . . . . . 217
12.5.2.6
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . .217
12.5.3 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.2
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.3
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
12.5.3.4
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
12.5.3.5
Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . .222
12.5.3.6
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.5.3.7
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.5.3.8
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
12.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
12.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
12.7
SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . .228
12.8
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
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12.8.2
TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
12.9 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.9.1 SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.9.2 SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
12.9.3 SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
12.9.4 SCI Status Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
12.9.5 SCI Status Register 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
12.9.6 SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
12.9.7 SCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . .244
Section 13. Clock Generator Module (CGM)
13.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247
13.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
13.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.3.1 Reference Frequency Source (OSCXCLK) . . . . . . . . . . . . 250
13.3.2 Voltage Controlled Oscillator . . . . . . . . . . . . . . . . . . . . . . .250
13.3.3 Reference Divider. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.3.4 VCO Frequency Divider . . . . . . . . . . . . . . . . . . . . . . . . . . .251
13.3.5 Phase Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
13.3.6 Phase Detector Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.3.7 Lock Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
13.4.1 CGM Power Supply Pins (VDDA, VSSA0, VSSA1) . . . . . . . . 252
13.4.2 CGM1 Voltage Regulator Out (VREGA0). . . . . . . . . . . . . . . 252
13.4.3 CGM2 Voltage Regulator In (VREGA1) . . . . . . . . . . . . . . . . 252
13.4.4 External Filter Capacitor Pins (CGMXFC1, CGMXFC2) . . 253
13.4.5 CGM Clock Output Pins (CGMOUT1, CGMOUT2) . . . . . . 253
13.5
CGMXFC External Connections . . . . . . . . . . . . . . . . . . . . . . . 253
13.6
CGMOUT External Connections. . . . . . . . . . . . . . . . . . . . . . . 254
13.7
Calculation of VCO Frequency . . . . . . . . . . . . . . . . . . . . . . . . 254
13.8
Programming the PLL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
13.9
CGM I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
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13.9.1
13.9.2
13.9.3
13.9.4
13.9.5
13.9.6
Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . . . . . 256
VCO Control Register (PVCR) . . . . . . . . . . . . . . . . . . . . . . 256
VCO and Reference Divider Select Registers High . . . . . . 257
VCO Divider Select Register Low . . . . . . . . . . . . . . . . . . . 258
Reference Divider Select Register Low . . . . . . . . . . . . . . . 259
Phase Detector Control Register (PDCR) . . . . . . . . . . . . . 260
13.10 Pre-Defined VCO Output Frequency Settings . . . . . . . . . . . . 260
13.11 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
13.11.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
13.11.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Section 14. Input/Output (I/O) Ports
14.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263
14.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
14.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14.3.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14.3.2 Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . 267
14.4 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
14.4.1 Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
14.4.2 Data Direction Register C. . . . . . . . . . . . . . . . . . . . . . . . . . 270
14.5 Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
14.5.1 Port D Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
14.5.2 Data Direction Register D. . . . . . . . . . . . . . . . . . . . . . . . . . 273
14.6 Port E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
14.6.1 Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
14.6.2 Data Direction Register E. . . . . . . . . . . . . . . . . . . . . . . . . . 277
14.7 Port Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
14.7.1 Port Option Control Register . . . . . . . . . . . . . . . . . . . . . . .279
Section 15. External Interrupt (IRQ)
15.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281
15.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
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Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
15.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282
15.5
IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
15.6
PTE4/D– Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
15.7
IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . . 285
15.8
IRQ Status and Control Register . . . . . . . . . . . . . . . . . . . . . . 286
15.9
IRQ Option Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . 287
Section 16. Keyboard Interrupt Module (KBI)
16.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289
16.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
16.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
16.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
16.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291
16.6
Keyboard Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
16.7 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
16.7.1 Keyboard Status and Control Register. . . . . . . . . . . . . . . . 294
16.7.2 Keyboard Interrupt Enable Register . . . . . . . . . . . . . . . . . . 295
16.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
16.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
16.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
16.9
Keyboard Module During Break Interrupts . . . . . . . . . . . . . . . 296
Section 17. Computer Operating Properly (COP)
17.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
17.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .298
17.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
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17.4.1
17.4.2
17.4.3
17.4.4
17.4.5
17.4.6
17.4.7
17.4.8
OSCDCLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299
STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299
Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . 300
17.5
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
17.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301
17.7
Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301
17.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
17.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
17.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
17.9
COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . . 302
Section 18. Low-Voltage Inhibit (LVI)
18.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303
18.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
18.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
18.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304
18.4.1 Low VDD Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304
18.4.2 Low VREG Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
18.5
LVI Control and Configuration . . . . . . . . . . . . . . . . . . . . . . . . 305
18.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
18.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
18.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
Section 19. Break Module (BRK)
19.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
19.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
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19.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
19.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308
19.4.1 Flag Protection During Break Interrupts . . . . . . . . . . . . . . . 310
19.4.2 CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .310
19.4.3 TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . 310
19.4.4 COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 310
19.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
19.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
19.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
19.6 Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
19.6.1 Break Status and Control Register. . . . . . . . . . . . . . . . . . . 311
19.6.2 Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . 312
19.6.3 SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 312
19.6.4 SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 314
Section 20. Electrical Specifications
20.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
20.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
20.3
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . 316
20.4
Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . . 317
20.5
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
20.6
DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 318
20.7
Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
20.8
Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
20.9
TImer Interface Module Characteristics . . . . . . . . . . . . . . . . . 320
20.10 USB DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 320
20.11 USB Low-Speed Source Electrical Characteristics . . . . . . . . 321
20.12 USB Signaling Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
20.13 CGM Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 322
20.14 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . 324
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Section 21. Mechanical Specifications
21.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .325
21.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
21.3
32-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . . 326
21.4
28-Pin Small Outline Integrated Circuit (SOIC) . . . . . . . . . . . 327
Section 22. Ordering Information
22.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329
22.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
22.3
MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
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List of Figures
Figure
Title
1-1
1-2
1-3
1-4
1-5
MC68HC908JB16 MCU Block Diagram . . . . . . . . . . . . . . . . . . 32
32-Pin LQFP Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . 33
28-Pin SOIC Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Power Supply Bypassing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Regulator Supply Capacitor Configuration . . . . . . . . . . . . . . . . 35
2-1
2-2
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Control, Status, and Data Registers . . . . . . . . . . . . . . . . . . . . .44
4-1
4-2
4-3
4-4
4-5
FLASH I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . 60
FLASH Control Register (FLCR) . . . . . . . . . . . . . . . . . . . . . . . 61
FLASH Programming Flowchart . . . . . . . . . . . . . . . . . . . . . . . . 65
FLASH Block Protect Register (FLBPR). . . . . . . . . . . . . . . . . . 66
FLASH Block Protect Start Address . . . . . . . . . . . . . . . . . . . . .66
5-1
Configuration Register (CONFIG). . . . . . . . . . . . . . . . . . . . . . . 72
6-1
6-2
6-3
6-4
6-5
6-6
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Accumulator (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Index Register (H:X) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Condition Code Register (CCR) . . . . . . . . . . . . . . . . . . . . . . . . 80
7-1
Oscillator External Connections . . . . . . . . . . . . . . . . . . . . . . . .94
8-1
8-2
8-3
8-4
SIM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SIM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .100
SIM Clock Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
External Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102
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8-5
8-6
8-7
8-8
8-9
8-10
8-11
8-12
8-13
8-14
8-15
8-16
8-17
8-18
8-19
8-20
8-21
Internal Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Sources of Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
POR Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Interrupt Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Interrupt Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Interrupt Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Interrupt Recognition Example . . . . . . . . . . . . . . . . . . . . . . . . 111
Interrupt Status Register 1 (INT1). . . . . . . . . . . . . . . . . . . . . . 112
Interrupt Status Register 2 (INT2). . . . . . . . . . . . . . . . . . . . . . 114
Wait Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Wait Recovery from Interrupt or Break . . . . . . . . . . . . . . . . . . 116
Wait Recovery from Internal Reset. . . . . . . . . . . . . . . . . . . . . 116
Stop Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Stop Mode Recovery from Interrupt or Break . . . . . . . . . . . . . 117
SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . . 118
SIM Reset Status Register (SRSR) . . . . . . . . . . . . . . . . . . . . 119
SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . . 120
9-1
9-2
9-3
9-4
9-5
9-6
9-7
9-8
Monitor Mode Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Low-Voltage Monitor Mode Entry Flowchart. . . . . . . . . . . . . . 127
Monitor Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Break Transaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Read Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130
Write Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Stack Pointer at Monitor Mode Entry . . . . . . . . . . . . . . . . . . . 134
Monitor Mode Entry Timing. . . . . . . . . . . . . . . . . . . . . . . . . . .135
10-1
10-2
10-3
10-4
10-5
10-6
10-7
10-8
10-9
TIM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
TIM I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .141
PWM Period and Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . 146
TIM Status and Control Register (TSC) . . . . . . . . . . . . . . . . . 152
TIM Counter Registers High (TCNTH) . . . . . . . . . . . . . . . . . . 154
TIM Counter Registers Low (TCNTL) . . . . . . . . . . . . . . . . . . . 155
TIM Counter Modulo Register High (TMODH) . . . . . . . . . . . . 155
TIM Counter Modulo Register Low (TMODL) . . . . . . . . . . . . . 155
TIM Channel 0 Status and Control Register (TSC0) . . . . . . . 156
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10-11
10-12
10-13
10-14
10-15
TIM Channel 1 Status and Control Register (TSC1) . . . . . . . 156
CHxMAX Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
TIM Channel 0 Register High (TCH0H) . . . . . . . . . . . . . . . . . 160
TIM Channel 0 Register Low (TCH0L) . . . . . . . . . . . . . . . . . . 160
TIM Channel 1 Register High (TCH1H) . . . . . . . . . . . . . . . . . 160
TIM Channel 1 Register Low (TCH1L) . . . . . . . . . . . . . . . . . . 160
11-1
11-2
11-3
11-4
11-5
11-6
11-7
11-8
11-9
11-10
11-11
11-12
11-13
11-14
11-15
11-16
11-17
11-18
11-19
11-20
11-21
11-22
11-23
11-24
11-25
11-26
11-27
11-28
11-29
USB I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 164
USB Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Supported Transaction Types Per Endpoint. . . . . . . . . . . . . . 169
Supported USB Packet Types . . . . . . . . . . . . . . . . . . . . . . . . 170
Sync Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
SOP, Sync Signaling, and Voltage Levels . . . . . . . . . . . . . . . 171
EOP Transaction Voltage Levels . . . . . . . . . . . . . . . . . . . . . . 173
EOP Width Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
External Low-Speed Device Configuration . . . . . . . . . . . . . . . 176
Regulator Electrical Connections . . . . . . . . . . . . . . . . . . . . . . 177
Receiver Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Differential Input Sensitivity Range. . . . . . . . . . . . . . . . . . . . . 179
Data Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Data Signal Rise and Fall Time . . . . . . . . . . . . . . . . . . . . . . .180
USB Address Register (UADDR) . . . . . . . . . . . . . . . . . . . . . . 182
USB Interrupt Register 0 (UIR0) . . . . . . . . . . . . . . . . . . . . . . . 183
USB Interrupt Register 1 (UIR1) . . . . . . . . . . . . . . . . . . . . . . . 185
USB Interrupt Register 2 (UIR2) . . . . . . . . . . . . . . . . . . . . . . . 188
USB Control Register 0 (UCR0) . . . . . . . . . . . . . . . . . . . . . . . 189
USB Control Register 1 (UCR1) . . . . . . . . . . . . . . . . . . . . . . . 190
USB Control Register 2 (UCR2) . . . . . . . . . . . . . . . . . . . . . . . 191
USB Control Register 3 (UCR3) . . . . . . . . . . . . . . . . . . . . . . . 193
USB Control Register 4 (UCR4) . . . . . . . . . . . . . . . . . . . . . . . 195
USB Status Register 0 (USR0). . . . . . . . . . . . . . . . . . . . . . . . 196
USB Status Register 2 (USR1). . . . . . . . . . . . . . . . . . . . . . . . 197
USB Endpoint 0 Data Registers (UE0D0–UE0D7). . . . . . . . . 198
USB Endpoint 1 Data Registers (UE1D0–UE1D7). . . . . . . . . 199
USB Endpoint 2 Data Registers (UE2D0–UE2D7). . . . . . . . . 200
OUT Token Data Flow for Receive Endpoint 0. . . . . . . . . . . . 202
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11-30 SETUP Token Data Flow for Receive Endpoint 0 . . . . . . . . . 203
11-31 IN Token Data Flow for Transmit Endpoint 0 . . . . . . . . . . . . . 204
11-32 IN Token Data Flow for Transmit Endpoint 1 . . . . . . . . . . . . . 205
12-1
12-2
12-3
12-4
12-5
12-6
12-7
12-8
12-9
12-10
12-11
12-12
12-13
12-14
12-15
12-16
SCI Module Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . .211
SCI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .212
SCI Data Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213
SCI Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
SCI Receiver Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 219
Receiver Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Slow Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Fast Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
SCI Control Register 1 (SCC1). . . . . . . . . . . . . . . . . . . . . . . . 230
SCI Control Register 2 (SCC2). . . . . . . . . . . . . . . . . . . . . . . . 233
SCI Control Register 3 (SCC3). . . . . . . . . . . . . . . . . . . . . . . . 235
SCI Status Register 1 (SCS1) . . . . . . . . . . . . . . . . . . . . . . . . 238
Flag Clearing Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
SCI Status Register 2 (SCS2) . . . . . . . . . . . . . . . . . . . . . . . . 242
SCI Data Register (SCDR) . . . . . . . . . . . . . . . . . . . . . . . . . . .243
SCI Baud Rate Register (SCBR) . . . . . . . . . . . . . . . . . . . . . . 244
13-1
13-2
13-3
13-4
13-5
13-6
13-7
13-8
13-9
13-10
13-11
13-12
13-13
13-14
CGM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . 248
CGM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
CGM Power Supply Connection . . . . . . . . . . . . . . . . . . . . . . . 252
CGMXFC External Connections . . . . . . . . . . . . . . . . . . . . . . . 253
CGMOUT External Connections. . . . . . . . . . . . . . . . . . . . . . . 254
PLL Bandwidth Control Register (PBCR) . . . . . . . . . . . . . . . . 256
VCO Control Register (PVCR) . . . . . . . . . . . . . . . . . . . . . . . . 256
PLL1 N & R Divider Select Register High (PNRH1) . . . . . . . . 257
PLL2 N & R Divider Select Register High (PNRH2) . . . . . . . . 257
PLL1 N Divider Select Register Low (PNSL1) . . . . . . . . . . . . 258
PLL2 N Divider Select Register Low (PNSL2) . . . . . . . . . . . . 258
PLL1 R Divider Select Register Low (PRSL1) . . . . . . . . . . . . 259
PLL2 R Divider Select Register Low (PRSL2) . . . . . . . . . . . . 259
Phase Detector Control Register (PDCR) . . . . . . . . . . . . . . . 260
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14-1
14-2
14-3
14-4
14-5
14-6
14-7
14-8
14-9
14-10
14-11
14-12
14-13
14-14
I/O Port Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .264
Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . . . . 267
Port A I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . . . . 269
Data Direction Register C (DDRC) . . . . . . . . . . . . . . . . . . . . . 270
Port C I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Data Direction Register D (DDRD) . . . . . . . . . . . . . . . . . . . . . 273
Port D I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Port E Data Register (PTE) . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Data Direction Register E (DDRE) . . . . . . . . . . . . . . . . . . . . . 277
Port E I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Port Option Control Register (POCR). . . . . . . . . . . . . . . . . . . 279
15-1
15-2
15-3
15-4
IRQ Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 283
IRQ I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .283
IRQ Status and Control Register (ISCR) . . . . . . . . . . . . . . . . 286
IRQ Option Control Register (IOCR) . . . . . . . . . . . . . . . . . . . 287
16-1
16-2
16-3
16-4
I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .290
Keyboard Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . 291
Keyboard Status and Control Register (KBSCR) . . . . . . . . . . 294
Keyboard Interrupt Enable Register (KBIER) . . . . . . . . . . . . . 295
17-1 COP Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17-2 Configuration Register (CONFIG). . . . . . . . . . . . . . . . . . . . . . 300
17-3 COP Control Register (COPCTL) . . . . . . . . . . . . . . . . . . . . . . 301
18-1 LVI Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . .304
18-2 Configuration Register (CONFIG). . . . . . . . . . . . . . . . . . . . . . 305
19-1
19-2
19-3
19-4
Break Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 309
Break Module I/O Register Summary . . . . . . . . . . . . . . . . . . . 309
Break Status and Control Register (BRKSCR). . . . . . . . . . . . 311
Break Address Register High (BRKH) . . . . . . . . . . . . . . . . . . 312
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
List of Figures
25
List of Figures
Figure
Title
Page
19-5 Break Address Register Low (BRKL) . . . . . . . . . . . . . . . . . . . 312
19-6 SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . . 313
19-7 SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . . 314
21-1 32-Pin LQFP (Case #873A) . . . . . . . . . . . . . . . . . . . . . . . . . . 326
21-2 28-Pin SOIC (Case #751F). . . . . . . . . . . . . . . . . . . . . . . . . . .327
Technical Data
26
MC68HC908JB16 — Rev. 1.1
List of Figures
Freescale Semiconductor
Technical Data — MC68HC908JB16
List of Tables
Table
Title
1-1
Summary of Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2-1
Vector Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
4-1
4-2
4-3
4-4
4-5
ROM-Resident Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Summary of FLASH Routine Variables . . . . . . . . . . . . . . . . . . 68
ERASE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
PROGRAM Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
VERIFY Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
6-1
6-2
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
8-1
8-2
8-3
8-4
SIM Module Signal Name Conventions . . . . . . . . . . . . . . . . . . 99
PIN Bit Set Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Registers not Affected by Normal Reset. . . . . . . . . . . . . . . . . 107
Interrupt Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
9-1
9-2
9-3
9-4
9-5
9-6
9-7
9-8
9-9
9-10
Mode Entry Requirements and Options . . . . . . . . . . . . . . . . . 126
Monitor Mode Vector Differences . . . . . . . . . . . . . . . . . . . . . . 128
Monitor Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . 129
READ (Read Memory) Command . . . . . . . . . . . . . . . . . . . . . 131
WRITE (Write Memory) Command. . . . . . . . . . . . . . . . . . . . . 132
IREAD (Indexed Read) Command . . . . . . . . . . . . . . . . . . . . . 132
IWRITE (Indexed Write) Command . . . . . . . . . . . . . . . . . . . . 133
READSP (Read Stack Pointer) Command . . . . . . . . . . . . . . . 133
RUN (Run User Program) Command . . . . . . . . . . . . . . . . . . . 134
Monitor Mode Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Page
Technical Data
List of Tables
27
List of Tables
Table
Title
Page
10-1 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
10-2 Prescaler Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
10-3 Mode, Edge, and Level Selection . . . . . . . . . . . . . . . . . . . . . . 158
11-1 USB Module Pin Name Conventions . . . . . . . . . . . . . . . . . . . 164
11-2 Supported Packet Identifiers. . . . . . . . . . . . . . . . . . . . . . . . . . 171
12-1
12-2
12-3
12-4
12-5
12-6
12-7
12-8
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Start Bit Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Data Bit Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
Stop Bit Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222
Character Format Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 232
SCI Baud Rate Prescaling . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
SCI Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
SCI Baud Rate Selection Examples . . . . . . . . . . . . . . . . . . . .246
13-1 Predefined Programming Setting for PLL . . . . . . . . . . . . . . . . 260
14-1
14-2
14-3
14-4
14-5
Port Control Register Bits Summary. . . . . . . . . . . . . . . . . . . .265
Port A Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
Port C Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Port D Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Port E Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
16-1 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
22-1 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Technical Data
28
MC68HC908JB16 — Rev. 1.1
List of Tables
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 1. General Description
1.1 Contents
1.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.4
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.5
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.6
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
1.6.1
Power Supply Pins (VDD, VSS) . . . . . . . . . . . . . . . . . . . . . . . 34
1.6.2
Voltage Regulator Output Pin (VREG). . . . . . . . . . . . . . . . . . 34
1.6.3
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . 35
1.6.4
External Reset Pin (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.6.5
External Interrupt Pins (IRQ, PTE4/D–) . . . . . . . . . . . . . . . . 35
1.6.6
CGM Power Supply Pins (VDDA, VSSA0, VSSA1) . . . . . . . . . 36
1.6.7
CGM Voltage Regulator Out (VREGA0) . . . . . . . . . . . . . . . . . 36
1.6.8
CGM Voltage Regulator In (VREGA1) . . . . . . . . . . . . . . . . . . 36
1.6.9
External Filter Capacitor Pins (CGMXFC1, CGMXFC2) . . . 36
1.6.10 CGM Clock Output Pins (CGMOUT1, CGMOUT2) . . . . . . . 36
1.6.11 Port A Input/Output (I/O) Pins (PTA7/KBA7–PTA0/KBA0). . 36
1.6.12 Port C I/O Pins (PTC1/RxD, PTC0/TxD) . . . . . . . . . . . . . . . 37
1.6.13 Port D I/O Pins (PTD5–PTD0) . . . . . . . . . . . . . . . . . . . . . . . 37
1.6.14 Port E I/O Pins (PTE4/D–, PTE3/D+, PTE2/T2CH01,
PTE1/T1CH01, PTE0/TCLK). . . . . . . . . . . . . . . . . . . . . . 37
1.2 Introduction
The MC68HC908JB16 is a member of the low-cost, high-performance
M68HC08 Family of 8-bit microcontroller units (MCUs). The M68HC08
Family is based on the customer-specified integrated circuit (CSIC)
design strategy.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
29
General Description
1.3 Features
Features of the MC68HC908JB16 MCU include the following:
•
High-performance M68HC08 architecture
•
Fully upward-compatible object code with M6805, M146805, and
M68HC05 families
•
Low-power design; fully static with stop and wait modes
•
6-MHz internal bus frequency
•
16,384 bytes of on-chip FLASH memory with security1 feature
•
384 bytes of on-chip random access memory (RAM)
•
Up to 21 general-purpose input/output (I/O) pins, including:
– 15 shared-function I/O pins
– 8-bit keyboard interrupt port
– 10mA high current drive for PS/2 connection on 2 pins
(with USB module disabled)
– 1 dedicated I/O pin, with 25mA direct drive for infrared LED
(32-pin package)
– 6 dedicated I/O pins, with 25mA direct drive for infrared LED
on 2 pins and 10mA direct drive for normal LED on 4 pins
(28-pin package)
•
Two 16-bit, 2-channel timer interface modules (TIM1 and TIM2)
with selectable input capture, output compare, PWM capability on
each channel, and external clock input option (TCLK)
•
Universal Serial Bus specification 2.0 low-speed functions:
– 1.5Mbps data rate
– On-chip 3.3V regulator
– Endpoint 0 with 8-byte transmit buffer and 8-byte receive buffer
– Endpoint 1 with 8-byte transmit buffer
– Endpoint 2 with 8-byte transmit buffer and 8-byte receive buffer
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Technical Data
30
MC68HC908JB16 — Rev. 1.1
General Description
Freescale Semiconductor
General Description
•
Serial communications interface module (SCI)
•
Dual clock generator modules (CGM) (32-pin package)
•
In-circuit programming capability using USB communication or
standard serial link on PTA0 pin
•
System protection features:
– Optional computer operating properly (COP) reset
– Optional Low-voltage detection with reset
– Illegal opcode detection with reset
– Illegal address detection with reset
•
Master reset pin with internal pull-up and power-on reset
•
IRQ interrupt pin with internal pull-up and schmitt-trigger input
•
32-pin low-profile quad flat pack (LQFP) and 28-pin small outline
integrated circuit package (SOIC)
Features of the CPU08 include the following:
•
Enhanced HC05 programming model
•
Extensive loop control functions
•
16 addressing modes (eight more than the HC05)
•
16-bit index register and stack pointer
•
Memory-to-memory data transfers
•
Fast 8 × 8 multiply instruction
•
Fast 16/8 divide instruction
•
Binary-coded decimal (BCD) instructions
•
Optimization for controller applications
•
Third party C language support
1.4 MCU Block Diagram
Figure 1-1 shows the structure of the MC68HC908JB16.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
31
General Description
(1) OSC1
(1) OSC2
OSCILLATOR
(5)
CGMXFC1
(1), (5) CGMOUT1
(5) CGMXFC2
(1), (5)
CGMOUT2
(2)
RST
(3) IRQ
DUAL CLOCK
GENERATOR MODULE
SYSTEM INTEGRATION
MODULE
IRQ
MODULE
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
VDD
VSS
VREG (3.3V)
(5) V
(5)
VSSA0
(5) V
(5)
DDA
POWER AND INTERNAL
VOLTAGE REGULATORS
PTC1/RxD (3)
PTC0/TxD (3)
PTD5 (4), (6)
POWER-ON RESET
MODULE
PTD4 (4), (6)
DDRD
USER FLASH VECTORS — 48 BYTES
(3)
LOW VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING
PROPERLY MODULE
PTD3 (4), (6)
PTD2 (4), (6)
PTD1 (4), (6)
PTD0 (4)
2-CHANNEL TIMER INTERFACE
MODULE 1
2-CHANNEL TIMER INTERFACE
MODULE 2
PTE4/D– (3), (4)
PTE3/D+
USB MODULE
USB ENDPOINT 0, 1, 2
LS USB
TRANSCEIVER
MONITOR ROM — 1,472 BYTES
PTA
DDRA
USER RAM — 384 BYTES
PTC
SERIAL COMMUNICATIONS
INTERFACE MODULE
DDRC
USER FLASH MEMORY — 16,384 BYTES
PTA7/KBA7
:
PTA0/KBA0
BREAK
MODULE
PTD
CONTROL AND STATUS REGISTERS — 64 BYTES
KEYBOARD INTERRUPT
MODULE
(1) Pins have 3V logic.
(2) Pins have integrated pullup device.
(3) Pins have software configurable pull-up device.
(4) Pins are open-drain when configured as output.
(5) Pins available on 32-pin package only.
(6) Pins available on 28-pin package only.
SSA1
VREGA0 (3.3V)
(5) V
REGA1 (3.3V)
Figure 1-1. MC68HC908JB16 MCU Block Diagram
PTE
ARITHMETIC/LOGIC
UNIT (ALU)
DDRE
CPU
REGISTERS
(3), (4)
PTE2/T2CH01 (3)
PTE1/T1CH01 (3)
PTE0/TCLK (3)
General Description
Technical Data
32
INTERNAL BUS
M68HC08 CPU
General Description
VDDA
VREGA0
VSSA0
CGMXFC1
CGMXFC2
30
29
28
27
26
25 VREGA1
CGMOUT1
VSS 1
31
32 RST
1.5 Pin Assignments
24 VSSA1
VREG
4
21
PTA1/KBA1
VDD
5
20
PTA2/KBA2
PTD0
6
19
PTA3/KBA3
PTE1/T1CH01
7
18
PTE0/TCLK
17 PTE2/T2CH01
PTA4/KBA4 16
15
PTA5/KBA5
PTA6/KBA6
PTA7/KBA7
PTE4/D– 9
PTE3/D+ 8
14
PTA0/KBA0
13
22
12
3
PTC1/RxD
OSC2
11
CGMOUT2
IRQ
23
10
2
PTC0/TxD
OSC1
Pins not available on 32-pin package:
PTD5
PTD4
PTD2
PTD1
PTD3
Figure 1-2. 32-Pin LQFP Pin Assignment
VSS
1
28
RST
OSC1
2
27
PTA0/KBA0
OSC2
3
26
PTA1/KBA1
VREG
4
25
PTA2/KBA2
VDD
5
24
PTA3/KBA3
PTD0
6
23
PTE0/TCLK
PTD1
7
22
PTE2/T2CH01
PTD2
8
21
PTA4/KBA4
PTD3
9
20
PTA5/KBA5
PTD4
10
19
PTA6/KBA6
PTE1/T1CH01
11
18
PTA7/KBA7
PTE3/D+
12
17
PTD5
PTE4/D–
13
16
PTC1/RxD
PTC0/TxD
14
15
IRQ
Pins not available on 28-pin package:
CGMXFC1
CGMXFC2
CGMOUT1
CGMOUT2
VREGA0
VREGA1
VSSA0
VSSA1
VDDA
Figure 1-3. 28-Pin SOIC Pin Assignment
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
33
General Description
1.6 Pin Functions
Description of pin functions are provided here.
1.6.1 Power Supply Pins (VDD, VSS)
VDD and VSS are the power supply and ground pins. The MCU operates
from a single power supply.
Fast signal transitions on MCU pins place high, short-duration current
demands on the power supply. To prevent noise problems, take special
care to provide power supply bypassing at the MCU as Figure 1-4
shows. Place the bypass capacitors as close to the MCU power pins as
possible. Use high-frequency-response ceramic capacitors for CBYPASS.
CBULK are optional bulk current bypass capacitors for use in applications
that require the port pins to source high current levels.
MCU
VDD
VSS
CBYPASS
0.1 µF
+
CBULK
VDD
NOTE: Values shown are typical values.
Figure 1-4. Power Supply Bypassing
1.6.2 Voltage Regulator Output Pin (VREG)
VREG is the 3.3V output of the on-chip voltage regulator. VREG is used
internally for the MCU operation and the USB data driver. It is also used
to supply the voltage for the external pullup resistor required on the
USB’s D– line. The VREG pin requires an external bulk capacitor 4.7µF
or larger and a 0.1µF ceramic bypass capacitor as Figure 1-5 shows.
Place the bypass capacitors as close to the VREG pin as possible.
Technical Data
34
MC68HC908JB16 — Rev. 1.1
General Description
Freescale Semiconductor
General Description
VREG
MCU
VSS
CREGBYPASS
0.1 µF
+
CREGBULK
> 4.7 µF
VREG
Figure 1-5. Regulator Supply Capacitor Configuration
1.6.3 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator
circuit.
1.6.4 External Reset Pin (RST)
A logic zero on the RST pin forces the MCU to a known start-up state.
RST is bidirectional, allowing a reset of the entire system. It is driven low
when any internal reset source is asserted. The RST pin contains an
internal pullup device to VDD. (See Section 8. System Integration
Module (SIM).)
1.6.5 External Interrupt Pins (IRQ, PTE4/D–)
IRQ is an asynchronous external interrupt pin. IRQ is also the pin to
enter Monitor mode. The IRQ pin contains a software configurable pullup
device to VDD. PTE4/D– can be programmed to trigger the IRQ interrupt.
(See Section 15. External Interrupt (IRQ).)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
35
General Description
1.6.6 CGM Power Supply Pins (VDDA, VSSA0, VSSA1)
VDDA is the power supply pin, VSSA0 and VSSA1 are the ground pins for
the analog portion of the clock generator modules (CGMs). Connect
VDDA to the same voltage potential as VDD. Connect VSSA0 and VSSA1
pins to the same voltage potential as VSS. Decoupling of these pins
should be as per the digital supply.
1.6.7 CGM Voltage Regulator Out (VREGA0)
VREGA0 is the 3.3V output of the second on-chip voltage regulator.
VREGA0 is used for CGM1 and CGM2 operation. Decoupling of this pin
should be as per the digital VREG.
1.6.8 CGM Voltage Regulator In (VREGA1)
VREGA1 is the 3.3V input pin for CGM2. Connect VREGA1 directly to
VREGA0. Decoupling of VREGA1 pin should be as per VREGA0.
1.6.9 External Filter Capacitor Pins (CGMXFC1, CGMXFC2)
CGMXFC1 and CGMXFC2 are external capacitor connections for the
respective CGMs.
1.6.10 CGM Clock Output Pins (CGMOUT1, CGMOUT2)
CGMOUT1 and CGMOUT2 are buffered VCO outputs of the respective
CGMs.
1.6.11 Port A Input/Output (I/O) Pins (PTA7/KBA7–PTA0/KBA0)
PTA7/KBA7–PTA0/KBA0 are general-purpose bidirectional I/O port
pins. (See Section 14. Input/Output (I/O) Ports.) Each pin contains a
software configurable pullup device to VDD when the pin is configured as
an input. (See 14.7 Port Options.) Each pin can also be programmed
as an external keyboard interrupt pin. (See Section 16. Keyboard
Interrupt Module (KBI).)
Technical Data
36
MC68HC908JB16 — Rev. 1.1
General Description
Freescale Semiconductor
General Description
1.6.12 Port C I/O Pins (PTC1/RxD, PTC0/TxD)
Port C is a 2-bit special function port that shares its pins with the SCI
module. (See Section 14. Input/Output (I/O) Ports.) Each pin contains
a software configurable pullup device to VDD when the pin is configured
as an input. (See 14.7 Port Options.)
1.6.13 Port D I/O Pins (PTD5–PTD0)
PTD5–PTD0 are general-purpose bidirectional I/O port pins; open-drain
when configured as output. (See Section 14. Input/Output (I/O) Ports.)
PTD5–PTC2 are software configurable to be 10mA sink pins for direct
LED connections. PTD1–PTD0 are software configurable to be 25mA
sink pins for direct infrared LED connections. (See 14.7 Port Options.)
1.6.14 Port E I/O Pins (PTE4/D–, PTE3/D+, PTE2/T2CH01, PTE1/T1CH01, PTE0/TCLK)
Port E is a 5-bit special function port that shares two of its pins with the
USB module and three of its pins with the two timer interface modules.
Each PTE2–PTE0 pin contains a software configurable pullup device to
VDD when the pin is configured as an input or output.
When the USB module is disabled, the PTE4 and PTE3 pins are
general-purpose bidirectional I/O port pins with 10mA sink capability.
Each pin is open-drain when configured as an output; and each pin
contains a software configurable 5kΩ pullup to VDD when configured as
an input. The PTE4 pin can also be enabled to trigger the IRQ interrupt.
When the USB module is enabled, the PTE4/D– and PTE3/D+ pins
become the USB module D– and D+ pins. The USB D– pin contains a
1.5kΩ software configurable pullup device to VREG. (See Section 10.
Timer Interface Module (TIM), Section 11. Universal Serial Bus
Module (USB) and Section 14. Input/Output (I/O) Ports.)
NOTE:
Any unused inputs and I/O ports should be tied to an appropriate logic
level (either VDD or VSS). Although the I/O ports of the MC68HC908JB16
do not require termination, termination is recommended to reduce the
possibility of static damage.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
37
General Description
Summary of the pin functions are provided in Table 1-1.
Table 1-1. Summary of Pin Functions
PIN NAME
PIN DESCRIPTION
IN/OUT
VOLTAGE
LEVEL
IN
4.0 to 5.5V
VDD
Power supply.
VSS
Power supply ground.
OUT
0V
VREG
3.3V regulated output from MCU.
OUT
VREG (3.3V)
RST
Reset input, active low.
With internal pull-up and schmitt trigger input.
IN/OUT
VDD
External IRQ pin; with programmable internal pull-up and
schmitt trigger input.
IN
VDD
Used for mode entry selection.
IN
VREG to VTST
OSC1
Crystal oscillator input.
IN
VREG
OSC2
Crystal oscillator output; inverting of OSC1 signal.
OUT
VREG
VDDA(1)
Analog power supply.
IN
4.0 to 5.5V
Analog power supply ground.
OUT
0V
VREGA0(1)
3.3V regulated output from MCU.
OUT
VREGA0 (3.3V)
VREGA1(1)
3.3V input for CGM2.
IN
VREGA0
IRQ
VSSA0(1)
VSSA1(1)
CGMXFC1(1)
CGM1 external filter capacitor connection.
OUT
VREGA0
CGMXFC2(1)
CGM2 external filter capacitor connection.
OUT
VREGA0
CGMOUT1(1)
CGM1 clock output.
OUT
VREGA0
CGMOUT2(1)
CGM2 clock output.
OUT
VREGA0
IN/OUT
VDD
Pins as keyboard interrupts, KBA0–KBA7.
IN
VDD
Each pin has programmable internal pullup when configured
as input.
IN
VDD
PTA0/KBA0
:
PTA7/KBA7
8-bit general purpose I/O port.
Technical Data
38
MC68HC908JB16 — Rev. 1.1
General Description
Freescale Semiconductor
General Description
Table 1-1. Summary of Pin Functions
PIN NAME
PIN DESCRIPTION
2-bit general purpose I/O port.
IN/OUT
VOLTAGE
LEVEL
IN/OUT
VDD
IN
VDD
PTC0/TxD
Each pin has programmable internal pull-up device.
PTC1/RxD
PTC0 as TxD of SCI module.
OUT
VDD
PTC1 as RxD of SCI module.
IN
VDD
6-bit general purpose I/O port;
open-drain when configured as output.
IN
OUT
VDD
VREG or VDD
PTD0–PTD1 have configurable 25mA sink for infrared LED.
OUT
VREG or VDD
PTD2–PTD5 have configurable 10mA sink for LED.
OUT
VREG or VDD
PTE0–PTE2 are general purpose I/O lines.
IN/OUT
VDD
PTE0–PTE2 have programmable internal pullup when
configured as input or output.
IN/OUT
VDD
IN
VDD
PTE1 as T1CH01 of TIM1.
IN/OUT
VDD
PTE2 as T2CH01 of TIM2.
IN/OUT
VDD
IN
OUT
VDD
VREG or VDD
IN
VDD
PTD0–PTD5(2)
PTE0/TCLK
PTE1/T1CH01
PTE2/T2CH01
PTE0 as TCLK of TIM1 and TIM2.
PTE3–PTE4 general purpose I/O lines;
open-drain when configured as output.
PTE3/D+
PTE3–PTE4 have programmable internal pullup when
configured as input.
PTE4/D–
PTE3 as D+ of USB module.
IN/OUT
VREG
PTE4 as D– of USB module.
IN/OUT
VREG
IN
VDD
PTE4 as additional IRQ interrupt.
Notes:
1. Pin available on 32-pin package only.
2. PTD[5:1] pins available on 28-pin package only.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
General Description
39
General Description
Technical Data
40
MC68HC908JB16 — Rev. 1.1
General Description
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 2. Memory Map
2.1 Contents
2.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . 41
2.4
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.5
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.2 Introduction
The CPU08 can address 64k-bytes of memory space. The memory map,
shown in Figure 2-1, includes:
•
16,384 bytes of FLASH memory
•
384 bytes of random-access memory (RAM)
•
48 bytes of user-defined vectors
•
1,024 + 448 bytes of monitor ROM
2.3 Unimplemented Memory Locations
Accessing an unimplemented location can cause an illegal address
reset if illegal address resets are enabled. In the memory map
(Figure 2-1) and in register figures in this document, unimplemented
locations are shaded.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
41
Memory Map
2.4 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on MCU
operation. In the Figure 2-1 and in register figures in this document,
reserved locations are marked with the word Reserved or with the
letter R.
2.5 Input/Output (I/O) Section
Most of the control, status, and data registers are in the zero page area
of $0000–$007F. Additional I/O registers have these addresses:
•
$FE00; SIM break status register, SBSR
•
$FE01; SIM reset status register, SRSR
•
$FE02; Reserved
•
$FE03; SIM break flag control register, SBFCR
•
$FE04; Interrupt status register 1, INT1
•
$FE05; Interrupt status register 2, INT2
•
$FE06; Reserved
•
$FE07; Reserved
•
$FE08; FLASH control register, FLCR
•
$FE09; FLASH block protect register, FLBPR
•
$FE0A; Reserved
•
$FE0B; Reserved
•
$FE0C; Break address register high, BRKH
•
$FE0D; Break address register low, BRKL
•
$FE0E; Break status and control register, BRKSCR
•
$FE0F; Reserved
•
$FFFF; COP control register, COPCTL
Data registers are shown in Figure 2-2. Table 2-1 is a list of vector
locations.
Technical Data
42
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
$0000
↓
$007F
I/O Registers
128 Bytes
$0080
↓
$01FF
RAM
384 Bytes
$0200
↓
$B9FF
Unimplemented
47,104 Bytes
$BA00
↓
$F9FF
FLASH Memory
16,384 Bytes
$FA00
↓
$FDFF
Monitor ROM 1
1,024 Bytes
$FE00
SIM Break Status Register (SBSR)
$FE01
SIM Reset Status Register (SRSR)
$FE02
Reserved
$FE03
SIM Break Flag Control Register (SBFCR)
$FE04
Interrupt Status Register 1 (INT1)
$FE05
Interrupt Status Register 2 (INT2)
$FE06
Reserved
$FE07
Reserved
$FE08
FLASH Control Register (FLCR)
$FE09
FLASH Block Protect Register (FLBPR)
$FE0A
Reserved
$FE0B
Reserved
$FE0C
Break Address Register High (BRKH)
$FE0D
Break Address Register Low (BRKL)
$FE0E
Break Status and Control Register (BRKSCR)
$FE0F
Reserved
$FE10
↓
$FFCF
Monitor ROM 2
448 Bytes
$FFD0
↓
$FFFF
FLASH Vectors
48 Bytes
Figure 2-1. Memory Map
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
43
Memory Map
Addr.
Register Name
$0000
Read:
Port A Data Register
Write:
(PTA)
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
R
R
PTC1
PTC0
PTD2
PTD1
PTD0
Unaffected by reset
Read:
R
R
R
R
R
R
Read:
Port C Data Register
Write:
(PTC)
Reset:
0
0
0
0
0
0
Read:
Port D Data Register
Write:
(PTD)
Reset:
0
$0001
Reserved Write:
Reset:
$0002
$0003
Unaffected by reset
0
PTD5
PTD4
PTD3
Unaffected by reset
Read:
DDRA7
Data Direction Register A
$0004
Write:
(DDRA)
Reset:
0*
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
Read:
Data Direction Register C
Write:
$0006
(DDRC)
Reset:
0
0
0
0
0
0
DDRC1
DDRC0
0
0
0
0
0
0
0
0
Read:
Data Direction Register D
$0007
Write:
(DDRD)
Reset:
0
0
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
0
0
0
0
0
0
0
0
Read:
Port E Data Register
Write:
(PTE)
Reset:
0
0
0
PTE4
PTE3
PTE2
PTE1
PTE0
Read:
Data Direction Register E
$0009
Write:
(DDRE)
Reset:
0
0
0
0
0
0
* DDRA7 bit is reset by POR or LVI reset only.
Read:
Reserved Write:
$0005
Reset:
$0008
U = Unaffected
Unaffected by reset
X = Indeterminate
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 1 of 12)
Technical Data
44
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
Register Name
Bit 7
6
5
Read:
Timer 1 Status and Control
$000A
Register Write:
(T1SC)
Reset:
TOF
TOIE
TSTOP
0
0
1
0
R
R
R
Timer 1 Counter Read:
Register High Write:
(T1CNTH)
Reset:
Bit15
Bit14
0
Timer 1 Counter Read:
Register Low Write:
(T1CNTL)
Reset:
Read:
$000B
Reserved Write:
2
1
Bit 0
PS2
PS1
PS0
0
0
0
0
R
R
R
R
R
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
0
0
0
0
0
0
0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
0
0
0
0
0
0
0
0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
1
1
1
1
1
1
1
1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
1
1
1
1
1
1
1
1
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
Bit2
Bit1
Bit0
0
4
3
0
0
TRST
Reset:
$000C
$000D
$000E
$000F
$0010
$0011
$0012
$0013
Timer 1 Counter Modulo Read:
Register High Write:
(T1MODH)
Reset:
Timer 1 Counter Modulo Read:
Register Low Write:
(T1MODL)
Reset:
Timer 1 Channel 0 Read:
Status and Control Write:
Register
(T1SC0) Reset:
Read:
Timer 1 Channel 0
Register High Write:
(T1CH0H) Reset:
Timer 1 Channel 0 Read:
Register Low Write:
(T1CH0L) Reset:
Timer 1 Channel 1 Read:
Status and Control Write:
Register
(T1SC1) Reset:
U = Unaffected
CH0F
0
Indeterminate after reset
Bit7
Bit6
Bit5
Bit4
Bit3
Indeterminate after reset
CH1F
0
0
CH1IE
CH01IE
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 2 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
45
Memory Map
Addr.
$0014
$0015
$0016
Register Name
Read:
Timer 1 Channel 1
Register High Write:
(T1CH1H)
Reset:
Read:
Timer 1 Channel 1
Register Low Write:
(T1CH1L)
Reset:
$0019
$001A
6
5
4
3
2
1
Bit 0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
Bit2
Bit1
Bit0
IMASKK
MODEK
Indeterminate after reset
Bit7
Bit6
Bit5
Bit4
Bit3
Indeterminate after reset
Keyboard Status and Read:
Control Register Write:
(KBSCR)
Reset:
Keyboard Interrupt Enable Read:
$0017
Register Write:
(KBIER)
Reset:
$0018
Bit 7
0
0
0
0
KEYF
0
ACKK
0
0
0
0
0
0
0
0
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RSTFR
TXD2FR
RXD2FR
0
0
0
0
0
0
0
STALL2
TX2E
RX2E
TP2SIZ3
TP2SIZ2
TP2SIZ1
TP2SIZ0
0
0
0
0
0
0
0
Read:
0
USB Interrupt Register 2
Write: EOPFR
(UIR2)
Reset:
0
Read:
T2SEQ
USB Control Register 2
Write:
(UCR2)
Reset:
0
Read: TX1ST
USB Control Register 3
Write:
(UCR3)
Reset:
0
0
TX1STR
OSTALL0 ISTALL0
TDX1FR RESUMFR TXD0FR
0
0
0
0
0
RXD0FR
PULLEN ENABLE2 ENABLE1
0*
0
0
FUSBO
FDP
FDM
0
0
PTE4IE
IRQPD
* PULLEN bit is reset by POR or LVI reset only.
$001B
$001C
$001D
Read:
USB Control Register 4
Write:
(UCR4)
Reset:
0
0
0
0
0
0
0
0
0
0
0
IRQ Option Control Read:
Register Write:
(IOCR) Reset:
0
0
0
0
0
PTE4IF
0
0
0
0
0
0
0
0
PTE4P
PTE3P
PCP
R
PAP
0
0
0
0
0
= Unimplemented
R
= Reserved
Port Option Control Read: PTE20P
Register Write:
(POCR) Reset:
0
U = Unaffected
PTDLDD PTDILDD
0
0
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 3 of 12)
Technical Data
46
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
$001E
$001F
Register Name
Read:
IRQ Status and Control
Register Write:
(INTSCR)
Reset:
Read:
Configuration Register
Write:
(CONFIG)†
Reset:
Bit 7
6
5
4
3
2
0
0
0
0
IRQF
0
ACK
1
Bit 0
IMASK
MODE
0
0
0
0
0
0
0
0
LVIDR
LVI5OR3
URSTD
LVID
SSREC
COPRS
STOP
COPD
0*
0*
0*
0*
0
0
0
0
† One-time writable register after each reset.
* LVIDR, LVI5OR3, URSTD, and LVID, are reset by POR or LVI reset only.
$0020
$0021
$0022
$0023
$0024
$0025
$0026
$0027
Read: UE0R07
USB Endpoint 0 Data
Register 0 Write: UE0T07
(UE0D0) Reset:
UE0R06
UE0R05
UE0R04
UE0R03
UE0R02
UE0R01
UE0R00
UE0T06
UE0T05
UE0T04
UE0T03
UE0T02
UE0T01
UE0T00
Read: UE0R17
USB Endpoint 0 Data
Register 1 Write: UE0T17
(UE0D1) Reset:
UE0R16
UE0R15
UE0R14
UE0R13
UE0R12
UE0R11
UE0R10
UE0T16
UE0T15
UE0T14
UE0T13
UE0T12
UE0T11
UE0T10
Read: UE0R27
USB Endpoint 0 Data
Register 2 Write: UE0T27
(UE0D2) Reset:
UE0R26
UE0R25
UE0R24
UE0R23
UE0R22
UE0R21
UE0R20
UE0T26
UE0T25
UE0T24
UE0T23
UE0T22
UE0T21
UE0T20
Read: UE0R37
USB Endpoint 0 Data
Register 3 Write: UE0T37
(UE0D3) Reset:
UE0R36
UE0R35
UE0R34
UE0R33
UE0R32
UE0R31
UE0R30
UE0T36
UE0T35
UE0T34
UE0T33
UE0T32
UE0T31
UE0T30
Read: UE0R47
USB Endpoint 0 Data
Register 4 Write: UE0T47
(UE0D4) Reset:
UE0R46
UE0R45
UE0R44
UE0R43
UE0R42
UE0R41
UE0R40
UE0T46
UE0T45
UE0T44
UE0T43
UE0T42
UE0T41
UE0T40
USB Endpoint 0 Data Read: UE0R57
Register 5 Write: UE0T57
(UE0D5) Reset:
UE0R56
UE0R55
UE0R54
UE0R53
UE0R52
UE0R51
UE0R50
UE0T56
UE0T55
UE0T54
UE0T53
UE0T52
UE0T51
UE0T50
USB Endpoint 0 Data Read: UE0R67
Register 6 Write: UE0T67
(UE0D6) Reset:
UE0R66
UE0R65
UE0R64
UE0R63
UE0R62
UE0R61
UE0R60
UE0T66
UE0T65
UE0T64
UE0T63
UE0T62
UE0T61
UE0T60
USB Endpoint 0 Data Read: UE0R77
Register 7 Write: UE0T77
(UE0D7) Reset:
UE0R76
UE0R75
UE0R74
UE0R73
UE0R72
UE0R71
UE0R70
UE0T76
UE0T75
UE0T74
UE0T73
UE0T72
UE0T71
UE0T70
R
= Reserved
U = Unaffected
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
X = Indeterminate
= Unimplemented
Figure 2-2. Control, Status, and Data Registers (Sheet 4 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
47
Memory Map
Addr.
Register Name
$0028
$0029
$002A
$002B
$002C
$002D
$002E
$002F
$0030
$0031
Bit 7
6
5
4
3
2
1
Bit 0
Read:
USB Endpoint 1 Data
Register 0 Write: UE1T07
(UE1D0)
Reset:
UE1T06
UE1T05
UE1T04
UE1T03
UE1T02
UE1T01
UE1T00
Read:
USB Endpoint 1 Data
Register 1 Write: UE1T17
(UE1D1)
Reset:
UE1T16
UE1T12
UE1T11
UE1T10
Read:
USB Endpoint 1 Data
Register 2 Write: UE1T27
(UE1D2)
Reset:
UE1T26
UE1T22
UE1T21
UE1T20
USB Endpoint 1 Data Read:
Register 3 Write: UE1T37
(UE1D3)
Reset:
UE1T36
UE1T32
UE1T31
UE1T30
USB Endpoint 1 Data Read:
Register 4 Write: UE1T47
(UE1D4)
Reset:
UE1T46
UE1T42
UE1T41
UE1T40
USB Endpoint 1 Data Read:
Register 5 Write: UE1T57
(UE1D5)
Reset:
UE1T56
UE1T52
UE1T51
UE1T50
USB Endpoint 1 Data Read:
Register 6 Write: UE1T67
(UE1D6)
Reset:
UE1T66
UE1T62
UE1T61
UE1T60
Read:
USB Endpoint 1 Data
Register 7 Write: UE1T77
(UE1D7)
Reset:
UE1T76
UE1T72
UE1T71
UE1T70
Unaffected by reset
UE1T15
UE1T14
UE1T13
Unaffected by reset
UE1T25
UE1T24
UE1T23
Unaffected by reset
UE1T35
UE1T34
UE1T33
Unaffected by reset
UE1T45
UE1T44
UE1T43
Unaffected by reset
UE1T55
UE1T54
UE1T53
Unaffected by reset
UE1T65
UE1T64
UE1T63
Unaffected by reset
UE1T75
UE1T74
UE1T73
Unaffected by reset
Read: UE2R07
USB Endpoint 2 Data
Register 0 Write: UE2T07
(UE2D0) Reset:
UE2R06
UE2R05
UE2R04
UE2R03
UE2R02
UE2R01
UE2R00
UE2T06
UE2T05
UE2T04
UE2T03
UE2T02
UE2T01
UE2T00
Read: UE2R17
USB Endpoint 2 Data
Register 1 Write: UE2T17
(UE2D1) Reset:
UE2R16
UE2R15
UE2R14
UE2R13
UE2R12
UE2R11
UE2R10
UE2T16
UE2T15
UE2T14
UE2T13
UE2T12
UE2T11
UE2T10
R
= Reserved
U = Unaffected
Unaffected by reset
Unaffected by reset
X = Indeterminate
= Unimplemented
Figure 2-2. Control, Status, and Data Registers (Sheet 5 of 12)
Technical Data
48
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
Register Name
$0032
$0033
$0034
$0035
$0036
$0037
$0038
Bit 7
6
5
4
3
2
1
Bit 0
Read: UE2R27
USB Endpoint 2 Data
Register 2 Write: UE2T27
(UE2D2)
Reset:
UE2R26
UE2R25
UE2R24
UE2R23
UE2R22
UE2R21
UE2R20
UE2T26
UE2T25
UE2T24
UE2T23
UE2T22
UE2T21
UE2T20
Read: UE2R37
USB Endpoint 2 Data
Register 3 Write: UE2T37
(UE2D3)
Reset:
UE2R36
UE2R35
UE2R34
UE2R33
UE2R32
UE2R31
UE2R30
UE2T36
UE2T35
UE2T34
UE2T33
UE2T32
UE2T31
UE2T30
Read: UE2R47
USB Endpoint 2 Data
Register 4 Write: UE2T47
(UE2D4)
Reset:
UE2R46
UE2R45
UE2R44
UE2R43
UE2R42
UE2R41
UE2R40
UE2T46
UE2T45
UE2T44
UE2T43
UE2T42
UE2T41
UE2T40
USB Endpoint 2 Data Read: UE2R57
Register 5 Write: UE2T57
(UE2D5)
Reset:
UE2R56
UE2R55
UE2R54
UE2R53
UE2R52
UE2R51
UE2R50
UE2T56
UE2T55
UE2T54
UE2T53
UE2T52
UE2T51
UE2T50
Read: UE2R67
USB Endpoint 2 Data
Register 6 Write: UE2T67
(UE2D6)
Reset:
UE2R66
UE2R65
UE2R64
UE2R63
UE2R62
UE2R61
UE2R60
UE2T66
UE2T65
UE2T64
UE2T63
UE2T62
UE2T61
UE2T60
USB Endpoint 2 Data Read: UE2R77
Register 7 Write: UE2T77
(UE2D7)
Reset:
UE2R76
UE2R75
UE2R74
UE2R73
UE2R72
UE2R71
UE2R70
UE2T76
UE2T75
UE2T74
UE2T73
UE2T72
UE2T71
UE2T70
Read:
USBEN
USB Address Register
Write:
(UADDR)
Reset:
0*
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
UADD6
UADD5
UADD4
UADD3
UADD2
UADD1
UADD0
0
0
0
0
0
0
0
EOPIE
SUSPND
TXD2IE
RXD2IE
TXD1IE
TXD0IE
RXD0IE
0
0
0
0
0
0
0
0
EOPF
RSTF
TXD2F
RXD2F
TXD1F
RESUMF
TXD0F
RXD0F
0
0
0
0
0
0
0
0
TX0E
RX0E
TP0SIZ3
TP0SIZ2
TP0SIZ1
TP0SIZ0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
* USBEN bit is reset by POR or LVI reset only.
$0039
$003A
$003B
Read:
USB Interrupt Register 0
Write:
(UIR0)
Reset:
Read:
USB Interrupt Register 1
Write:
(UIR1)
Reset:
Read:
T0SEQ
USB Control Register 0
Write:
(UCR0)
Reset:
0
U = Unaffected
0
0
X = Indeterminate
0
Figure 2-2. Control, Status, and Data Registers (Sheet 6 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
49
Memory Map
Addr.
$003C
$003D
$003E
Register Name
Bit 7
6
5
2
1
Bit 0
STALL1
TX1E
TP1SIZ2
TP1SIZ1
TP1SIZ0
0
0
0
0
0
0
0
Read: R0SEQ
USB Status Register 0
Write:
(USR0)
Reset:
SETUP
0
0
RP0SIZ3
RP0SIZ2
RP0SIZ1
RP0SIZ0
Read: R2SEQ
USB Status Register 1
Write:
(USR1)
Reset:
U
TXACK
TXNAK
TXSTL
RP2SIZ3
RP2SIZ2
RP2SIZ1
RP2SIZ0
0
0
0
U
U
U
U
TOIE
TSTOP
0
0
PS2
PS1
PS0
0
0
1
0
0
0
0
0
R
R
R
R
R
R
R
R
Timer 2 Counter Read:
Register High Write:
(T2CNTH)
Reset:
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
0
0
0
0
0
0
0
0
Read:
Timer 2 Counter
Register Low Write:
(T2CNTL) Reset:
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
0
0
0
0
0
0
0
0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
1
1
1
1
1
1
1
1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
1
1
1
1
1
1
1
1
= Unimplemented
R
= Reserved
Read:
T1SEQ
USB Control Register 1
Write:
(UCR1)
Reset:
0
4
3
FRESUM TP1SIZ3
Unaffected by reset
Read:
$003F
Unimplemented Write:
Timer 2 Status and Control Read:
$0040
Register Write:
(T2SC)
Reset:
Read:
$0041
Reserved Write:
TOF
0
TRST
Reset:
$0042
$0043
$0044
$0045
Read:
Timer 2 Counter Modulo
Register High Write:
(T2MODH) Reset:
Read:
Timer 2 Counter Modulo
Register Low Write:
(T2MODL) Reset:
U = Unaffected
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 7 of 12)
Technical Data
50
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
$0046
$0047
$0048
$0049
$004A
$004B
Register Name
Bit 7
Timer 2 Channel 0 Read:
Status and Control Write:
Register
(T2SC0) Reset:
Read:
Timer 2 Channel 0
Register High Write:
(T2CH0H) Reset:
Read:
Timer 2 Channel 0
Register Low Write:
(T2CH0L) Reset:
Timer 2 Channel 1 Read:
Status and Control
Write:
Register
(T2SC1) Reset:
Read:
Timer 2 Channel 1
Register High Write:
(T2CH1H) Reset:
Timer 2 Channel 1 Read:
Register Low Write:
(T2CH1L) Reset:
Read:
$004C
Reserved Write:
6
5
4
3
2
1
Bit 0
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
Bit2
Bit1
Bit0
CH0F
0
Indeterminate after reset
Bit7
Bit6
Bit5
Bit4
Bit3
Indeterminate after reset
CH1F
CH1IE
CH01IE
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
0
Bit15
Bit14
Bit13
Bit12
Bit11
Bit10
Bit9
Bit8
Bit2
Bit1
Bit0
0
Indeterminate after reset
Bit7
Bit6
Bit5
Bit4
Bit3
Indeterminate after reset
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
= Unimplemented
R
= Reserved
Reset:
Read:
$004D
Reserved Write:
Reset:
Read:
$004E
Reserved Write:
Reset:
Read:
$004F
Reserved Write:
Reset:
U = Unaffected
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 8 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
51
Memory Map
Addr.
Register Name
Read:
$0050
Reserved Write:
Bit 7
6
5
4
3
2
1
Bit 0
R
R
R
R
R
R
R
R
R
PLLON1
R
R
PLLON2
Reset:
$0051
$0052
Read:
PLL Bandwidth Control
Register Write:
(PBWC)
Reset:
R
LOCK1
0
Read:
VCO_7
VCO Control Register
Write:
(PVCR)
Reset:
0
$0054
$0055
PLL1 R Divider Select Read: RDS1_7
Register Low Write:
(PRSL1)
Reset:
1
$0057
$0058
$0059
Read:
PLL2 R Divider Select
RDS2_7
Register Low Write:
(PRSL2) Reset:
1
Read:
Phase Detector Control
PHD_7
Register Write:
(PDCR) Reset:
1
U = Unaffected
0
VCO_5
VCO_4
VCO_3
VCO_2
VCO_1
VCO_0
0
1
1
0
0
0
0
VDS1_9
VDS1_8
0
0
RDS1_9
RDS1_8
1
0
0
0
0
0
VDS1_6
VDS1_5
VDS1_4
VDS1_3
VDS1_2
VDS1_1
VDS1_0
1
1
1
1
1
0
1
RDS1_6
RDS1_5
RDS1_4
RDS1_3
RDS1_2
RDS1_1
RDS1_0
0
0
1
0
0
0
0
VDS2_9
VDS2_8
0
0
RDS2_9
RDS2_8
1
0
0
0
0
0
VDS2_6
VDS2_5
VDS2_4
VDS2_3
VDS2_2
VDS2_1
VDS2_0
1
1
1
1
1
0
1
RDS2_6
RDS2_5
RDS2_4
RDS2_3
RDS2_2
RDS2_1
RDS2_0
0
0
1
0
0
0
0
PHD_6
PHD_5
PHD_4
PHD_3
PHD_2
PHD_1
PHD_0
0
0
1
0
0
0
0
= Unimplemented
R
= Reserved
PLL2 N & R Divider Select Read: VDS2_11 VDS2_10
$0056
Register High Write:
(PNRH2)
Reset:
0
0
Read:
PLL2 N Divider Select
VDS2_7
Register Low Write:
(PNSL1) Reset:
0
0
VCO_6
PLL1 N & R Divider Select Read: VDS1_11 VDS1_10
$0053
Register High Write:
(PNRH1)
Reset:
0
0
PLL1 N Divider Select Read: VDS1_7
Register Low Write:
(PNSL1)
Reset:
0
0
LOCK2
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 9 of 12)
Technical Data
52
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
$005A
$005B
$005C
$005D
$005E
$005F
$0060
Register Name
Bit 7
5
4
3
2
1
Bit 0
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
0
0
0
0
0
0
0
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
Read:
LOOPS
SCI Control Register 1
Write:
(SCC1)
Reset:
0
Read:
SCI Control Register 2
Write:
(SCC2)
Reset:
Read:
SCI Control Register 3
Write:
(SCC3)
Reset:
R8
U
U
0
0
0
0
0
0
Read:
SCI Status Register 1
Write:
(SCS1)
Reset:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
1
1
0
0
0
0
0
0
Read:
SCI Status Register 2
Write:
(SCS2)
Reset:
0
0
0
0
0
0
BKF
RPF
0
0
0
0
0
0
0
0
Read:
SCI Data Register
Write:
(SCDR)
Reset:
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
U
U
U
U
U
U
U
U
Read:
SCI Baud Rate Register
Write:
(SCBR)
Reset:
0
0
SCP1
SCP0
R
SCR2
SCR1
SCR0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
= Unimplemented
R
= Reserved
Read:
$0061
6
Reserved Write:
Reset:
Read:
$0062
Reserved Write:
Reset:
Read:
$0063
Reserved Write:
Reset:
U = Unaffected
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 10 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
53
Memory Map
Addr.
Register Name
Bit 7
6
5
4
3
2
R
R
R
R
R
R
1
Bit 0
Read:
$0064
to
$007F
Unimplemented Write:
Reset:
Read:
SIM Break Status Register
Write:
$FE00
(SBSR)
Reset:
SBSW
Note
R
0
Note: Writing a logic 0 clears SBSW.
Read:
SIM Reset Status Register
$FE01
Write:
(SRSR)
POR:
Read:
$FE02
Reserved Write:
POR
PIN
COP
ILOP
ILAD
USB
LVI
0
1
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
BCFE
R
R
R
R
R
R
R
Reset:
$FE03
SIM Break Flag Control Read:
Register Write:
(SBFCR) Reset:
0
Read:
Interrupt Status Register 1
$FE04
Write:
(INT1)
Reset:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Read:
Interrupt Status Register 2
Write:
$FE05
(INT2)
Reset:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
= Unimplemented
R
= Reserved
Read:
$FE06
Reserved Write:
Reset:
Read:
$FE07
Reserved Write:
Reset:
U = Unaffected
X = Indeterminate
Figure 2-2. Control, Status, and Data Registers (Sheet 11 of 12)
Technical Data
54
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Memory Map
Addr.
$FE08
$FE09
Register Name
Read:
FLASH Control Register
Write:
(FLCR)
Reset:
FLASH Block Protect Read:
Register Write:
(FLBPR)
Reset:
Read:
$FE0A
Reserved Write:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
HVEN
MASS
ERASE
PGM
0
0
0
0
0
0
0
0
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
BRKE
BRKA
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R
= Reserved
Reset:
Read:
$FE0B
Reserved Write:
Reset:
$FE0C
$FE0D
Read:
Break Address High
Write:
Register (BRKH)
Reset:
Read:
Break Address Low
Write:
Register (BRKL)
Reset:
Read:
Break Status and Control
$FE0E
Register Write:
(BRKSCR)
Reset:
$FFFF
Read:
COP Control Register
Write:
(COPCTL)
Reset:
U = Unaffected
Low byte of reset vector
Clears COP counter (any value)
Unaffected by reset
X = Indeterminate
= Unimplemented
Figure 2-2. Control, Status, and Data Registers (Sheet 12 of 12)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Memory Map
55
Memory Map
.
Table 2-1. Vector Addresses
Vector Priority
Lowest
Vector
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
IF6
IF5
IF4
IF3
IF2
IF1
—
Highest
—
Address
$FFE0
Keyboard Vector (High)
$FFE1
Keyboard Vector (Low)
$FFE2
SCI Transmit Vector (High)
$FFE3
SCI Transmit Vector (Low)
$FFE4
SCI Receive Vector (High)
$FFE5
SCI Receive Vector (Low)
$FFE6
SCI Error Vector (High)
$FFE7
SCI Error Vector (Low)
$FFE8
TIM2 Overflow Vector (High)
$FFE9
TIM2 Overflow Vector (Low)
$FFEA
TIM2 Channel 0 and 1 Vector (High)
$FFEB
TIM2 Channel 0 and 1 Vector (Low)
$FFEC
TIM2 Channel 1 Vector (High)
$FFED
TIM2 Channel 1 Vector (Low)
$FFEE
TIM2 Channel 0 Vector (High)
$FFEF
TIM2 Channel 0 Vector (Low)
$FFF0
TIM1 Overflow Vector (High)
$FFF1
TIM1 Overflow Vector (Low)
$FFF2
TIM1 Channel 0 and 1 Vector (High)
$FFF3
TIM1 Channel 0 and 1 Vector (Low)
$FFF4
TIM1 Channel 1 Vector (High)
$FFF5
TIM1 Channel 1 Vector (Low)
$FFF6
TIM1 Channel 0 Vector (High)
$FFF7
TIM1 Channel 0 Vector (Low)
$FFF8
IRQ Vector (High)
$FFF9
IRQ Vector (Low)
$FFFA
USB Vector (High)
$FFFB
USB Vector (Low)
$FFFC
SWI Vector (High)
$FFFD
SWI Vector (Low)
$FFFE
Reset Vector (High)
$FFFF
Reset Vector (Low)
Technical Data
56
Vector
MC68HC908JB16 — Rev. 1.1
Memory Map
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
3.2 Introduction
This section describes the 384 bytes of RAM (random-access memory).
3.3 Functional Description
Addresses $0080 through $01FF are RAM locations. The location of the
stack RAM is programmable. The 16-bit stack pointer allows the stack to
be anywhere in the 64K-byte memory space.
NOTE:
For correct operation, the stack pointer must point only to RAM
locations.
Within page zero are 128 bytes of RAM. Because the location of the
stack RAM is programmable, all page zero RAM locations can be used
for I/O control and user data or code. When the stack pointer is moved
from its reset location at $00FF out of page zero, direct addressing mode
instructions can efficiently access all page zero RAM locations. Page
zero RAM, therefore, provides ideal locations for frequently accessed
global variables.
Before processing an interrupt, the CPU uses five bytes of the stack to
save the contents of the CPU registers.
NOTE:
For M6805 compatibility, the H register is not stacked.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Random-Access Memory (RAM)
57
Random-Access Memory (RAM)
During a subroutine call, the CPU uses two bytes of the stack to store
the return address. The stack pointer decrements during pushes and
increments during pulls.
NOTE:
Be careful when using nested subroutines. The CPU may overwrite data
in the RAM during a subroutine or during the interrupt stacking
operation.
Technical Data
58
MC68HC908JB16 — Rev. 1.1
Random-Access Memory (RAM)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 4. FLASH Memory
4.1 Contents
4.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
4.4
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.5
FLASH Block Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.6
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.7
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .64
4.8
FLASH Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
4.8.1
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . . 66
4.9
ROM-Resident Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.9.1
Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.9.2
ERASE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.9.3
PROGRAM Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.9.4
VERIFY Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.2 Introduction
This section describes the operation of the embedded FLASH memory.
This memory can be read, programmed, and erased from a single
external supply. The program and erase operations are enabled through
the use of an internal charge pump.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
FLASH Memory
59
FLASH Memory
Addr.
$FE08
$FE09
Register Name
Bit 7
6
5
4
Read:
0
0
0
0
FLASH Control Register
Write:
(FLCR)
Reset:
0
0
0
BPR7
BPR6
0
0
Read:
FLASH Block Protect
Register Write:
(FLBPR)
Reset:
3
2
1
Bit 0
HVEN
MASS
ERASE
PGM
0
0
0
0
0
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
0
0
0
0
0
0
= Unimplemented
Figure 4-1. FLASH I/O Register Summary
4.3 Functional Description
The FLASH memory consists of an array of 16,384 bytes for user
memory plus a block of 48 bytes for user interrupt vectors. An erased bit
reads as logic 1 and a programmed bit reads as a logic 0. The FLASH
memory is block erasable. The minimum erase block size is 512 bytes.
Program and erase operation operations are facilitated through control
bits in FLASH Control Register (FLCR).The address ranges for the
FLASH memory are shown as follows:
•
$BA00–$F9FF (user memory, 16,384 bytes)
•
$FFD0–$FFFF (user interrupt vectors, 48 bytes)
Programming tools are available from Freescale. Contact your local
Freescale representative for more information.
NOTE:
A security feature prevents viewing of the FLASH contents.1
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Technical Data
60
MC68HC908JB16 — Rev. 1.1
FLASH Memory
Freescale Semiconductor
FLASH Memory
4.4 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase
operation.
Address:
Read:
$FE08
Bit 7
6
5
4
0
0
0
0
0
0
0
0
Write:
Reset:
3
2
1
Bit 0
HVEN
MASS
ERASE
PGM
0
0
0
0
= Unimplemented
Figure 4-2. FLASH Control Register (FLCR)
HVEN — High Voltage Enable Bit
This read/write bit enables high voltage from the charge pump to the
memory for either program or erase operation. It can only be set if
either PGM=1 or ERASE=1 and the sequence for erase or
program/verify is followed.
1 = High voltage enabled to array and charge pump on
0 = High voltage disabled to array and charge pump off
MASS — Mass Erase Control Bit
This read/write bit configures the memory for mass erase operation or
block erase operation when the ERASE bit is set.
1 = Mass Erase operation selected
0 = Block Erase operation selected
ERASE — Erase Control Bit
This read/write bit configures the memory for erase operation. This bit
and the PGM bit should not be set to 1 at the same time.
1 = Erase operation selected
0 = Erase operation not selected
PGM — Program Control Bit
This read/write bit configures the memory for program operation. This
bit and the ERASE bit should not be set to 1 at the same time.
1 = Program operation selected
0 = Program operation not selected
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4.5 FLASH Block Erase Operation
Use the following procedure to erase a block of FLASH memory. A block
consists of 512 consecutive bytes starting from addresses $X000,
$X200, $X400, $X600, $X800, $XA00, $XC00 or $XE00. The 48-byte
user interrupt vectors area also forms a block. Any block within the 16K
bytes user memory area ($BA00–$F9FF) can be erased alone.
NOTE:
The 48-byte user interrupt vectors, $FFD0–$FFFF, cannot be erased by
the block erase operation because of security reasons. Mass erase is
required to erase this block.
1. Set the ERASE bit and clear the MASS bit in the FLASH control
register.
2. Write any data to any FLASH address within the address range of
the block to be erased.
3. Wait for a time, tnvs (5µs).
4. Set the HVEN bit.
5. Wait for a time tErase (10ms).
6. Clear the ERASE bit.
7. Wait for a time, tnvh (5µs).
8. Clear the HVEN bit.
9. After time, trcv (1µs), the memory can be accessed in read mode
again.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory. While these operations
must be performed in the order as shown, but other unrelated operations
may occur between the steps.
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4.6 FLASH Mass Erase Operation
Use the following procedure to erase the entire FLASH memory:
1. Set both the ERASE bit and the MASS bit in the FLASH control
register.
2. Write any data to any FLASH address within the address range
$FFD0–$FFFF.
3. Wait for a time, tnvs (5µs).
4. Set the HVEN bit.
5. Wait for a time tMErase (200ms).
6. Clear the ERASE bit.
7. Wait for a time, tnvhl (100µs).
8. Clear the HVEN bit.
9. After time, trcv (1µs), the memory can be accessed in read mode
again.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps.
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FLASH Memory
4.7 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row
consists of 64 consecutive bytes starting from addresses $XX00,
$XX40, $XX80 or $XXC0. The procedure for programming a row of the
FLASH memory is outlined below:
1. Set the PGM bit. This configures the memory for program
operation and enables the latching of address and data for
programming.
2. Write any data to any FLASH address within the address range of
the row to be programmed.
3. Wait for a time, tnvs (5µs).
4. Set the HVEN bit.
5. Wait for a time, tpgs (10µs).
6. Write data to the byte being programmed.
7. Wait for time, tProg (30µs).
8. Repeat steps 6 and 7 until all the bytes within the row are
programmed.
9. Clear the PGM bit.
10. Wait for time, tnvh (5µs).
11. Clear the HVEN bit.
12. After time, trcv (1µs), the memory can be accessed in read mode
again.
This program sequence is repeated throughout the memory until all data
is programmed.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps. Do
not exceed tProg maximum. See 20.14 FLASH Memory
Characteristics.
Figure 4-3 shows a flowchart representation for programming the
FLASH memory.
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1
Algorithm for programming
a row (64 bytes) of FLASH memory
Set PGM bit
2
Write any data to any FLASH address
within the row address range desired
3
Wait for a time, tnvs
4
Set HVEN bit
5
Wait for a time, tpgs
6
Write data to the FLASH address
to be programmed
7
Wait for a time, tProg
Completed
programming
this row?
Y
N
NOTE:
The time between each FLASH address change (step 6 to step 6), or
the time between the last FLASH address programmed
to clearing PGM bit (step 6 to step 9)
must not exceed the maximum programming
time, tProg max.
9
Clear PGM bit
10
Wait for a time, tnvh
11
Clear HVEN bit
12
Wait for a time, trcv
This row program algorithm assumes the row/s
to be programmed are initially erased.
End of Programming
Figure 4-3. FLASH Programming Flowchart
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FLASH Memory
4.8 FLASH Protection
Due to the ability of the on-board charge pump to erase and program the
FLASH memory in the target application, provision is made to protect
blocks of memory from unintentional erase or program operations due to
system malfunction. This protection is done by use of a FLASH Block
Protect Register (FLBPR). The FLBPR determines the range of the
FLASH memory which is to be protected. The range of the protected
area starts from a location defined by FLBPR and ends to the bottom of
the FLASH memory ($FFFF). When the memory is protected, the HVEN
bit cannot be set in either ERASE or PROGRAM operations.
NOTE:
When the FLBPR is cleared (all 0’s), the entire FLASH memory is
protected from being programmed and erased. When all the bits are set,
the entire FLASH memory is accessible for program and erase.
4.8.1 FLASH Block Protect Register
The FLASH block protect register is implemented as an 8-bit I/O register.
The 7 bits of the 8-bit content of this register determine the starting
location of the protected range within the FLASH memory.
Address:
Read:
Write:
Reset:
$FE09
Bit 7
6
5
4
3
2
1
Bit 0
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
0
0
0
0
0
0
0
0
Figure 4-4. FLASH Block Protect Register (FLBPR)
BPR[7:0] — FLASH Block Protect Register Bit 7 to Bit 0
BPR[7:1] represent bits [15:9] of a 16-bit memory address; bits [8:0]
are logic 0’s.
16-bit memory address
Start address of FLASH block protect
0 0 0 0 0 0 0 0 0
BPR[7:1]
Figure 4-5. FLASH Block Protect Start Address
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BPR0 is used only for BPR[7:0] = $FF, for no block protection.
The resultant 16-bit address is used for specifying the start address
of the FLASH memory for block protection. The FLASH is protected
from this start address to the end of FLASH memory, at $FFFF. With
this mechanism, the protect start address can be X000, X200, X400,
X600, X800, XA00, XC00, or XE00 within the FLASH memory.
Examples of protect start address:
BPR[7:0]
Start of Address of Protect Range
$00 to $BA
The entire FLASH memory is protected.
$BC (1011 1100)
$BC00 (1011 1100 0000 0000)
$BE (1011 1110)
$BE00 (1011 1110 0000 0000)
$C0 (1100 0000)
$C000 (1100 0000 0000 0000)
$C2 (1100 0010)
$C200 (1100 0010 0000 0000)
and so on...
$FE
$FFD0–$FFFF (User vectors)
$FF
The entire FLASH memory is not protected.
Note:
The end address of the protected range is always $FFFF.
4.9 ROM-Resident Routines
ROM-resident routines can be called by a program running in user mode
or in monitor mode (see Section 9. Monitor ROM (MON)) for FLASH
programming, erasing, and verifying. The range of the FLASH memory
must be unprotected (see 4.8 FLASH Protection) before calling the
erase or programming routine.
Table 4-1. ROM-Resident Routines
Routine Name
Call Address
VERIFY
$FC03
FLASH verify routine
ERASE
$FC06
FLASH mass or block erase routine
PROGRAM
$FC09
FLASH program routine
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FLASH Memory
4.9.1 Variables
The ROM-resident routines use three variables: CTRLBYT, CPUSPD
and LADDR; and one data buffer. The minimum size of the data buffer
is one byte and the maximum size is 64 bytes.
CPUSPD must be set before calling the erase or programming routines,
and should be set to four times the value of the CPU internal bus speed
in MHz. For example: for CPU speed of 6MHz, CPUSPD should be set
to 24.
Table 4-2. Summary of FLASH Routine Variables
Variable
Address
Description
CTRLBYT
$0088
Control byte for setting mass or block erase.
CPUSPD
$0089
Timing adjustment for different CPU speeds.
LADDR
$008A–$008B
Last FLASH address to be programmed.
DATABUF
$0100–$013F
Data buffer for programming and verifying.
4.9.2 ERASE Routine
The ERASE routine erases the entire or a block of FLASH memory. The
routine does not check for a blank range before or after erase.
NOTE:
A block erase cannot be performed on the last block of FLASH memory
(user vector at $FFD0)–$FFFF).
Table 4-3. ERASE Routine
Routine
ERASE
Calling Address
$FC06
Stack Use
5 Bytes
Input
CPUSPD — CPU speed
HX —
Contains any address in the range to be
erased
CTRLBYT — Mass or block erase
Mass erase if bit 6 = 1
Block erase if bit 6 = 0
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4.9.3 PROGRAM Routine
The PROGRAM routine programs a range of addresses in FLASH
memory, which does not have to be on page boundaries, either at the
begin or end address.
Table 4-4. PROGRAM Routine
Routine
PROGRAM
Calling Address
$FC09
Stack Use
7 Bytes
Input
CPUSPD —
HX —
LADDR —
DATABUF —
CPU speed
FLASH start address to be programmed
FLASH end address to be programmed
Contains the data to be programmed
4.9.4 VERIFY Routine
The VERIFY routine reads and verifies a range of FLASH memory.
Table 4-5. VERIFY Routine
Routine
VERIFY
Calling Address
$FC03
Stack Use
6 Bytes
Input
HX —
FLASH start address to be verified
LADDR — FLASH end address to be verified
DATABUF — Contains the data to be verified
Output
C Bit —
C bit is set if verify passes
DATABUF — Contains the data in the range of the
FLASH memory
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Section 5. Configuration Register (CONFIG)
5.1 Contents
5.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
5.4
Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
5.2 Introduction
This section describes the configuration register, CONFIG. The
configuration register enables or disables these options:
•
Low voltage inhibit (LVI) module control and voltage trip point
selection
•
USB reset
•
Stop mode recovery time (2048 or 4096 OSCDCLK cycles)
•
COP timeout period (218 – 24 or 213 – 24 OSCDCLK cycles)
•
STOP instruction
•
Computer operating properly module (COP)
5.3 Functional Description
The configuration register is used in the initialization of various options.
The configuration register can be written once after each reset. All of the
configuration register bits are cleared during reset. Since the various
options affect the operation of the MCU, it is recommended that this
register be written immediately after reset. The configuration register is
located at $001F. The configuration register may be read at anytime.
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Configuration Register (CONFIG)
5.4 Configuration Register
Address:
Read:
Write:
Reset:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
LVIDR
LVI5OR3
URSTD
LVID
SSREC
COPRS
STOP
COPD
0*
0*
0*
0*
0
0
0
0
* LVIDR, LVI5OR3, URSTD, and LVID bits are reset by POR (power-on reset) or LVI reset only.
Figure 5-1. Configuration Register (CONFIG)
LVIDR — LVI Disable Bit for VREG
LVIDR disables the LVI circuit for VREG. (See Section 18. LowVoltage Inhibit (LVI).)
1 = LVI circuit for VREG disabled
0 = LVI circuit for VREG enabled
NOTE:
There is no LVI circuit for VREGA.
LVI5OR3 — LVI Trip Point Voltage Select Bit for VDD
LVI5OR3 selects the trip point voltage of the LVI circuit for VDD.
(See Section 18. Low-Voltage Inhibit (LVI).)
1 = LVI trips at 3.3V
0 = LVI trips at 2.4V
URSTD — USB Reset Disable Bit
URSTD disables the USB reset signal generating an internal reset to
the CPU and internal registers. Instead, it will generate an interrupt
request to the CPU. (See Section 11. Universal Serial Bus Module
(USB).)
1 = USB reset generates a USB interrupt request to CPU
0 = USB reset generates a chip reset
LVID — LVI Disable Bit for VDD
LVID disables the LVI circuit for VDD. (See Section 18. Low-Voltage
Inhibit (LVI).)
1 = LVI circuit for VDD disabled
0 = LVI circuit for VDD enabled
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SSREC — Short Stop Recovery Bit
SSREC enables the CPU to exit stop mode with a delay of 2048
OSCDCLK cycles instead of a 4096 OSCDCLK cycle delay.
1 = Stop mode recovery after 2048 OSCDCLK cycles
0 = Stop mode recovery after 4096 OSCDCLK cycles
NOTE:
Exiting stop mode by pulling reset will result in the long stop recovery.
If using an external crystal oscillator, do not set the SSREC bit.
COPRS — COP Rate Select Bit
COPRS selects the COP timeout period. Reset clears COPRS. (See
Section 17. Computer Operating Properly (COP).)
1 = COP timeout period is 213 – 24 OSCDCLK cycles
0 = COP timeout period is 218 – 24 OSCDCLK cycles
STOP — STOP Instruction Enable Bit
STOP enables the STOP instruction.
1 = STOP instruction enabled
0 = STOP instruction treated as illegal opcode
COPD — COP Disable Bit
COPD disables the COP module. (See Section 17. Computer
Operating Properly (COP).)
1 = COP module disabled
0 = COP module enabled
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Configuration Register (CONFIG)
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Technical Data — MC68HC908JB16
Section 6. Central Processor Unit (CPU)
6.1 Contents
6.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.4.1
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.4.2
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.4.3
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.4.4
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.4.5
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
6.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.7
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.8
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.9
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
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Central Processor Unit (CPU)
6.2 Introduction
The M68HC08 CPU (central processor unit) is an enhanced and fully
object-code-compatible version of the M68HC05 CPU. The CPU08
Reference Manual (Freescale document order number CPU08RM/AD)
contains a description of the CPU instruction set, addressing modes,
and architecture.
6.3 Features
Feature of the CPU include:
•
Object code fully upward-compatible with M68HC05 Family
•
16-bit stack pointer with stack manipulation instructions
•
16-Bit index register with X-register manipulation instructions
•
6-MHz CPU internal bus frequency
•
64-Kbyte program/data memory space
•
16 addressing modes
•
Memory-to-memory data moves without using accumulator
•
Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
•
Enhanced binary-coded decimal (BCD) data handling
•
Modular architecture with expandable internal bus definition for
extension of addressing range beyond 64-Kbytes
•
Low-power stop and wait modes
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6.4 CPU Registers
Figure 6-1 shows the five CPU registers. CPU registers are not part of
the memory map.
0
7
ACCUMULATOR (A)
0
15
H
X
INDEX REGISTER (H:X)
15
0
STACK POINTER (SP)
15
0
PROGRAM COUNTER (PC)
7
0
V 1 1 H I N Z C
CONDITION CODE REGISTER (CCR)
CARRY/BORROW FLAG
ZERO FLAG
NEGATIVE FLAG
INTERRUPT MASK
HALF-CARRY FLAG
TWO’S COMPLEMENT OVERFLOW FLAG
Figure 6-1. CPU Registers
6.4.1 Accumulator
The accumulator is a general-purpose 8-bit register. The CPU uses the
accumulator to hold operands and the results of arithmetic/logic
operations.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Unaffected by reset
Figure 6-2. Accumulator (A)
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6.4.2 Index Register
The 16-bit index register allows indexed addressing of a 64K-byte
memory space. H is the upper byte of the index register, and X is the
lower byte. H:X is the concatenated 16-bit index register.
In the indexed addressing modes, the CPU uses the contents of the
index register to determine the conditional address of the operand.
The index register can serve also as a temporary data storage location.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
Read:
Write:
Reset:
X = Indeterminate
Figure 6-3. Index Register (H:X)
6.4.3 Stack Pointer
The stack pointer is a 16-bit register that contains the address of the next
location on the stack. During a reset, the stack pointer is preset to
$00FF. The reset stack pointer (RSP) instruction sets the least
significant byte to $FF and does not affect the most significant byte. The
stack pointer decrements as data is pushed onto the stack and
increments as data is pulled from the stack.
In the stack pointer 8-bit offset and 16-bit offset addressing modes, the
stack pointer can function as an index register to access data on the
stack. The CPU uses the contents of the stack pointer to determine the
conditional address of the operand.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Read:
Write:
Reset:
Figure 6-4. Stack Pointer (SP)
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NOTE:
The location of the stack is arbitrary and may be relocated anywhere in
RAM. Moving the SP out of page 0 ($0000 to $00FF) frees direct
address (page 0) space. For correct operation, the stack pointer must
point only to RAM locations.
6.4.4 Program Counter
The program counter is a 16-bit register that contains the address of the
next instruction or operand to be fetched.
Normally, the program counter automatically increments to the next
sequential memory location every time an instruction or operand is
fetched. Jump, branch, and interrupt operations load the program
counter with an address other than that of the next sequential location.
During reset, the program counter is loaded with the reset vector
address located at $FFFE and $FFFF. The vector address is the
address of the first instruction to be executed after exiting the reset state.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
Read:
Write:
Reset:
Loaded with Vector from $FFFE and $FFFF
Figure 6-5. Program Counter (PC)
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6.4.5 Condition Code Register
The 8-bit condition code register contains the interrupt mask and five
flags that indicate the results of the instruction just executed. Bits 6 and
5 are set permanently to logic 1. The following paragraphs describe the
functions of the condition code register.
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
V
1
1
H
I
N
Z
C
X
1
1
X
1
X
X
X
X = Indeterminate
Figure 6-6. Condition Code Register (CCR)
V — 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.
1 = Overflow
0 = No overflow
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 addwith-carry (ADC) operation. The half-carry flag is required for binarycoded decimal (BCD) arithmetic operations. The DAA instruction
uses the states of the H and C flags to determine the appropriate
correction factor.
1 = Carry between bits 3 and 4
0 = No carry between bits 3 and 4
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I — Interrupt Mask
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 interrupt vector is fetched.
1 = Interrupts disabled
0 = Interrupts enabled
NOTE:
To maintain M6805 Family compatibility, the upper byte of the index
register (H) is not stacked automatically. If the interrupt service routine
modifies H, then the user must stack and unstack H using the PSHH and
PULH instructions.
After the I bit is cleared, the highest-priority interrupt request is
serviced first.
A return-from-interrupt (RTI) instruction pulls the CPU registers from
the stack and restores the interrupt mask from the stack. After any
reset, the interrupt mask is set and can be cleared only by the clear
interrupt mask software instruction (CLI).
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.
1 = Negative result
0 = Non-negative result
Z — Zero Flag
The CPU sets the zero flag when an arithmetic operation, logic
operation, or data manipulation produces a result of $00.
1 = Zero result
0 = Non-zero result
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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.
1 = Carry out of bit 7
0 = No carry out of bit 7
6.5 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the
instruction set.
Refer to the CPU08 Reference Manual (Freescale document order
number CPU08RM/AD) for a description of the instructions and
addressing modes and more detail about the architecture of the CPU.
6.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption
standby modes.
6.6.1 Wait Mode
The WAIT instruction:
•
Clears the interrupt mask (I bit) in the condition code register,
enabling interrupts. After exit from wait mode by interrupt, the I bit
remains clear. After exit by reset, the I bit is set.
•
Disables the CPU clock.
Technical Data
82
MC68HC908JB16 — Rev. 1.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
6.6.2 Stop Mode
The STOP instruction:
•
Clears the interrupt mask (I bit) in the condition code register,
enabling external interrupts. After exit from stop mode by external
interrupt, the I bit remains clear. After exit by reset, the I bit is set.
•
Disables the CPU clock.
After exiting stop mode, the CPU clock begins running after the oscillator
stabilization delay.
6.7 CPU During Break Interrupts
If the break module is enabled, a break interrupt causes the CPU to
execute the software interrupt instruction (SWI) at the completion of the
current CPU instruction. (See Section 19. Break Module (BRK).) The
program counter vectors to $FFFC–$FFFD ($FEFC–$FEFD in monitor
mode).
A return-from-interrupt instruction (RTI) in the break routine ends the
break interrupt and returns the MCU to normal operation if the break
interrupt has been deasserted.
6.8 Instruction Set Summary
Table 6-1 provides a summary of the M68HC08 instruction set.
6.9 Opcode Map
The opcode map is provided in Table 6-2.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Central Processor Unit (CPU)
83
Central Processor Unit (CPU)
V H I N Z C
ADC #opr
ADC opr
ADC opr
ADC opr,X
ADC opr,X
ADC ,X
ADC opr,SP
ADC opr,SP
A ← (A) + (M) + (C)
Add with Carry
↕ ↕
IMM
DIR
EXT
IX2
– ↕ ↕ ↕
IX1
IX
SP1
SP2
A9
B9
C9
D9
E9
F9
9EE9
9ED9
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
– ↕ ↕ ↕
IX1
IX
SP1
SP2
AB
BB
CB
DB
EB
FB
9EEB
9EDB
ii
dd
hh ll
ee ff
ff
ADD #opr
ADD opr
ADD opr
ADD opr,X
ADD opr,X
ADD ,X
ADD opr,SP
ADD opr,SP
Add without Carry
AIS #opr
Add Immediate Value (Signed) to SP
SP ← (SP) + (16 « M)
– – – – – – IMM
AIX #opr
Add Immediate Value (Signed) to H:X
H:X ← (H:X) + (16 « M)
– – – – – – IMM
AND #opr
AND opr
AND opr
AND opr,X
AND opr,X
AND ,X
AND opr,SP
AND opr,SP
ASL opr
ASLA
ASLX
ASL opr,X
ASL ,X
ASL opr,SP
Arithmetic Shift Left
(Same as LSL)
Arithmetic Shift Right
BCC rel
Branch if Carry Bit Clear
C
C
PC ← (PC) + 2 + rel ? (C) = 0
Mn ← 0
Technical Data
84
ff
ee ff
2
3
4
4
3
2
4
5
A7
ii
2
AF
ii
2
2
3
4
4
3
2
4
5
A4
B4
C4
D4
E4
F4
9EE4
9ED4
ii
dd
hh ll
ee ff
ff
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
38
48
58
68
78
9E68
dd
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
37
47
57
67
77
9E67
dd
ff
4
1
1
4
3
5
– – – – – – REL
24
rr
3
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
4
4
4
4
4
4
4
4
↕
b0
b0
2
3
4
4
3
2
4
5
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
0 – – ↕ ↕
0
b7
b7
Clear Bit n in M
↕ ↕
A ← (A) & (M)
Logical AND
ASR opr
ASRA
ASRX
ASR opr,X
ASR opr,X
ASR opr,SP
BCLR n, opr
A ← (A) + (M)
ff
ee ff
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 1 of 8)
↕
ff
ee ff
ff
ff
ff
4
1
1
4
3
5
MC68HC908JB16 — Rev. 1.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
Effect on
CCR
V H I N Z C
Cycles
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 2 of 8)
BCS rel
Branch if Carry Bit Set (Same as BLO)
PC ← (PC) + 2 + rel ? (C) = 1
– – – – – – REL
25
rr
3
BEQ rel
Branch if Equal
PC ← (PC) + 2 + rel ? (Z) = 1
– – – – – – REL
27
rr
3
BGE opr
Branch if Greater Than or Equal To
(Signed Operands)
PC ← (PC) + 2 + rel ? (N ⊕ V) = 0
– – – – – – REL
90
rr
3
BGT opr
Branch if Greater Than (Signed
Operands)
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 0 – – – – – – REL
92
rr
3
BHCC rel
Branch if Half Carry Bit Clear
PC ← (PC) + 2 + rel ? (H) = 0
– – – – – – REL
28
rr
3
BHCS rel
Branch if Half Carry Bit Set
PC ← (PC) + 2 + rel ? (H) = 1
– – – – – – REL
29
rr
3
BHI rel
Branch if Higher
PC ← (PC) + 2 + rel ? (C) | (Z) = 0
– – – – – – REL
22
rr
3
BHS rel
Branch if Higher or Same
(Same as BCC)
PC ← (PC) + 2 + rel ? (C) = 0
– – – – – – REL
24
rr
3
BIH rel
Branch if IRQ Pin High
PC ← (PC) + 2 + rel ? IRQ = 1
– – – – – – REL
2F
rr
3
BIL rel
Branch if IRQ Pin Low
PC ← (PC) + 2 + rel ? IRQ = 0
– – – – – – REL
2E
rr
3
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
A5
B5
C5
D5
E5
F5
9EE5
9ED5
BIT #opr
BIT opr
BIT opr
BIT opr,X
BIT opr,X
BIT ,X
BIT opr,SP
BIT opr,SP
Bit Test
BLE opr
Branch if Less Than or Equal To
(Signed Operands)
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 1
– – – – – – REL
93
rr
3
BLO rel
Branch if Lower (Same as BCS)
PC ← (PC) + 2 + rel ? (C) = 1
– – – – – – REL
25
rr
3
BLS rel
Branch if Lower or Same
PC ← (PC) + 2 + rel ? (C) | (Z) = 1
– – – – – – REL
23
rr
3
BLT opr
Branch if Less Than (Signed Operands)
PC ← (PC) + 2 + rel ? (N ⊕ V) =1
– – – – – – REL
91
rr
3
BMC rel
Branch if Interrupt Mask Clear
PC ← (PC) + 2 + rel ? (I) = 0
– – – – – – REL
2C
rr
3
BMI rel
Branch if Minus
PC ← (PC) + 2 + rel ? (N) = 1
– – – – – – REL
2B
rr
3
BMS rel
Branch if Interrupt Mask Set
PC ← (PC) + 2 + rel ? (I) = 1
– – – – – – REL
2D
rr
3
BNE rel
Branch if Not Equal
PC ← (PC) + 2 + rel ? (Z) = 0
– – – – – – REL
26
rr
3
BPL rel
Branch if Plus
PC ← (PC) + 2 + rel ? (N) = 0
– – – – – – REL
2A
rr
3
BRA rel
Branch Always
PC ← (PC) + 2 + rel
– – – – – – REL
20
rr
3
(A) & (M)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
0 – – ↕ ↕
Technical Data
Central Processor Unit (CPU)
85
Central Processor Unit (CPU)
Table 6-1. Instruction Set Summary (Sheet 3 of 8)
Operand
Cycles
Effect on
CCR
Opcode
Operation
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
– – – – – ↕
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
– – – – – – REL
21
rr
3
PC ← (PC) + 3 + rel ? (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 rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
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
4
4
4
4
4
4
4
4
– – – – – – REL
AD
rr
4
dd rr
ii rr
ii rr
ff rr
rr
ff rr
5
4
4
5
4
6
Description
V H I N Z C
BRCLR n,opr,rel Branch if Bit n in M Clear
BRN rel
Branch Never
BRSET n,opr,rel Branch if Bit n in M Set
BSET n,opr
Set Bit n in M
BSR rel
Branch to Subroutine
CBEQ opr,rel
CBEQA #opr,rel
CBEQX #opr,rel
Compare and Branch if Equal
CBEQ opr,X+,rel
CBEQ X+,rel
CBEQ opr,SP,rel
PC ← (PC) + 3 + rel ? (Mn) = 0
PC ← (PC) + 2
PC ← (PC) + 2; push (PCL)
SP ← (SP) – 1; push (PCH)
SP ← (SP) – 1
PC ← (PC) + rel
Address
Mode
Source
Form
DIR
PC ← (PC) + 3 + rel ? (A) – (M) = $00
IMM
PC ← (PC) + 3 + rel ? (A) – (M) = $00
IMM
PC ← (PC) + 3 + rel ? (X) – (M) = $00
– – – – – –
IX1+
PC ← (PC) + 3 + rel ? (A) – (M) = $00
IX+
PC ← (PC) + 2 + rel ? (A) – (M) = $00
SP1
PC ← (PC) + 4 + rel ? (A) – (M) = $00
31
41
51
61
71
9E61
CLC
Clear Carry Bit
C←0
– – – – – 0 INH
98
1
CLI
Clear Interrupt Mask
I←0
– – 0 – – – INH
9A
2
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
DIR
INH
INH
0 – – 0 1 – INH
IX1
IX
SP1
3F
4F
5F
8C
6F
7F
9E6F
CLR opr
CLRA
CLRX
CLRH
CLR opr,X
CLR ,X
CLR opr,SP
Clear
Technical Data
86
dd
ff
ff
3
1
1
1
3
2
4
MC68HC908JB16 — Rev. 1.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
V H I N Z C
CMP #opr
CMP opr
CMP opr
CMP opr,X
CMP opr,X
CMP ,X
CMP opr,SP
CMP opr,SP
Compare A with M
(A) – (M)
COM opr
COMA
COMX
COM opr,X
COM ,X
COM opr,SP
Complement (One’s Complement)
CPHX #opr
CPHX opr
Compare H:X with M
CPX #opr
CPX opr
CPX opr
CPX ,X
CPX opr,X
CPX opr,X
CPX opr,SP
CPX opr,SP
Compare X with M
DAA
Decimal Adjust A
M ← (M) = $FF – (M)
A ← (A) = $FF – (M)
X ← (X) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
(H:X) – (M:M + 1)
(X) – (M)
(A)10
↕
IMM
DIR
EXT
IX2
– – ↕ ↕ ↕
IX1
IX
SP1
SP2
A1
B1
C1
D1
E1
F1
9EE1
9ED1
ii
dd
hh ll
ee ff
ff
DIR
INH
INH
1
IX1
IX
SP1
33
43
53
63
73
9E63
dd
0 – – ↕ ↕
IMM
DIR
↕
– – ↕ ↕ ↕
↕
IMM
DIR
EXT
IX2
– – ↕ ↕ ↕
IX1
IX
SP1
SP2
ff
ee ff
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 4 of 8)
2
3
4
4
3
2
4
5
ff
4
1
1
4
3
5
65
75
ii ii+1
dd
3
4
A3
B3
C3
D3
E3
F3
9EE3
9ED3
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
ff
ff
ee ff
U – – ↕ ↕ ↕ INH
72
DIR
INH
– – – – – – INH
IX1
IX
SP1
3B
4B
5B
6B
7B
9E6B
dd rr
rr
rr
ff rr
rr
ff rr
5
3
3
5
4
6
DIR
INH
INH
–
IX1
IX
SP1
3A
4A
5A
6A
7A
9E6A
dd
4
1
1
4
3
5
2
A ← (A) – 1 or M ← (M) – 1 or X ← (X) – 1
DBNZ opr,rel
DBNZA rel
Decrement and Branch if Not Zero
DBNZX rel
DBNZ opr,X,rel
DBNZ X,rel
DBNZ opr,SP,rel
DEC opr
DECA
DECX
DEC opr,X
DEC ,X
DEC opr,SP
Decrement
DIV
Divide
EOR #opr
EOR opr
EOR opr
EOR opr,X
EOR opr,X
EOR ,X
EOR opr,SP
EOR opr,SP
Exclusive OR M with A
PC ← (PC) + 3 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 3 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 4 + rel ? (result) ≠ 0
M ← (M) – 1
A ← (A) – 1
X ← (X) – 1
M ← (M) – 1
M ← (M) – 1
M ← (M) – 1
A ← (H:A)/(X)
H ← Remainder
A ← (A ⊕ M)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
↕
– – ↕ ↕
– – – – ↕ ↕ INH
0 – – ↕ ↕
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
ff
ff
52
A8
B8
C8
D8
E8
F8
9EE8
9ED8
7
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
Technical Data
Central Processor Unit (CPU)
87
Central Processor Unit (CPU)
V H I N Z C
INC opr
INCA
INCX
INC opr,X
INC ,X
INC opr,SP
JMP opr
JMP opr
JMP opr,X
JMP opr,X
JMP ,X
JSR opr
JSR opr
JSR opr,X
JSR opr,X
JSR ,X
Increment
Jump to Subroutine
Load A from M
LDHX #opr
LDHX opr
Load H:X from M
LSL opr
LSLA
LSLX
LSL opr,X
LSL ,X
LSL opr,SP
LSR opr
LSRA
LSRX
LSR opr,X
LSR ,X
LSR opr,SP
Logical Shift Right
dd
ff
ff
4
1
1
4
3
5
PC ← Jump Address
dd
hh ll
ee ff
ff
2
3
4
3
2
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – 1
Push (PCH); SP ← (SP) – 1
PC ← Unconditional Address
DIR
EXT
– – – – – – IX2
IX1
IX
BD
CD
DD
ED
FD
dd
hh ll
ee ff
ff
4
5
6
5
4
A6
B6
C6
D6
E6
F6
9EE6
9ED6
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
ii jj
dd
3
4
2
3
4
4
3
2
4
5
A ← (M)
0 – – ↕ ↕
H:X ← (M:M + 1)
X ← (M)
C
0
b7
0
C
b7
b0
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
IMM
DIR
45
55
0 – – ↕ ↕
–
0 – – ↕ ↕
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
AE
BE
CE
DE
EE
FE
9EEE
9EDE
ii
dd
hh ll
ee ff
ff
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
38
48
58
68
78
9E68
dd
DIR
INH
INH
– – 0 ↕ ↕
IX1
IX
SP1
34
44
54
64
74
9E64
dd
↕
b0
Technical Data
88
– – ↕ ↕
3C
4C
5C
6C
7C
9E6C
BC
CC
DC
EC
FC
Load X from M
Logical Shift Left
(Same as ASL)
↕
DIR
INH
INH
–
IX1
IX
SP1
DIR
EXT
– – – – – – IX2
IX1
IX
Jump
LDA #opr
LDA opr
LDA opr
LDA opr,X
LDA opr,X
LDA ,X
LDA opr,SP
LDA opr,SP
LDX #opr
LDX opr
LDX opr
LDX opr,X
LDX opr,X
LDX ,X
LDX opr,SP
LDX opr,SP
M ← (M) + 1
A ← (A) + 1
X ← (X) + 1
M ← (M) + 1
M ← (M) + 1
M ← (M) + 1
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 5 of 8)
↕
ff
ee ff
ff
ff
ff
ff
4
1
1
4
3
5
4
1
1
4
3
5
MC68HC908JB16 — Rev. 1.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
V H I N Z C
MOV opr,opr
MOV opr,X+
MOV #opr,opr
MOV X+,opr
Move
MUL
Unsigned multiply
(M)Destination ← (M)Source
0 – – ↕ ↕
H:X ← (H:X) + 1 (IX+D, DIX+)
X:A ← (X) × (A)
DD
DIX+
–
IMD
IX+D
– 0 – – – 0 INH
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 6 of 8)
4E
5E
6E
7E
dd dd
dd
ii dd
dd
5
4
4
4
42
30
40
50
60
70
9E60
5
dd
4
1
1
4
3
5
NEG opr
NEGA
NEGX
NEG opr,X
NEG ,X
NEG opr,SP
Negate (Two’s Complement)
NOP
No Operation
None
– – – – – – INH
9D
1
NSA
Nibble Swap A
A ← (A[3:0]:A[7:4])
– – – – – – INH
62
3
M ← –(M) = $00 – (M)
A ← –(A) = $00 – (A)
X ← –(X) = $00 – (X)
M ← –(M) = $00 – (M)
M ← –(M) = $00 – (M)
↕
IMM
DIR
EXT
IX2
–
IX1
IX
SP1
SP2
AA
BA
CA
DA
EA
FA
9EEA
9EDA
ff
ff
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
ORA #opr
ORA opr
ORA opr
ORA opr,X
ORA opr,X
ORA ,X
ORA opr,SP
ORA opr,SP
Inclusive OR A and M
PSHA
Push A onto Stack
Push (A); SP ← (SP) – 1
– – – – – – INH
87
2
PSHH
Push H onto Stack
Push (H); SP ← (SP) – 1
– – – – – – INH
8B
2
PSHX
Push X onto Stack
Push (X); SP ← (SP) – 1
– – – – – – INH
89
2
PULA
Pull A from Stack
SP ← (SP + 1); Pull (A)
– – – – – – INH
86
2
PULH
Pull H from Stack
SP ← (SP + 1); Pull (H)
– – – – – – INH
8A
2
PULX
Pull X from Stack
SP ← (SP + 1); Pull (X)
– – – – – – INH
88
2
ROL opr
ROLA
ROLX
ROL opr,X
ROL ,X
ROL opr,SP
Rotate Left through Carry
A ← (A) | (M)
C
↕
b7
ROR opr
RORA
RORX
ROR opr,X
ROR ,X
ROR opr,SP
Rotate Right through Carry
RSP
Reset Stack Pointer
0 – – ↕ ↕
b0
C
b7
b0
SP ← $FF
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
↕
ff
ee ff
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
39
49
59
69
79
9E69
dd
DIR
INH
INH
– – ↕ ↕ ↕
IX1
IX
SP1
36
46
56
66
76
9E66
dd
– – – – – – INH
9C
ff
ff
ff
ff
4
1
1
4
3
5
4
1
1
4
3
5
1
Technical Data
Central Processor Unit (CPU)
89
Central Processor Unit (CPU)
V H I N Z C
RTI
Return from Interrupt
RTS
Return from Subroutine
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 7 of 8)
SP ← (SP) + 1; Pull (CCR)
SP ← (SP) + 1; Pull (A)
SP ← (SP) + 1; Pull (X)
SP ← (SP) + 1; Pull (PCH)
SP ← (SP) + 1; Pull (PCL)
↕ ↕ ↕ ↕ ↕ ↕ INH
80
7
SP ← SP + 1; Pull (PCH)
SP ← SP + 1; Pull (PCL)
– – – – – – INH
81
4
IMM
DIR
EXT
IX2
– – ↕ ↕ ↕
IX1
IX
SP1
SP2
A2
B2
C2
D2
E2
F2
9EE2
9ED2
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
SBC #opr
SBC opr
SBC opr
SBC opr,X
SBC opr,X
SBC ,X
SBC opr,SP
SBC opr,SP
Subtract with Carry
SEC
Set Carry Bit
C←1
– – – – – 1 INH
99
1
SEI
Set Interrupt Mask
I←1
– – 1 – – – INH
9B
2
STA opr
STA opr
STA opr,X
STA opr,X
STA ,X
STA opr,SP
STA opr,SP
Store A in M
STHX opr
Store H:X in M
STOP
Enable IRQ Pin; Stop Oscillator
STX opr
STX opr
STX opr,X
STX opr,X
STX ,X
STX opr,SP
STX opr,SP
SUB #opr
SUB opr
SUB opr
SUB opr,X
SUB opr,X
SUB ,X
SUB opr,SP
SUB opr,SP
Store X in M
Subtract
A ← (A) – (M) – (C)
M ← (A)
(M:M + 1) ← (H:X)
I ← 0; Stop Oscillator
M ← (X)
A ← (A) – (M)
Technical Data
90
↕
DIR
EXT
IX2
– IX1
IX
SP1
SP2
B7
C7
D7
E7
F7
9EE7
9ED7
– DIR
35
– – 0 – – – INH
8E
0 – – ↕ ↕
0 – – ↕ ↕
ff
ee ff
3
4
4
3
2
4
5
dd
4
dd
hh ll
ee ff
ff
1
DIR
EXT
IX2
– IX1
IX
SP1
SP2
BF
CF
DF
EF
FF
9EEF
9EDF
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
– – ↕ ↕ ↕
IX1
IX
SP1
SP2
A0
B0
C0
D0
E0
F0
9EE0
9ED0
ii
dd
hh ll
ee ff
ff
0 – – ↕ ↕
↕
ff
ee ff
ff
ee ff
ff
ee ff
3
4
4
3
2
4
5
2
3
4
4
3
2
4
5
MC68HC908JB16 — Rev. 1.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
V H I N Z C
Cycles
Effect on
CCR
Description
Operand
Operation
Opcode
Source
Form
Address
Mode
Table 6-1. Instruction Set Summary (Sheet 8 of 8)
SWI
Software Interrupt
PC ← (PC) + 1; Push (PCL)
SP ← (SP) – 1; Push (PCH)
SP ← (SP) – 1; Push (X)
SP ← (SP) – 1; Push (A)
SP ← (SP) – 1; Push (CCR)
SP ← (SP) – 1; I ← 1
PCH ← Interrupt Vector High Byte
PCL ← Interrupt Vector Low Byte
TAP
Transfer A to CCR
CCR ← (A)
↕ ↕ ↕ ↕ ↕ ↕ INH
84
2
TAX
Transfer A to X
X ← (A)
– – – – – – INH
97
1
TPA
Transfer CCR to A
A ← (CCR)
– – – – – – INH
85
1
TST opr
TSTA
TSTX
TST opr,X
TST ,X
TST opr,SP
Test for Negative or Zero
TSX
Transfer SP to H:X
TXA
Transfer X to A
TXS
Transfer H:X to SP
A
C
CCR
dd
dd rr
DD
DIR
DIX+
ee ff
EXT
ff
H
H
hh ll
I
ii
IMD
IMM
INH
IX
IX+
IX+D
IX1
IX1+
IX2
M
N
(A) – $00 or (X) – $00 or (M) – $00
83
9
0 – – ↕ ↕
DIR
INH
INH
–
IX1
IX
SP1
3D
4D
5D
6D
7D
9E6D
dd
ff
ff
3
1
1
3
2
4
H:X ← (SP) + 1
– – – – – – INH
95
2
A ← (X)
– – – – – – INH
9F
1
(SP) ← (H:X) – 1
– – – – – – INH
94
2
Accumulator
Carry/borrow bit
Condition code register
Direct address of operand
Direct address of operand and relative offset of branch instruction
Direct to direct addressing mode
Direct addressing mode
Direct to indexed with post increment addressing mode
High and low bytes of offset in indexed, 16-bit offset addressing
Extended addressing mode
Offset byte in indexed, 8-bit offset addressing
Half-carry bit
Index register high byte
High and low bytes of operand address in extended addressing
Interrupt mask
Immediate operand byte
Immediate source to direct destination addressing mode
Immediate addressing mode
Inherent addressing mode
Indexed, no offset addressing mode
Indexed, no offset, post increment addressing mode
Indexed with post increment to direct addressing mode
Indexed, 8-bit offset addressing mode
Indexed, 8-bit offset, post increment addressing mode
Indexed, 16-bit offset addressing mode
Memory location
Negative bit
n
opr
PC
PCH
PCL
REL
rel
rr
SP1
SP2
SP
U
V
X
Z
&
|
⊕
()
–( )
#
«
←
?
:
↕
—
Any bit
Operand (one or two bytes)
Program counter
Program counter high byte
Program counter low byte
Relative addressing mode
Relative program counter offset byte
Relative program counter offset byte
Stack pointer, 8-bit offset addressing mode
Stack pointer 16-bit offset addressing mode
Stack pointer
Undefined
Overflow bit
Index register low byte
Zero bit
Logical AND
Logical OR
Logical EXCLUSIVE OR
Contents of
Negation (two’s complement)
Immediate value
Sign extend
Loaded with
If
Concatenated with
Set or cleared
Not affected
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
– – 1 – – – INH
Technical Data
Central Processor Unit (CPU)
91
MSB
Branch
REL
DIR
INH
3
4
1
2
3
4
5
6
7
8
9
A
B
C
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
1
2
5
BRSET0
3 DIR
5
BRCLR0
3 DIR
5
BRSET1
3 DIR
5
BRCLR1
3 DIR
5
BRSET2
3 DIR
5
BRCLR2
3 DIR
5
BRSET3
3 DIR
5
BRCLR3
3 DIR
5
BRSET4
3 DIR
5
BRCLR4
3 DIR
5
BRSET5
3 DIR
5
BRCLR5
3 DIR
5
BRSET6
3 DIR
5
BRCLR6
3 DIR
5
BRSET7
3 DIR
5
BRCLR7
3 DIR
4
BSET0
2 DIR
4
BCLR0
2 DIR
4
BSET1
2 DIR
4
BCLR1
2 DIR
4
BSET2
2 DIR
4
BCLR2
2 DIR
4
BSET3
2 DIR
4
BCLR3
2 DIR
4
BSET4
2 DIR
4
BCLR4
2 DIR
4
BSET5
2 DIR
4
BCLR5
2 DIR
4
BSET6
2 DIR
4
BCLR6
2 DIR
4
BSET7
2 DIR
4
BCLR7
2 DIR
3
BRA
2 REL
3
BRN
2 REL
3
BHI
2 REL
3
BLS
2 REL
3
BCC
2 REL
3
BCS
2 REL
3
BNE
2 REL
3
BEQ
2 REL
3
BHCC
2 REL
3
BHCS
2 REL
3
BPL
2 REL
3
BMI
2 REL
3
BMC
2 REL
3
BMS
2 REL
3
BIL
2 REL
3
BIH
2 REL
5
6
1
NEGX
1 INH
4
CBEQX
3 IMM
7
DIV
1 INH
1
COMX
1 INH
1
LSRX
1 INH
4
LDHX
2 DIR
1
RORX
1 INH
1
ASRX
1 INH
1
LSLX
1 INH
1
ROLX
1 INH
1
DECX
1 INH
3
DBNZX
2 INH
1
INCX
1 INH
1
TSTX
1 INH
4
MOV
2 DIX+
1
CLRX
1 INH
4
NEG
2
IX1
5
CBEQ
3 IX1+
3
NSA
1 INH
4
COM
2 IX1
4
LSR
2 IX1
3
CPHX
3 IMM
4
ROR
2 IX1
4
ASR
2 IX1
4
LSL
2 IX1
4
ROL
2 IX1
4
DEC
2 IX1
5
DBNZ
3 IX1
4
INC
2 IX1
3
TST
2 IX1
4
MOV
3 IMD
3
CLR
2 IX1
SP1
IX
9E6
7
Control
INH
INH
8
9
Register/Memory
IX2
SP2
IMM
DIR
EXT
A
B
C
D
9ED
4
SUB
3 EXT
4
CMP
3 EXT
4
SBC
3 EXT
4
CPX
3 EXT
4
AND
3 EXT
4
BIT
3 EXT
4
LDA
3 EXT
4
STA
3 EXT
4
EOR
3 EXT
4
ADC
3 EXT
4
ORA
3 EXT
4
ADD
3 EXT
3
JMP
3 EXT
5
JSR
3 EXT
4
LDX
3 EXT
4
STX
3 EXT
4
SUB
3 IX2
4
CMP
3 IX2
4
SBC
3 IX2
4
CPX
3 IX2
4
AND
3 IX2
4
BIT
3 IX2
4
LDA
3 IX2
4
STA
3 IX2
4
EOR
3 IX2
4
ADC
3 IX2
4
ORA
3 IX2
4
ADD
3 IX2
4
JMP
3 IX2
6
JSR
3 IX2
4
LDX
3 IX2
4
STX
3 IX2
5
SUB
4 SP2
5
CMP
4 SP2
5
SBC
4 SP2
5
CPX
4 SP2
5
AND
4 SP2
5
BIT
4 SP2
5
LDA
4 SP2
5
STA
4 SP2
5
EOR
4 SP2
5
ADC
4 SP2
5
ORA
4 SP2
5
ADD
4 SP2
IX1
SP1
IX
E
9EE
F
LSB
0
Central Processor Unit (CPU)
0
Read-Modify-Write
INH
IX1
D
E
F
4
1
NEG
NEGA
2 DIR 1 INH
5
4
CBEQ CBEQA
3 DIR 3 IMM
5
MUL
1 INH
4
1
COM
COMA
2 DIR 1 INH
4
1
LSR
LSRA
2 DIR 1 INH
4
3
STHX
LDHX
2 DIR 3 IMM
4
1
ROR
RORA
2 DIR 1 INH
4
1
ASR
ASRA
2 DIR 1 INH
4
1
LSL
LSLA
2 DIR 1 INH
4
1
ROL
ROLA
2 DIR 1 INH
4
1
DEC
DECA
2 DIR 1 INH
5
3
DBNZ DBNZA
3 DIR 2 INH
4
1
INC
INCA
2 DIR 1 INH
3
1
TST
TSTA
2 DIR 1 INH
5
MOV
3 DD
3
1
CLR
CLRA
2 DIR 1 INH
INH Inherent
REL Relative
IMM Immediate
IX
Indexed, No Offset
DIR Direct
IX1 Indexed, 8-Bit Offset
EXT Extended
IX2 Indexed, 16-Bit Offset
DD Direct-Direct
IMD Immediate-Direct
IX+D Indexed-Direct DIX+ Direct-Indexed
*Pre-byte for stack pointer indexed instructions
5
3
NEG
NEG
3 SP1 1 IX
6
4
CBEQ
CBEQ
4 SP1 2 IX+
2
DAA
1 INH
5
3
COM
COM
3 SP1 1 IX
5
3
LSR
LSR
3 SP1 1 IX
4
CPHX
2 DIR
5
3
ROR
ROR
3 SP1 1 IX
5
3
ASR
ASR
3 SP1 1 IX
5
3
LSL
LSL
3 SP1 1 IX
5
3
ROL
ROL
3 SP1 1 IX
5
3
DEC
DEC
3 SP1 1 IX
6
4
DBNZ
DBNZ
4 SP1 2 IX
5
3
INC
INC
3 SP1 1 IX
4
2
TST
TST
3 SP1 1 IX
4
MOV
2 IX+D
4
2
CLR
CLR
3 SP1 1 IX
SP1 Stack Pointer, 8-Bit Offset
SP2 Stack Pointer, 16-Bit Offset
IX+ Indexed, No Offset with
Post Increment
IX1+ Indexed, 1-Byte Offset with
Post Increment
7
3
RTI
BGE
1 INH 2 REL
4
3
RTS
BLT
1 INH 2 REL
3
BGT
2 REL
9
3
SWI
BLE
1 INH 2 REL
2
2
TAP
TXS
1 INH 1 INH
1
2
TPA
TSX
1 INH 1 INH
2
PULA
1 INH
2
1
PSHA
TAX
1 INH 1 INH
2
1
PULX
CLC
1 INH 1 INH
2
1
PSHX
SEC
1 INH 1 INH
2
2
PULH
CLI
1 INH 1 INH
2
2
PSHH
SEI
1 INH 1 INH
1
1
CLRH
RSP
1 INH 1 INH
1
NOP
1 INH
1
STOP
*
1 INH
1
1
WAIT
TXA
1 INH 1 INH
2
SUB
2 IMM
2
CMP
2 IMM
2
SBC
2 IMM
2
CPX
2 IMM
2
AND
2 IMM
2
BIT
2 IMM
2
LDA
2 IMM
2
AIS
2 IMM
2
EOR
2 IMM
2
ADC
2 IMM
2
ORA
2 IMM
2
ADD
2 IMM
3
SUB
2 DIR
3
CMP
2 DIR
3
SBC
2 DIR
3
CPX
2 DIR
3
AND
2 DIR
3
BIT
2 DIR
3
LDA
2 DIR
3
STA
2 DIR
3
EOR
2 DIR
3
ADC
2 DIR
3
ORA
2 DIR
3
ADD
2 DIR
2
JMP
2 DIR
4
4
BSR
JSR
2 REL 2 DIR
2
3
LDX
LDX
2 IMM 2 DIR
2
3
AIX
STX
2 IMM 2 DIR
MSB
0
3
SUB
2 IX1
3
CMP
2 IX1
3
SBC
2 IX1
3
CPX
2 IX1
3
AND
2 IX1
3
BIT
2 IX1
3
LDA
2 IX1
3
STA
2 IX1
3
EOR
2 IX1
3
ADC
2 IX1
3
ORA
2 IX1
3
ADD
2 IX1
3
JMP
2 IX1
5
JSR
2 IX1
5
3
LDX
LDX
4 SP2 2 IX1
5
3
STX
STX
4 SP2 2 IX1
4
SUB
3 SP1
4
CMP
3 SP1
4
SBC
3 SP1
4
CPX
3 SP1
4
AND
3 SP1
4
BIT
3 SP1
4
LDA
3 SP1
4
STA
3 SP1
4
EOR
3 SP1
4
ADC
3 SP1
4
ORA
3 SP1
4
ADD
3 SP1
2
SUB
1 IX
2
CMP
1 IX
2
SBC
1 IX
2
CPX
1 IX
2
AND
1 IX
2
BIT
1 IX
2
LDA
1 IX
2
STA
1 IX
2
EOR
1 IX
2
ADC
1 IX
2
ORA
1 IX
2
ADD
1 IX
2
JMP
1 IX
4
JSR
1 IX
4
2
LDX
LDX
3 SP1 1 IX
4
2
STX
STX
3 SP1 1 IX
High Byte of Opcode in Hexadecimal
LSB
Low Byte of Opcode in Hexadecimal
0
5
Cycles
BRSET0 Opcode Mnemonic
3 DIR Number of Bytes / Addressing Mode
Central Processor Unit (CPU)
Technical Data
92
Table 6-2. Opcode Map
Bit Manipulation
DIR
DIR
Technical Data — MC68HC908JB16
Section 7. Oscillator (OSC)
7.1 Contents
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.3
Oscillator External Connections . . . . . . . . . . . . . . . . . . . . . . . .94
7.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.4.1
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . . 95
7.4.2
Crystal Amplifier Output Pin (OSC1) . . . . . . . . . . . . . . . . . . 95
7.4.3
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . . 95
7.4.4
Crystal Output Frequency Signal (OSCXCLK). . . . . . . . . . . 95
7.4.5
Clock Doubler Out (OSCDCLK) . . . . . . . . . . . . . . . . . . . . . . 95
7.4.6
Oscillator Out (OSCOUT). . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
7.5.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
7.6
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.2 Introduction
The oscillator circuit is designed for use with crystals or ceramic
resonators. The oscillator circuit generates the crystal clock signal,
OSCXCLK, and passes through a clock doubler to produce OSCDCLK.
This clock doubler clock is further divided by two before being passed on
to the system integration module (SIM) for bus clock generation.
Figure 7-1 shows the structure of the oscillator. The oscillator requires
various external components.
The MC68HC908JB16 operates from a nominal 12MHz crystal,
providing a 6MHz internal bus clock. The 12MHz clock is required for
various modules, such as the CGMs and USB. The clock doubler clock,
OSCDCLK, is used as the base clock for the COP module.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Oscillator (OSC)
93
Oscillator (OSC)
7.3 Oscillator External Connections
In its typical configuration, the oscillator requires five external
components. The crystal oscillator is normally connected in a Pierce
oscillator configuration, as shown in Figure 7-1. This figure shows only
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
•
Crystal, X1 (nominally 12MHz)
•
Fixed capacitor, C1
•
Tuning capacitor, C2 (can also be a fixed capacitor)
•
Feedback resistor, RB
•
Series resistor, RS (not required for 12MHz)
FROM SIM
TO CGM
OSCXCLK
TO COP, SCI
CLOCK
DOUBLER
OSCDCLK
TO SIM
÷2
OSCOUT
SIMOSCEN
÷2
TO USB
MCU
OSC1
OSC2
RB
RS *
X1
C1
12 MHz
C2
* RS can be 0 (shorted) when used with
higher frequency crystals.
Refer to manufacturer’s data.
Figure 7-1. Oscillator External Connections
The series resistor (RS) is included in the diagram to follow strict Pierce
oscillator guidelines and may not be required for all ranges of operation,
especially with high-frequency crystals. Refer to the crystal
manufacturer’s data for more information.
Technical Data
94
MC68HC908JB16 — Rev. 1.1
Oscillator (OSC)
Freescale Semiconductor
Oscillator (OSC)
7.4 I/O Signals
The following paragraphs describe the oscillator input/output (I/O)
signals.
7.4.1 Crystal Amplifier Input Pin (OSC1)
The OSC1 pin is an input to the crystal oscillator amplifier.
7.4.2 Crystal Amplifier Output Pin (OSC1)
The OSC2 pin is the output of the crystal oscillator inverting amplifier.
7.4.3 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal comes from the system integration module (SIM)
and enables the oscillator.
7.4.4 Crystal Output Frequency Signal (OSCXCLK)
OSCXCLK is the crystal oscillator output signal. It runs at the full speed
of the crystal (fXCLK) and comes directly from the crystal oscillator circuit.
Figure 7-1 shows only the logical relation of OSCXCLK to OSC1 and
OSC2 and may not represent the actual circuitry. The duty cycle of
OSCXCLK is unknown and may depend on the crystal and other
external factors. Also, the frequency and amplitude of OSCXCLK can be
unstable at startup.
7.4.5 Clock Doubler Out (OSCDCLK)
OSCDCLK is the clock doubler output signal. It runs at twice the speed
of the crystal (fXCLK) and comes from the clock doubler circuit.
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Technical Data
Oscillator (OSC)
95
Oscillator (OSC)
7.4.6 Oscillator Out (OSCOUT)
OSCOUT is the divide-by-two signal after the clock doubler circuit. It
runs at the same speed as OSCXCLK, at crystal frequency (fXCLK). This
signal goes to the SIM, which generates the MCU clocks. OSCOUT will
be divided-by-two again in the SIM and results in the internal bus
frequency being one half of the crystal frequency.
7.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low-powerconsumption standby modes.
7.5.1 Wait Mode
The WAIT instruction has no effect on the oscillator logic. OSCXCLK
continues to drive to the MCU.
7.5.2 Stop Mode
The STOP instruction disables the OSCXCLK output.
7.6 Oscillator During Break Mode
The oscillator continues to drive OSCXCLK when the chip enters the
break state.
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Technical Data — MC68HC908JB16
Section 8. System Integration Module (SIM)
8.1 Contents
8.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
8.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . . 100
8.3.1
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
8.3.2
Clock Startup from POR or LVI Reset . . . . . . . . . . . . . . . . 101
8.3.3
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . . 101
8.4
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . . 101
8.4.1
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
8.4.2
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . 103
8.4.2.1
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104
8.4.2.2
Computer Operating Properly (COP) Reset. . . . . . . . . . 105
8.4.2.3
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
8.4.2.4
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .105
8.4.2.5
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . 106
8.4.2.6
Universal Serial Bus (USB) Reset . . . . . . . . . . . . . . . . . 106
8.4.2.7
Registers Values After Different Resets. . . . . . . . . . . . . 106
8.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
8.5.1
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . 107
8.5.2
SIM Counter During Stop Mode Recovery . . . . . . . . . . . . . 108
8.5.3
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . . 108
8.6
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108
8.6.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.6.1.1
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.6.1.2
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2
Interrupt Status Registers. . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2.1
Interrupt Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . 112
8.6.2.2
Interrupt Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . 114
8.6.3
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8.6.4
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
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8.6.5
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . 114
8.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
8.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
8.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116
8.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
8.8.1
SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . 118
8.8.2
SIM Reset Status Register (SRSR) . . . . . . . . . . . . . . . . . . 119
8.8.3
SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . 120
8.2 Introduction
This section describes the system integration module (SIM). Together
with the CPU, the SIM controls all MCU activities. The SIM is a system
state controller that coordinates CPU and exception timing. A block
diagram of the SIM is shown in Figure 8-1. Figure 8-2 is a summary of
the SIM I/O registers. The SIM is responsible for:
•
Bus clock generation and control for CPU and peripherals
– Stop/wait/reset/break entry and recovery
– Internal clock control
•
Master reset control, including power-on reset (POR) and COP
timeout
•
Interrupt control:
– Acknowledge timing
– Arbitration control timing
– Vector address generation
•
CPU enable/disable timing
•
Modular architecture expandable to 128 interrupt sources
Table 8-1 shows the internal signal names used in this section.
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System Integration Module (SIM)
MODULE STOP
MODULE WAIT
CPU STOP (FROM CPU)
CPU WAIT (FROM CPU)
STOP/WAIT
CONTROL
SIMOSCEN (TO OSCILLATOR)
SIM
COUNTER
COP CLOCK
OSCDCLK (FROM OSC)
OSCOUT (FROM OSC)
÷2
VDD
CLOCK
CONTROL
INTERNAL
PULL-UP
RESET
PIN LOGIC
CLOCK GENERATORS
POR CONTROL
MASTER
RESET
CONTROL
RESET PIN CONTROL
SIM RESET STATUS REGISTER
INTERNAL CLOCKS
ILLEGAL OPCODE (FROM CPU)
ILLEGAL ADDRESS (FROM ADDRESS
MAP DECODERS)
COP TIMEOUT (FROM COP MODULE)
LVI RESET (FROM LVI MODULE)
USB RESET (FROM USB MODULE)
RESET
INTERRUPT SOURCES
INTERRUPT CONTROL
AND PRIORITY DECODE
CPU INTERFACE
Figure 8-1. SIM Block Diagram
Table 8-1. SIM Module Signal Name Conventions
Signal Name
Description
OSCDCLK
Clock doubler output which has twice the frequency of OSC1 from the oscillator
OSCOUT
The OSCDCLK frequency divided by two. This signal is again divided by two in the
SIM to generate the internal bus clocks.
(Bus clock = OSCDCLK ÷ 4 = OSCXCLK ÷ 2)
IAB
Internal address bus
IDB
Internal data bus
PORRST
Signal from the power-on reset module to the SIM
IRST
Internal reset signal
R/W
Read/write signal
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System Integration Module (SIM)
Addr.
Register Name
Read:
SIM Break Status Register
$FE00
Write:
(SBSR)
Reset:
Bit 7
6
5
4
3
2
R
R
R
R
R
R
1
SBSW
See note
Bit 0
R
0
Note: Writing a logic 0 clears SBSW.
Read:
SIM Reset Status Register
$FE01
Write:
(SRSR)
POR:
$FE03
Read:
SIM Break Flag Control
Register Write:
(SBFCR)
Reset:
POR
PIN
COP
ILOP
ILAD
USB
LVI
0
1
0
0
0
0
0
0
0
BCFE
R
R
R
R
R
R
R
0
Read:
Interrupt Status Register 1
Write:
$FE04
(INT1)
Reset:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Read:
Interrupt Status Register 2
$FE05
Write:
(INT2)
Reset:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Figure 8-2. SIM I/O Register Summary
8.3 SIM Bus Clock Control and Generation
The bus clock generator provides system clock signals for the CPU and
peripherals on the MCU. The system clocks are generated from an
incoming clock, OSCOUT, as shown in Figure 8-3.
OSCDCLK
FROM OSC
OSCOUT
SIM COUNTER
BUS CLOCK
GENERATORS
÷2
SIM
Figure 8-3. SIM Clock Signals
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System Integration Module (SIM)
8.3.1 Bus Timing
In user mode, the internal bus frequency is the oscillator frequency
divided by two.
8.3.2 Clock Startup from POR or LVI Reset
When the power-on reset (POR) module or the low-voltage inhibit
module generates a reset, the clocks to the CPU and peripherals are
inactive and held in an inactive phase until after the 4096 OSCDCLK
cycle POR timeout has completed. The RST pin is driven low by the SIM
during this entire period. The IBUS clocks start upon completion of the
timeout.
8.3.3 Clocks in Stop Mode and Wait Mode
Upon exit from stop mode by an interrupt, break, or reset, the SIM allows
OSCDCLK to clock the SIM counter. The CPU and peripheral clocks do
not become active until after the stop delay timeout. This timeout is
selectable as 4096 or 2048 OSCDCLK cycles. (See 8.7.2 Stop Mode.)
In wait mode, the CPU clocks are inactive. The SIM also produces two
sets of clocks for other modules. Refer to the wait mode subsection of
each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
8.4 Reset and System Initialization
The MCU has the following reset sources:
•
Power-on reset module (POR)
•
External reset pin (RST)
•
Computer operating properly module (COP)
•
Illegal opcode
•
Illegal address
•
Universal serial bus module (USB)
•
Low-voltage inhibit module (LVI)
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System Integration Module (SIM)
All of these resets produce the vector $FFFE–FFFF ($FEFE–FEFF in
monitor mode) and assert the internal reset signal (IRST). IRST causes
all registers to be returned to their default values and all modules to be
returned to their reset states.
An internal reset clears the SIM counter (see 8.5 SIM Counter), but an
external reset does not. Each of the resets sets a corresponding bit in
the SIM reset status register (SRSR). (See 8.8 SIM Registers.)
8.4.1 External Pin Reset
The RST pin circuit includes an internal pullup device. Pulling the
asynchronous RST pin low halts all processing. The PIN bit of the SIM
reset status register (SRSR) is set as long as RST is held low for a
minimum of 67 OSCDCLK cycles, assuming that neither the POR nor
the LVI was the source of the reset. See Table 8-2 for details.
Figure 8-4 shows the relative timing.
Table 8-2. PIN Bit Set Timing
Reset Type
Number of Cycles Required to Set PIN
POR/LVI
4163 (4096 + 64 + 3)
All others
67 (64 + 3)
OSCOUT
RST
IAB
VECT H VECT L
PC
Figure 8-4. External Reset Timing
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System Integration Module (SIM)
8.4.2 Active Resets from Internal Sources
All internal reset sources actively pull the RST pin low for 32 OSCDCLK
cycles to allow resetting of external peripherals. The internal reset signal
IRST continues to be asserted for an additional 32 cycles. (See Figure
8-5.) An internal reset can be caused by an illegal address, illegal
opcode, COP timeout, LVI, the USB module or POR. (See Figure 8-6 .
Sources of Internal Reset.)
NOTE:
For LVI or POR resets, the SIM cycles through 4096 OSCDCLK cycles
during which the SIM forces the RST pin low. The internal reset signal
then follows the sequence from the falling edge of RST shown in
Figure 8-5.
IRST
RST
RST PULLED LOW BY MCU
32 CYCLES
32 CYCLES
OSCDCLK
IAB
VECTOR HIGH
Figure 8-5. Internal Reset Timing
The COP reset is asynchronous to the bus clock.
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
POR
LVI
USB
INTERNAL RESET
Figure 8-6. Sources of Internal Reset
The active reset feature allows the part to issue a reset to peripherals
and other chips within a system built around the MCU.
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System Integration Module (SIM)
8.4.2.1 Power-On Reset
When power is first applied to the MCU, the power-on reset module
(POR) generates a pulse to indicate that power-on has occurred. The
external reset pin (RST) is held low while the SIM counter counts out
4096 OSCDCLK cycles. Sixty-four OSCDCLK cycles later, the CPU and
memories are released from reset to allow the reset vector sequence to
occur.
At power-on, the following events occur:
•
A POR pulse is generated.
•
The internal reset signal is asserted.
•
The SIM enables the oscillator to drive OSCDCLK.
•
Internal clocks to the CPU and modules are held inactive for 4096
OSCDCLK cycles to allow stabilization of the oscillator.
•
The RST pin is driven low during the oscillator stabilization time.
•
The POR bit of the SIM reset status register (SRSR) is set and all
other bits in the register are cleared.
OSC1
PORRST
4096
CYCLES
32
CYCLES
32
CYCLES
OSCDCLK
OSCOUT
RST
IAB
$FFFE
$FFFF
Figure 8-7. POR Recovery
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System Integration Module (SIM)
8.4.2.2 Computer Operating Properly (COP) Reset
An input to the SIM is reserved for the COP reset signal. The overflow of
the COP counter causes an internal reset and sets the COP bit in the
SIM reset status register (SRSR). The SIM actively pulls down the RST
pin for all internal reset sources.
To prevent a COP module timeout, write any value to location $FFFF.
Writing to location $FFFF clears the COP counter and stages 12 through
5 of the SIM counter. The SIM counter output, which occurs at least
every 212 – 24 OSCDCLK cycles, drives the COP counter. The COP
should be serviced as soon as possible out of reset to guarantee the
maximum amount of time before the first timeout.
The COP module is disabled if the RST pin or the IRQ pin is held at VTST
while the MCU is in monitor mode. The COP module can be disabled
only through combinational logic conditioned with the high voltage signal
on the RST or the IRQ pin. This prevents the COP from becoming
disabled as a result of external noise. During a break state, VTST on the
RST pin disables the COP module.
8.4.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An
illegal instruction sets the ILOP bit in the SIM reset status register
(SRSR) and causes a reset.
If the stop enable bit, STOP, in the mask option register is logic 0, the
SIM treats the STOP instruction as an illegal opcode and causes an
illegal opcode reset. The SIM actively pulls down the RST pin for all
internal reset sources.
8.4.2.4 Illegal Address Reset
An opcode fetch from an unmapped address generates an illegal
address reset. The SIM verifies that the CPU is fetching an opcode prior
to asserting the ILAD bit in the SIM reset status register (SRSR) and
resetting the MCU. A data fetch from an unmapped address does not
generate a reset. The SIM actively pulls down the RST pin for all internal
reset sources.
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System Integration Module (SIM)
8.4.2.5 Low-Voltage Inhibit (LVI) Reset
The low-voltage inhibit module (LVI) asserts its output to the SIM when
the VDD or VREG voltage falls to the LVI reset voltage, VTRIP. The LVI bit
in the SIM reset status register (SRSR) is set, and the external reset pin
(RST) is held low while the SIM counter counts out 4096 OSCDCLK
cycles. Sixty-four OSCDCLK cycles later, the CPU is released from reset
to allow the reset vector sequence to occur. The SIM actively pulls down
the RST pin for all internal reset sources.
8.4.2.6 Universal Serial Bus (USB) Reset
The USB module will detect a reset signaled on the bus by the presence
of an extended SE0 at the USB data pins of a device. The MCU seeing
a single-ended 0 on its USB data inputs for more than 2.5µs treats that
signal as a reset. After the reset is removed, the device will be in the
attached, but not yet addressed or configured, state (refer to Section 9.1
USB Devices of the Universal Serial Bus Specification Rev. 2.0). The
device must be able to accept the device address via a SET_ADDRESS
command (refer to Section 9.4 of the Universal Serial Bus Specification
Rev. 2.0) no later than 10ms after the reset is removed.
USB reset can be disabled to generate an internal reset. It can be
configured to generate IRQ interrupt. (See Section 5. Configuration
Register (CONFIG).)
NOTE:
USB reset is disabled when the USB module is disabled by clearing the
USBEN bit of the USB address register (UADDR).
8.4.2.7 Registers Values After Different Resets
Some registers are reset by POR or LVI reset only. Table 8-3 shows the
registers or register bits which are unaffected by normal resets.
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System Integration Module (SIM)
Table 8-3. Registers not Affected by Normal Reset
Bits
Registers
After Reset
(except POR or
LVI)
After POR or LVI
LVIDR, LVI5OR3,
URSTD, LVID
CONFIG
Unaffected
0
USBEN
UADDR
Unaffected
0
PULLEN
UCR3
Unaffected
0
All
USR0, USR1
Unaffected
Indeterminate
All
UE0D0–UE0D7
Unaffected
Indeterminate
All
UE1D0–UE1D7
Unaffected
Indeterminate
All
UE2D0–UE2D7
Unaffected
Indeterminate
All
PTA, PTC, PTD,
and PTE
Unaffected
Indeterminate
DDRA7
DDRA
Unaffected
0
8.5 SIM Counter
The SIM counter is used by the power-on reset module (POR) and in
stop mode recovery to allow the oscillator time to stabilize before
enabling the internal bus (IBUS) clocks. The SIM counter also serves as
a prescaler for the computer operating properly module (COP). The SIM
counter uses 12 stages for counting, followed by a 13th stage that
triggers a reset of SIM counters and supplies the clock for the COP
module. The SIM counter is clocked by the falling edge of OSCDCLK.
8.5.1 SIM Counter During Power-On Reset
The power-on reset module (POR) detects power applied to the MCU.
At power-on, the POR circuit asserts the signal PORRST. Once the SIM
is initialized, it enables the oscillator to drive the bus clock state machine.
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System Integration Module (SIM)
8.5.2 SIM Counter During Stop Mode Recovery
The SIM counter also is used for stop mode recovery. The STOP
instruction clears the SIM counter. After an interrupt, break, or reset, the
SIM senses the state of the short stop recovery bit, SSREC, in the
configuration register (CONFIG). If the SSREC bit is a logic 1, then the
stop recovery is reduced from the normal delay of 4096 OSCDCLK
cycles down to 2048 OSCDCLK cycles. This is ideal for applications
using canned oscillators that do not require long startup times from stop
mode. External crystal applications should use the full stop recovery
time, that is, with SSREC cleared in the configuration register (CONFIG).
8.5.3 SIM Counter and Reset States
External reset has no effect on the SIM counter. (See 8.7.2 Stop Mode
for details.) The SIM counter is free-running after all reset states. (See
8.4.2 Active Resets from Internal Sources for counter control and
internal reset recovery sequences.)
8.6 Exception Control
Normal, sequential program execution can be changed in three different
ways:
•
Interrupts
– Maskable hardware CPU interrupts
– Non-maskable software interrupt instruction (SWI)
•
Reset
•
Break interrupts
8.6.1 Interrupts
An interrupt temporarily changes the sequence of program execution to
respond to a particular event. Figure 8-8 flow charts the handling of
system interrupts.
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System Integration Module (SIM)
FROM RESET
BREAK
INTERRUPT?
I BIT
SET?
YES
NO
YES
I BIT SET?
NO
USB
INTERRUPT?
YES
NO
IRQ
INTERRUPT?
YES
NO
STACK CPU REGISTERS.
SET I BIT.
LOAD PC WITH INTERRUPT VECTOR.
(As many interrupts as exist on chip)
FETCH NEXT
INSTRUCTION.
SWI
INSTRUCTION?
YES
NO
RTI
INSTRUCTION?
YES
UNSTACK CPU REGISTERS.
NO
EXECUTE INSTRUCTION.
Figure 8-8. Interrupt Processing
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System Integration Module (SIM)
Interrupts are latched and arbitration is performed in the SIM at the start
of interrupt processing. The arbitration result is a constant that the CPU
uses to determine which vector to fetch. Once an interrupt is latched by
the SIM, no other interrupt can take precedence, regardless of priority,
until the latched interrupt is serviced or the I bit is cleared.
At the beginning of an interrupt, the CPU saves the CPU register
contents on the stack and sets the interrupt mask (I bit) to prevent
additional interrupts. At the end of an interrupt, the RTI instruction
recovers the CPU register contents from the stack so that normal
processing can resume. Figure 8-9 shows interrupt entry timing. Figure
8-10 shows interrupt recovery timing.
MODULE
INTERRUPT
I BIT
IAB
IDB
SP
DUMMY
DUMMY
SP – 1
SP – 2
PC – 1[7:0] PC – 1[15:8]
SP – 3
X
SP – 4
A
VECT H
CCR
VECT L
V DATA H
START ADDR
V DATA L
OPCODE
R/W
Figure 8-9. Interrupt Entry
MODULE
INTERRUPT
I BIT
IAB
IDB
SP – 4
SP – 3
CCR
SP – 2
A
SP – 1
X
SP
PC
PC + 1
PC – 1[15:8] PC – 1 [7:0] OPCODE
OPERAND
R/W
Figure 8-10. Interrupt Recovery
Technical Data
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System Integration Module (SIM)
8.6.1.1 Hardware Interrupts
A hardware interrupt does not stop the current instruction. Processing of
a hardware interrupt begins after completion of the current instruction.
When the current instruction is complete, the SIM checks all pending
hardware interrupts. If interrupts are not masked (I bit clear in the
condition code register) and if the corresponding interrupt enable bit is
set, the SIM proceeds with interrupt processing; otherwise, the next
instruction is fetched and executed.
If more than one interrupt is pending at the end of an instruction
execution, the highest priority interrupt is serviced first. Figure 8-11
demonstrates what happens when two interrupts are pending. If an
interrupt is pending upon exit from the original interrupt service routine,
the pending interrupt is serviced before the LDA instruction is executed.
CLI
BACKGROUND
ROUTINE
LDA #$FF
INT1
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
INT2
PSHH
INT2 INTERRUPT SERVICE ROUTINE
PULH
RTI
Figure 8-11. Interrupt Recognition Example
The LDA opcode is prefetched by both the INT1 and INT2 RTI
instructions. However, in the case of the INT1 RTI prefetch, this is a
redundant operation.
NOTE:
To maintain compatibility with the M6805 Family, the H register is not
pushed on the stack during interrupt entry. If the interrupt service routine
modifies the H register or uses the indexed addressing mode, software
should save the H register and then restore it prior to exiting the routine.
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8.6.1.2 SWI Instruction
The SWI instruction is a non-maskable instruction that causes an
interrupt regardless of the state of the interrupt mask (I bit) in the
condition code register.
NOTE:
A software interrupt pushes PC onto the stack. A software interrupt does
not push PC–1, as a hardware interrupt does.
8.6.2 Interrupt Status Registers
The flags in the interrupt status registers identify maskable interrupt
sources. Table 8-4 summarizes the interrupt sources and the interrupt
status register flags that they set. The interrupt status registers can be
useful for debugging.
8.6.2.1 Interrupt Status Register 1
Address:
$FE04
Bit 7
6
5
4
3
2
1
Bit 0
Read:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 8-12. Interrupt Status Register 1 (INT1)
IF6–IF1 — Interrupt Flags 6–1
These flags indicate the presence of interrupt requests from the
sources shown in Table 8-4.
1 = Interrupt request present
0 = No interrupt request present
Bit 1 and Bit 0 — Always read 0
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Freescale Semiconductor
System Integration Module (SIM)
Table 8-4. Interrupt Sources
Flags
Mask(1)
INT Register
Flag
Priority(2)
Vector Address
Reset
None
None
None
0
$FFFE–$FFFF
SWI instruction
None
None
None
0
$FFFC–$FFFD
USB reset interrupt
RSTF
URSTD
USB endpoint 0 transmit
TXD0F
TXD0IE
USB endpoint 0 receive
RXD0F
RXD0IE
USB endpoint 1 transmit
TXD1F
TXD1IE
IF1
1
$FFFA–$FFFB
USB endpoint 2 transmit
TXD2F
TXD2IE
USB endpoint 2 receive
RXD2F
RXD2IE
USB end of packet
EOPF
EOPIE
RESUMF
—
IRQF, PTE4IF
IMASK
IF2
2
$FFF8–$FFF9
TIM 1 channel 0
CH0F
CH0IE
IF3
3
$FFF6–$FFF7
TIM 1 channel 1
CH1F
CH1IE
IF4
4
$FFF4–$FFF5
CH0F & CH1F
CH01IE
IF5
5
$FFF2–$FFF3
TOF
TOIE
IF6
6
$FFF0–$FFF1
TIM 2 channel 0
CH0F
CH0IE
IF7
7
$FFEE–$FFEF
TIM 2 channel 1
CH1F
CH1IE
IF8
8
$FFEC–$FFED
CH0F & CH1F
CH01IE
IF9
9
$FFEA–$FFEB
TIM 2 overflow
TOF
TOIE
IF10
10
$FFE8–$FFE9
SCI receiver overrun
OR
ORIE
SCI noise fag
NF
NEIE
IF11
11
$FFE6–$FFE7
SCI framing error
FE
FEIE
SCI parity error
PE
PEIE
SCI receiver full
SCRF
SCRIE
IF12
12
$FFE4–$FFE5
SCI input idle
IDLE
ILIE
SCI transmitter empty
SCTE
SCTIE
IF13
13
$FFE2–$FFE3
TC
TCIE
KEYF
IMASKK
IF14
14
$FFE0–$FFE1
Source
USB resume interrupt
IRQ interrupt (IRQ, PTE4)
TIM 1 channel 0 & 1
TIM 1 overflow
TIM 2 channel 0 & 1
SCI transmission complete
Keyboard interrupt
Notes:
1. The I bit in the condition code register is a global mask for all interrupt sources except the SWI instruction.
2. Highest priority = 0.
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System Integration Module (SIM)
8.6.2.2 Interrupt Status Register 2
Address:
$FE05
Bit 7
6
5
4
3
2
1
Bit 0
Read:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 8-13. Interrupt Status Register 2 (INT2)
IF14–IF7 — Interrupt Flags 14–7
These flags indicate the presence of interrupt requests from the
sources shown in Table 8-4.
1 = Interrupt request present
0 = No interrupt request present
8.6.3 Reset
All reset sources always have equal and highest priority and cannot be
arbitrated.
8.6.4 Break Interrupts
The break module can stop normal program flow at a softwareprogrammable break point by asserting its break interrupt output. (See
Section 19. Break Module (BRK).) The SIM puts the CPU into the
break state by forcing it to the SWI vector location. Refer to the break
interrupt subsection of each module to see how each module is affected
by the break state.
8.6.5 Status Flag Protection in Break Mode
The SIM controls whether status flags contained in other modules can
be cleared during break mode. The user can select whether flags are
protected from being cleared by properly initializing the break clear flag
enable bit (BCFE) in the break flag control register (BFCR).
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Freescale Semiconductor
System Integration Module (SIM)
Protecting flags in break mode ensures that set flags will not be cleared
while in break mode. This protection allows registers to be freely read
and written during break mode without losing status flag information.
Setting the BCFE bit enables the clearing mechanisms. Once cleared in
break mode, a flag remains cleared even when break mode is exited.
Status flags with a 2-step clearing mechanism — for example, a read of
one register followed by the read or write of another — are protected,
even when the first step is accomplished prior to entering break mode.
Upon leaving break mode, execution of the second step will clear the flag
as normal.
8.7 Low-Power Modes
Executing the WAIT or STOP instruction puts the MCU in a low-powerconsumption mode for standby situations. The SIM holds the CPU in a
non-clocked state. The operation of each of these modes is described
here. Both STOP and WAIT clear the interrupt mask (I) in the condition
code register, allowing interrupts to occur.
8.7.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks
continue to run. Figure 8-14 shows the timing for wait mode entry.
A module that is active during wait mode can wake up the CPU with an
interrupt if the interrupt is enabled. Stacking for the interrupt begins one
cycle after the WAIT instruction during which the interrupt occurred. In
wait mode, the CPU clocks are inactive. Refer to the wait mode
subsection of each module to see if the module is active or inactive in
wait mode. Some modules can be programmed to be active in wait
mode.
Wait mode can also be exited by a reset or break. A break interrupt
during wait mode sets the SIM break stop/wait bit, SBSW, in the SIM
break status register (SBSR). If the COP disable bit, COPD, in the
configuration register (CONFIG) is logic 0, then the computer operating
properly module (COP) is enabled and remains active in wait mode.
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Technical Data
System Integration Module (SIM)
115
System Integration Module (SIM)
WAIT ADDR
IAB
WAIT ADDR + 1
PREVIOUS DATA
IDB
SAME
NEXT OPCODE
SAME
SAME
SAME
R/W
NOTE: Previous data can be operand data or the WAIT opcode, depending on the last instruction
Figure 8-14. Wait Mode Entry Timing
Figure 8-15 and Figure 8-16 show the timing for WAIT recovery.
IAB
$6E0B
IDB
$A6
$A6
$6E0C
$A6
$01
$00FF
$00FE
$0B
$00FD
$00FC
$6E
EXITSTOPWAIT
NOTE: EXITSTOPWAIT = RST pin or CPU interrupt or break interrupt
Figure 8-15. Wait Recovery from Interrupt or Break
32
CYCLES
$6E0B
IAB
IDB
$A6
$A6
32
CYCLES
RST VCT H RST VCT L
$A6
RST
OSCDCLK
Figure 8-16. Wait Recovery from Internal Reset
8.7.2 Stop Mode
In stop mode, the SIM counter is reset and the system clocks are
disabled. An interrupt request from a module can cause an exit from stop
mode. Stacking for interrupts begins after the selected stop recovery
time has elapsed. Reset or break also causes an exit from stop mode.
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Freescale Semiconductor
System Integration Module (SIM)
The SIM disables the oscillator signals (OSCOUT and OSCDCLK) in
stop mode, stopping the CPU and peripherals. Stop recovery time is
selectable using the SSREC bit in the configuration register (CONFIG).
If SSREC is set, stop recovery is reduced from the normal delay of 4096
OSCDCLK cycles down to 2048. This is ideal for applications using
canned oscillators that do not require long startup times from stop mode.
NOTE:
External crystal applications should use the full stop recovery time by
clearing the SSREC bit.
A break interrupt during stop mode sets the SIM break stop/wait bit
(SBSW) in the SIM break status register (SBSR).
The SIM counter is held in reset from the execution of the STOP
instruction until the beginning of stop recovery. It is then used to time the
recovery period. Figure 8-17 shows stop mode entry timing.
NOTE:
To minimize stop current, all pins configured as inputs should be driven
to a logic 1 or logic 0.
CPUSTOP
IAB
STOP ADDR
IDB
STOP ADDR + 1
PREVIOUS DATA
SAME
NEXT OPCODE
SAME
SAME
SAME
R/W
NOTE: Previous data can be operand data or the STOP opcode, depending on the last instruction
Figure 8-17. Stop Mode Entry Timing
STOP RECOVERY PERIOD
OSCDCLK
INT/BREAK
IAB
STOP +1
STOP + 2
STOP + 2
SP
SP – 1
SP – 2
SP – 3
Figure 8-18. Stop Mode Recovery from Interrupt or Break
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System Integration Module (SIM)
8.8 SIM Registers
The SIM has three memory mapped registers.
•
SIM break status register (SBSR)
•
SIM reset status register (SRSR)
•
SIM break flag control register (SBFCR)
8.8.1 SIM Break Status Register (SBSR)
The SIM break status register contains a flag to indicate that a break
caused an exit from stop or wait mode.
Address:
Read:
Write:
$FE00
Bit 7
6
5
4
3
2
R
R
R
R
R
R
Reset:
1
SBSW
Note 1
Bit 0
R
0
Note 1. Writing a logic 0 clears SBSW.
R
= Reserved
Figure 8-19. SIM Break Status Register (SBSR)
SBSW — SIM Break Stop/Wait
This status bit is useful in applications requiring a return to wait or stop
mode after exiting from a break interrupt. Clear SBSW by writing a
logic 0 to it. Reset clears SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break state SWI routine. The user can
modify the return address on the stack by subtracting one from it.
The following code is an example of this. Writing 0 to the SBSW bit
clears it.
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Freescale Semiconductor
System Integration Module (SIM)
; This code works if the H register has been pushed onto the stack in the break
; service routine software. This code should be executed at the end of the break
; service routine software.
HIBYTE
EQU
5
LOBYTE
EQU
6
;
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
; See if wait mode or stop mode was exited by
; break.
TST
LOBYTE,SP
;If RETURNLO is not zero,
BNE
DOLO
;then just decrement low byte.
DEC
HIBYTE,SP
;Else deal with high byte, too.
DOLO
DEC
LOBYTE,SP
;Point to WAIT/STOP opcode.
RETURN
PULH
RTI
;Restore H register.
8.8.2 SIM Reset Status Register (SRSR)
This register contains seven flags that show the source of the last reset.
All flag bits are cleared automatically following a read of the register. The
register is initialized on power-up as shown with the POR bit set and all
other bits cleared. However, during a POR or any other internal reset,
the RST pin is pulled low. After the pin is released, it will be sampled 32
OSCDCLK cycles later. If the pin is not above a VIH at that time, then the
PIN bit in the SRSR may be set in addition to whatever other bits are set.
Address:
Read:
$FE01
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
ILAD
USB
LVI
0
1
0
0
0
0
0
0
0
Write:
POR:
= Unimplemented
Figure 8-20. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
System Integration Module (SIM)
119
System Integration Module (SIM)
PIN — External Reset Bit
1 = Last reset caused by external reset pin (RST)
0 = POR or read of SRSR
COP — Computer Operating Properly Reset Bit
1 = Last reset caused by COP counter
0 = POR or read of SRSR
ILOP — Illegal Opcode Reset Bit
1 = Last reset caused by an illegal opcode
0 = POR or read of SRSR
ILAD — Illegal Address Reset Bit (opcode fetches only)
1 = Last reset caused by an opcode fetch from an illegal address
0 = POR or read of SRSR
USB — Universal Serial Bus Reset Bit
1 = Last reset caused by the USB module
0 = POR or read of SRSR
LVI — Low Voltage Inhibit Reset Bit
1 = Last reset caused by the LVI circuit
0 = POR or read of SRSR
8.8.3 SIM Break Flag Control Register (SBFCR)
The SIM break flag control register contains a bit that enables software
to clear status bits while the MCU is in a break state.
Address:
Read:
Write:
Reset:
$FE03
Bit 7
6
5
4
3
2
1
Bit 0
BCFE
R
R
R
R
R
R
R
0
R
= Reserved
Figure 8-21. SIM Break Flag Control Register (SBFCR)
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Freescale Semiconductor
System Integration Module (SIM)
BCFE — Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
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Technical Data
System Integration Module (SIM)
121
System Integration Module (SIM)
Technical Data
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MC68HC908JB16 — Rev. 1.1
System Integration Module (SIM)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 9. Monitor ROM (MON)
9.1 Contents
9.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
9.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
9.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124
9.4.1
Entering Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
9.4.2
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9.4.3
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9.4.4
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
9.4.5
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
9.5
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
9.5.1
Extended Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
9.2 Introduction
This section describes the monitor ROM (MON) and the monitor mode
entry methods. The monitor ROM allows complete testing of the MCU
through a single-wire interface with host computer. This mode is also
used for programming and erasing of FLASH memory in the MCU.
Monitor mode entry can be achieved without use of the higher voltage,
VTST, as long as vector addresses $FFFE and $FFFF are blank, thus
reducing the hardware requirements for in-circuit programming.
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Technical Data
Monitor ROM (MON)
123
Monitor ROM (MON)
9.3 Features
Features of the monitor ROM include the following:
•
Normal user-mode pin functionality
•
One pin dedicated to serial communication between monitor ROM
and host computer
•
Standard mark/space non-return-to-zero (NRZ) communication
with host computer
•
Execution of code in RAM or FLASH
•
FLASH memory security feature1
•
FLASH memory programming interface
•
1,472 bytes monitor ROM code size
•
Monitor mode entry without high voltage, VTST, if reset vector is
blank ($FFFE and $FFFF contain $FF)
•
Standard monitor mode entry if high voltage, VTST, is applied to
IRQ
9.4 Functional Description
The monitor ROM receives and executes commands from a host
computer. Figure 9-1 shows a example circuit used to enter monitor
mode and communicate with a host computer via a standard RS-232
interface.
Simple monitor commands can access any memory address. In monitor
mode, the MCU can execute host-computer code in RAM while most
MCU pins retain normal operating mode functions. All communication
between the host computer and the MCU is through the PTA0 pin. A
level-shifting and multiplexing interface is required between PTA0 and
the host computer. PTA0 is used in a wired-OR configuration and
requires a pull-up resistor.
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
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Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
VDD
10k Ω
VTST
RST
0.1 µF
10k Ω
C
(SEE NOTE 2)
HC908JB16
SW2
IRQ
D
VREG
+
4.7 µF
0.1 µF
VDD
VDD
12MHz
VDD
0.1 µF
VSS
(SEE NOTE 3)
10 µF
10 µF
MC145407
+
+
E
20
+
3
18
4
17
2
19
SW3
fXCLK
12MHz
10 µF
20 pF
OSC1
F
E
10MΩ
1
OSC2
F
+
10 µF
VDD
VDD
20 pF
10 kΩ
DB-25
2
3
A
5
6
7
16
(SEE NOTE 1)
SW1
PTA3
B
15
VDD
1
MC74HC125
VDD
14
2
3
6
5
10 kΩ
PTA0
VDD
4
10 kΩ
7
PTA1
VDD
NOTES:
1. Affects high voltage entry to monitor mode only (SW2 at position C):
SW1: Position A — Bus clock = fXCLK ÷ 2
SW1: Position B — Bus clock = fXCLK
2. SW2: Position C — High-voltage entry to monitor mode.
SW2: Position D — Low-voltage entry to monitor mode (with blank reset vector).
See Section 20. for IRQ voltage level requirements.
3. SW3: Position E — OSC1 directly driven by external oscillator.
SW3: Position F — OSC1 driven by crystal oscillator circuit.
10 kΩ
PTE3
PTA2
10 kΩ
Figure 9-1. Monitor Mode Circuit
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Monitor ROM (MON)
125
Monitor ROM (MON)
9.4.1 Entering Monitor Mode
Table 9-1 shows the pin conditions for entering monitor mode. As
specified in the table, monitor mode may be entered after a POR and will
allow communication at 19200 baud provided one of the following sets
of conditions is met:
1. If IRQ = VTST:
– External clock on OSC1 is 12MHz
– PTA3 = high
– PTE3 = high
2. If $FFFE & $FFFF is blank (contains $FF):
– External clock on OSC1 is 12MHz
– IRQ = VDD
– PTE3 = high
VTST(2)
X
VTST(2)
X
VDD
BLANK
(contain
$FF)
VDD
NOT
BLANK
1
1
1
1
PTA0
PTA1
PTA2
PTA3(1)
PTE3
$FFFE
and
$FFFF
IRQ
Table 9-1. Mode Entry Requirements and Options
0
0
1
1
Factory use only
1
X
X
0
X
X
1
X
X
1
1
X
External Clock,
fXCLK
Bus
Frequency,
fBUS
Comments
12 MHz
12 MHz
(fXCLK)
High-voltage entry to
monitor mode.
38400 baud communication
on PTA0. COP disabled.
12 MHz
6 MHz
(fXCLK ÷ 2)
High-voltage entry to
monitor mode.
19200 baud communication
on PTA0. COP disabled.
12 MHz
6 MHz
(fXCLK ÷ 2)
Low-voltage entry to
monitor mode.
19200 baud communication
on PTA0. COP disabled.
12 MHz
6 MHz
(fXCLK ÷ 2)
Enters user mode.
If $FFFE and $FFFF is
blank, MCU will encounter
an illegal address reset.
Notes:
1. PTA3 = 0: Bypasses the divide-by-two prescaler to SIM when using VTST for monitor mode entry.
2. See Section 20. Electrical Specifications for VTST voltage level requirements.
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Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
If VTST is applied to IRQ and PTA3 is low upon monitor mode entry
(Table 9-1 condition set 1), the bus frequency is a equal to the external
clock, fXCLK. If PTA3 is high with VTST applied to IRQ upon monitor mode
entry (Table 9-1 condition set 2), the bus frequency is a divide-by-two of
the external clock. Holding the PTA3 pin low when entering monitor
mode causes a bypass of a divide-by-two stage at the oscillator only if
VTST is applied to IRQ. In this event, the OSCOUT frequency is equal to
the OSCDCLK frequency.
Entering monitor mode with VTST on IRQ, the COP is disabled as long
as VTST is applied to either the IRQ or the RST. (See Section 8. System
Integration Module (SIM) for more information on modes of operation.)
If entering monitor mode without high voltage on IRQ and reset vector
being blank ($FFFE and $FFFF) (Table 9-1 condition set 3, where IRQ
applied voltage is VDD), then all port A pin requirements and conditions,
including the PTA3 frequency divisor selection, are not in effect. This is
to reduce circuit requirements when performing in-circuit programming.
Entering monitor mode with the reset vector being blank, the COP is
always disabled regardless of the state of IRQ or the RST.
POR RESET
IS VECTOR
BLANK?
NO
NORMAL USER
MODE
YES
MONITOR MODE
EXECUTE
MONITOR
CODE
POR
TRIGGERED?
NO
YES
Figure 9-2. Low-Voltage Monitor Mode Entry Flowchart
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Monitor ROM (MON)
127
Monitor ROM (MON)
Figure 9-2. shows a simplified diagram of the monitor mode entry when
the reset vector is blank and IRQ = VDD. An external clock of 12MHz is
required for a baud rate of 19200.
Enter monitor mode with the pin configuration shown in Figure 9-1 by
pulling RST low and then high. The rising edge of RST latches monitor
mode. Once monitor mode is latched, the values on the specified pins
can change.
Once out of reset, the MCU waits for the host to send eight security
bytes. (See 9.5 Security.) After the security bytes, the MCU sends a
break signal (10 consecutive logic zeros) to the host, indicating that it is
ready to receive a command. The break signal also provides a timing
reference to allow the host to determine the necessary baud rate.
In monitor mode, the MCU uses different vectors for reset, SWI
(software interrupt), and break interrupt than those for user mode. The
alternate vectors are in the $FE page instead of the $FF page and allow
code execution from the internal monitor firmware instead of user code.
Table 9-2 is a summary of the vector differences between user mode
and monitor mode.
Table 9-2. Monitor Mode Vector Differences
Functions
Modes
COP
Reset
Vector
High
Reset
Vector
Low
Break
Vector
High
Break
Vector
Low
SWI
Vector
High
SWI
Vector
Low
User
Enabled
$FFFE
$FFFF
$FFFC
$FFFD
$FFFC
$FFFD
Monitor
Disabled(1)
$FEFE
$FEFF
$FEFC
$FEFD
$FEFC
$FEFD
Notes:
1. If the high voltage (VTST) is removed from the IRQ pin or the RST pin, the SIM asserts its
COP enable output. The COP is a mask option enabled or disabled by the COPD bit in the
configuration register.
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Freescale Semiconductor
Monitor ROM (MON)
9.4.2 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. Transmit and receive baud rates must
be identical.
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
STOP
BIT
NEXT
START
BIT
Figure 9-3. Monitor Data Format
9.4.3 Break Signal
A start bit (logic 0) followed by nine logic 0 bits is a break signal. When
the monitor receives a break signal, it drives the PTA0 pin high for the
duration of two bits and then echoes back the break signal.
MISSING STOP BIT
0
1
2
3
4
5
TWO-STOP-BIT DELAY BEFORE ZERO ECHO
6
0
7
1
2
3
4
5
6
7
Figure 9-4. Break Transaction
9.4.4 Baud Rate
The communication baud rate is dependant on oscillator frequency,
fXCLK. The state of PTA3 also affects baud rate if entry to monitor mode
is by IRQ = VTST. When PTA3 is high, the divide by ratio is 625. If the
PTA3 pin is at logic zero upon entry into monitor mode, the divide by ratio
is 312.
Table 9-3. Monitor Baud Rate Selection
Monitor Mode
Entry By:
IRQ = VTST
Blank reset vector,
IRQ = VDD
Oscillator Clock
Frequency,
fCLK
PTA3
Baud Rate
12 MHz
0
38400 bps
12 MHz
1
19200 bps
12 MHz
X
19200 bps
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Technical Data
Monitor ROM (MON)
129
Monitor ROM (MON)
9.4.5 Commands
The monitor ROM uses the following commands:
•
READ (read memory)
•
WRITE (write memory)
•
IREAD (indexed read)
•
IWRITE (indexed write)
•
READSP (read stack pointer)
•
RUN (run user program)
The monitor ROM firmware echoes each received byte back to the PTA0
pin for error checking. An 11-bit delay at the end of each command
allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ,
IREAD, or READSP data is returned. The data returned by a read
command appears after the echo of the last byte of the command.
NOTE:
Wait one bit time after each echo before sending the next byte.
FROM
HOST
4
ADDRESS
HIGH
READ
READ
1
4
ADDRESS
HIGH
1
ADDRESS
LOW
4
ADDRESS
LOW
DATA
1
3, 2
ECHO
4
RETURN
Notes:
1 = Echo delay, 2 bit times
2 = Data return delay, 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Figure 9-5. Read Transaction
Technical Data
130
MC68HC908JB16 — Rev. 1.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
FROM
HOST
3
ADDRESS
HIGH
WRITE
WRITE
1
3
ADDRESS
HIGH
1
ADDRESS
LOW
3
ADDRESS
LOW
1
DATA
DATA
3
1
2, 3
ECHO
Notes:
1 = Echo delay, 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
Figure 9-6. Write Transaction
A brief description of each monitor mode command is given in
Table 9-4 through Table 9-9.
Table 9-4. READ (Read Memory) Command
Description
Read byte from memory
Operand
Specifies 2-byte address in high byte:low byte order
Data
Returned
Returns contents of specified address
Opcode
$4A
Command Sequence
SENT TO
MONITOR
READ
READ
ADDRESS
HIGH
ADDRESS
HIGH
ECHO
ADDRESS
LOW
DATA
RETURN
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
ADDRESS
LOW
Technical Data
Monitor ROM (MON)
131
Monitor ROM (MON)
Table 9-5. WRITE (Write Memory) Command
Description
Write byte to memory
Operand
Specifics 2-byte address in high byte:low byte order; low byte
followed by data byte
Data
Returned
None
Opcode
$49
Command Sequence
SEMT TO
MONITOR
WRITE
WRITE
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
ECHO
Table 9-6. IREAD (Indexed Read) Command
Description
Read next 2 bytes in memory from last address accessed
Operand
Specifies 2-byte address in high byte:low byte order
Data
Returned
Returns contents of next two addresses
Opcode
$1A
Command Sequence
SENT TO
MONITOR
IREAD
IREAD
ECHO
Technical Data
132
DATA
DATA
RETURN
MC68HC908JB16 — Rev. 1.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
Table 9-7. IWRITE (Indexed Write) Command
Description
Write to last address accessed + 1
Operand
Specifies single data byte
Data
Returned
None
Opcode
$19
Command Sequence
SENT TO
MONITOR
IWRITE
IWRITE
DATA
DATA
ECHO
NOTE:
A sequence of IREAD or IWRITE commands can sequentially access a
block of memory over the full 64k-byte memory map.
Table 9-8. READSP (Read Stack Pointer) Command
Description
Reads stack pointer
Operand
None
Data
Returned
Returns stack pointer in high byte:low byte order
Opcode
$0C
Command Sequence
SENT TO
MONITOR
READSP
READSP
ECHO
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
SP
HIGH
SP
LOW
RETURN
Technical Data
Monitor ROM (MON)
133
Monitor ROM (MON)
Table 9-9. RUN (Run User Program) Command
Description
Executes RTI instruction
Operand
None
Data
Returned
None
Opcode
$28
Command Sequence
SENT TO
MONITOR
RUN
RUN
ECHO
The MCU executes the SWI and PSHH instructions when it enters
monitor mode. The RUN command tells the MCU to execute the PULH
and RTI instructions. Before sending the RUN command, the host can
modify the stacked CPU registers to prepare to run the host program.
The READSP command returns the incremented stack pointer value,
SP + 1. The high and low bytes of the program counter are at addresses
SP + 5 and SP + 6.
SP
HIGH BYTE OF INDEX REGISTER
SP + 1
CONDITION CODE REGISTER
SP + 2
ACCUMULATOR
SP + 3
LOW BYTE OF INDEX REGISTER
SP + 4
HIGH BYTE OF PROGRAM COUNTER SP + 5
LOW BYTE OF PROGRAM COUNTER SP + 6
SP + 7
Figure 9-7. Stack Pointer at Monitor Mode Entry
Technical Data
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Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
9.5 Security
A security feature discourages unauthorized reading of FLASH locations
while in monitor mode. The host can bypass the security feature at
monitor mode entry by sending eight security bytes that match the bytes
at locations $FFF6–$FFFD. Locations $FFF6–$FFFD contain userdefined data.
NOTE:
Do not leave locations $FFF6–$FFFD blank. For security reasons,
program locations $FFF6–$FFFD.
During monitor mode entry, the MCU waits after the power-on reset for
the host to send the eight security bytes on pin PTA0. If the received
bytes match those at locations $FFF6–$FFFD, the host bypasses the
security feature and can read all FLASH locations and execute code
from FLASH. Security remains bypassed until a power-on or an LVI
reset occurs. If the reset was not a power-on or an LVI reset, security
remains bypassed and security code entry is not required.
(See Figure 9-8.)
VDD
4096 + 32 OSCDCLK CYCLES
RST
COMMAND
BYTE 8
BYTE 2
BYTE 1
256 BUS CYCLES (MINIMUM)
FROM HOST
PTA0
4
BREAK
2
1
COMMAND ECHO
NOTES:
1 = Echo delay, 2 bit times.
2 = Data return delay, 2 bit times.
4 = Wait 1 bit time before sending next byte.
1
BYTE 8 ECHO
BYTE 1 ECHO
FROM MCU
1
BYTE 2 ECHO
4
1
Figure 9-8. Monitor Mode Entry Timing
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Monitor ROM (MON)
135
Monitor ROM (MON)
Upon power-on reset, if the received bytes of the security code do not
match the data at locations $FFF6–$FFFD, the host fails to bypass the
security feature. The MCU remains in monitor mode, but reading a
FLASH location returns an invalid value and trying to execute code from
FLASH causes an illegal address reset. After receiving the eight security
bytes from the host, the MCU transmits a break character, signifying that
it is ready to receive a command.
NOTE:
The MCU does not transmit a break character until after the host sends
the eight security bytes.
To determine whether the security code entered is correct, check to see
if bit 6 of RAM address $80 is set. If it is, then the correct security code
has been entered and FLASH can be accessed.
If the security sequence fails, the device should be reset by a power-on
reset and brought up in monitor mode to attempt another entry. After
failing the security sequence, the FLASH module can also be mass
erased by executing an erase routine that was downloaded into internal
RAM. The mass erase operation clears the security code locations so
that all eight security bytes become $FF (blank).
9.5.1 Extended Security
To further disable monitor mode functions, the monitor commands can
be disabled by writing $7B to the FLASH location $FFD1 and $87 to the
FLASH location $FFD0. Table 9-10 shows the security settings that
affect monitor mode operations.
Table 9-10. Monitor Mode Security
Extended Security
Monitor Mode Entry Security
BYPASSED
Read/write of RAM and FLASH.
FAILED
Read/write of RAM.
Read of FLASH disabled. FLASH can only
be mass erased.
BYPASSED
Read/write of RAM and FLASH disabled.
FAILED
Read/write of RAM.
Read of FLASH disabled. FLASH can only
be mass erased.
NOT SET
SET
Technical Data
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Monitor Functions Available
MC68HC908JB16 — Rev. 1.1
Monitor ROM (MON)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 10. Timer Interface Module (TIM)
10.1 Contents
10.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
10.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
10.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
10.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
10.5.1 TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10.5.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10.5.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
10.5.3.1
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . 144
10.5.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . .145
10.5.4 Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . 145
10.5.4.1
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . 146
10.5.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . 147
10.5.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
10.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149
10.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
10.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
10.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
10.8
TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 150
10.9 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
10.9.1 TIM Clock Pin (PTE0/TCLK) . . . . . . . . . . . . . . . . . . . . . . .151
10.9.2 TIM Channel I/O Pins (PTE1/T1CH01:PTE2/T2CH01) . . . 151
10.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
10.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . . 152
10.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
10.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . 155
10.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . . 156
10.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
MC68HC908JB16 — Rev. 1.1
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Technical Data
Timer Interface Module (TIM)
137
Timer Interface Module (TIM)
10.2 Introduction
This section describes the timer interface (TIM) module. The TIM is a
two-channel timer that provides a timing reference with input capture,
output compare, and pulse-width-modulation functions. Figure 10-1 is a
block diagram of the TIM.
This particular MCU has two timer interface modules which are denoted
as TIM1 and TIM2.
NOTE:
TIM1 and TIM2 each have channel 0 and channel 1 I/Os connected
together, forming a common I/O. Because of this common I/O, both
channels should not be simultaneously configured for output compare
functions, otherwise, port pin contention will occur.
10.3 Features
Features of the TIM include:
•
Two input capture/output compare channels on one common I/O:
– Rising-edge, falling-edge, or any-edge input capture trigger
– Set, clear, or toggle output compare action
•
Buffered and unbuffered pulse-width-modulation (PWM) signal
generation
•
Programmable TIM clock input
– 7-frequency internal bus clock prescaler selection
– External TIM clock input (bus frequency ÷2 maximum)
•
Free-running or modulo up-count operation
•
Toggle any channel pin on overflow
•
TIM counter stop and reset bits
Technical Data
138
MC68HC908JB16 — Rev. 1.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
10.4 Pin Name Conventions
The text that follows describes both timers, TIM1 and TIM2. The TIM
input/output (I/O) pin names are T[1,2]CH01 (timer channel 01), where
“1” is used to indicate TIM1 and “2” is used to indicate TIM2. The two
TIMs share two I/O pins with two I/O port pins. The full names of the TIM
I/O pins are listed in Table 10-1. The generic pin names appear in the
text that follows.
Table 10-1. Pin Name Conventions
TIM Generic Pin Names:
Full TIM
Pin Names:
NOTE:
T[1,2]CH01
TIM1
PTE1/T1CH01
TIM2
PTE2/T2CH01
TCLK
PTE0/TCLK
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TCH01 may refer generically
to T1CH01 and T2CH01.
10.5 Functional Description
Figure 10-1 shows the structure of the TIM. The central component of
the TIM is the 16-bit TIM counter that can operate as a free-running
counter or a modulo up-counter. The TIM counter provides the timing
reference for the input capture and output compare functions. The TIM
counter modulo registers, TMODH:TMODL, control the modulo value of
the TIM counter. Software can read the TIM counter value at any time
without affecting the counting sequence.
Channel 0 and channel 1 I/Os are connected together, forming a
common I/O. Although the two TIM channels are programmable
independently as input capture channels, the input capture signal will be
the same for both channels. Output compare functions should only be
enabled for one channel to avoid I/O contention.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Timer Interface Module (TIM)
139
Timer Interface Module (TIM)
TCLK
PRESCALER SELECT
INTERNAL
BUS CLOCK
PRESCALER
TSTOP
PS2
TRST
PS1
PS0
16-BIT COUNTER
TOF
TOIE
16-BIT COMPARATOR
INTERRUPT
LOGIC
TMODH:TMODL
TOV0
CHANNEL 0
ELS0B
ELS0A
CH0MAX
16-BIT COMPARATOR
PORT
LOGIC
CH0F
TCH0H:TCH0L
16-BIT LATCH
MS0A
CH0IE
INTERRUPT
LOGIC
T[1,2]CH01
MS0B
INTERNAL BUS
TOV1
CHANNEL 1
ELS0B
ELS0A
CH1MAX
PORT
LOGIC
CH01IE
INTERRUPT
LOGIC
16-BIT COMPARATOR
CH1F
TCH1H:TCH1L
16-BIT LATCH
MS0A
CH1IE
Figure 10-1. TIM Block Diagram
Figure 10-2 summarizes the timer registers.
NOTE:
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC and T2SC.
Technical Data
140
MC68HC908JB16 — Rev. 1.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Addr.
Register Name
Bit 7
Read:
Timer 1 Status and Control
$000A
Register Write:
(T1SC)
Reset:
TOF
$000C
$000D
$000E
$000F
6
5
TOIE
TSTOP
0
0
1
0
Read:
Timer 1 Counter
Register High Write:
(T1CNTH)
Reset:
Bit 15
14
13
0
0
Read:
Timer 1 Counter
Register Low Write:
(T1CNTL)
Reset:
Bit 7
Read:
Timer 1 Counter Modulo
Register High Write:
(T1MODH)
Reset:
Read:
Timer 1 Counter Modulo
Register Low Write:
(T1MODL)
Reset:
Read:
Timer 1 Channel 0 Status
$0010
and Control Register Write:
(T1SC0)
Reset:
$0011
$0012
Read:
Timer 1 Channel 0
Register High Write:
(T1CH0H)
Reset:
Read:
Timer 1 Channel 0
Register Low Write:
(T1CH0L)
Reset:
Read:
Timer 1 Channel 1 Status
$0013
and Control Register Write:
(T1SC1)
Reset:
2
1
Bit 0
PS2
PS1
PS0
0
0
0
0
12
11
10
9
Bit 8
0
0
0
0
0
0
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
1
1
1
1
1
1
1
1
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
2
1
Bit 0
0
CH0F
0
4
3
0
0
TRST
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
CH1F
0
0
CH1IE
CH01IE
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
= Unimplemented
Figure 10-2. TIM I/O Register Summary (Sheet 1 of 3)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Timer Interface Module (TIM)
141
Timer Interface Module (TIM)
Addr.
$0014
$0015
Register Name
Read:
Timer 1 Channel 1
Register High Write:
(T1CH1H)
Reset:
Read:
Timer 1 Channel 1
Register Low Write:
(T1CH1L)
Reset:
Read:
$0040
$0043
$0044
$0045
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
2
1
Bit 0
PS2
PS1
PS0
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
TOF
0
0
TSTOP
0
0
1
0
0
0
0
0
Read:
Timer 2 Counter
Register High Write:
(T2CNTH)
Reset:
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Read:
Timer 2 Counter
Register Low Write:
(T2CNTL)
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
1
1
1
1
1
1
1
1
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Read:
Timer 2 Counter Modulo
Register High Write:
(T2MODH)
Reset:
Read:
Timer 2 Counter Modulo
Register Low Write:
(T2MODL)
Reset:
Read:
Timer 2 Channel 0 Status
$0046
and Control Register Write:
(T2SC0)
Reset:
$0047
6
TOIE
Timer 2 Status and Control
Write:
Register (T2SC)
Reset:
$0042
Bit 7
Read:
Timer 2 Channel 0
Register High Write:
(T2CH0H)
Reset:
0
CH0F
0
TRST
Indeterminate after reset
= Unimplemented
Figure 10-2. TIM I/O Register Summary (Sheet 2 of 3)
Technical Data
142
MC68HC908JB16 — Rev. 1.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Addr.
$0048
Register Name
Read:
Timer 2 Channel 0
Register Low Write:
(T2CH0L)
Reset:
Read:
Timer 2 Channel 1 Status
$0049
and Control Register Write:
(T2SC1)
Reset:
$004A
$004B
Read:
Timer 2 Channel 1
Register High Write:
(T2CH1H)
Reset:
Read:
Timer 2 Channel 1
Register Low Write:
(T2CH1L)
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
Indeterminate after reset
CH1F
CH1IE
CH01IE
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
2
1
Bit 0
0
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
= Unimplemented
Figure 10-2. TIM I/O Register Summary (Sheet 3 of 3)
10.5.1 TIM Counter Prescaler
The TIM clock source can be one of the seven prescaler outputs or the
TIM clock pin, PTE0/TCLK. The prescaler generates seven clock rates
from the internal bus clock. The prescaler select bits, PS[2:0], in the TIM
status and control register (TSC) select the TIM clock source.
10.5.2 Input Capture
With the input capture function, the TIM can capture the time at which an
external event occurs. When an active edge occurs on the pin of an input
capture channel, the TIM latches the contents of the TIM counter into the
TIM channel registers, TCHxH:TCHxL. The polarity of the active edge is
programmable. Input captures can generate TIM CPU interrupt
requests.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Timer Interface Module (TIM)
143
Timer Interface Module (TIM)
10.5.3 Output Compare
With the output compare function, the TIM can generate a periodic pulse
with a programmable polarity, duration, and frequency. When the
counter reaches the value in the registers of an output compare channel,
the TIM can set, clear, or toggle the channel pin. Output compares can
generate TIM CPU interrupt requests.
10.5.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare
pulses as described in 10.5.3 Output Compare. The pulses are
unbuffered because changing the output compare value requires writing
the new value over the old value currently in the TIM channel registers.
An unsynchronized write to the TIM channel registers to change an
output compare value could cause incorrect operation for up to two
counter overflow periods. For example, writing a new value before the
counter reaches the old value but after the counter reaches the new
value prevents any compare during that counter overflow period. Also,
using a TIM overflow interrupt routine to write a new, smaller output
compare value may cause the compare to be missed. The TIM may pass
the new value before it is written.
Use the following methods to synchronize unbuffered changes in the
output compare value on channel x:
•
When changing to a smaller value, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current output compare pulse. The interrupt routine has until
the end of the counter overflow period to write the new value.
•
When changing to a larger output compare value, enable TIM
overflow interrupts and write the new value in the TIM overflow
interrupt routine. The TIM overflow interrupt occurs at the end of
the current counter overflow period. Writing a larger value in an
output compare interrupt routine (at the end of the current pulse)
could cause two output compares to occur in the same counter
overflow period.
Technical Data
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MC68HC908JB16 — Rev. 1.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
10.5.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare
channel whose output appears on the TCH0 pin. The TIM channel
registers of the linked pair alternately control the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The output compare value in the TIM
channel 0 registers initially controls the output on the TCH0 pin. Writing
to the TIM channel 1 registers enables the TIM channel 1 registers to
synchronously control the output after the TIM overflows. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
output are the ones written to last. TSC0 controls and monitors the
buffered output compare function, and TIM channel 1 status and control
register (TSC1) is unused. While the MS0B bit is set, the channel 1 pin,
TCH1, is available as a general-purpose I/O pin.
NOTE:
In buffered output compare operation, do not write new output compare
values to the currently active channel registers. User software should
track the currently active channel to prevent writing a new value to the
active channel. Writing to the active channel registers is the same as
generating unbuffered output compares.
10.5.4 Pulse Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel,
the TIM can generate a PWM signal. The value in the TIM counter
modulo registers determines the period of the PWM signal. The channel
pin toggles when the counter reaches the value in the TIM counter
modulo registers. The time between overflows is the period of the PWM
signal.
As Figure 10-3 shows, the output compare value in the TIM channel
registers determines the pulse width of the PWM signal. The time
between overflow and output compare is the pulse width. Program the
TIM to clear the channel pin on output compare if the state of the PWM
pulse is logic 1. Program the TIM to set the pin if the state of the PWM
pulse is logic 0.
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Timer Interface Module (TIM)
The value in the TIM counter modulo registers and the selected
prescaler output determines the frequency of the PWM output. The
frequency of an 8-bit PWM signal is variable in 256 increments. Writing
$00FF (255) to the TIM counter modulo registers produces a PWM
period of 256 times the internal bus clock period if the prescaler select
value is $000. See 10.10.1 TIM Status and Control Register.
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PULSE
WIDTH
TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 10-3. PWM Period and Pulse Width
The value in the TIM channel registers determines the pulse width of the
PWM output. The pulse width of an 8-bit PWM signal is variable in 256
increments. Writing $0080 (128) to the TIM channel registers produces
a duty cycle of 128/256 or 50%.
10.5.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as
described in 10.5.4 Pulse Width Modulation (PWM). The pulses are
unbuffered because changing the pulse width requires writing the new
pulse width value over the old value currently in the TIM channel
registers.
An unsynchronized write to the TIM channel registers to change a pulse
width value could cause incorrect operation for up to two PWM periods.
For example, writing a new value before the counter reaches the old
value but after the counter reaches the new value prevents any compare
during that PWM period. Also, using a TIM overflow interrupt routine to
write a new, smaller pulse width value may cause the compare to be
missed. The TIM may pass the new value before it is written.
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Timer Interface Module (TIM)
Use the following methods to synchronize unbuffered changes in the
PWM pulse width on channel x:
NOTE:
•
When changing to a shorter pulse width, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current pulse. The interrupt routine has until the end of the
PWM period to write the new value.
•
When changing to a longer pulse width, enable TIM overflow
interrupts and write the new value in the TIM overflow interrupt
routine. The TIM overflow interrupt occurs at the end of the current
PWM period. Writing a larger value in an output compare interrupt
routine (at the end of the current pulse) could cause two output
compares to occur in the same PWM period.
In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to selfcorrect in the event of software error or noise. Toggling on output
compare also can cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
10.5.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose
output appears on the TCH0 pin. The TIM channel registers of the linked
pair alternately control the pulse width of the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The TIM channel 0 registers initially
control the pulse width on the TCH0 pin. Writing to the TIM channel 1
registers enables the TIM channel 1 registers to synchronously control
the pulse width at the beginning of the next PWM period. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
pulse width are the ones written to last. TSC0 controls and monitors the
buffered PWM function, and TIM channel 1 status and control register
(TSC1) is unused. While the MS0B bit is set, the channel 1 pin, TCH1,
is available as a general-purpose I/O pin.
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Timer Interface Module (TIM)
NOTE:
In buffered PWM signal generation, do not write new pulse width values
to the currently active channel registers. User software should track the
currently active channel to prevent writing a new value to the active
channel. Writing to the active channel registers is the same as
generating unbuffered PWM signals.
10.5.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered
PWM signals, use the following initialization procedure:
1. In the TIM status and control register (TSC):
a. Stop the TIM counter by setting the TIM stop bit, TSTOP.
b. Reset the TIM counter and prescaler by setting the TIM reset
bit, TRST.
2. In the TIM counter modulo registers (TMODH:TMODL), write the
value for the required PWM period.
3. In the TIM channel x registers (TCHxH:TCHxL), write the value for
the required pulse width.
4. In TIM channel x status and control register (TSCx):
a. Write 0:1 (for unbuffered output compare or PWM signals) or
1:0 (for buffered output compare or PWM signals) to the
mode select bits, MSxB:MSxA. (See Table 10-3.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (to clear output on compare) or 1:1 (to set output on
compare) to the edge/level select bits, ELSxB:ELSxA. The
output action on compare must force the output to the
complement of the pulse width level. (See Table 10-3.)
NOTE:
In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to selfcorrect in the event of software error or noise. Toggling on output
compare can also cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
5. In the TIM status control register (TSC), clear the TIM stop bit,
TSTOP.
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Timer Interface Module (TIM)
Setting MS0B links channels 0 and 1 and configures them for buffered
PWM operation. The TIM channel 0 registers (TCH0H:TCH0L) initially
control the buffered PWM output. TIM status control register 0 (TSCR0)
controls and monitors the PWM signal from the linked channels.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM
overflows. Subsequent output compares try to force the output to a state
it is already in and have no effect. The result is a 0% duty cycle output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the
TOVx bit generates a 100% duty cycle output. (See 10.10.4 TIM
Channel Status and Control Registers.)
10.6 Interrupts
The following TIM sources can generate interrupt requests:
•
TIM overflow flag (TOF) — The TOF bit is set when the TIM
counter reaches the modulo value programmed in the TIM counter
modulo registers. The TIM overflow interrupt enable bit, TOIE,
enables TIM overflow CPU interrupt requests. TOF and TOIE are
in the TIM status and control register.
•
TIM channel flags (CH1F:CH0F) — The CHxF bit is set when an
input capture or output compare occurs on channel x. Channel x
TIM CPU interrupt requests are controlled by the channel x
interrupt enable bit, CHxIE. Channel x TIM CPU interrupt requests
are enabled when CHxIE = 1. CHxF and CHxIE are in the TIM
channel x status and control register.
10.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low powerconsumption standby modes.
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Timer Interface Module (TIM)
10.7.1 Wait Mode
The TIM remains active after the execution of a WAIT instruction. In wait
mode, the TIM registers are not accessible by the CPU. Any enabled
CPU interrupt request from the TIM can bring the MCU out of wait mode.
If TIM functions are not required during wait mode, reduce power
consumption by stopping the TIM before executing the WAIT instruction.
10.7.2 Stop Mode
The TIM is inactive after the execution of a STOP instruction. The STOP
instruction does not affect register conditions or the state of the TIM
counter. TIM operation resumes when the MCU exits stop mode after an
external interrupt.
10.8 TIM During Break Interrupts
A break interrupt stops the TIM counter.
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See 8.8.3 SIM Break Flag Control
Register (SBFCR).)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
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Timer Interface Module (TIM)
10.9 I/O Signals
Port E shares three of its pins with the TIM. PTE0/TCLK is an external
clock input to the TIM prescaler. The two TIM channel I/O pins are
PTE1/T1CH01 and PTE2/T2CH01.
10.9.1 TIM Clock Pin (PTE0/TCLK)
PTE0/TCLK is an external clock input that can be the clock source for
the TIM counter instead of the prescaled internal bus clock. Select the
PTE0/TCLK input by writing logic 1s to the three prescaler select bits,
PS[2:0]. (See 10.10.1 TIM Status and Control Register.) The minimum
TCLK pulse width, TCLKLMIN or TCLKHMIN, is:
1
------------------------------------- + t SU
bus frequency
The maximum TCLK frequency is:
bus frequency ÷ 2
PTE0/TCLK is available as a general-purpose I/O pin when not used as
the TIM clock input. When the PTE0/TCLK pin is the TIM clock input, it
is an input regardless of the state of the DDRE0 bit in data direction
register E.
10.9.2 TIM Channel I/O Pins (PTE1/T1CH01:PTE2/T2CH01)
Each TIM I/O pin is programmable independently as an input capture pin
or an output compare pin, or configured as buffered output compare or
buffered PWM pins.
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Timer Interface Module (TIM)
10.10 I/O Registers
NOTE:
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC and T2SC.
These I/O registers control and monitor operation of the TIM:
•
TIM status and control register (TSC)
•
TIM counter registers (TCNTH:TCNTL)
•
TIM counter modulo registers (TMODH:TMODL)
•
TIM channel status and control registers (TSC0, TSC1)
•
TIM channel registers (TCH0H:TCH0L, TCH1H:TCH1L)
10.10.1 TIM Status and Control Register
The TIM status and control register (TSC):
•
Enables TIM overflow interrupts
•
Flags TIM overflows
•
Stops the TIM counter
•
Resets the TIM counter
•
Prescales the TIM counter clock
Address: T1SC, $000A and T2SC, $0040
Bit 7
Read:
TOF
Write:
0
Reset:
0
6
5
TOIE
TSTOP
0
1
4
3
0
0
TRST
0
0
2
1
Bit 0
PS2
PS1
PS0
0
0
0
= Unimplemented
Figure 10-4. TIM Status and Control Register (TSC)
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Timer Interface Module (TIM)
TOF — TIM Overflow Flag Bit
This read/write flag is set when the TIM counter reaches the modulo
value programmed in the TIM counter modulo registers. Clear TOF by
reading the TIM status and control register when TOF is set and then
writing a logic 0 to TOF. If another TIM overflow occurs before the
clearing sequence is complete, then writing logic 0 to TOF has no
effect. Therefore, a TOF interrupt request cannot be lost due to
inadvertent clearing of TOF. Reset clears the TOF bit. Writing a
logic 1 to TOF has no effect.
1 = TIM counter has reached modulo value
0 = TIM counter has not reached modulo value
TOIE — TIM Overflow Interrupt Enable Bit
This read/write bit enables TIM overflow interrupts when the TOF bit
becomes set. Reset clears the TOIE bit.
1 = TIM overflow interrupts enabled
0 = TIM overflow interrupts disabled
TSTOP — TIM Stop Bit
This read/write bit stops the TIM counter. Counting resumes when
TSTOP is cleared. Reset sets the TSTOP bit, stopping the TIM
counter until software clears the TSTOP bit.
1 = TIM counter stopped
0 = TIM counter active
NOTE:
Do not set the TSTOP bit before entering wait mode if the TIM is required
to exit wait mode.
TRST — TIM Reset Bit
Setting this write-only bit resets the TIM counter and the TIM
prescaler. Setting TRST has no effect on any other registers.
Counting resumes from $0000. TRST is cleared automatically after
the TIM counter is reset and always reads as logic 0. Reset clears the
TRST bit.
1 = Prescaler and TIM counter cleared
0 = No effect
NOTE:
Setting the TSTOP and TRST bits simultaneously stops the TIM counter
at a value of $0000.
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Timer Interface Module (TIM)
PS[2:0] — Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the
input to the TIM counter as Table 10-2 shows. Reset clears the
PS[2:0] bits.
Table 10-2. Prescaler Selection
PS2
PS1
PS0
TIM Clock Source
0
0
0
Internal bus clock ÷ 1
0
0
1
Internal bus clock ÷ 2
0
1
0
Internal bus clock ÷ 4
0
1
1
Internal bus clock ÷ 8
1
0
0
Internal bus clock ÷ 16
1
0
1
Internal bus clock ÷ 32
1
1
0
Internal bus clock ÷ 64
1
1
1
TCLK
10.10.2 TIM Counter Registers
The two read-only TIM counter registers contain the high and low bytes
of the value in the TIM counter. Reading the high byte (TCNTH) latches
the contents of the low byte (TCNTL) into a buffer. Subsequent reads of
TCNTH do not affect the latched TCNTL value until TCNTL is read.
Reset clears the TIM counter registers. Setting the TIM reset bit (TRST)
also clears the TIM counter registers.
NOTE:
If you read TCNTH during a break interrupt, be sure to unlatch TCNTL
by reading TCNTL before exiting the break interrupt. Otherwise, TCNTL
retains the value latched during the break.
Address: T1CNTH, $000C and T2CNTH, $0042
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 10-5. TIM Counter Registers High (TCNTH)
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Timer Interface Module (TIM)
Address: T1CNTL, $000D and T2CNTL, $0043
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 10-6. TIM Counter Registers Low (TCNTL)
10.10.3 TIM Counter Modulo Registers
The read/write TIM modulo registers contain the modulo value for the
TIM counter. When the TIM counter reaches the modulo value, the
overflow flag (TOF) becomes set, and the TIM counter resumes counting
from $0000 at the next timer clock. Writing to the high byte (TMODH)
inhibits the TOF bit and overflow interrupts until the low byte (TMODL) is
written. Reset sets the TIM counter modulo registers.
Address: T1MODH, $000E and T2MODH, $0044
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
1
1
1
1
1
1
1
1
Figure 10-7. TIM Counter Modulo Register High (TMODH)
Address: T1MODL, $000F and T2MODL, $0045
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
Figure 10-8. TIM Counter Modulo Register Low (TMODL)
NOTE:
Reset the TIM counter before writing to the TIM counter modulo registers.
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Timer Interface Module (TIM)
10.10.4 TIM Channel Status and Control Registers
Each of the TIM channel status and control registers:
•
Flags input captures and output compares
•
Enables input capture and output compare interrupts
•
Selects input capture, output compare, or PWM operation
•
Selects high, low, or toggling output on output compare
•
Selects rising edge, falling edge, or any edge as the active input
capture trigger
•
Selects output toggling on TIM overflow
•
Selects 0% and 100% PWM duty cycle
•
Selects buffered or unbuffered output compare/PWM operation
Address: T1SC0, $0010 and T2SC0, $0046
Bit 7
Read:
CH0F
Write:
0
Reset:
0
6
5
4
3
2
1
Bit 0
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
Figure 10-9. TIM Channel 0 Status and Control Register (TSC0)
Address: T1SC1, $0013 and T2SC1, $0049
Bit 7
Read:
CH1F
Write:
0
Reset:
0
6
5
4
3
2
1
Bit 0
CH1IE
CH01IE
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
Figure 10-10. TIM Channel 1 Status and Control Register (TSC1)
CHxF — Channel x Flag Bit
When channel x is an input capture channel, this read/write bit is set
when an active edge occurs on the channel x pin. When channel x is
an output compare channel, CHxF is set when the value in the TIM
counter registers matches the value in the TIM channel x registers.
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Timer Interface Module (TIM)
When TIM CPU interrupt requests are enabled (CHxIE = 1), clear
CHxF by reading TIM channel x status and control register with CHxF
set and then writing a logic 0 to CHxF. If another interrupt request
occurs before the clearing sequence is complete, then writing logic 0
to CHxF has no effect. Therefore, an interrupt request cannot be lost
due to inadvertent clearing of CHxF.
Reset clears the CHxF bit. Writing a logic 1 to CHxF has no effect.
1 = Input capture or output compare on channel x
0 = No input capture or output compare on channel x
CHxIE — Channel x Interrupt Enable Bit
This read/write bit enables TIM CPU interrupt service requests on
channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
CH01IE — CH0F and CH1F Interrupt Enable Bit
This read/write bit enables TIM CPU interrupt service requests when
CH0F and CH1F are set.
Reset clears the CH01IE bit.
1 = CPU interrupt requests when CH0F and CH1F are set
0 = No CPU interrupt requests when CH0F and CH1F are set
MS0B — Mode Select Bit B
This read/write bit selects buffered output compare/PWM operation.
MS0B exists only in the TIM1 channel 0 and TIM2 channel 0 status
and control registers.
Setting MS0B disables the channel 1 status and control register.
Reset clears the MS0B bit.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MSxA — Mode Select Bit A
When ELSxB:ELSxA ≠ 0:0, this read/write bit selects either input
capture operation or unbuffered output compare/PWM operation.
See Table 10-3.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
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Timer Interface Module (TIM)
When ELSxB:ELSxA = 0:0, this read/write bit selects the initial output
level of the TCHx pin. See Table 10-3. Reset clears the MSxA bit.
1 = Initial output level low
0 = Initial output level high
NOTE:
Before changing a channel function by writing to the MSxB or MSxA bit,
set the TSTOP and TRST bits in the TIM status and control register.
ELSxB and ELSxA — Edge/Level Select Bits
When channel x is an input capture channel, these read/write bits
control the active edge-sensing logic on channel x.
When channel x is an output compare channel, ELSxB and ELSxA
control the channel x output behavior when an output compare
occurs.
When ELSxB and ELSxA are both clear, channel x is not connected
to an I/O port, and pin TCHx is available as a general-purpose I/O pin.
Table 10-3 shows how ELSxB and ELSxA work. Reset clears the
ELSxB and ELSxA bits.
Table 10-3. Mode, Edge, and Level Selection
MS0B:MSxA
ELSxB:ELSxA
X0
00
Mode
Output preset
Configuration
Pin under port control;
initial output level high
X1
00
Pin under port control;
initial output level low
00
01
Capture on rising edge only
00
10
00
11
01
01
01
10
01
11
1X
01
1X
10
1X
11
Input capture
Capture on falling edge only
Capture on rising or
falling edge
Output
compare or
PWM(1)
Toggle output on compare
Buffered
output
compare or
buffered PWM
Toggle output on compare
Clear output on compare
Set output on compare
Clear output on compare
Set output on compare
Notes:
1. Enable only one channel for unbuffered output compare or PWM functions. Avoid the
following configuration: MS0B = 0, MS0A = 1, MS1A = 1, and ELSxB:A ≠ 00
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Timer Interface Module (TIM)
NOTE:
Before enabling a TIM channel register for input capture operation, make
sure that the TCHx pin is stable for at least two bus clocks.
TOVx — Toggle On Overflow Bit
When channel x is an output compare channel, this read/write bit
controls the behavior of the channel x output when the TIM counter
overflows. When channel x is an input capture channel, TOVx has no
effect.
Reset clears the TOVx bit.
1 = Channel x pin toggles on TIM counter overflow
0 = Channel x pin does not toggle on TIM counter overflow
NOTE:
When TOVx is set, a TIM counter overflow takes precedence over a
channel x output compare if both occur at the same time.
CHxMAX — Channel x Maximum Duty Cycle Bit
When the TOVx bit is at logic 1, setting the CHxMAX bit forces the
duty cycle of buffered and unbuffered PWM signals to 100%. As
Figure 10-11 shows, the CHxMAX bit takes effect in the cycle after it
is set or cleared. The output stays at the 100% duty cycle level until
the cycle after CHxMAX is cleared.
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
CHxMAX
Figure 10-11. CHxMAX Latency
10.10.5 TIM Channel Registers
These read/write registers contain the captured TIM counter value of the
input capture function or the output compare value of the output
compare function. The state of the TIM channel registers after reset is
unknown.
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Timer Interface Module (TIM)
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the
TIM channel x registers (TCHxH) inhibits input captures until the low
byte (TCHxL) is read.
In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of
the TIM channel x registers (TCHxH) inhibits output compares until the
low byte (TCHxL) is written.
Address: T1CH0H, $0011 and T2CH0H, $0047
Read:
Write:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Reset:
Indeterminate after reset
Figure 10-12. TIM Channel 0 Register High (TCH0H)
Address: T1CH0L, $0012 and T2CH0L $0048
Read:
Write:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
Reset:
Indeterminate after reset
Figure 10-13. TIM Channel 0 Register Low (TCH0L)
Address: T1CH1H, $0014 and T2CH1H, $004A
Read:
Write:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Reset:
Indeterminate after reset
Figure 10-14. TIM Channel 1 Register High (TCH1H)
Address: T1CH1L, $0015 and T2CH1L, $004B
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
Indeterminate after reset
Figure 10-15. TIM Channel 1 Register Low (TCH1L)
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Technical Data — MC68HC908JB16
Section 11. Universal Serial Bus Module (USB)
11.1 Contents
11.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
11.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
11.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
11.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168
11.5.1 USB Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
11.5.1.1
Sync Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
11.5.1.2
Packet Identifier Field . . . . . . . . . . . . . . . . . . . . . . . . . . 171
11.5.1.3
Address Field (ADDR) . . . . . . . . . . . . . . . . . . . . . . . . . . 172
11.5.1.4
Endpoint Field (ENDP). . . . . . . . . . . . . . . . . . . . . . . . . . 172
11.5.1.5
Cyclic Redundancy Check (CRC) . . . . . . . . . . . . . . . . . 172
11.5.1.6
End-of-Packet (EOP) . . . . . . . . . . . . . . . . . . . . . . . . . . .172
11.5.2 Reset Signaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
11.5.3 Suspend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
11.5.4 Resume After Suspend . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
11.5.4.1
Host Initiated Resume . . . . . . . . . . . . . . . . . . . . . . . . . . 175
11.5.4.2
USB Reset Signalling. . . . . . . . . . . . . . . . . . . . . . . . . . .175
11.5.4.3
Remote Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175
11.5.5 Low-Speed Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
11.6
Clock Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
11.7 Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.1 Voltage Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.2 USB Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
11.7.2.1
Output Driver Characteristics . . . . . . . . . . . . . . . . . . . . . 178
11.7.2.2
Low Speed (1.5 Mbps) Driver Characteristics . . . . . . . . 178
11.7.2.3
Receiver Data Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11.7.2.4
Data Source Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11.7.2.5
Data Signal Rise and Fall Time . . . . . . . . . . . . . . . . . . . 180
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Universal Serial Bus Module (USB)
11.7.3
USB Control Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
11.8 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
11.8.1 USB Address Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.8.2 USB Interrupt Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.8.3 USB Interrupt Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 185
11.8.4 USB Interrupt Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.8.5 USB Control Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
11.8.6 USB Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.8.7 USB Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
11.8.8 USB Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.8.9 USB Control Register 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.8.10 USB Status Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
11.8.11 USB Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
11.8.12 USB Endpoint 0 Data Registers . . . . . . . . . . . . . . . . . . . . . 198
11.8.13 USB Endpoint 1 Data Registers . . . . . . . . . . . . . . . . . . . . . 199
11.8.14 USB Endpoint 2 Data Registers . . . . . . . . . . . . . . . . . . . . . 200
11.9 USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.9.1 USB End-of-Transaction Interrupt . . . . . . . . . . . . . . . . . . . 201
11.9.1.1
Receive Control Endpoint 0 . . . . . . . . . . . . . . . . . . . . . . 202
11.9.1.2
Transmit Control Endpoint 0 . . . . . . . . . . . . . . . . . . . . . 204
11.9.1.3
Transmit Endpoint 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
11.9.1.4
Transmit Endpoint 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.1.5
Receive Endpoint 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.2 Resume Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.9.3 End-of-Packet Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.2 Introduction
This section describes the universal serial bus (USB) module. The USB
module is designed to serve as a low-speed (LS) USB device per the
Universal Serial Bus Specification Rev. 2.0. Control and interrupt data
transfers are supported. Endpoint 0 functions as a transmit/receive
control endpoint; endpoint 1 functions as interrupt transmit endpoint;
endpoint 2 functions as interrupt transmit or receive endpoint.
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Universal Serial Bus Module (USB)
11.3 Features
Features of the USB module include:
•
Universal Serial Bus Specification 2.0 low-speed functions
•
1.5 Mbps data rate
•
On-chip 3.3V regulator
•
Endpoint 0 with 8-byte transmit buffer and 8-byte receive buffer
•
Endpoint 1 with 8-byte transmit buffer
•
Endpoint 2 with 8-byte transmit buffer and 8-byte receive buffer
•
USB data control logic:
– Control endpoint 0 and interrupt endpoints 1 and 2
– Packet decoding/generation
– CRC generation and checking
– NRZI (Non-Return-to Zero Inserted) encoding/decoding
– Bit-stuffing
•
USB reset options:
– Internal MCU reset generation
– CPU interrupt request generation
•
Suspend and resume operations, with remote wakeup support
•
USB-generated interrupts:
– Transaction interrupt driven
– Resume interrupt
– End-of-packet interrupt
– USB reset
•
STALL, NAK, and ACK handshake generation
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Technical Data
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163
Universal Serial Bus Module (USB)
11.4 Pin Name Conventions
The USB share two I/O pins with two port E I/O pins. The full name of the
USB I/O pin is listed in Table 11-1. The generic pin name appear in the
text that follows.
Table 11-1. USB Module Pin Name Conventions
Addr.
$0018
$0019
$001A
Register Name
USB Generic Pin Names:
D+
D–
Full USB Pin Names:
PTE3/D+
PTE4/D–
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
RSTFR
TXD2FR
RXD2FR
0
0
0
0
0
0
0
T2SEQ
STALL2
TX2E
RX2E
TP2SIZ3
TP2SIZ2
TP2SIZ1
TP2SIZ0
0
0
0
0
0
0
0
0
TX1ST
0
Read:
0
USB Interrupt Register 2
Write: EOPFR
(UIR2)
Reset:
0
Read:
USB Control Register 2
Write:
(UCR2)
Reset:
Read:
USB Control Register 3
Write:
(UCR3)
Reset:
TX1STR
OSTALL0 ISTALL0
TXD1FR RESUMFR TXD0FR
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Read: UE0R07
USB Endpoint 0 Data
Register 0 Write: UE0T07
(UE0D0)
Reset:
UE0R06
UE0R05
UE0T06
UE0T05
Read: UE0R17
USB Endpoint 0 Data
Register 1 Write: UE0T17
(UE0D1)
Reset:
UE0R16
UE0R15
UE0R14
UE0T16
UE0T15
UE0T14
RXD0FR
PULLEN ENABLE2 ENABLE1
0*
0
0
FUSBO
FDP
FDM
0
0
0
0
UE0R04
UE0R03
UE0R02
UE0R01
UE0R00
UE0T04
UE0T03
UE0T02
UE0T01
UE0T00
UE0R13
UE0R12
UE0R11
UE0R10
UE0T13
UE0T12
UE0T11
UE0T10
* PULLEN bit is reset by POR or LVI reset only.
$001B
$0020
$0021
Read:
USB Control Register 4
Write:
(UCR4)
Reset:
Unaffected by reset
Unaffected by reset
= Unimplemented
U = Unaffected by reset
Figure 11-1. USB I/O Register Summary (Sheet 1 of 4)
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Freescale Semiconductor
Universal Serial Bus Module (USB)
Addr.
Register Name
$0022
$0023
$0024
$0025
$0026
$0027
$0028
$0029
$002A
$002B
Bit 7
6
5
4
3
2
1
Bit 0
Read: UE0R27
USB Endpoint 0 Data
Register 2 Write: UE0T27
(UE0D2)
Reset:
UE0R26
UE0R25
UE0R24
UE0R23
UE0R22
UE0R21
UE0R20
UE0T26
UE0T25
UE0T24
UE0T23
UE0T22
UE0T21
UE0T20
Read: UE0R37
USB Endpoint 0 Data
Register 3 Write: UE0T37
(UE0D3)
Reset:
UE0R36
UE0R35
UE0R34
UE0R33
UE0R32
UE0R31
UE0R30
UE0T36
UE0T35
UE0T34
UE0T33
UE0T32
UE0T31
UE0T30
Read: UE0R47
USB Endpoint 0 Data
Register 4 Write: UE0T47
(UE0D4)
Reset:
UE0R46
UE0R45
UE0R44
UE0R43
UE0R42
UE0R41
UE0R40
UE0T46
UE0T45
UE0T44
UE0T43
UE0T42
UE0T41
UE0T40
Read: UE0R57
USB Endpoint 0 Data
Register 5 Write: UE0T57
(UE0D5)
Reset:
UE0R56
UE0R55
UE0R54
UE0R53
UE0R52
UE0R51
UE0R50
UE0T56
UE0T55
UE0T54
UE0T53
UE0T52
UE0T51
UE0T50
Read: UE0R67
USB Endpoint 0 Data
Register 6 Write: UE0T67
(UE0D6)
Reset:
UE0R66
UE0R65
UE0R64
UE0R63
UE0R62
UE0R61
UE0R60
UE0T66
UE0T65
UE0T64
UE0T63
UE0T62
UE0T61
UE0T60
Read: UE0R77
USB Endpoint 0 Data
Register 7 Write: UE0T77
(UE0D7)
Reset:
UE0R76
UE0R75
UE0R74
UE0R73
UE0R72
UE0R71
UE0R70
UE0T76
UE0T75
UE0T74
UE0T73
UE0T72
UE0T71
UE0T70
UE1T02
UE1T01
UE1T00
UE1T12
UE1T11
UE1T10
UE1T22
UE1T21
UE1T20
UE1T32
UE1T31
UE1T30
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Read:
USB Endpoint 1 Data
Register 0 Write: UE1T07
(UE1D0)
Reset:
UE1T06
Read:
USB Endpoint 1 Data
Register 1 Write: UE1T17
(UE1D1)
Reset:
UE1T16
Read:
USB Endpoint 1 Data
Register 2 Write: UE1T27
(UE1D2)
Reset:
UE1T26
Read:
USB Endpoint 1 Data
Register 3 Write: UE1T37
(UE1D3)
Reset:
UE1T36
UE1T05
UE1T04
UE1T03
Unaffected by reset
UE1T15
UE1T14
UE1T13
Unaffected by reset
UE1T25
UE1T24
UE1T23
Unaffected by reset
UE1T35
UE1T34
UE1T33
Unaffected by reset
= Unimplemented
U = Unaffected by reset
Figure 11-1. USB I/O Register Summary (Sheet 2 of 4)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Universal Serial Bus Module (USB)
165
Universal Serial Bus Module (USB)
Addr.
$002C
$002D
$002E
$002F
$0030
$0031
$0032
$0033
$0034
$0035
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
USB Endpoint 1 Data
Register 4 Write: UE1T47
(UE1D4)
Reset:
UE1T46
UE1T45
UE1T44
UE1T43
UE1T42
UE1T41
UE1T40
Read:
USB Endpoint 1 Data
Register5 Write: UE1T57
(UE1D5)
Reset:
UE1T56
UE1T52
UE1T51
UE1T50
Read:
USB Endpoint 1 Data
Register 6 Write: UE1T67
(UE1D6)
Reset:
UE1T66
UE1T62
UE1T61
UE1T60
Read:
USB Endpoint 1 Data
Register 7 Write: UE1T77
(UE1D7)
Reset:
UE1T76
UE1T72
UE1T71
UE1T70
Unaffected by reset
UE1T55
UE1T54
UE1T53
Unaffected by reset
UE1T65
UE1T64
UE1T63
Unaffected by reset
UE1T75
UE1T74
UE1T73
Unaffected by reset
Read: UE2R07
USB Endpoint 2 Data
Register 0 Write: UE2T07
(UE2D0)
Reset:
UE2R06
UE2R05
UE2R04
UE2R03
UE2R02
UE2R01
UE2R00
UE2T06
UE2T05
UE2T04
UE2T03
UE2T02
UE2T01
UE2T00
Read: UE2R17
USB Endpoint 2 Data
Register 1 Write: UE2T17
(UE2D1)
Reset:
UE2R16
UE2R15
UE2R14
UE2R13
UE2R12
UE2R11
UE2R10
UE2T16
UE2T15
UE2T14
UE2T13
UE2T12
UE2T11
UE2T10
Read: UE2R27
USB Endpoint 2 Data
Register 2 Write: UE2T27
(UE2D2)
Reset:
UE2R26
UE2R25
UE2R24
UE2R23
UE2R22
UE2R21
UE2R20
UE2T26
UE2T25
UE2T24
UE2T23
UE2T22
UE2T21
UE2T20
Read: UE2R37
USB Endpoint 2 Data
Register 3 Write: UE2T37
(UE2D3)
Reset:
UE2R36
UE2R35
UE2R34
UE2R33
UE2R32
UE2R31
UE2R30
UE2T36
UE2T35
UE2T34
UE2T33
UE2T32
UE2T31
UE2T30
Read: UE2R47
USB Endpoint 2 Data
Register 4 Write: UE2T47
(UE2D4)
Reset:
UE2R46
UE2R45
UE2R44
UE2R43
UE2R42
UE2R41
UE2R40
UE2T46
UE2T45
UE2T44
UE2T43
UE2T42
UE2T41
UE2T40
Read: UE2R57
USB Endpoint 2 Data
Register 5 Write: UE2T57
(UE2D5)
Reset:
UE2R56
UE2R55
UE2R54
UE2R53
UE2R52
UE2R51
UE2R50
UE2T56
UE2T55
UE2T54
UE2T53
UE2T52
UE2T51
UE2T50
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
= Unimplemented
U = Unaffected by reset
Figure 11-1. USB I/O Register Summary (Sheet 3 of 4)
Technical Data
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Freescale Semiconductor
Universal Serial Bus Module (USB)
Addr.
Register Name
$0036
$0037
$0038
Bit 7
6
5
4
3
2
1
Bit 0
Read: UE2R67
USB Endpoint 2 Data
Register 6 Write: UE2T67
(UE2D6)
Reset:
UE2R66
UE2R65
UE2R64
UE2R63
UE2R62
UE2R61
UE2R60
UE2T66
UE2T65
UE2T64
UE2T63
UE2T62
UE2T61
UE2T60
Read: UE2R77
USB Endpoint 2 Data
Register 7 Write: UE2T77
(UE2D7)
Reset:
UE2R76
UE2R75
UE2R74
UE2R73
UE2R72
UE2R71
UE2R70
UE2T76
UE2T75
UE2T74
UE2T73
UE2T72
UE2T71
UE2T70
Read:
USBEN
USB Address Register
Write:
(UADDR)
Reset:
0*
Unaffected by reset
Unaffected by reset
UADD6
UADD5
UADD4
UADD3
UADD2
UADD1
UADD0
0
0
0
0
0
0
0
EOPIE
SUSPND
TXD2IE
RXD2IE
TXD1IE
TXD0IE
RXD0IE
0
0
0
0
0
0
0
0
EOPF
RSTF
TXD2F
RXD2F
TXD1F
RESUMF
TXD0F
RXD0F
0
0
0
0
0
0
0
0
TX0E
RX0E
TP0SIZ3
TP0SIZ2
TP0SIZ1
TP0SIZ0
0
0
0
0
0
TP1SIZ2
TP1SIZ1
TP1SIZ0
* USBEN bit is reset by POR or LVI reset only.
$0039
$003A
$003B
$003C
$003D
$003E
Read:
USB Interrupt Register 0
Write:
(UIR0)
Reset:
Read:
USB Interrupt Register 1
Write:
(UIR1)
Reset:
Read:
USB Control Register 0
Write:
(UCR0)
Reset:
T0SEQ
0
0
0
0
0
T1SEQ
STALL1
TX1E
0
0
0
0
0
0
0
0
Read: R0SEQ
USB Status Register 0
Write:
(USR0)
Reset:
SETUP
0
0
RP0SIZ3
RP0SIZ2
RP0SIZ1
RP0SIZ0
Read: R2SEQ
USB Status Register 1
Write:
(USR1)
Reset:
U
TXACK
TXNAK
TXSTL
RP2SIZ3
RP2SIZ2
RP2SIZ1
RP2SIZ0
0
0
0
U
U
U
U
Read:
USB Control Register 1
Write:
(UCR1)
Reset:
FRESUM TP1SIZ3
Unaffected by reset
= Unimplemented
U = Unaffected by reset
Figure 11-1. USB I/O Register Summary (Sheet 4 of 4)
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Technical Data
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Universal Serial Bus Module (USB)
11.5 Functional Description
Figure 11-2 shows the block diagram of the USB module. The USB
module manages communications between the host and the USB
function. The module is partitioned into three functional blocks. These
blocks consist of a dual-function transceiver, the USB control logic, and
the endpoint registers. The blocks are further detailed later in this section
(see 11.7 Hardware Description).
USB
VPIN
CONTROL
VMIN
LOGIC
VPOUT
TRANSCEIVER
RCV
D+
D–
USB
UPSTREAM
PORT
VMOUT
FROM OSC
CPU BUS
6MHZ
USB REGISTERS
Figure 11-2. USB Block Diagram
Technical Data
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Universal Serial Bus Module (USB)
11.5.1 USB Protocol
Figure 11-3 shows the various transaction types supported by the USB
module. The transactions are portrayed as error free. The effect of errors
in the data flow are discussed later.
ENDPOINT 0 TRANSACTIONS:
Control Write
SETUP
DATA0
ACK
OUT
DATA0
OUT
ACK
DATA1
ACK
OUT
DATA0/1
IN
ACK
DATA1
ACK
Control Read
SETUP
DATA0
ACK
IN
DATA0
IN
ACK
DATA1
ACK
IN
DATA0/1
OUT
ACK
DATA1
ACK
No-Data Control
SETUP
DATA0
ACK
IN
ACK
DATA1
ENDPOINTS 1 & 2 TRANSACTIONS:
KEY:
Interrupt
IN
DATA0/1
ACK
Unrelated Bus
Traffic
Host
Generated
Bulk Transmit
IN
DATA0/1
ACK
Device
Generated
Figure 11-3. Supported Transaction Types Per Endpoint
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Technical Data
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Universal Serial Bus Module (USB)
Each USB transaction is comprised of a series of packets. The USB
module supports the packet types shown in Figure 11-4. Token packets
are generated by the USB host and decoded by the USB device. Data
and handshake packets are both decoded and generated by the USB
device, depending on the type of transaction.
Token Packet:
IN
OUT
SYNC
PID
PID
SYNC
PID
PID
ADDR
ENDP
CRC5
EOP
CRC16
EOP
SETUP
Data Packet:
DATA0
DATA1
DATA
0 – 8 Bytes
Handshake Packet:
ACK
NAK
SYNC
PID
PID
EOP
STALL
Figure 11-4. Supported USB Packet Types
The following sections detail each segment used to form a complete
USB transaction.
11.5.1.1 Sync Pattern
The NRZI bit pattern shown in Figure 11-5 is used as a synchronization
pattern and is prefixed to each packet. This pattern is equivalent to a
data pattern of seven 0s followed by a 1 ($80).
SYNC PATTERN
NRZI Data
Encoding
Idle
PID0
PID1
Figure 11-5. Sync Pattern
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Universal Serial Bus Module (USB)
The start of a packet (SOP) is signaled by the originating port by driving
the D+ and D– lines from the idle state (also referred to as the J state) to
the opposite logic level (also referred to as the K state). This switch in
levels represents the first bit of the sync field. Figure 11-6 shows the
data signaling and voltage levels for the start of packet and the sync
pattern.
VOH (min.)
VSE (max)
VSE (min.)
VOL (min.)
VSS
FIRST BIT OF PACKET
BUS IDLE
SOP
END OF SYNC
Figure 11-6. SOP, Sync Signaling, and Voltage Levels
11.5.1.2 Packet Identifier Field
The packet identifier field is an 8-bit number comprised of the 4-bit
packet identification and its complement. The field follows the sync
pattern and determines the direction and type of transaction on the bus.
Table 11-2 shows the packet identifier values for the supported packet
types.
Table 11-2. Supported Packet Identifiers
Packet Identifier Value
Packet Identifier Type
%1001
IN Token
%0001
OUT Token
%1101
SETUP Token
%0011
DATA0 Packet
%1011
DATA1 Packet
%0010
ACK Handshake
%1010
NAK Handshake
%1110
STALL Handshake
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Universal Serial Bus Module (USB)
11.5.1.3 Address Field (ADDR)
The address field is a 7-bit number that is used to select a particular USB
device. This field is compared to the lower seven bits of the UADDR
register to determine if a given transaction is targeting the MCU USB
device.
11.5.1.4 Endpoint Field (ENDP)
The endpoint field is a 4-bit number that is used to select a particular
endpoint within a USB device. For the MCU, this will be a binary number
between 0 and 2 inclusive. Any other value will cause the transaction to
be ignored.
11.5.1.5 Cyclic Redundancy Check (CRC)
Cyclic redundancy checks are used to verify the address and data
stream of a USB transaction. This field is five bits wide for token packets
and 16 bits wide for data packets. CRCs are generated in the transmitter
and sent on the USB data lines after both the endpoint field and the data
field.
11.5.1.6 End-of-Packet (EOP)
The single-ended 0 (SE0) state is used to signal an end-of-packet
(EOP). The single-ended 0 state is indicated by both D+ and D– being
below 0.8V. EOP will be signaled by driving D+ and D– to the singleended 0 state for two bit times followed by driving the lines to the idle
state for one bit time. The transition from the single-ended 0 to the idle
state defines the end of the packet. The idle state is asserted for one bit
time and then both the D+ and D– output drivers are placed in their highimpedance state. The bus termination resistors hold the bus in the idle
state. Figure 11-7 shows the data signaling and voltage levels for an
end-of-packet transaction.
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LAST BIT OF
PACKET
EOP
STROBE
BUS DRIVEN TO
IDLE STATE
BUS FLOATS
BUS IDLE
VOH (min.)
VSE (max)
VSE (min.)
VOL (min.)
VSS
Figure 11-7. EOP Transaction Voltage Levels
The width of the SE0 in the EOP is about two bit times. The EOP width
is measured with the same capacitive load used for maximum rise and
fall times and is measured at the same level as the differential signal
crossover points of the data lines.
tPeriod
DATA
CROSSOVER
LEVEL
DIFFERENTIAL
DATA LINES
EOP
WIDTH
Figure 11-8. EOP Width Timing
11.5.2 Reset Signaling
The USB module will detect a reset signaled on the bus by the presence
of an extended SE0 at the USB data pins of a device. The MCU seeing
a single-ended 0 on its USB data inputs for more than 8µs treats that
signal as a reset.
A USB sourced reset will hold the MCU in reset for the duration of the
reset on the USB bus. The USB bit in the reset status register (SRSR)
will be set after the internal reset is removed. Refer to 8.8.2 SIM Reset
Status Register (SRSR) for more detail. The MCU’s reset recovery
sequence is detailed in Section 8. System Integration Module (SIM).
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The reset flag bit (RSTF) in the USB interrupt register 1 (UIR1) also will
be set after the internal reset is removed. Refer to 11.8.3 USB Interrupt
Register 1 for more detail.
After a reset is removed, the device will be in the default, but not yet
addressed or configured state (refer to Section 9.1 USB Device States
of the Universal Serial Bus Specification Rev. 2.0). The device must be
able to accept a device address via a SET_ADDRESS command (refer
to Section 9.4 Standard Device Request in the Universal Serial Bus
Specification Rev. 2.0) no later than 10ms after the reset is removed.
Reset can wake a device from the suspended mode.
NOTE:
USB reset can be configured not to generate a reset signal to the CPU
by setting the URSTD bit of the configuration register (see Section 5.
Configuration Register (CONFIG)). When a USB reset is detected, the
CPU generates an USB interrupt.
11.5.3 Suspend
The MCU supports suspend mode for low power. Suspend mode should
be entered when the USB data lines are in the idle state for more than
3ms. Entry into suspend mode is controlled by the SUSPND bit in the
USB interrupt register. Any low-speed bus activity should keep the
device out of the suspend state. Low-speed devices are kept awake by
periodic low-speed EOP signals from the host. This is referred to as low
speed keep alive (refer to Section 11.8.4.1 Low-speed Keep-alive in the
Universal Serial Bus Specification Rev. 2.0).
Firmware should monitor the EOPF flag and enter suspend mode by
setting the SUSPND bit if an EOP is not detected for 3ms.
Per the USB specification, the bus powered USB system is required to
draw less than 500µA from the VDD supply when in the suspend state.
This includes the current supplied by the voltage regulator to the 1.5kΩ
to ground termination resistors placed at the host end of the USB bus.
This low-current requirement means that firmware is responsible for
entering stop mode once the USB module has been placed in the
suspend state.
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11.5.4 Resume After Suspend
The MCU can be activated from the suspend state by normal bus
activity, a USB reset signal, or by a forced resume driven from the MCU.
11.5.4.1 Host Initiated Resume
The host signals resume by initiating resume signalling (K state) for at
least 20ms followed by a standard low-speed EOP signal. This 20ms
ensures that all devices in the USB network are awakened.
After resuming the bus, the host must begin sending bus traffic within
3ms to prevent the device from re-entering suspend mode.
11.5.4.2 USB Reset Signalling
Reset can wake a device from the suspended mode.
11.5.4.3 Remote Wakeup
The MCU also supports the remote wakeup feature. The firmware has
the ability to exit suspend mode by signaling a resume state to the
upstream host or hub. A non-idle state (K state) on the USB data lines is
accomplished by asserting the FRESUM bit in the UCR1 register.
When using the remote wakeup capability, the firmware must wait for at
least 5ms after the bus is in the idle state before sending the remote
wakeup resume signaling. This allows the upstream devices to get into
their suspend state and prepare for propagating resume signaling. The
FRESUM bit should be asserted to cause the resume state on the USB
data lines for at least 10ms, but not more than 15ms. Note that the
resume signalling is controlled by the FRESUM bit and meeting the
timing specifications is dependent on the firmware. When FRESUM is
cleared by firmware, the data lines will return to their high-impedance
state.
Refer to register definitions (see 11.8.6 USB Control Register 1) for
more information about how the force resume (FRESUM) bit can be
used to initiate the remote wakeup feature.
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11.5.5 Low-Speed Device
Low-speed devices are configured by the position of a pull-up resistor on
the USB D– pin of the MCU. Low-speed devices are terminated as
shown in Figure 11-9 with the pull-up on the D– line.
VREG (3.3V)
MCU
D+
1.5 kΩ
USB LOW-SPEED CABLE
D–
Figure 11-9. External Low-Speed Device Configuration
For low-speed transmissions, the transmitter’s EOP width must be
between 1.25µs and 1.50µs. These ranges include timing variations due
to differential buffer delay and rise/fall time mismatches and to noise and
other random effects. A low-speed receiver must accept a 670ns SE0
followed by a J transition as a valid EOP. An SE0 shorter than
330ns or an SE0 not followed by a J transition are rejected as an EOP.
Any SE0 that is 8µs or longer is automatically a reset.
11.6 Clock Requirements
The low-speed data rate is nominally 1.5 Mbps. The OSCXCLK÷2
(6MHz) signal driven by the oscillator circuits is the clock source for the
USB module and requires that a 12MHz oscillator circuit be connected
to the OSC1 and OSC2 pins. The permitted frequency tolerance for lowspeed functions is approximately ±1.5% (15,000 ppm). This tolerance
includes inaccuracies from all sources: initial frequency accuracy, crystal
capacitive loading, supply voltage on the oscillator, temperature, and
aging. The jitter in the low-speed data rate must be less than 10ns.
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11.7 Hardware Description
The USB module as previously shown in Figure 11-2 contains three
functional blocks: the low-speed USB transceiver, the USB control logic,
and the USB registers. The following details the function of the regulator,
transceiver, and control logic. See 11.8 I/O Registers for details of
register settings.
11.7.1 Voltage Regulator
The USB data lines are required by the USB specification to have an
output voltage between 2.8V and 3.6V. The data lines also are required
to have an external 1.5kΩ pull-up resistor connected between a data line
and a voltage source between 3.0V and 3.6V. Figure 11-10 shows the
worst case electrical connection for the voltage regulator.
4.0V TO 5.5V
3.3V
REGULATOR
LOW-SPEED
TRANSCEIVER
USB DATA LINES
D+
R1
HOST
OR
HUB
USB CABLE
D–
R1 = 1.5kΩ ±5%
R2 = 15kΩ ±5%
R2
R2
Figure 11-10. Regulator Electrical Connections
11.7.2 USB Transceiver
The USB transceiver provides the physical interface to the USB D+ and
D– data lines. The transceiver is composed of two parts: an output drive
circuit and a receiver.
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11.7.2.1 Output Driver Characteristics
The USB transceiver uses a differential output driver to drive the USB
data signal onto the USB cable. The static output swing of the driver in
its low state is below the VOL of 0.3V with a 1.5kΩ load to 3.6V and in
its high state is above the VOH of 2.8V with a 15kΩ load to ground. The
output swings between the differential high and low state are well
balanced to minimize signal skew. Slew rate control on the driver is used
to minimize the radiated noise and cross talk. The driver’s outputs
support 3-state operation to achieve bidirectional half duplex operation.
The driver can tolerate a voltage on the signal pins of –1.0V to 5.5V with
respect to local ground reference without damage.
11.7.2.2 Low Speed (1.5 Mbps) Driver Characteristics
The rise and fall time of the signals on this cable are greater than 75ns
and less than 300ns. The edges are matched to within ±20% to minimize
RFI emissions and signal skew.
USB data transmission is done with differential signals. A differential
input receiver is used to accept the USB data signal. A differential 1 on
the bus is represented by D+ being at least 200mV more positive than
D– as seen at the receiver, and a differential 0 is represented by D–
being at least 200mV more positive than D+ as seen at the receiver. The
signal cross over point must be between 1.3V and 2.0V.
ONE BIT
TIME
(1.5 Mb/s)
VSE (max)
VSE (min.)
SIGNAL PINS
PASS OUTPUT SPEC
LEVELS WITH MINIMAL
REFLECTIONS AND RINGING
VSS
Figure 11-11. Receiver Characteristics
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The receiver features an input sensitivity of 200mV when both
differential data inputs are in the differential common mode range of
0.8V to 2.5V as shown in Figure 11-12. In addition to the differential
receiver, there is a single-ended receiver (schmitt trigger) for each of the
two data lines.
Differential Input voltage Range
Differential Output
Crossover
Voltage Range
–1.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
5.5
INPUT VOLTAGE RANGE (VOLTS)
Figure 11-12. Differential Input Sensitivity Range
11.7.2.3 Receiver Data Jitter
The data receivers for all types of devices must be able to properly
decode the differential data in the presence of jitter. The more of the bit
time that any data edge can occupy and still be decoded, the more
reliable the data transfer will be. Data receivers are required to decode
differential data transitions that occur in a window plus and minus a
nominal quarter bit time from the nominal (centered) data edge position.
Jitter will be caused by the delay mismatches and by mismatches in the
source and destination data rates (frequencies). The receive data jitter
budget for low speed is given in Section 20. Electrical Specifications.
The specification includes the consecutive (next) and paired transition
values for each source of jitter.
11.7.2.4 Data Source Jitter
The source of data can have some variation (jitter) in the timing of edges
of the data transmitted. The time between any set of data transitions is
N × TPeriod ± jitter time, where N is the number of bits between the
transitions and TPeriod is defined as the actual period of the data rate.
The data jitter is measured with the same capacitive load used for
maximum rise and fall times and is measured at the crossover points of
the data lines as shown in Figure 11-13.
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tPeriod
CROSSOVER
POINTS
DIFFERENTIAL
DATA LINES
JITTER
CONSECUTIVE
TRANSITIONS
PAIRED
TRANSITIONS
Figure 11-13. Data Jitter
For low-speed transmissions, the jitter time for any consecutive
differential data transitions must be within ±25ns and within ±10ns for
any set of paired differential data transitions. These jitter numbers
include timing variations due to differential buffer delay, rise/fall time
mismatches, internal clock source jitter, noise and other random effects.
11.7.2.5 Data Signal Rise and Fall Time
The output rise time and fall time are measured between 10% and 90%
of the signal. Edge transition time for the rising and falling edges of lowspeed signals is 75ns (minimum) into a capacitive load (CL) of 200pF
and 300ns (maximum) into a capacitive load of 600pF. The rising and
falling edges should be transitioning (monotonic) smoothly when driving
the cable to avoid excessive EMI.
FALL TIME
RISE TIME
+
+
CL
90%
90%
DIFFERENTIAL
DATA LINES
10%
CL
10%
tR
tF
LOW SPEED: 75ns at CL = 200pF, 300ns at CL = 600 pF
Figure 11-14. Data Signal Rise and Fall Time
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11.7.3 USB Control Logic
The USB control logic manages data movement between the CPU and
the transceiver. The control logic handles both transmit and receive
operations on the USB. It contains the logic used to manipulate the
transceiver and the endpoint registers.
The byte count buffer is loaded with the active transmit endpoints byte
count value during transmit operations. This same buffer is used for
receive transactions to count the number of bytes received and, upon
the end of the transaction, transfer that number to the receive endpoints
byte count register.
When transmitting, the control logic handles parallel-to-serial
conversion, CRC generation, NRZI encoding, and bit stuffing.
When receiving, the control logic handles sync detection, packet
identification, end-of-packet detection, bit (un)stuffing, NRZI decoding,
CRC validation, and serial-to-parallel conversion. Errors detected by the
control logic include bad CRC, timeout while waiting for EOP, and bit
stuffing violations.
11.8 I/O Registers
These I/O registers control and monitor USB operation:
•
USB address register (UADDR)
•
USB control registers 0–4 (UCR0–UCR4)
•
USB status registers 0–1 (USR0–USR1)
•
USB interrupt registers 0–2 (UIR0–UIR2)
•
USB endpoint 0 data registers 0–7 (UE0D0–UE0D7)
•
USB endpoint 1 data registers 0–7 (UE1D0–UE1D7)
•
USB endpoint 2 data registers 0–7 (UE2D0–UE2D7)
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11.8.1 USB Address Register
Address:
Read:
Write:
Reset:
$0038
Bit 7
6
5
4
3
2
1
Bit 0
USBEN
UADD6
UADD5
UADD4
UADD3
UADD2
UADD1
UADD0
0*
0
0
0
0
0
0
0
* USBEN bit is reset by POR or LVI reset only.
Figure 11-15. USB Address Register (UADDR)
USBEN — USB Module Enable
This read/write bit enables and disables the USB module and the USB
pins. When USBEN is set, the USB module is enabled and the PTE4
interrupt is disabled. When USBEN is clear, the USB module will not
respond to any tokens, USB reset and USB related interrupts are
disabled, and pins PTE4/D– and PTE3/D+ function as high current
open-drain I/O port pins PTE4 and PTE3.
1 = USB function enabled and PTE4 interrupt is disabled
0 = USB function disabled including USB interrupt, reset and reset
interrupt
UADD[6:0] — USB Function Address
These bits specify the USB address of the device. Reset clears these
bits.
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11.8.2 USB Interrupt Register 0
Address:
Read:
Write:
Reset:
$0039
Bit 7
6
5
4
3
EOPIE
SUSPND
TXD2IE
RXD2IE
TXD1IE
0
0
0
0
0
2
0
0
1
Bit 0
TXD0IE
RXD0IE
0
0
= Unimplemented
Figure 11-16. USB Interrupt Register 0 (UIR0)
EOPIE — End-of-Packet Detect Interrupt Enable
This read/write bit enables the USB to generate CPU interrupt
requests when the EOPF bit becomes set. Reset clears the EOPIE
bit.
1 = End-of-packet sequence detection can generate a CPU
interrupt request
0 = End-of-packet sequence detection cannot generate a CPU
interrupt request
SUSPND — USB Suspend Bit
To save power, this read/write bit should be set by the software if a
3ms constant idle state is detected on the USB bus. Setting this bit
puts the transceiver into a power-saving mode. The RESUMF flag
must be cleared before setting SUSPND. Software must clear this bit
after the resume flag (RESUMF) is set while this resume interrupt flag
is serviced.
TXD2IE — Endpoint 2 Transmit Interrupt Enable
This read/write bit enables the transmit endpoint 2 to generate CPU
interrupt requests when the TXD2F bit becomes set. Reset clears the
TXD2IE bit.
1 = Transmit endpoint 2 can generate a CPU interrupt request
0 = Transmit endpoint 2 cannot generate a CPU interrupt request
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RXD2IE — Endpoint 2 Receive Interrupt Enable
This read/write bit enables the receive endpoint 2 to generate CPU
interrupt requests when the RXD2F bit becomes set. Reset clears the
RXD2IE bit.
1 = Receive endpoint 2 can generate a CPU interrupt request
0 = Receive endpoint 2 cannot generate a CPU interrupt request
TXD1IE — Endpoint 1 Transmit Interrupt Enable
This read/write bit enables the transmit endpoint 1 to generate CPU
interrupt requests when the TXD1F bit becomes set. Reset clears the
TXD1IE bit.
1 = Transmit endpoints 1 can generate a CPU interrupt request
0 = Transmit endpoints 1 cannot generate a CPU interrupt request
TXD0IE — Endpoint 0 Transmit Interrupt Enable
This read/write bit enables the transmit endpoint 0 to generate CPU
interrupt requests when the TXD0F bit becomes set. Reset clears the
TXD0IE bit.
1 = Transmit endpoint 0 can generate a CPU interrupt request
0 = Transmit endpoint 0 cannot generate a CPU interrupt request
RXD0IE — Endpoint 0 Receive Interrupt Enable
This read/write bit enables the receive endpoint 0 to generate CPU
interrupt requests when the RXD0F bit becomes set. Reset clears the
RXD0IE bit.
1 = Receive endpoint 0 can generate a CPU interrupt request
0 = Receive endpoint 0 cannot generate a CPU interrupt request
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11.8.3 USB Interrupt Register 1
Address:
Read:
$003A
Bit 7
6
5
4
3
2
1
Bit 0
EOPF
RSTF
TXD2F
RXD2F
TXD1F
RESUMF
TXD0F
RXD0F
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 11-17. USB Interrupt Register 1 (UIR1)
EOPF — End-of-Packet Detect Flag
This read-only bit is set when a valid end-of-packet sequence is
detected on the D+ and D– lines. Software must clear this flag by
writing a logic 1 to the EOPFR bit.
Reset clears this bit. Writing to EOPF has no effect.
1 = End-of-packet sequence has been detected
0 = End-of-packet sequence has not been detected
RSTF — USB Reset Flag
This read-only bit is set when a valid reset signal state is detected on
the D+ and D– lines. If the URSTD bit of the configuration register
(CONFIG) is clear, this reset detection will generate an internal reset
signal to reset the CPU and other peripherals including the USB
module. If the URSTD bit is set, this reset detection will generate an
USB interrupt. This bit is cleared by writing a logic 1 to the RSTFR bit.
This bit also is cleared by a POR reset.
NOTE:
The USB bit in the SRSR (see 8.8.2 SIM Reset Status Register
(SRSR)) is also a USB reset indicator.
TXD2F — Endpoint 2 Data Transmit Flag
This read-only bit is set after the data stored in endpoint 2 transmit
buffers has been sent and an ACK handshake packet from the host is
received. Once the next set of data is ready in the transmit buffers,
software must clear this flag by writing a logic 1 to the TXD2FR bit.
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To enable the next data packet transmission, TX2E also must be set.
If the TXD2F bit is not cleared, a NAK handshake will be returned in
the next IN transaction.
Reset clears this bit. Writing to TXD2F has no effect.
1 = Transmit on endpoint 2 has occurred
0 = Transmit on endpoint 2 has not occurred
RXD2F — Endpoint 2 Data Receive Flag
This read-only bit is set after the USB module has received a data
packet and responded with an ACK handshake packet. Software
must clear this flag by writing a logic 1 to the RXD2FR bit after all of
the received data has been read. Software also must set the RX2E bit
to 1 to enable the next data packet reception. If the RXD2F bit is not
cleared, a NAK handshake will be returned in the next OUT
transaction.
Reset clears this bit. Writing to RXD2F has no effect.
1 = Receive on endpoint 2 has occurred
0 = Receive on endpoint 2 has not occurred
TXD1F — Endpoint 1 Data Transmit Flag
This read-only bit is set after the data stored in the endpoint 1 transmit
buffer has been sent and an ACK handshake packet from the host is
received. Once the next set of data is ready in the transmit buffers,
software must clear this flag by writing a logic 1 to the TXD1FR bit. To
enable the next data packet transmission, TX1E also must be set. If
the TXD1F bit is not cleared, a NAK handshake will be returned in the
next IN transaction.
Reset clears this bit. Writing to TXD1F has no effect.
1 = Transmit on endpoint 1has occurred
0 = Transmit on endpoint 1has not occurred
RESUMF — Resume Flag
This read-only bit is set when USB bus activity is detected while the
SUSPND bit is set. Software must clear this flag by writing a logic 1 to
the RESUMFR bit. Reset clears this bit. Writing a logic 0 to RESUMF
has no effect.
1 = USB bus activity has been detected
0 = No USB bus activity has been detected
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TXD0F — Endpoint 0 Data Transmit Flag
This read-only bit is set after the data stored in endpoint 0 transmit
buffers has been sent and an ACK handshake packet from the host is
received. Once the next set of data is ready in the transmit buffers,
software must clear this flag by writing a logic 1 to the TXD0FR bit. To
enable the next data packet transmission, TX0E also must be set. If
the TXD0F bit is not cleared, a NAK handshake will be returned in the
next IN transaction.
Reset clears this bit. Writing to TXD0F has no effect.
1 = Transmit on endpoint 0 has occurred
0 = Transmit on endpoint 0 has not occurred
RXD0F — Endpoint 0 Data Receive Flag
This read-only bit is set after the USB module has received a data
packet and responded with an ACK handshake packet. Software
must clear this flag by writing a logic 1 to the RXD0FR bit after all of
the received data has been read. Software also must set the RX0E bit
to 1 to enable the next data packet reception. If the RXD0F bit is not
cleared, the USB will respond with a NAK handshake to any
endpoint 0 OUT tokens; but does not respond to a SETUP token.
Reset clears this bit. Writing to RXD0F has no effect.
1 = Receive on endpoint 0 has occurred
0 = Receive on endpoint 0 has not occurred
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11.8.4 USB Interrupt Register 2
Address:
$0018
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
0
0
Write:
EOPFR
RSTFR
TXD2FR
RXD2FR
Reset:
0
0
0
0
TXD1FR RESUMFR TXD0FR
0
0
0
RXD0FR
0
Figure 11-18. USB Interrupt Register 2 (UIR2)
EOPFR — End-of-Packet Flag Reset
Writing a logic 1 to this write-only bit will clear the EOPF bit if it is set.
Writing a logic 0 to the EOPFR has no effect. Reset clears this bit.
RSTFR — Clear Reset Indicator Bit
Writing a logic 1 to this write-only bit will clear the RSTF bit if it is set.
Writing a logic 0 to the RSTFR has no effect. Reset clears this bit.
TXD2FR — Endpoint 2 Transmit Flag Reset
Writing a logic 1 to this write-only bit will clear the TXD2F bit if it is set.
Writing a logic 0 to TXD2FR has no effect. Reset clears this bit.
RXD2FR — Endpoint 2 Receive Flag Reset
Writing a logic 1 to this write-only bit will clear the RXD2F bit if it is set.
Writing a logic 0 to RXD2FR has no effect. Reset clears this bit.
TXD1FR — Endpoint 1 Transmit Flag Reset
Writing a logic 1 to this write-only bit will clear the TXD1F bit if it is set.
Writing a logic 0 to TXD1FR has no effect. Reset clears this bit.
RESUMFR — Resume Flag Reset
Writing a logic 1 to this write-only bit will clear the RESUMF bit if it is
set. Writing to RESUMFR has no effect. Reset clears this bit.
TXD0FR — Endpoint 0 Transmit Flag Reset
Writing a logic 1 to this write-only bit will clear the TXD0F bit if it is set.
Writing a logic 0 to TXD0FR has no effect. Reset clears this bit.
RXD0FR — Endpoint 0 Receive Flag Reset
Writing a logic 1 to this write-only bit will clear the RXD0F bit if it is set.
Writing a logic 0 to RXD0FR has no effect. Reset clears this bit.
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Freescale Semiconductor
Universal Serial Bus Module (USB)
11.8.5 USB Control Register 0
Address:
$003B
Bit 7
Read:
Write:
Reset:
T0SEQ
0
6
0
0
5
4
3
2
1
Bit 0
TX0E
RX0E
TP0SIZ3
TP0SIZ2
TP0SIZ1
TP0SIZ0
0
0
0
0
0
0
Figure 11-19. USB Control Register 0 (UCR0)
T0SEQ — Endpoint 0 Transmit Sequence Bit
This read/write bit determines which type of data packet (DATA0 or
DATA1) will be sent during the next IN transaction directed at
endpoint 0. Toggling of this bit must be controlled by software. Reset
clears this bit.
1 = DATA1 token active for next endpoint 0 transmit
0 = DATA0 token active for next endpoint 0 transmit
TX0E — Endpoint 0 Transmit Enable
This read/write bit enables a transmit to occur when the USB host
controller sends an IN token to endpoint 0. Software should set this
bit when data is ready to be transmitted. It must be cleared by
software when no more endpoint 0 data needs to be transmitted.
If this bit is 0 or the TXD0F is set, the USB will respond with a NAK
handshake to any endpoint 0 IN tokens. Reset clears this bit.
1 = Data is ready to be sent
0 = Data is not ready. Respond with NAK
RX0E — Endpoint 0 Receive Enable
This read/write bit enables a receive to occur when the USB host
controller sends an OUT token to endpoint 0. Software should set this
bit when data is ready to be received. It must be cleared by software
when data cannot be received.
If this bit is 0 or the RXD0F is set, the USB will respond with a NAK
handshake to any endpoint 0 OUT tokens; but does not respond to a
SETUP token. Reset clears this bit.
1 = Data is ready to be received
0 = Not ready for data. Respond with NAK
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Technical Data
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Universal Serial Bus Module (USB)
TP0SIZ3–TP0SIZ0 — Endpoint 0 Transmit Data Packet Size
These read/write bits store the number of transmit data bytes for the
next IN token request for endpoint 0. These bits are cleared by reset.
11.8.6 USB Control Register 1
Address:
Read:
Write:
Reset:
$003C
Bit 7
6
5
T1SEQ
STALL1
TX1E
0
0
0
4
3
FRESUM TP1SIZ3
0
0
2
1
Bit 0
TP1SIZ2
TP1SIZ1
TP1SIZ0
0
0
0
Figure 11-20. USB Control Register 1 (UCR1)
T1SEQ — Endpoint 1 Transmit Sequence Bit
This read/write bit determines which type of data packet (DATA0 or
DATA1) will be sent during the next IN transaction directed to
endpoint 1. Toggling of this bit must be controlled by software. Reset
clears this bit.
1 = DATA1 token active for next endpoint 1 transmit
0 = DATA0 token active for next endpoint 1 transmit
STALL1 — Endpoint 1 Force Stall Bit
This read/write bit causes endpoint 1 to return a STALL handshake
when polled by either an IN or OUT token by the USB host controller.
Reset clears this bit.
1 = Send STALL handshake
0 = Default
TX1E — Endpoint 1 Transmit Enable
This read/write bit enables a transmit to occur when the USB host
controller sends an IN token to endpoint 1. The appropriate endpoint
enable bit, ENABLE1 bit in the UCR3 register, also should be set.
Software should set the TX1E bit when data is ready to be
transmitted. It must be cleared by software when no more data needs
to be transmitted.
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Freescale Semiconductor
Universal Serial Bus Module (USB)
If this bit is 0 or the TXD1F is set, the USB will respond with a NAK
handshake to any endpoint 1 directed IN tokens. Reset clears this bit.
1 = Data is ready to be sent
0 = Data is not ready. Respond with NAK
FRESUM — Force Resume
This read/write bit forces a resume state (K or non-idle state) onto the
USB data lines to initiate a remote wakeup. Software should control
the timing of the forced resume to be between 10 and 15 ms. Setting
this bit will not cause the RESUMF bit to be set.
1 = Force data lines to K state
0 = Default
TP1SIZ3–TP1SIZ0 — Endpoint 1 Transmit Data Packet Size
These read/write bits store the number of transmit data bytes for the
next IN token request for endpoint 1. These bits are cleared by reset.
11.8.7 USB Control Register 2
Address:
Read:
Write:
Reset:
$0019
Bit 7
6
5
4
3
2
1
Bit 0
T2SEQ
STALL2
TX2E
RX2E
TP2SIZ3
TP2SIZ2
TP2SIZ1
TP2SIZ0
0
0
0
0
0
0
0
0
Figure 11-21. USB Control Register 2 (UCR2)
T2SEQ — Endpoint 2 Transmit Sequence Bit
This read/write bit determines which type of data packet (DATA0 or
DATA1) will be sent during the next IN transaction directed to
endpoint 2. Toggling of this bit must be controlled by software. Reset
clears this bit.
1 = DATA1 token active for next endpoint 2 transmit
0 = DATA0 token active for next endpoint 2 transmit
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Technical Data
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Universal Serial Bus Module (USB)
STALL2 — Endpoint 2 Force Stall Bit
This read/write bit causes endpoint 2 to return a STALL handshake
when polled by either an IN or OUT token by the USB host controller.
Reset clears this bit.
1 = Send STALL handshake
0 = Default
TX2E — Endpoint 2 Transmit Enable
This read/write bit enables a transmit to occur when the USB host
controller sends an IN token to endpoint 2. The appropriate endpoint
enable bit, ENABLE2 bit in the UCR3 register, also should be set.
Software should set the TX2E bit when data is ready to be
transmitted. It must be cleared by software when no more data needs
to be transmitted.
If this bit is 0 or the TXD2F is set, the USB will respond with a NAK
handshake to any endpoint 2 directed IN tokens. Reset clears this bit.
1 = Data is ready to be sent
0 = Data is not ready. Respond with NAK
RX2E — Endpoint 2 Receive Enable
This read/write bit enables a receive to occur when the USB host
controller sends an OUT token to endpoint 2. Software should set this
bit when data is ready to be received. It must be cleared by software
when data cannot be received.
If this bit is 0 or the RXD2F is set, the USB will respond with a NAK
handshake to any endpoint 2 OUT tokens. Reset clears this bit.
1 = Data is ready to be received
0 = Not ready for data. Respond with NAK
TP2SIZ3–TP2SIZ0 — Endpoint 2 Transmit Data Packet Size
These read/write bits store the number of transmit data bytes for the
next IN token request for endpoint 2. These bits are cleared by reset.
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Universal Serial Bus Module (USB)
Freescale Semiconductor
Universal Serial Bus Module (USB)
11.8.8 USB Control Register 3
Address:
Read:
$001A
Bit 7
6
TX1ST
0
Write:
Reset:
TX1STR
0
0
5
4
OSTALL0 ISTALL0
0
0
3
0
2
1
Bit 0
PULLEN ENABLE2 ENABLE1
0
0*
0
0
= Unimplemented
* PULLEN bit is reset by POR or LVI reset only.
Figure 11-22. USB Control Register 3 (UCR3)
TX1ST — Endpoint 0 Transmit First Flag
This read-only bit is set if the endpoint 0 data transmit flag (TXD0F) is
set when the USB control logic is setting the endpoint 0 data receive
flag (RXD0F). In other words, if an unserviced endpoint 0 transmit flag
is still set at the end of an endpoint 0 reception, then this bit will be set.
This bit lets the firmware know that the endpoint 0 transmission
happened before the endpoint 0 reception.
Reset clears this bit.
1 = IN transaction occurred before SETUP/OUT
0 = IN transaction occurred after SETUP/OUT
TX1STR — Clear Endpoint 0 Transmit First Flag
Writing a logic 1 to this write-only bit will clear the TX1ST bit if it is set.
Writing a logic 0 to the TX1STR has no effect. Reset clears this bit.
OSTALL0 — Endpoint 0 Force STALL Bit for OUT token
This read/write bit causes endpoint 0 to return a STALL handshake
when polled by an OUT token by the USB host controller. The USB
hardware clears this bit when a SETUP token is received. Reset
clears this bit.
1 = Send STALL handshake
0 = Default
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Technical Data
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Universal Serial Bus Module (USB)
ISTALL0 — Endpoint 0 Force STALL Bit for IN token
This read/write bit causes endpoint 0 to return a STALL handshake
when polled by an IN token by the USB host controller. The USB
hardware clears this bit when a SETUP token is received. Reset
clears this bit.
1 = Send STALL handshake
0 = Default
PULLEN — Pull-up Enable
This read/write bit controls the pull-up option for the USB D– pin if the
USB module is enabled.
1 = Configure D– pin to have internal pull-up
0 = Disconnect D– pin internal pull-up
ENABLE2 — Endpoint 2 Enable
This read/write bit enables endpoint 2 and allows the USB to respond
to IN or OUT packets addressed to endpoint 2. Reset clears this bit.
1 = Endpoint 2 is enabled and can respond to an IN or OUT token
0 = Endpoint 2 is disabled
ENABLE1 — Endpoint 1 Enable
This read/write bit enables endpoint 1 and allows the USB to respond
to IN packets addressed to endpoint 1. Reset clears this bit.
1 = Endpoint 1 is enabled and can respond to an IN token
0 = Endpoint 1 is disabled
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Universal Serial Bus Module (USB)
Freescale Semiconductor
Universal Serial Bus Module (USB)
11.8.9 USB Control Register 4
USB control register 4 directly controls the USB data pins D+ and D–. If
the FUSBO bit, and the USBEN bit of the USB address register
(UADDR) are set, the output buffers of the USB modules are enabled
and the corresponding levels of the USB data pins D+ and D– are equal
to the values set by the FDP and the FDM bits.
Address:
Read:
$001B
Bit 7
6
5
4
3
0
0
0
0
0
0
0
0
0
0
Write:
Reset:
2
1
Bit 0
FUSBO
FDP
FDM
0
0
0
= Unimplemented
Figure 11-23. USB Control Register 4 (UCR4)
FUSBO — Force USB Output
This read/write bit enables the USB output buffers.
1 = Enables USB output buffers
0 = USB module in normal operation
FDP — Force D+
This read/write bit determinates the output level of D+.
1 = D+ at output high level
0 = D+ at output low level
FDM — Force D–
This read/write bit determinates the output level of D–.
1 = D– at output high level
0 = D– at output low level
NOTE:
Customers must be very careful when setting the UCR4 register. When
the FUSBO and the USBEN bits are set, the USB module is in output
mode and it will not recognize any USB signals including the USB reset
signal. The UCR4 register is used for some special applications.
Customers are not normally expected to use this register.
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Universal Serial Bus Module (USB)
11.8.10 USB Status Register 0
Address:
Read:
$003D
Bit 7
6
5
4
3
2
1
Bit 0
R0SEQ
SETUP
0
0
RP0SIZ3
RP0SIZ2
RP0SIZ1
RP0SIZ0
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 11-24. USB Status Register 0 (USR0)
R0SEQ — Endpoint 0 Receive Sequence Bit
This read-only bit indicates the type of data packet last received for
endpoint 0 (DATA0 or DATA1).
1 = DATA1 token received in last endpoint 0 receive
0 = DATA0 token received in last endpoint 0 receive
SETUP — SETUP Token Detect Bit
This read-only bit indicates that a valid SETUP token has been
received.
1 = Last token received for endpoint 0 was a SETUP token
0 = Last token received for endpoint 0 was not a SETUP token
RP0SIZ3–RP0SIZ0 — Endpoint 0 Receive Data Packet Size
These read-only bits store the number of data bytes received for the
last OUT or SETUP transaction for endpoint 0.
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Universal Serial Bus Module (USB)
Freescale Semiconductor
Universal Serial Bus Module (USB)
11.8.11 USB Status Register 1
Address:
Read:
$003E
Bit 7
6
5
4
3
2
1
Bit 0
R2SEQ
TXACK
TXNAK
TXSTL
RP2SIZ3
RP2SIZ2
RP2SIZ1
RP2SIZ0
U
0
0
0
U
U
U
U
Write:
Reset:
= Unimplemented
U = Unaffected by reset
Figure 11-25. USB Status Register 2 (USR1)
R2SEQ — Endpoint 2 Receive Sequence Bit
This read-only bit indicates the type of data packet last received for
endpoint 2 (DATA0 or DATA1).
1 = DATA1 token received in last endpoint 2 receive
0 = DATA0 token received in last endpoint 2 receive
TXACK — ACK Token Transmit Bit
This read-only bit indicates that an ACK token has been transmitted.
This bit is updated at the end of the data transmission.
1 = Last token transmitted for endpoint 0 was an ACK token
0 = Last token transmitted for endpoint 0 was not an ACK token
TXNAK — NAK Token Transmit Bit
This read-only bit indicates that a TXNAK token has been transmitted.
This bit is updated at the end of the data transmission.
1 = Last token transmitted for endpoint 0 was a NAK token
0 = Last token transmitted for endpoint 0 was not a NAK token
TXSTL — STALL Token Transmit Bit
This read-only bit indicates that a STALL token has been transmitted.
This bit is updated at the end of the data transmission.
1 = Last token transmitted for endpoint 0 was a STALL token
0 = Last token transmitted for endpoint 0 was not a STALL token
RP2SIZ3–RP2SIZ0 — Endpoint 2 Receive Data Packet Size
These read-only bits store the number of data bytes received for the
last OUT transaction for endpoint 2.
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Technical Data
Universal Serial Bus Module (USB)
197
Universal Serial Bus Module (USB)
11.8.12 USB Endpoint 0 Data Registers
Address:
$0020
UE0D0
Bit 7
6
5
4
3
2
1
Bit 0
Read: UE0R07
UE0R06
UE0R05
UE0R04
UE0R03
UE0R02
UE0R01
UE0R00
Write: UE0T07
UE0T06
UE0T05
UE0T04
UE0T03
UE0T02
UE0T01
UE0T00
Reset:
Unaffected by reset
↓
Address:
$0027
↓
UE0D7
Read: UE0R77
UE0R76
UE0R75
UE0R74
UE0R73
UE0R72
UE0R71
UE0R70
Write: UE0T77
UE0T76
UE0T75
UE0T74
UE0T73
UE0T72
UE0T71
UE0T70
Reset:
Unaffected by reset
Figure 11-26. USB Endpoint 0 Data Registers (UE0D0–UE0D7)
UE0Rx7–UE0Rx0 — Endpoint 0 Receive Data Buffer
These read-only bits are serially loaded with OUT token or SETUP
token data directed at endpoint 0. The data is received over the USB’s
D+ and D– pins.
UE0Tx7–UE0Tx0 — Endpoint 0 Transmit Data Buffer
These write-only buffers are loaded by software with data to be sent
on the USB bus on the next IN token directed at endpoint 0.
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Freescale Semiconductor
Universal Serial Bus Module (USB)
11.8.13 USB Endpoint 1 Data Registers
Address:
$0028
UE1D0
Bit 7
6
5
4
3
2
1
Bit 0
UE1T06
UE1T05
UE1T04
UE1T03
UE1T02
UE1T01
UE1T00
Read:
Write: UE1T07
Reset:
Unaffected by reset
↓
Address:
$002F
↓
UE1D7
Read:
Write: UE1T77
UE1T76
UE1T75
Reset:
UE1T74
UE1T73
UE1T72
UE1T71
UE1T70
Unaffected by reset
= Unimplemented
Figure 11-27. USB Endpoint 1 Data Registers (UE1D0–UE1D7)
UE1Tx7–UE1Tx0 — Endpoint 1 Transmit or Receive Data Buffer
These write-only buffers are loaded by software with data to be sent
on the USB bus on the next IN token directed at endpoint 1.
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Technical Data
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Universal Serial Bus Module (USB)
11.8.14 USB Endpoint 2 Data Registers
Address:
$0030
UE2D0
Bit 7
6
5
4
3
2
1
Bit 0
Read: UE2R07
UE2R06
UE2R05
UE2R04
UE2R03
UE2R02
UE2R01
UE2R00
Write: UE2T07
UE2T06
UE2T05
UE2T04
UE2T03
UE2T02
UE2T01
UE2T00
Reset:
Unaffected by reset
↓
Address:
$0037
↓
UE2D7
Read: UE2R77
UE2R76
UE2R75
UE2R74
UE2R73
UE2R72
UE2R71
UE2R70
Write: UE2T77
UE2T76
UE2T75
UE2T74
UE2T73
UE2T72
UE2T71
UE2T70
Reset:
Unaffected by reset
Figure 11-28. USB Endpoint 2 Data Registers (UE2D0–UE2D7)
UE2Rx7–UE2Rx0 — Endpoint 2 Receive Data Buffer
These read-only bits are serially loaded with OUT token data directed
at endpoint 2. The data is received over the USB’s D+ and D– pins.
UE2Tx7–UE2Tx0 — Endpoint 2 Transmit Data Buffer
These write-only buffers are loaded by software with data to be sent
on the USB bus on the next IN token directed at endpoint 2.
Technical Data
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Universal Serial Bus Module (USB)
Freescale Semiconductor
Universal Serial Bus Module (USB)
11.9 USB Interrupts
The USB module is capable of generating interrupts and causing the
CPU to execute the USB interrupt service routine. There are three types
of USB interrupts:
•
End-of-transaction interrupts signify either a completed
transaction receive or transmit transaction.
•
Resume interrupts signify that the USB bus is reactivated after
having been suspended.
•
End-of-packet interrupts signify that a low-speed end-of-packet
signal was detected.
All USB interrupts share the same interrupt vector. Firmware is
responsible for determining which interrupt is active.
11.9.1 USB End-of-Transaction Interrupt
There are five possible end-of-transaction interrupts:
•
Endpoint 0 or 2 receive
•
Endpoint 0, 1 or 2 transmit
End-of-transaction interrupts occur as detailed in the following sections.
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Universal Serial Bus Module (USB)
11.9.1.1 Receive Control Endpoint 0
For a control OUT transaction directed at endpoint 0, the USB module
will generate an interrupt by setting the RXD0F flag in the UIR0 register.
The conditions necessary for the interrupt to occur are shown in the
flowchart in Figure 11-29.
VALID OUT TOKEN
RECEIVED FOR ENDPOINT 0
Y
VALID DATA TOKEN
RECEIVED FOR ENDPOINT 0?
N
TIMEOUT
NO RESPONSE
FROM USB FUNCTION
Y
USB MODULE ENABLED?
(USBEN = 1)
N
NO RESPONSE
FROM USB FUNCTION
N
SEND STALL
HANDSHAKE
N
SEND NAK
HANDSHAKE
Y
ENDPOINT 0 RECEIVE NOT STALLED?
(OSTALL0 = 0)
Y
ENDPOINT 0 RECEIVE READY TO RECEIVE?
(RX0E = 1) AND (RXD0F = 0)
Y
ACCEPT DATA
SET/CLEAR R0SEQ BIT
ERROR FREE DATA PACKET?
N
IGNORE TRANSACTION
NO RESPONSE FROM
USB FUNCTION
Y
SET RXD0F TO 1
RECEIVE CONTROL ENDPOINT
INTERRUPT ENABLED?
(RXD0IE = 1)
N
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-29. OUT Token Data Flow for Receive Endpoint 0
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Freescale Semiconductor
Universal Serial Bus Module (USB)
SETUP transactions cannot be stalled by the USB function. A SETUP
received by a control endpoint will clear the ISTALL0 and OSTALL0 bits.
The conditions for receiving a SETUP interrupt are shown in
Figure 11-30.
VALID SETUP TOKEN
RECEIVED FOR ENDPOINT 0?
Y
USB MODULE ENABLED?
(USBEN = 1)
N
NO RESPONSE
FROM USB FUNCTION
N
NO RESPONSE
FROM USB FUNCTION
Y
ENDPOINT 0 RECEIVE READY TO RECEIVE?
(RX0E = 1) AND (RXD0F = 0)
Y
ACCEPT DATA
SET/CLEAR R0SEQ BIT
SET SETUP BIT TO 1
ERROR FREE DATA PACKET?
N
IGNORE TRANSACTION
NO RESPONSE FROM
USB FUNCTION
Y
SET RXD0F TO 1
RECEIVE CONTROL ENDPOINT
INTERRUPT ENABLED?
(RXD0IE = 1)
N
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-30. SETUP Token Data Flow for Receive Endpoint 0
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Universal Serial Bus Module (USB)
11.9.1.2 Transmit Control Endpoint 0
For a control IN transaction directed at endpoint 0, the USB module will
generate an interrupt by setting the TXD0F flag in the UIR1 register. The
conditions necessary for the interrupt to occur are shown in the flowchart
in Figure 11-31.
VALID IN TOKEN
RECEIVED FOR ENDPOINT 0
Y
USB MODULE ENABLED?
(USBEN = 1)
N
NO RESPONSE
FROM USB FUNCTION
N
SEND STALL
HANDSHAKE
N
SEND NAK
HANDSHAKE
N
NO RESPONSE
FROM USB FUNCTION
Y
TRANSMIT ENDPOINT NOT STALLED
BY FIRMWARE (ISTALL0 = 0)?
Y
TRANSMIT ENDPOINT READY TO TRANSFER?
(TX0E = 1) AND (TXD0F = 0)
Y
SEND DATA
DATA PID SET BY T0SEQ
ACK RECEIVED AND NO
TIMEOUT CONDITION OCCURS?
Y
SET TXD0F TO 1
TRANSMIT ENDPOINT
INTERRUPT ENABLED?
(TXD0IE = 1)
N
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-31. IN Token Data Flow for Transmit Endpoint 0
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Universal Serial Bus Module (USB)
11.9.1.3 Transmit Endpoint 1
For an IN transaction directed at endpoint 1, the USB module will
generate an interrupt by setting the TXD1F in the UIR1 register. The
conditions necessary for the interrupt to occur are shown in
Figure 11-32.
VALID IN TOKEN
RECEIVED FOR ENDPOINT 1
Y
USB MODULE ENABLED?
(USBEN = 1)
N
NO RESPONSE
FROM USB FUNCTION
N
SEND STALL
HANDSHAKE
N
SEND NAK
HANDSHAKE
N
NO RESPONSE
FROM USB FUNCTION
N
NO RESPONSE
FROM USB FUNCTION
Y
TRANSMIT ENDPOINT NOT STALLED
BY FIRMWARE (STALL1 = 1)?
Y
TRANSMIT ENDPOINT READY TO TRANSFER?
(TX1E = 1) AND (TXD1F = 0) AND (UE1TR = 0)
Y
TRANSMIT ENDPOINT ENABLED?
(ENABLE = 1)
Y
SEND DATA
DATA PID SET BY T1SEQ
ACK RECEIVED AND NO
TIMEOUT CONDITION OCCURS?
Y
SET TXD1F TO 1
TRANSMIT ENDPOINT
INTERRUPT ENABLED?
(TXD1IE = 1)
N
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-32. IN Token Data Flow for Transmit Endpoint 1
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Universal Serial Bus Module (USB)
11.9.1.4 Transmit Endpoint 2
For an IN transaction directed at endpoint 2, the USB module will
generate an interrupt by setting the TXD2F in the UIR1 register.
11.9.1.5 Receive Endpoint 2
For an OUT transaction directed at endpoint 2, the USB module will
generate an interrupt by setting the RXD2F in the UIR1 register.
11.9.2 Resume Interrupt
The USB module will generate a CPU interrupt if low-speed bus activity
is detected after entering the suspend state. A transition of the USB data
lines to the non-idle state (K state) while in the suspend mode will set the
RESUMF flag in the UIR1 register. There is no interrupt enable bit for this
interrupt source and an interrupt will be executed if the I-bit in the CCR
is cleared. A resume interrupt can only occur while the MCU is in the
suspend mode.
11.9.3 End-of-Packet Interrupt
The USB module can generate a USB interrupt upon detection of an
end-of-packet signal for low-speed devices. Upon detection of an endof-packet signal, the USB module sets the EOPF bit and will generate a
CPU interrupt if the EOPIE bit in the UIR0 register is set.
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Technical Data — MC68HC908JB16
Section 12. Serial Communications Interface Module
(SCI)
12.1 Contents
12.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
12.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
12.5.1 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.5.2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.5.2.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
12.5.2.2
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . 215
12.5.2.3
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
12.5.2.4
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
12.5.2.5
Inversion of Transmitted Output. . . . . . . . . . . . . . . . . . . 217
12.5.2.6
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . .217
12.5.3 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.2
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.5.3.3
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
12.5.3.4
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
12.5.3.5
Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . .222
12.5.3.6
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.5.3.7
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.5.3.8
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
12.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
12.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
12.7
SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . .228
12.8 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
12.8.1 TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
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Serial Communications Interface
12.8.2
RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
12.9 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.9.1 SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.9.2 SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
12.9.3 SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
12.9.4 SCI Status Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
12.9.5 SCI Status Register 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
12.9.6 SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
12.9.7 SCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . .244
12.2 Introduction
This section describes the serial communications interface (SCI)
module, which allows high-speed asynchronous communications with
peripheral devices and other MCUs.
NOTE:
References to DMA (direct-memory access) and associated functions
are only valid if the MCU has a DMA module. This MCU does not have
the DMA function. Any DMA-related register bits should be left in their
reset state for normal MCU operation.
12.3 Features
Features of the SCI module include the following:
•
Full-duplex operation
•
Standard mark/space non-return-to-zero (NRZ) format
•
32 programmable baud rates
•
Programmable 8-bit or 9-bit character length
•
Separately enabled transmitter and receiver
•
Separate receiver and transmitter CPU interrupt requests
•
Programmable transmitter output polarity
•
Baud rate clock source is OSCDCLK (2 × OSCXCLK)
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Serial Communications Interface Module (SCI)
•
Two receiver wakeup methods:
– Idle line wakeup
– Address mark wakeup
•
Interrupt-driven operation with eight interrupt flags:
– Transmitter empty
– Transmission complete
– Receiver full
– Idle receiver input
– Receiver overrun
– Noise error
– Framing error
– Parity error
•
Receiver framing error detection
•
Hardware parity checking
•
1/16 bit-time noise detection
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Serial Communications Interface
12.4 Pin Name Conventions
The generic names of the SCI I/O pins are:
•
RxD (receive data)
•
TxD (transmit data)
SCI I/O (input/output) lines are implemented by sharing parallel I/O port
pins. The full name of an SCI input or output reflects the name of the
shared port pin. Table 12-1 shows the full names and the generic names
of the SCI I/O pins.
The generic pin names appear in the text of this section.
Table 12-1. Pin Name Conventions
Generic Pin Names:
RxD
TxD
Full Pin Names:
PTC1/RxD
PTC0/TxD
12.5 Functional Description
Figure 12-1 shows the structure of the SCI module. The SCI allows fullduplex, asynchronous, NRZ serial communication among the MCU and
remote devices, including other MCUs. The transmitter and receiver of
the SCI operate independently, although they use the same baud rate
generator. During normal operation, the CPU monitors the status of the
SCI, writes the data to be transmitted, and processes received data.
The baud rate clock source for the SCI is the OSCDCLK from the
oscillator circuit, which is two times the crystal clock, OSCXCLK.
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Serial Communications Interface Module (SCI)
INTERNAL BUS
SCI DATA
REGISTER
ERROR
INTERRUPT
CONTROL
RECEIVER
INTERRUPT
CONTROL
DMA
INTERRUPT
CONTROL
RECEIVE
SHIFT REGISTER
RxD
TRANSMITTER
INTERRUPT
CONTROL
SCI DATA
REGISTER
TRANSMIT
SHIFT REGISTER
TxD
TXINV
SCTIE
R8
TCIE
T8
SCRIE
ILIE
DMARE
TE
SCTE
RE
DMATE
TC
RWU
SBK
SCRF
OR
ORIE
IDLE
NF
NEIE
FE
FEIE
PE
PEIE
LOOPS
LOOPS
WAKEUP
CONTROL
FLAG
CONTROL
RECEIVE
CONTROL
ENSCI
ENSCI
TRANSMIT
CONTROL
BKF
M
RPF
WAKE
ILTY
OSCDCLK
÷3
PRESCALER
BAUD
DIVIDER
÷ 16
PEN
PTY
DATA SELECTION
CONTROL
Figure 12-1. SCI Module Block Diagram
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Serial Communications Interface
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
0
0
0
0
0
0
0
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
Read:
$005A
LOOPS
SCI Control Register 1
Write:
(SCC1)
Reset:
0
Read:
$005B
$005C
SCI Control Register 2
Write:
(SCC2)
Reset:
Read:
R8
SCI Control Register 3
Write:
(SCC3)
Reset:
U
U
0
0
0
0
0
0
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
1
1
0
0
0
0
0
0
BKF
RPF
Read:
$005D
SCI Status Register 1
Write:
(SCS1)
Reset:
Read:
$005E
$005F
$0060
SCI Status Register 2
Write:
(SCS2)
Reset:
0
0
0
0
0
0
0
0
Read:
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
SCR2
SCR1
SCR0
0
0
0
SCI Data Register
Write:
(SCDR)
Reset:
Unaffected by reset
Read:
0
0
SCI Baud Rate Register
Write:
(SCBR)
Reset:
0
0
SCP1
SCP0
0
0
= Unimplemented
R
R = Reserved
U = Unaffected
Figure 12-2. SCI I/O Register Summary
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Serial Communications Interface Module (SCI)
12.5.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format
illustrated in Figure 12-3.
8-BIT DATA FORMAT
BIT M IN SCC1 CLEAR
START
BIT
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
PARITY
BIT
BIT 6
BIT 7
9-BIT DATA FORMAT
BIT M IN SCC1 SET
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
STOP
BIT
NEXT
START
BIT
PARITY
BIT
BIT 6
BIT 7
BIT 8
STOP
BIT
NEXT
START
BIT
Figure 12-3. SCI Data Formats
12.5.2 Transmitter
Figure 12-4 shows the structure of the SCI transmitter.
The baud rate clock source for the SCI is the OSCDCLK.
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Serial Communications Interface
INTERNAL BUS
÷ 16
SCI DATA REGISTER
SCP1
11-BIT
TRANSMIT
SHIFT REGISTER
STOP
SCP0
SCR1
H
SCR2
7
6
5
4
3
2
1
0
L
TxD
MSB
TXINV
PEN
PTY
PARITY
GENERATION
T8
DMATE
DMATE
SCTIE
SCTE
DMATE
SCTE
SCTIE
TC
TCIE
BREAK
ALL 0s
M
LOAD FROM SCDR
TRANSMITTER DMA SERVICE REQUEST
TRANSMITTER CPU INTERRUPT REQUEST
SCR0
8
START
BAUD
DIVIDER
PREAMBLE
ALL 1s
PRESCALER
÷3
SHIFT ENABLE
OSCDCLK
TRANSMITTER
CONTROL LOGIC
SCTE
SBK
LOOPS
SCTIE
ENSCI
TC
TE
TCIE
Figure 12-4. SCI Transmitter
Technical Data
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Serial Communications Interface Module (SCI)
12.5.2.1 Character Length
The transmitter can accommodate either 8-bit or 9-bit data. The state of
the M bit in SCI control register 1 (SCC1) determines character length.
When transmitting 9-bit data, bit T8 in SCI control register 3 (SCC3) is
the ninth bit (bit 8).
12.5.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character
out to the TxD pin. The SCI data register (SCDR) is the write-only buffer
between the internal data bus and the transmit shift register. To initiate
an SCI transmission:
1. Enable the SCI by writing a logic 1 to the enable SCI bit (ENSCI)
in SCI control register 1 (SCC1).
2. Enable the transmitter by writing a logic 1 to the transmitter enable
bit (TE) in SCI control register 2 (SCC2).
3. Clear the SCI transmitter empty bit by first reading SCI status
register 1 (SCS1) and then writing to the SCDR.
4. Repeat step 3 for each subsequent transmission.
At the start of a transmission, transmitter control logic automatically
loads the transmit shift register with a preamble of logic 1s. After the
preamble shifts out, control logic transfers the SCDR data into the
transmit shift register. A logic 0 start bit automatically goes into the least
significant bit position of the transmit shift register. A logic 1 stop bit goes
into the most significant bit position.
The SCI transmitter empty bit, SCTE, in SCS1 becomes set when the
SCDR transfers a byte to the transmit shift register. The SCTE bit
indicates that the SCDR can accept new data from the internal data bus.
If the SCI transmit interrupt enable bit, SCTIE, in SCC2 is also set, the
SCTE bit generates a transmitter CPU interrupt request.
When the transmit shift register is not transmitting a character, the TxD
pin goes to the idle condition, logic 1. If at any time software clears the
ENSCI bit in SCI control register 1 (SCC1), the transmitter and receiver
relinquish control of the port pin.
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Serial Communications Interface
12.5.2.3 Break Characters
Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit
shift register with a break character. A break character contains all logic
0s and has no start, stop, or parity bit. Break character length depends
on the M bit in SCC1. As long as SBK is at logic 1, transmitter logic
continuously loads break characters into the transmit shift register. After
software clears the SBK bit, the shift register finishes transmitting the
last break character and then transmits at least one logic 1. The
automatic logic 1 at the end of a break character guarantees the
recognition of the start bit of the next character.
The SCI recognizes a break character when a start bit is followed by
eight or nine logic 0 data bits and a logic 0 where the stop bit should be.
Receiving a break character has these effects on SCI registers:
•
Sets the framing error bit (FE) in SCS1
•
Sets the SCI receiver full bit (SCRF) in SCS1
•
Clears the SCI data register (SCDR)
•
Clears the R8 bit in SCC3
•
Sets the break flag bit (BKF) in SCS2
•
May set the overrun (OR), noise flag (NF), parity error (PE), or
reception in progress flag (RPF) bits
12.5.2.4 Idle Characters
An idle character contains all logic 1s and has no start, stop, or parity bit.
Idle character length depends on the M bit in SCC1. The preamble is a
synchronizing idle character that begins every transmission.
If the TE bit is cleared during a transmission, the TxD pin becomes idle
after completion of the transmission in progress. Clearing and then
setting the TE bit during a transmission queues an idle character to be
sent after the character currently being transmitted.
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Serial Communications Interface Module (SCI)
NOTE:
When queueing an idle character, return the TE bit to logic 1 before the
stop bit of the current character shifts out to the TxD pin. Setting TE after
the stop bit appears on TxD causes data previously written to the SCDR
to be lost.
Toggle the TE bit for a queued idle character when the SCTE bit
becomes set and just before writing the next byte to the SCDR.
12.5.2.5 Inversion of Transmitted Output
The transmit inversion bit (TXINV) in SCI control register 1 (SCC1)
reverses the polarity of transmitted data. All transmitted values, including
idle, break, start, and stop bits, are inverted when TXINV is at logic 1.
(See 12.9.1 SCI Control Register 1.)
12.5.2.6 Transmitter Interrupts
These conditions can generate CPU interrupt requests from the SCI
transmitter:
•
SCI transmitter empty (SCTE) — The SCTE bit in SCS1 indicates
that the SCDR has transferred a character to the transmit shift
register. SCTE can generate a transmitter CPU interrupt request.
Setting the SCI transmit interrupt enable bit, SCTIE, in SCC2
enables the SCTE bit to generate transmitter CPU interrupt
requests.
•
Transmission complete (TC) — The TC bit in SCS1 indicates that
the transmit shift register and the SCDR are empty and that no
break or idle character has been generated. The transmission
complete interrupt enable bit, TCIE, in SCC2 enables the TC bit to
generate transmitter CPU interrupt requests.
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Serial Communications Interface
12.5.3 Receiver
Figure 12-5 shows the structure of the SCI receiver.
12.5.3.1 Character Length
The receiver can accommodate either 8-bit or 9-bit data. The state of the
M bit in SCI control register 1 (SCC1) determines character length.
When receiving 9-bit data, bit R8 in SCI control register 2 (SCC2) is the
ninth bit (bit 8). When receiving 8-bit data, bit R8 is a copy of the eighth
bit (bit 7).
12.5.3.2 Character Reception
During an SCI reception, the receive shift register shifts characters in
from the RxD pin. The SCI data register (SCDR) is the read-only buffer
between the internal data bus and the receive shift register.
After a complete character shifts into the receive shift register, the data
portion of the character transfers to the SCDR. The SCI receiver full bit,
SCRF, in SCI status register 1 (SCS1) becomes set, indicating that the
received byte can be read. If the SCI receive interrupt enable bit, SCRIE,
in SCC2 is also set, the SCRF bit generates a receiver CPU interrupt
request.
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Serial Communications Interface Module (SCI)
INTERNAL BUS
SCR1
SCR2
SCP0
SCR0
BAUD
DIVIDER
÷ 16
DATA
RECOVERY
RxD
CPU INTERRUPT REQUEST
8
7
6
M
WAKE
ILTY
PEN
PTY
5
4
3
2
1
0
L
ALL 0s
RPF
ERROR CPU INTERRUPT REQUEST
DMA SERVICE REQUEST
H
ALL 1s
BKF
11-BIT
RECEIVE SHIFT REGISTER
STOP
PRESCALER
MSB
÷3
OSCDCLK
SCI DATA REGISTER
START
SCP1
SCRF
WAKEUP
LOGIC
IDLE
R8
PARITY
CHECKING
IDLE
ILIE
DMARE
SCRF
SCRIE
DMARE
SCRF
SCRIE
DMARE
ILIE
SCRIE
DMARE
OR
ORIE
RWU
OR
ORIE
NF
NEIE
FE
FEIE
PE
PEIE
NF
NEIE
FE
FEIE
PE
PEIE
Figure 12-5. SCI Receiver Block Diagram
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Serial Communications Interface
12.5.3.3 Data Sampling
The receiver samples the RxD pin at the RT clock rate. The RT clock is
an internal signal with a frequency 16 times the baud rate. To adjust for
baud rate mismatch, the RT clock is resynchronized at the following
times (see Figure 12-6):
•
After every start bit
•
After the receiver detects a data bit change from logic 1 to logic 0
(after the majority of data bit samples at RT8, RT9, and RT10
returns a valid logic 1 and the majority of the next RT8, RT9, and
RT10 samples returns a valid logic 0)
To locate the start bit, data recovery logic does an asynchronous search
for a logic 0 preceded by three logic 1s. When the falling edge of a
possible start bit occurs, the RT clock begins to count to 16.
START BIT
LSB
START BIT
VERIFICATION
DATA
SAMPLING
RT8
START BIT
QUALIFICATION
SAMPLES
RT3
RxD
RT4
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT7
RT6
RT5
RT4
RT2
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT CLOCK
STATE
RT1
RT
CLOCK
RT CLOCK
RESET
Figure 12-6. Receiver Data Sampling
Technical Data
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Serial Communications Interface Module (SCI)
To verify the start bit and to detect noise, data recovery logic takes
samples at RT3, RT5, and RT7. Table 12-2 summarizes the results of
the start bit verification samples.
Table 12-2. Start Bit Verification
RT3, RT5, and RT7
Samples
Start Bit
Verification
Noise Flag
000
Yes
0
001
Yes
1
010
Yes
1
011
No
0
100
Yes
1
101
No
0
110
No
0
111
No
0
Start bit verification is not successful if any two of the three verification
samples are logic 1s. If start bit verification is not successful, the RT
clock is reset and a new search for a start bit begins.
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10. Table 12-3 summarizes the
results of the data bit samples.
Table 12-3. Data Bit Recovery
RT8, RT9, and RT10
Samples
Data Bit
Determination
Noise Flag
000
0
0
001
0
1
010
0
1
011
1
1
100
0
1
101
1
1
110
1
1
111
1
0
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Serial Communications Interface
NOTE:
The RT8, RT9, and RT10 samples do not affect start bit verification. If
any or all of the RT8, RT9, and RT10 start bit samples are logic 1s
following a successful start bit verification, the noise flag (NF) is set and
the receiver assumes that the bit is a start bit.
To verify a stop bit and to detect noise, recovery logic takes samples at
RT8, RT9, and RT10. Table 12-4 summarizes the results of the stop bit
samples.
Table 12-4. Stop Bit Recovery
RT8, RT9, and RT10
Samples
Framing
Error Flag
Noise Flag
000
1
0
001
1
1
010
1
1
011
0
1
100
1
1
101
0
1
110
0
1
111
0
0
12.5.3.4 Framing Errors
If the data recovery logic does not detect a logic 1 where the stop bit
should be in an incoming character, it sets the framing error bit, FE, in
SCS1. A break character also sets the FE bit because a break character
has no stop bit. The FE bit is set at the same time that the SCRF bit is
set.
12.5.3.5 Baud Rate Tolerance
A transmitting device may be operating at a baud rate below or above
the receiver baud rate. Accumulated bit time misalignment can cause
one of the three stop bit data samples to fall outside the actual stop bit.
Then a noise error occurs. If more than one of the samples is outside the
stop bit, a framing error occurs. In most applications, the baud rate
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Serial Communications Interface Module (SCI)
tolerance is much more than the degree of misalignment that is likely to
occur.
As the receiver samples an incoming character, it resynchronizes the RT
clock on any valid falling edge within the character. Resynchronization
within characters corrects misalignments between transmitter bit times
and receiver bit times.
Slow Data Tolerance
Figure 12-7 shows how much a slow received character can be
misaligned without causing a noise error or a framing error. The slow
stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit
data samples at RT8, RT9, and RT10.
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
RT6
STOP
RT5
RT4
RT3
RT2
RECEIVER
RT CLOCK
RT1
MSB
DATA
SAMPLES
Figure 12-7. Slow Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in Figure 12-7, the receiver counts
154 RT cycles at the point when the count of the transmitting device is
9 bit times × 16 RT cycles + 3 RT cycles = 147 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 8-bit character with no errors is
154 – 147 × 100 = 4.54%
-------------------------154
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
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Serial Communications Interface
With the misaligned character shown in Figure 12-7, the receiver counts
170 RT cycles at the point when the count of the transmitting device is
10 bit times × 16 RT cycles + 3 RT cycles = 163 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 9-bit character with no errors is
170 – 163 × 100 = 4.12%
-------------------------170
Fast Data Tolerance
Figure 12-8 shows how much a fast received character can be
misaligned without causing a noise error or a framing error. The fast stop
bit ends at RT10 instead of RT16 but is still there for the stop bit data
samples at RT8, RT9, and RT10.
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
IDLE OR NEXT CHARACTER
RT6
RT5
RT4
RT3
RT2
RECEIVER
RT CLOCK
RT1
STOP
DATA
SAMPLES
Figure 12-8. Fast Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in Figure 12-8, the receiver counts
154 RT cycles at the point when the count of the transmitting device is
10 bit times × 16 RT cycles = 160 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 8-bit character with no errors is
·
154 – 160 × 100 = 3.90%
-------------------------154
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Serial Communications Interface Module (SCI)
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
With the misaligned character shown in Figure 12-8, the receiver counts
170 RT cycles at the point when the count of the transmitting device is
11 bit times × 16 RT cycles = 176 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 9-bit character with no errors is
170 – 176 × 100 = 3.53%
-------------------------170
12.5.3.6 Receiver Wakeup
So that the MCU can ignore transmissions intended only for other
receivers in multiple-receiver systems, the receiver can be put into a
standby state. Setting the receiver wakeup bit, RWU, in SCC2 puts the
receiver into a standby state during which receiver interrupts are
disabled.
Depending on the state of the WAKE bit in SCC1, either of two
conditions on the RxD pin can bring the receiver out of the standby state:
•
Address mark — An address mark is a logic 1 in the most
significant bit position of a received character. When the WAKE bit
is set, an address mark wakes the receiver from the standby state
by clearing the RWU bit. The address mark also sets the SCI
receiver full bit, SCRF. Software can then compare the character
containing the address mark to the user-defined address of the
receiver. If they are the same, the receiver remains awake and
processes the characters that follow. If they are not the same,
software can set the RWU bit and put the receiver back into the
standby state.
•
Idle input line condition — When the WAKE bit is clear, an idle
character on the RxD pin wakes the receiver from the standby
state by clearing the RWU bit. The idle character that wakes the
receiver does not set the receiver idle bit, IDLE, or the SCI receiver
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full bit, SCRF. The idle line type bit, ILTY, determines whether the
receiver begins counting logic 1s as idle character bits after the
start bit or after the stop bit.
NOTE:
With the WAKE bit clear, setting the RWU bit after the RxD pin has been
idle may cause the receiver to wake up immediately.
12.5.3.7 Receiver Interrupts
The following sources can generate CPU interrupt requests from the SCI
receiver:
•
SCI receiver full (SCRF) — The SCRF bit in SCS1 indicates that
the receive shift register has transferred a character to the SCDR.
SCRF can generate a receiver CPU interrupt request. Setting the
SCI receive interrupt enable bit, SCRIE, in SCC2 enables the
SCRF bit to generate receiver CPU interrupts.
•
Idle input (IDLE) — The IDLE bit in SCS1 indicates that 10 or 11
consecutive logic 1s shifted in from the RxD pin. The idle line
interrupt enable bit, ILIE, in SCC2 enables the IDLE bit to generate
CPU interrupt requests.
12.5.3.8 Error Interrupts
The following receiver error flags in SCS1 can generate CPU interrupt
requests:
•
Receiver overrun (OR) — The OR bit indicates that the receive
shift register shifted in a new character before the previous
character was read from the SCDR. The previous character
remains in the SCDR, and the new character is lost. The overrun
interrupt enable bit, ORIE, in SCC3 enables OR to generate SCI
error CPU interrupt requests.
•
Noise flag (NF) — The NF bit is set when the SCI detects noise on
incoming data or break characters, including start, data, and stop
bits. The noise error interrupt enable bit, NEIE, in SCC3 enables
NF to generate SCI error CPU interrupt requests.
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Serial Communications Interface Module (SCI)
•
Framing error (FE) — The FE bit in SCS1 is set when a logic 0
occurs where the receiver expects a stop bit. The framing error
interrupt enable bit, FEIE, in SCC3 enables FE to generate SCI
error CPU interrupt requests.
•
Parity error (PE) — The PE bit in SCS1 is set when the SCI
detects a parity error in incoming data. The parity error interrupt
enable bit, PEIE, in SCC3 enables PE to generate SCI error CPU
interrupt requests.
12.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low powerconsumption standby modes.
12.6.1 Wait Mode
The SCI module remains active after the execution of a WAIT
instruction. In wait mode, the SCI module registers are not accessible by
the CPU. Any enabled CPU interrupt request from the SCI module can
bring the MCU out of wait mode.
If SCI module functions are not required during wait mode, reduce power
consumption by disabling the module before executing the WAIT
instruction.
Refer to 8.7 Low-Power Modes for information on exiting wait mode.
12.6.2 Stop Mode
The SCI module is inactive after the execution of a STOP instruction.
The STOP instruction does not affect SCI register states. SCI module
operation resumes after an external interrupt.
Because the internal clock is inactive during stop mode, entering stop
mode during an SCI transmission or reception results in invalid data.
Refer to 8.7 Low-Power Modes for information on exiting stop mode.
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12.7 SCI During Break Module Interrupts
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state.
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
12.8 I/O Signals
Port C shares two of its pins with the SCI module. The two SCI I/O pins
are:
•
PTC0/TxD — Transmit data
•
PTC1/RxD — Receive data
12.8.1 TxD (Transmit Data)
The PTC0/TxD pin is the serial data output from the SCI transmitter. The
SCI shares the PTC0/TxD pin with port C. When the SCI is enabled, the
PTC0/TxD pin is an output regardless of the state of the DDRC0 bit in
data direction register C (DDRC).
12.8.2 RxD (Receive Data)
The PTC1/RxD pin is the serial data input to the SCI receiver. The SCI
shares the PTC1/RxD pin with port C. When the SCI is enabled, the
PTC1/RxD pin is an input regardless of the state of the DDRC1 bit in
data direction register C (DDRC).
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12.9 I/O Registers
These I/O registers control and monitor SCI operation:
•
SCI control register 1 (SCC1)
•
SCI control register 2 (SCC2)
•
SCI control register 3 (SCC3)
•
SCI status register 1 (SCS1)
•
SCI status register 2 (SCS2)
•
SCI data register (SCDR)
•
SCI baud rate register (SCBR)
12.9.1 SCI Control Register 1
SCI control register 1:
•
Enables loop mode operation
•
Enables the SCI
•
Controls output polarity
•
Controls character length
•
Controls SCI wakeup method
•
Controls idle character detection
•
Enables parity function
•
Controls parity type
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Address:
Read:
Write:
Reset:
$005A
Bit 7
6
5
4
3
2
1
Bit 0
LOOPS
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
0
0
0
0
0
0
0
0
Figure 12-9. SCI Control Register 1 (SCC1)
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the
RxD pin is disconnected from the SCI, and the transmitter output goes
into the receiver input. Both the transmitter and the receiver must be
enabled to use loop mode. Reset clears the LOOPS bit.
1 = Loop mode enabled
0 = Normal operation enabled
ENSCI — Enable SCI Bit
This read/write bit enables the SCI and the SCI baud rate generator.
Clearing ENSCI sets the SCTE and TC bits in SCI status register 1
and disables transmitter interrupts. Reset clears the ENSCI bit.
1 = SCI enabled
0 = SCI disabled
TXINV — Transmit Inversion Bit
This read/write bit reverses the polarity of transmitted data. Reset
clears the TXINV bit.
1 = Transmitter output inverted
0 = Transmitter output not inverted
NOTE:
Setting the TXINV bit inverts all transmitted values, including idle, break,
start, and stop bits.
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M — Mode (Character Length) Bit
This read/write bit determines whether SCI characters are eight or
nine bits long. (See Table 12-5.) The ninth bit can serve as an extra
stop bit, as a receiver wakeup signal, or as a parity bit. Reset clears
the M bit.
1 = 9-bit SCI characters
0 = 8-bit SCI characters
WAKE — Wakeup Condition Bit
This read/write bit determines which condition wakes up the SCI: a
logic 1 (address mark) in the most significant bit position of a received
character or an idle condition on the RxD pin. Reset clears the WAKE
bit.
1 = Address mark wakeup
0 = Idle line wakeup
ILTY — Idle Line Type Bit
This read/write bit determines when the SCI starts counting logic 1s
as idle character bits. The counting begins either after the start bit or
after the stop bit. If the count begins after the start bit, then a string of
logic 1s preceding the stop bit may cause false recognition of an idle
character. Beginning the count after the stop bit avoids false idle
character recognition, but requires properly synchronized
transmissions. Reset clears the ILTY bit.
1 = Idle character bit count begins after stop bit
0 = Idle character bit count begins after start bit
PEN — Parity Enable Bit
This read/write bit enables the SCI parity function. (See Table 12-5.)
When enabled, the parity function inserts a parity bit in the most
significant bit position. (See Figure 12-3.) Reset clears the PEN bit.
1 = Parity function enabled
0 = Parity function disabled
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PTY — Parity Bit
This read/write bit determines whether the SCI generates and checks
for odd parity or even parity. (See Table 12-5.) Reset clears the PTY
bit.
1 = Odd parity
0 = Even parity
NOTE:
Changing the PTY bit in the middle of a transmission or reception can
generate a parity error.
Table 12-5. Character Format Selection
Control Bits
Character Format
M
PEN and
PTY
Start
Bits
Data
Bits
Parity
Stop
Bits
Character
Length
0
0X
1
8
None
1
10 bits
1
0X
1
9
None
1
11 bits
0
10
1
7
Even
1
10 bits
0
11
1
7
Odd
1
10 bits
1
10
1
8
Even
1
11 bits
1
11
1
8
Odd
1
11 bits
12.9.2 SCI Control Register 2
SCI control register 2:
•
Enables the following CPU interrupt requests:
– Enables the SCTE bit to generate transmitter CPU interrupt
requests
– Enables the TC bit to generate transmitter CPU interrupt
requests
– Enables the SCRF bit to generate receiver CPU interrupt
requests
– Enables the IDLE bit to generate receiver CPU interrupt
requests
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•
Enables the transmitter
•
Enables the receiver
•
Enables SCI wakeup
•
Transmits SCI break characters
Address:
Read:
Write:
Reset:
$005B
Bit 7
6
5
4
3
2
1
Bit 0
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
Figure 12-10. SCI Control Register 2 (SCC2)
SCTIE — SCI Transmit Interrupt Enable Bit
This read/write bit enables the SCTE bit to generate SCI transmitter
CPU interrupt requests. Reset clears the SCTIE bit.
1 = SCTE enabled to generate CPU interrupt
0 = SCTE not enabled to generate CPU interrupt
TCIE — Transmission Complete Interrupt Enable Bit
This read/write bit enables the TC bit to generate SCI transmitter CPU
interrupt requests. Reset clears the TCIE bit.
1 = TC enabled to generate CPU interrupt requests
0 = TC not enabled to generate CPU interrupt requests
SCRIE — SCI Receive Interrupt Enable Bit
This read/write bit enables the SCRF bit to generate SCI receiver
CPU interrupt requests. Reset clears the SCRIE bit.
1 = SCRF enabled to generate CPU interrupt
0 = SCRF not enabled to generate CPU interrupt
ILIE — Idle Line Interrupt Enable Bit
This read/write bit enables the IDLE bit to generate SCI receiver CPU
interrupt requests. Reset clears the ILIE bit.
1 = IDLE enabled to generate CPU interrupt requests
0 = IDLE not enabled to generate CPU interrupt requests
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TE — Transmitter Enable Bit
Setting this read/write bit begins the transmission by sending a
preamble of 10 or 11 logic 1s from the transmit shift register to the
TxD pin. If software clears the TE bit, the transmitter completes any
transmission in progress before the TxD returns to the idle condition
(logic 1). Clearing and then setting TE during a transmission queues
an idle character to be sent after the character currently being
transmitted. Reset clears the TE bit.
1 = Transmitter enabled
0 = Transmitter disabled
NOTE:
Writing to the TE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RE — Receiver Enable Bit
Setting this read/write bit enables the receiver. Clearing the RE bit
disables the receiver but does not affect receiver interrupt flag bits.
Reset clears the RE bit.
1 = Receiver enabled
0 = Receiver disabled
NOTE:
Writing to the RE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RWU — Receiver Wakeup Bit
This read/write bit puts the receiver in a standby state during which
receiver interrupts are disabled. The WAKE bit in SCC1 determines
whether an idle input or an address mark brings the receiver out of the
standby state and clears the RWU bit. Reset clears the RWU bit.
1 = Standby state
0 = Normal operation
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SBK — Send Break Bit
Setting and then clearing this read/write bit transmits a break
character followed by a logic 1. The logic 1 after the break character
guarantees recognition of a valid start bit. If SBK remains set, the
transmitter continuously transmits break characters with no logic 1s
between them. Reset clears the SBK bit.
1 = Transmit break characters
0 = No break characters being transmitted
NOTE:
Do not toggle the SBK bit immediately after setting the SCTE bit.
Toggling SBK before the preamble begins causes the SCI to send a
break character instead of a preamble.
12.9.3 SCI Control Register 3
SCI control register 3:
•
Stores the ninth SCI data bit received and the ninth SCI data bit to
be transmitted
•
Enables these interrupts:
– Receiver overrun interrupts
– Noise error interrupts
– Framing error interrupts
•
Parity error interrupts
Address:
$005C
Bit 7
Read:
R8
Write:
Reset:
U
6
5
4
3
2
1
Bit 0
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
U
0
0
0
0
0
0
= Unimplemented
U = Unaffected
Figure 12-11. SCI Control Register 3 (SCC3)
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R8 — Received Bit 8
When the SCI is receiving 9-bit characters, R8 is the read-only ninth
bit (bit 8) of the received character. R8 is received at the same time
that the SCDR receives the other 8 bits.
When the SCI is receiving 8-bit characters, R8 is a copy of the eighth
bit (bit 7). Reset has no effect on the R8 bit.
T8 — Transmitted Bit 8
When the SCI is transmitting 9-bit characters, T8 is the read/write
ninth bit (bit 8) of the transmitted character. T8 is loaded into the
transmit shift register at the same time that the SCDR is loaded into
the transmit shift register. Reset has no effect on the T8 bit.
DMARE — DMA Receive Enable Bit
CAUTION:
The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
0 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
DMATE — DMA Transfer Enable Bit
CAUTION:
The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = SCTE DMA service requests enabled; SCTE CPU interrupt
requests disabled
0 = SCTE DMA service requests disabled; SCTE CPU interrupt
requests enabled
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ORIE — Receiver Overrun Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the receiver overrun bit, OR.
1 = SCI error CPU interrupt requests from OR bit enabled
0 = SCI error CPU interrupt requests from OR bit disabled
NEIE — Receiver Noise Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the noise error bit, NE. Reset clears NEIE.
1 = SCI error CPU interrupt requests from NE bit enabled
0 = SCI error CPU interrupt requests from NE bit disabled
FEIE — Receiver Framing Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the framing error bit, FE. Reset clears FEIE.
1 = SCI error CPU interrupt requests from FE bit enabled
0 = SCI error CPU interrupt requests from FE bit disabled
PEIE — Receiver Parity Error Interrupt Enable Bit
This read/write bit enables SCI receiver CPU interrupt
requests generated by the parity error bit, PE. (See 12.9.4 SCI Status
Register 1.) Reset clears PEIE.
1 = SCI error CPU interrupt requests from PE bit enabled
0 = SCI error CPU interrupt requests from PE bit disabled
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12.9.4 SCI Status Register 1
SCI status register 1 (SCS1) contains flags to signal these conditions:
•
Transfer of SCDR data to transmit shift register complete
•
Transmission complete
•
Transfer of receive shift register data to SCDR complete
•
Receiver input idle
•
Receiver overrun
•
Noisy data
•
Framing error
•
Parity error
Address:
Read:
$005D
Bit 7
6
5
4
3
2
1
Bit 0
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
1
1
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 12-12. SCI Status Register 1 (SCS1)
SCTE — SCI Transmitter Empty Bit
This clearable, read-only bit is set when the SCDR transfers a
character to the transmit shift register. SCTE can generate an SCI
transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set,
SCTE generates an SCI transmitter CPU interrupt request. In normal
operation, clear the SCTE bit by reading SCS1 with SCTE set and
then writing to SCDR. Reset sets the SCTE bit.
1 = SCDR data transferred to transmit shift register
0 = SCDR data not transferred to transmit shift register
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TC — Transmission Complete Bit
This read-only bit is set when the SCTE bit is set, and no data,
preamble, or break character is being transmitted. TC generates an
SCI transmitter CPU interrupt request if the TCIE bit in SCC2 is also
set. TC is automatically cleared when data, preamble or break is
queued and ready to be sent. There may be up to 1.5 transmitter
clocks of latency between queueing data, preamble, and break and
the transmission actually starting. Reset sets the TC bit.
1 = No transmission in progress
0 = Transmission in progress
SCRF — SCI Receiver Full Bit
This clearable, read-only bit is set when the data in the receive shift
register transfers to the SCI data register. SCRF can generate an SCI
receiver CPU interrupt request. When the SCRIE bit in SCC2 is set,
SCRF generates a CPU interrupt request. In normal operation, clear
the SCRF bit by reading SCS1 with SCRF set and then reading the
SCDR. Reset clears SCRF.
1 = Received data available in SCDR
0 = Data not available in SCDR
IDLE — Receiver Idle Bit
This clearable, read-only bit is set when 10 or 11 consecutive logic 1s
appear on the receiver input. IDLE generates an SCI error CPU
interrupt request if the ILIE bit in SCC2 is also set. Clear the IDLE bit
by reading SCS1 with IDLE set and then reading the SCDR. After the
receiver is enabled, it must receive a valid character that sets the
SCRF bit before an idle condition can set the IDLE bit. Also, after the
IDLE bit has been cleared, a valid character must again set the SCRF
bit before an idle condition can set the IDLE bit. Reset clears the IDLE
bit.
1 = Receiver input idle
0 = Receiver input active (or idle since the IDLE bit was cleared)
OR — Receiver Overrun Bit
This clearable, read-only bit is set when software fails to read the
SCDR before the receive shift register receives the next character.
The OR bit generates an SCI error CPU interrupt request if the ORIE
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bit in SCC3 is also set. The data in the shift register is lost, but the data
already in the SCDR is not affected. Clear the OR bit by reading SCS1
with OR set and then reading the SCDR. Reset clears the OR bit.
1 = Receive shift register full and SCRF = 1
0 = No receiver overrun
Software latency may allow an overrun to occur between reads of
SCS1 and SCDR in the flag-clearing sequence. Figure 12-13 shows
the normal flag-clearing sequence and an example of an overrun
caused by a delayed flag-clearing sequence. The delayed read of
SCDR does not clear the OR bit because OR was not set when SCS1
was read. Byte 2 caused the overrun and is lost. The next flagclearing sequence reads byte 3 in the SCDR instead of byte 2.
In applications that are subject to software latency or in which it is
important to know which byte is lost due to an overrun, the flagclearing routine can check the OR bit in a second read of SCS1 after
reading the data register.
NF — Receiver Noise Flag Bit
This clearable, read-only bit is set when the SCI detects noise on the
RxD pin. NF generates an NF CPU interrupt request if the NEIE bit in
SCC3 is also set. Clear the NF bit by reading SCS1 and then reading
the SCDR. Reset clears the NF bit.
1 = Noise detected
0 = No noise detected
FE — Receiver Framing Error Bit
This clearable, read-only bit is set when a logic 0 is accepted as the
stop bit. FE generates an SCI error CPU interrupt request if the FEIE
bit in SCC3 also is set. Clear the FE bit by reading SCS1 with FE set
and then reading the SCDR. Reset clears the FE bit.
1 = Framing error detected
0 = No framing error detected
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BYTE 1
BYTE 2
BYTE 3
SCRF = 0
SCRF = 1
SCRF = 0
SCRF = 1
SCRF = 0
SCRF = 1
NORMAL FLAG CLEARING SEQUENCE
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 1
READ SCDR
BYTE 2
READ SCDR
BYTE 3
BYTE 1
BYTE 2
BYTE 3
SCRF = 0
OR = 0
SCRF = 1
OR = 1
SCRF = 0
OR = 1
SCRF = 1
SCRF = 1
OR = 1
DELAYED FLAG CLEARING SEQUENCE
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 1
READ SCDR
BYTE 1
READ SCDR
BYTE 3
Figure 12-13. Flag Clearing Sequence
PE — Receiver Parity Error Bit
This clearable, read-only bit is set when the SCI detects a parity error
in incoming data. PE generates a PE CPU interrupt request if the
PEIE bit in SCC3 is also set. Clear the PE bit by reading SCS1 with
PE set and then reading the SCDR. Reset clears the PE bit.
1 = Parity error detected
0 = No parity error detected
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12.9.5 SCI Status Register 2
SCI status register 2 contains flags to signal the following conditions:
•
Break character detected
•
Incoming data
Address:
$005E
Bit 7
6
5
4
3
2
Read:
1
Bit 0
BKF
RPF
0
0
Write:
Reset:
0
0
0
0
0
0
= Unimplemented
Figure 12-14. SCI Status Register 2 (SCS2)
BKF — Break Flag Bit
This clearable, read-only bit is set when the SCI detects a break
character on the RxD pin. In SCS1, the FE and SCRF bits are also
set. In 9-bit character transmissions, the R8 bit in SCC3 is cleared.
BKF does not generate a CPU interrupt request. Clear BKF by
reading SCS2 with BKF set and then reading the SCDR. Once
cleared, BKF can become set again only after logic 1s again appear
on the RxD pin followed by another break character. Reset clears the
BKF bit.
1 = Break character detected
0 = No break character detected
RPF — Reception in Progress Flag Bit
This read-only bit is set when the receiver detects a logic 0 during the
RT1 time period of the start bit search. RPF does not generate an
interrupt request. RPF is reset after the receiver detects false start bits
(usually from noise or a baud rate mismatch) or when the receiver
detects an idle character. Polling RPF before disabling the SCI
module or entering stop mode can show whether a reception is in
progress.
1 = Reception in progress
0 = No reception in progress
Technical Data
242
MC68HC908JB16 — Rev. 1.1
Serial Communications Interface Module (SCI)
Freescale Semiconductor
Serial Communications Interface Module (SCI)
12.9.6 SCI Data Register
The SCI data register (SCDR) is the buffer between the internal data bus
and the receive and transmit shift registers.
Address:
$005F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
Reset:
Unaffected by reset
Figure 12-15. SCI Data Register (SCDR)
R7/T7–R0/T0 — Receive/Transmit Data Bits
Reading the SCI data register accesses the read-only received data
bits, R7:R0. Writing to the SCI data register writes the data to be
transmitted, T7:T0. Reset has no effect on the SCI data register.
NOTE:
Do not use read/modify/write instructions on the SCI data register.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Serial Communications Interface Module (SCI)
243
Serial Communications Interface
12.9.7 SCI Baud Rate Register
The baud rate register (SCBR) selects the baud rate for both the receiver
and the transmitter.
Address:
Read:
$0060
Bit 7
6
0
0
0
0
Write:
Reset:
5
4
3
2
1
Bit 0
SCP1
SCP0
R
SCR2
SCR1
SCR0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 12-16. SCI Baud Rate Register (SCBR)
SCP1 and SCP0 — SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown
in Table 12-6. Reset clears SCP1 and SCP0.
Table 12-6. SCI Baud Rate Prescaling
SCP1 and SCP0
Prescaler Divisor (PD)
00
1
01
3
10
4
11
13
SCR2–SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in
Table 12-7. Reset clears SCR2–SCR0.
Technical Data
244
MC68HC908JB16 — Rev. 1.1
Serial Communications Interface Module (SCI)
Freescale Semiconductor
Serial Communications Interface Module (SCI)
Table 12-7. SCI Baud Rate Selection
SCR2, SCR1, and SCR0
Baud Rate Divisor (BD)
000
1
001
2
010
4
011
8
100
16
101
32
110
64
111
128
Use this formula to calculate the SCI baud rate:
SCI clock source
baud rate = --------------------------------------------48 × PD × BD
where:
SCI clock source = OSCDCLK
PD = prescaler divisor
BD = baud rate divisor
Table 12-8 shows the SCI baud rates that can be generated with a
24MHz OSCDCLK (OSCXCLK=12MHz) as SCI clock source.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Serial Communications Interface Module (SCI)
245
Serial Communications Interface
Table 12-8. SCI Baud Rate Selection Examples
SCP1 and SCP0
Prescaler
Divisor (PD)
SCR2, SCR1,
and SCR0
Baud Rate
Divisor (BD)
00
1
000
1
00
1
001
2
00
1
010
4
00
1
011
8
00
1
100
16
00
1
101
32
00
1
110
64
00
1
111
128
01
3
000
1
01
3
001
2
01
3
010
4
01
3
011
8
01
3
100
16
01
3
101
32
01
3
110
64
01
3
111
128
10
4
000
1
10
4
001
2
10
4
010
4
10
4
011
8
10
4
100
16
10
4
101
32
10
4
110
64
10
4
111
128
11
13
000
1
38461.54
11
13
001
2
19230.77
11
13
010
4
9615.38
11
13
011
8
4807.69
11
13
100
16
2403.85
11
13
101
32
1201.92
11
13
110
64
600.96
11
13
111
128
300.48
Technical Data
246
Baud Rate
(OSCDCLK=24MHz)
Baud rate settings
not recommended
MC68HC908JB16 — Rev. 1.1
Serial Communications Interface Module (SCI)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 13. Clock Generator Module (CGM)
13.1 Contents
13.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
13.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.3.1 Reference Frequency Source (OSCXCLK) . . . . . . . . . . . . 250
13.3.2 Voltage Controlled Oscillator . . . . . . . . . . . . . . . . . . . . . . .250
13.3.3 Reference Divider. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.3.4 VCO Frequency Divider . . . . . . . . . . . . . . . . . . . . . . . . . . .251
13.3.5 Phase Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
13.3.6 Phase Detector Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.3.7 Lock Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
13.4.1 CGM Power Supply Pins (VDDA, VSSA0, VSSA1) . . . . . . . . 252
13.4.2 CGM1 Voltage Regulator Out (VREGA0). . . . . . . . . . . . . . . 252
13.4.3 CGM2 Voltage Regulator In (VREGA1) . . . . . . . . . . . . . . . . 252
13.4.4 External Filter Capacitor Pins (CGMXFC1, CGMXFC2) . . 253
13.4.5 CGM Clock Output Pins (CGMOUT1, CGMOUT2) . . . . . . 253
13.5
CGMXFC External Connections . . . . . . . . . . . . . . . . . . . . . . . 253
13.6
CGMOUT External Connections. . . . . . . . . . . . . . . . . . . . . . . 254
13.7
Calculation of VCO Frequency . . . . . . . . . . . . . . . . . . . . . . . . 254
13.8
Programming the PLL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
13.9 CGM I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
13.9.1 Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . . . . . 256
13.9.2 VCO Control Register (PVCR) . . . . . . . . . . . . . . . . . . . . . . 256
13.9.3 VCO and Reference Divider Select Registers High . . . . . . 257
13.9.4 VCO Divider Select Register Low . . . . . . . . . . . . . . . . . . . 258
13.9.5 Reference Divider Select Register Low . . . . . . . . . . . . . . . 259
13.9.6 Phase Detector Control Register (PDCR) . . . . . . . . . . . . . 260
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
247
Clock Generator Module (CGM)
13.10 Pre-Defined VCO Output Frequency Settings . . . . . . . . . . . . 260
13.11 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
13.11.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
13.11.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
13.2 Introduction
This section describes the clock generation module (CGM). The CGM
operates at the frequency of the crystal, OSCXCLK, and generates
frequencies in the 27MHz range. This frequency range is targeted for RF
applications, such as in a local oscillator in a down conversion mixer
receiver.
This particular MCU has two clock generation modules which are
denoted as CGM1 and CGM2. Each CGM contains all the functional
blocks for PLL control of a VCO.
NOTE:
Addr.
$0051
$0052
References to either CGM1 or CGM2 may be made in the following text
by omitting the CGM number. For example, CGMOUT may refer
generically to CGMOUT1 and CGMOUT2, and LOCK bit may refer to
LOCK1 and LOCK2 bits.
Register Name
Bit 7
Read:
PLL Bandwidth Control
Register Write:
(PBWC)
Reset:
Read:
VCO Control Register
Write:
(PVCR)
Reset:
R
6
LOCK1
5
4
3
R
PLLON1
R
0
0
2
LOCK2
1
Bit 0
R
PLLON2
0
0
VCO_7
VCO_6
VCO_5
VCO_4
VCO_3
VCO_2
VCO_1
VCO_0
0
0
1
1
0
0
0
0
VDS1_9
VDS1_8
0
0
RDS1_9
RDS1_8
1
0
0
0
0
0
Read:
PLL1 N & R Divider Select
VDS1_11 VDS1_10
$0053
Register High Write:
(PNRH1)
Reset:
0
0
Figure 13-1. CGM I/O Register Summary
Technical Data
248
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
$0054
$0055
Read:
PLL1 N Divider Select
VDS1_7
Register Low Write:
(PNSL1)
Reset:
0
VDS1_6
VDS1_5
VDS1_4
VDS1_3
VDS1_2
VDS1_1
VDS1_0
1
1
1
1
1
0
1
RDS1_6
RDS1_5
RDS1_4
RDS1_3
RDS1_2
RDS1_1
RDS1_0
0
0
1
0
0
0
0
VDS2_9
VDS2_8
0
0
RDS2_9
RDS2_8
1
0
0
0
0
0
VDS2_6
VDS2_5
VDS2_4
VDS2_3
VDS2_2
VDS2_1
VDS2_0
1
1
1
1
1
0
1
RDS2_6
RDS2_5
RDS2_4
RDS2_3
RDS2_2
RDS2_1
RDS2_0
0
0
1
0
0
0
0
PHD_7
PHD_6
PHD_5
PHD_4
PHD_3
PHD_2
PHD_1
PHD_0
1
0
0
1
0
0
0
0
Read:
PLL1 R Divider Select
RDS1_7
Register Low Write:
(PRSL1)
Reset:
1
Read:
PLL2 N & R Divider Select
VDS2_11 VDS2_10
$0056
Register High Write:
(PNRH2)
Reset:
0
0
$0057
$0058
$0059
Read:
PLL2 N Divider Select
VDS2_7
Register Low Write:
(PNSL1)
Reset:
0
Read:
PLL2 R Divider Select
RDS2_7
Register Low Write:
(PRSL2)
Reset:
1
Read:
Phase Detector Control
Register Write:
(PDCR)
Reset:
Figure 13-1. CGM I/O Register Summary
13.3 Functional Description
Figure 13-2 shows the structure of one CGM. There are two CGMs in
this MCU.
The two CGMs are independently programmable, with their respective
outputs at the CGMOUT1 and CGMOUT2 pins.
The following paragraphs describes the CGM circuit blocks and internal
signals.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
249
Clock Generator Module (CGM)
VDDA
CGMXFC
VSSA
VREGA
OSCXCLK
CGMRCLK
REFERENCE
DIVIDER
PHASE
DETECTOR
R
RDS[9:0]
VOLTAGE
CONTROLLED
OSCILLATOR
LOOP
FILTER
CGMOUT
PLL ANALOG
PHD_[7:0]
PLLON
VCO_[7:0]
LOCK
DETECTOR
LOCK
CGMFCLK
VCO
DIVIDER
CGMVCLK
N
VDS[11:0]
Figure 13-2. CGM Block Diagram
13.3.1 Reference Frequency Source (OSCXCLK)
The OSCXCLK signal is a buffered output of the crystal oscillator circuit
and runs at a rate equal to the crystal frequency. OSCXCLK is used as
the reference frequency source for both CGM modules.
13.3.2 Voltage Controlled Oscillator
The VCO clock frequency (CGMVCLK) is generated internally and it is
proportional to the controlled voltage setting by the phase detector
output. The VCO operating range is programmable for a wide range of
frequencies and for maximum immunity to external noise. The
CGMVCLK signal is also the CGM output signal, CGMOUT.
Technical Data
250
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.3.3 Reference Divider
The crystal oscillator frequency (OSCXCLK) is fed to the phase detector
through a 10-bit programmable divider module R. The divider output
(CGMRCLK) is equal to CGMXCLK divided by R and is used as the final
reference signal for the phase detector.
13.3.4 VCO Frequency Divider
The VCO output clock (CGMVCLK) is fed to the phase detector through
another 12-bit programmable divider module N. The divider output
(CGMFCLK) is equal to CGMVCLK divided by N and it is the feedback
signal for the phase detector.
13.3.5 Phase Detector
The phase detector compares the VCO feedback clock with the final
reference clock. A correction pulse is generated based on the phase
difference between the two signals. The loop filter then slightly alters the
DC voltage on the external capacitor connected to pin CGMXFC base
on the width and direction of the correction pulse.
13.3.6 Phase Detector Filter
The loop filter controls the dynamic characteristics of the PLL. The loop
filter can make fast or low corrections depending on whether the phase
detector is unlocked or stable.
13.3.7 Lock Detector
The lock detector compares the frequencies of the VCO feedback clock,
CGMFCLK, and the final reference clock, CGMRCLK. Therefore, the
speed of the lock detector is directly proportional to the final reference
clock, CGMRCLK.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
251
Clock Generator Module (CGM)
13.4 I/O Signals
The following paragraphs describe the CGM I/O signals.
13.4.1 CGM Power Supply Pins (VDDA, VSSA0, VSSA1)
VDDA is the power supply pin, VSSA0 and VSSA1 are the ground pins for
the analog portions of both CGMs.
13.4.2 CGM1 Voltage Regulator Out (VREGA0)
3.3V output of the on-chip voltage regulator for analog portions. Connect
VREGA0 directly to VREGA1 as shown in Figure 13-3.
13.4.3 CGM2 Voltage Regulator In (VREGA1)
3.3V input for CGM2 analog portions. Connect VREGA0 directly to
VREGA1 as shown in Figure 13-3.
VSSA0
CGM1
VREGA0
VREGA1
CGM2
CREGBYPASS
0.1 µF
CREGBYPASS
0.1 µF
+
CREGBULK
> 4.7 µF
+
CREGBULK
> 4.7 µF
VREGA0
VSSA1
VREGA1
Figure 13-3. CGM Power Supply Connection
Technical Data
252
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.4.4 External Filter Capacitor Pins (CGMXFC1, CGMXFC2)
The CGMXFC1 and CGMXFC2 pins are required by the loop filter to
filter out phase corrections for each PLL. An external filter network is
connected to each pin. (See 13.5 CGMXFC External Connections.)
13.4.5 CGM Clock Output Pins (CGMOUT1, CGMOUT2)
CGMOUT1 and CGMOUT2 are VCO output signals. The output signals
are buffered through logic stages to output pins without degrading the
loop performance.
13.5 CGMXFC External Connections
The external filter network is critical to the stability and reaction time of
the PLL. The configurations shown in Figure 13-4 (a) and (b) are
recommended for connection to CGMXFC1 and CGMXFC2.
CGMXFC1
56 kΩ
CGMXFC2
150 pF
2n2F
56 kΩ
150 pF
2n2F
VSSA0
(a)
VSSA1
(b)
Figure 13-4. CGMXFC External Connections
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
253
Clock Generator Module (CGM)
13.6 CGMOUT External Connections
The output of CGM clock is a standard CMOS output with push-pull
configuration. The output logic high and low levels are specified with
corresponding DC loading current (see 20.13 CGM Electrical
Characteristics). The transient current is mainly determined by the
maximum loading capacitor value.
VREGA
CGMOUT
RL
CL
VOH or VOL
VSSA
VSSA
Figure 13-5. CGMOUT External Connections
13.7 Calculation of VCO Frequency
The relationship between the VCO frequency, fVCLK, and the crystal
reference frequency, fXCLK, is:
fVCLK =
N
R
× fXCLK
Technical Data
254
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.8 Programming the PLL
With the PLLs off (PLLON = 0), use the following procedure to initialize
both PLLs:
1. Write $80 to the VCO control register (PVCR).
2. Write $70 to the phase detector register (PDCR).
Then for each PLL, use the following procedure to program the VCO and
reference dividers:
3. Write data to the VCO and reference divider select register high
(PNRH).
4. Write data to the VCO divider select register low (PNSL).
5. Write data to the reference divider select register low (PRSL).
6. Set PLLON = 1 in the bandwidth control register to enable the PLL.
To reprogram the PLL frequency, clear the PLLON bit (PLLON =0) and
repeat steps 3 to 6.
NOTE:
Do not program both PLLs to the same frequency. A difference of 50kHz
or more is recommended between the two PLL outputs.
13.9 CGM I/O Registers
These registers control and monitor operation of the CGMs:
•
Bandwidth control register (PBWC)
•
VCO control register (PVCR)
•
PLL1 VCO and reference divider select register high (PNRH1)
•
PLL1 VCO divider select register low (PNSL1)
•
PLL1 reference divider select register low (PRSL1)
•
PLL2 VCO and reference divider select register high (PNRH2)
•
PLL2 VCO divider select register low (PNSL2)
•
PLL2 reference divider select register low (PRSL2)
•
Phase detector control register (PDCR)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
255
Clock Generator Module (CGM)
13.9.1 Bandwidth Control Register
The bandwidth control register (PBWC) contains control/status bits for
both PLLs.
Address:
$0051
Bit 7
Read:
Write:
6
LOCK1
R
Reset:
5
4
3
R
PLLON1
R
0
0
= Unimplemented
2
LOCK2
1
Bit 0
R
PLLON2
0
R
0
= Reserved
Figure 13-6. PLL Bandwidth Control Register (PBCR)
LOCKx — Lock Indicator Bit
This read-only bit becomes set when the VCO clock is locked (running
at the programmed frequency).
1 = VCO frequency correct or locked
0 = VCO frequency incorrect or unlocked
PLLONx — PLL On Bit
This read/write bit activates each PLL and enables the VCO clock.
1 = PLL on
0 = PLL off
13.9.2 VCO Control Register (PVCR)
The VCO control register configures the VCO for both PLLs.
Address:
Read:
Write:
Reset:
$0052
Bit 7
6
5
4
3
2
1
Bit 0
VCO_7
VCO_6
VCO_5
VCO_4
VCO_3
VCO_2
VCO_1
VCO_0
0
0
1
1
0
0
0
0
Figure 13-7. VCO Control Register (PVCR)
VCO_[7:0] — VCO Control Bits for both PLLs
Set VCO_[7:0] = $80 for maximum performance.
Technical Data
256
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.9.3 VCO and Reference Divider Select Registers High
The VCO and reference divider select registers high (PNRH1 and
PNRH2) contain the programming information for the high byte of VCO
feedback divider, N, and reference divider, R.
Address:
$0053
Bit 7
Read:
Write:
Reset:
6
VDS1_11 VDS1_10
0
0
5
4
VDS1_9
VDS1_8
1
0
3
2
0
0
0
0
1
Bit 0
RDS1_9
RDS1_8
0
0
= Unimplemented
Figure 13-8. PLL1 N & R Divider Select Register High (PNRH1)
Address:
$0056
Bit 7
Read:
Write:
Reset:
6
VDS2_11 VDS2_10
0
0
5
4
VDS2_9
VDS2_8
1
0
3
2
0
0
0
0
1
Bit 0
RDS2_9
RDS2_8
0
0
= Unimplemented
Figure 13-9. PLL2 N & R Divider Select Register High (PNRH2)
VDSx_[11:8] — VCO Divider Select Bits
These read/write bits control the high byte of the VCO feedback
divider, N.
RDSx_[9:8] — Reference Divider Select Bits
These read/write bits control the high byte of the reference divider, R.
NOTE:
The VDSx_[11:8] and RDSx_[9:8] bits are not latched until the
respective low bytes are written.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
257
Clock Generator Module (CGM)
13.9.4 VCO Divider Select Register Low
The VCO divider select registers low (PNSL1 and PNSL2) contain the
programming information for the low byte of VCO feedback divider, N.
Address:
Read:
Write:
Reset:
$0054
Bit 7
6
5
4
3
2
1
Bit 0
VDS1_7
VDS1_6
VDS1_5
VDS1_4
VDS1_3
VDS1_2
VDS1_1
VDS1_0
0
1
1
1
1
1
0
1
Figure 13-10. PLL1 N Divider Select Register Low (PNSL1)
Address:
Read:
Write:
Reset:
$0057
Bit 7
6
5
4
3
2
1
Bit 0
VDS2_7
VDS2_6
VDS2_5
VDS2_4
VDS2_3
VDS2_2
VDS2_1
VDS2_0
0
1
1
1
1
1
0
1
Figure 13-11. PLL2 N Divider Select Register Low (PNSL2)
VDSx_[7:0] — VCO Divider Select Bits
These read/write bits control the low byte of the VCO feedback
divider, N.
NOTE:
Writing to PNSL also latches the respective high bits, VDSx_[11:8].
Technical Data
258
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.9.5 Reference Divider Select Register Low
The divider select registers low (PRSL1 and PRLS2) contain the
programming information for the low byte of reference divider, R.
Address:
Read:
Write:
Reset:
$0055
Bit 7
6
5
4
3
2
1
Bit 0
RDS1_7
RDS1_6
RDS1_5
RDS1_4
RDS1_3
RDS1_2
RDS1_1
RDS1_0
1
0
0
1
0
0
0
0
Figure 13-12. PLL1 R Divider Select Register Low (PRSL1)
Address:
Read:
Write:
Reset:
$0058
Bit 7
6
5
4
3
2
1
Bit 0
RDS2_7
RDS2_6
RDS2_5
RDS2_4
RDS2_3
RDS2_2
RDS2_1
RDS2_0
1
0
0
1
0
0
0
0
Figure 13-13. PLL2 R Divider Select Register Low (PRSL2)
RDSx_[7:0] — Reference Divider Select Bits
These read/write bits control the high byte of the reference divider, R.
NOTE:
Writing to PRSL also latches the respective high bits, RDSx_[9:8].
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
259
Clock Generator Module (CGM)
13.9.6 Phase Detector Control Register (PDCR)
The phase detector control register configures the phase detector for
both PLLs.
Address:
Read:
Write:
Reset:
$0059
Bit 7
6
5
4
3
2
1
Bit 0
PHD_7
PHD_6
PHD_5
PHD_4
PHD_3
PHD_2
PHD_1
PHD_0
1
0
0
1
0
0
0
0
Figure 13-14. Phase Detector Control Register (PDCR)
PHD_[7:0] — Phase detector Control Bits for both PLLs
Set PHD_[7:0] = $70 for maximum performance.
13.10 Pre-Defined VCO Output Frequency Settings
The exact frequency values for the following required channels cannot
be synthesized by using a reference frequency higher than 10kHz. An
absolute offset frequency from +1.66kHz to +1.89kHz will be introduced
for different channels and the maximum relative offset is only ±115Hz
with 1.775kHz as the center point (see Table 13-1 . Predefined
Programming Setting for PLL). The absolute offset frequency can be
further minimized by reducing the crystal frequency by 60 ppm (360Hz)
in actual application.
Table 13-1. Predefined Programming Setting for PLL
Channel
Frequency
(MHz)
Crystal
Frequency
(MHz)
Divider R
Reference
Frequency
(kHz)
Divider N
VCO
Frequency
(MHz)
Absolute
Offset
(kHz)
26.54
12
288
41.67
637
26.54166
+1.66
26.59
12
338
35.50
749
26.59171
+1.71
26.64
12
268
44.78
595
26.64179
+1.79
26.69
12
370
32.43
823
26.69189
+1.89
26.74
12
302
39.74
673
26.74172
+1.72
Technical Data
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Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
13.11 Low-Power Modes
The WAIT and STOP instructions put the MCU in low-power
consumption standby modes.
13.11.1 Wait Mode
The CGMs remain active and all PLL registers are not affected in wait
mode. If CGM functions are not required in wait mode, it can be disabled
by the PLLONx bit in the bandwidth control register (PBWC).
13.11.2 Stop Mode
The CGM is inactive and all PLL registers are not affected in stop mode.
CGM operation resumes when the MCU exits stop mode.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Clock Generator Module (CGM)
261
Clock Generator Module (CGM)
Technical Data
262
MC68HC908JB16 — Rev. 1.1
Clock Generator Module (CGM)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 14. Input/Output (I/O) Ports
14.1 Contents
14.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
14.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14.3.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14.3.2 Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . 267
14.4 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
14.4.1 Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
14.4.2 Data Direction Register C. . . . . . . . . . . . . . . . . . . . . . . . . . 270
14.5 Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
14.5.1 Port D Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
14.5.2 Data Direction Register D. . . . . . . . . . . . . . . . . . . . . . . . . . 273
14.6 Port E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
14.6.1 Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
14.6.2 Data Direction Register E. . . . . . . . . . . . . . . . . . . . . . . . . . 277
14.7 Port Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
14.7.1 Port Option Control Register . . . . . . . . . . . . . . . . . . . . . . .279
14.2 Introduction
Twenty-one (21) bidirectional input-output (I/O) pins form four parallel
ports. All I/O pins are programmable as inputs or outputs.
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Freescale Semiconductor
Technical Data
Input/Output (I/O) Ports
263
Input/Output (I/O) Ports
NOTE:
Connect any unused I/O pins to an appropriate logic level, either VDD or
VSS. Although the I/O ports do not require termination for proper
operation, termination reduces excess current consumption and the
possibility of electrostatic damage.
Addr.
Register Name
$0000
Read:
Port A Data Register
Write:
(PTA)
Reset:
Read:
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
R
R
PTC1
PTC0
PTD2
PTD1
PTD0
Unaffected by reset
R
R
R
R
R
R
Read:
Port C Data Register
Write:
(PTC)
Reset:
0
0
0
0
0
0
Read:
Port D Data Register
Write:
(PTD)
Reset:
0
$0001
Reserved Write:
Reset:
$0002
$0003
Unaffected by reset
0
PTD5
PTD4
PTD3
Unaffected by reset
Read:
DDRA7
Data Direction Register A
$0004
Write:
(DDRA)
Reset:
0*
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
DDRC1
DDRC0
0
0
0
0
0
0
0
0
Read:
Data Direction Register D
$0007
Write:
(DDRD)
Reset:
0
0
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
0
0
0
0
0
0
0
0
Read:
Port E Data Register
Write:
(PTE)
Reset:
0
0
0
PTE4
PTE3
PTE2
PTE1
PTE0
* DDRA7 bit is reset by POR or LVI reset only.
Read:
$0005
Reserved Write:
Reset:
Read:
Data Direction Register C
$0006
Write:
(DDRC)
Reset:
$0008
Unaffected by reset
= Unimplemented
R
= Reserved
Figure 14-1. I/O Port Register Summary
Technical Data
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MC68HC908JB16 — Rev. 1.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Addr.
Register Name
Bit 7
6
5
Read:
Data Direction Register E
$0009
Write:
(DDRE)
Reset:
0
0
0
0
0
0
Read:
Port Option Control
PTE20P
Register Write:
(POCR)
Reset:
0
$001D
PTDLDD PTDILDD
0
4
3
2
1
Bit 0
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
0
0
0
0
0
PTE4P
PTE3P
PCP
R
PAP
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 14-1. I/O Port Register Summary
Table 14-1. Port Control Register Bits Summary
Port
A
C
D
Module Control
Bit
DDR
0
DDRA0
KBIE0
PTA0/KBA0
1
DDRA1
KBIE1
PTA1/KBA1
2
DDRA2
KBIE2
PTA2/KBA2
3
DDRA3
KBIE3
PTA3/KBA3
4
DDRA4
KBIE4
PTA4/KBA4
5
DDRA5
KBIE5
PTA5/KBA5
6
DDRA6
KBIE6
PTA6/KBA6
7
DDRA7
KBIE7
PTA7/KBA7
0
DDRC0
1
DDRC1
0–5
Module
KBI
Register
KBIER
$0017
Control Bit
Pin
PTC0/TxD
SCI
SCC1
$005A
ENSCI
DDRD[0:5]
—
—
—
PTD0–PTD5
0
DDRE0
TIM1
or
TIM2
T1SC $000A
or
T2SC $0040
PS[2:0]
PTE0/TCLK
1
DDRE1
TIM1
T1SC0 $0010 ELS0B:ELS0A
or
or
T1SC1 $0013 ELS1B:ELS1A
PTE1/T1CH01
2
DDRE2
TIM2
T2SC0 $0046 ELS0B:ELS0A
or
or
T2SC1 $0049 ELS1B:ELS1A
PTE2/T2CH01
3
DDRE3
4
DDRE4
E
USB
UADDR
$0038
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
USBEN
PTC1/RxD
PTE3/D+
PTE4/D–
Technical Data
Input/Output (I/O) Ports
265
Input/Output (I/O) Ports
14.3 Port A
Port A is an 8-bit general-purpose bidirectional I/O port with software
configurable pullups, and shares its pins with the keyboard interrupt
module (KBI).
14.3.1 Port A Data Register
The port A data register contains a data latch for each of the eight
port A pins.
Address:
Read:
Write:
$0000
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Unaffected by reset
Reset:
Alternative
Function:
KBA7
Additional Optional
Function: pullup
KBA6
KBA5
KBA4
KBA3
KBA2
KBA1
KBA0
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Figure 14-2. Port A Data Register (PTA)
PTA[7:0] — Port A Data Bits
These read/write bits are software programmable. Data direction of
each port A pin is under the control of the corresponding bit in data
direction register A. Reset has no effect on port A data.
The port A pullup control bit, PAP, in the port option control register
(POCR) enables pullups on port A pins if the respective pin is
configured as an input. (See 14.7 Port Options.)
KBA7–KBA0 — Keyboard Interrupts
The keyboard interrupt enable bits, KBIE7–KBIE0, in the keyboard
interrupt enable register (KBIER), enable the port A pins as external
interrupt pins. (See Section 16. Keyboard Interrupt Module (KBI).)
Technical Data
266
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Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
14.3.2 Data Direction Register A
Data direction register A determines whether each port A pin is an input
or an output. Writing a logic 1 to a DDRA bit enables the output buffer for
the corresponding port A pin; a logic 0 disables the output buffer.
Address:
Read:
Write:
Reset:
$0004
Bit 7
6
5
4
3
2
1
Bit 0
DDRA7
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
0*
0
0
0
0
0
0
0
* DDRA7 bit is reset by POR or LVI reset only.
Figure 14-3. Data Direction Register A (DDRA)
DDRA[7:0] — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears
DDRA[7:0], configuring all port A pins as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
NOTE:
Avoid glitches on port A pins by writing to the port A data register before
changing data direction register A bits from 0 to 1.
Figure 14-4 shows the port A I/O logic.
READ DDRA ($0004)
INTERNAL DATA BUS
WRITE DDRA ($0004)
RESET
DDRAx
WRITE PTA ($0000)
PTAx
PTAx
READ PTA ($0000)
Figure 14-4. Port A I/O Circuit
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
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Input/Output (I/O) Ports
267
Input/Output (I/O) Ports
When bit DDRAx is a logic 1, reading address $0000 reads the PTAx
data latch. When bit DDRAx is a logic 0, reading address $0000 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 14-2 summarizes
the operation of the port A pins.
Table 14-2. Port A Pin Functions
DDRA
Bit
PTA Bit
I/O Pin Mode
Accesses
to DDRA
Accesses to PTA
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRA[7:0]
Pin
PTA[7:0](3)
1
X
Output
DDRA[7:0]
PTA[7:0]
PTA[7:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
Technical Data
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Freescale Semiconductor
Input/Output (I/O) Ports
14.4 Port C
Port C is a 2-bit special function port that shares its pins with the serial
communications interface (SCI) module. These pins have software
configurable pullups.
14.4.1 Port C Data Register
The port C data register contains a data latch for each of the two
port C pins.
Address:
Read:
$0002
Bit 7
6
5
4
3
2
0
0
0
0
0
0
Write:
1
Bit 0
PTC1
PTC0
RxD
TxD
Optional
pullup
Optional
pullup
Unaffected by reset
Reset:
Alternative
Function:
Additional
Function:
Figure 14-5. Port C Data Register (PTC)
PTC[1:0] — Port C Data Bits
These read/write bits are software-programmable. Data direction of
each port C pin is under the control of the corresponding bit in data
direction register C. Reset has no effect on port C data.
The port C pullup enable bit, PCP, in the port option control register
(POCR) enables pullups on PTC[1:0] if the respective pin is
configured as an input. (See 14.7 Port Options.)
TxD, RxD — SCI Data I/O Pins
The TxD and RxD pins are the transmit data output and receive data
input for the SCI module. The SCI enable bit, ENSCI, in the SCI
control register 1 enables the PTC0/TxD and PTC1/RxD pins as SCI
TxD and RxD pins and overrides any control from the port I/O. See
Section 12. Serial Communications Interface Module (SCI).
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Input/Output (I/O) Ports
269
Input/Output (I/O) Ports
14.4.2 Data Direction Register C
Data direction register C determines whether each port C pin is an input
or an output. Writing a logic 1 to a DDRC bit enables the output buffer for
the corresponding port C pin; a logic 0 disables the output buffer.
Address:
Read:
$0006
Bit 7
6
5
4
3
2
0
0
0
0
0
0
0
0
0
0
0
0
Write:
Reset:
1
Bit 0
DDRC1
DDRC0
0
0
Figure 14-6. Data Direction Register C (DDRC)
DDRC[1:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears
DDRC[1:0], configuring all port C pins as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
NOTE:
Avoid glitches on port C pins by writing to the port C data register before
changing data direction register C bits from 0 to 1.
Figure 14-7 shows the port C I/O logic.
READ DDRC ($0006)
INTERNAL DATA BUS
WRITE DDRC ($0006)
RESET
DDRCx
WRITE PTC ($0002)
PTCx
PTCx
READ PTC ($0002)
Figure 14-7. Port C I/O Circuit
Technical Data
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MC68HC908JB16 — Rev. 1.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
When bit DDRCx is a logic 1, reading address $0002 reads the PTCx
data latch. When bit DDRCx is a logic 0, reading address $0002 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 14-3 summarizes
the operation of the port C pins.
Table 14-3. Port C Pin Functions
DDRC
Bit
PTC Bit
I/O Pin Mode
Accesses
to DDRC
Accesses to PTC
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRC[1:0]
Pin
PTC[1:0](3)
1
X
Output
DDRC[1:0]
PTC[1:0]
PTC[1:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
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Freescale Semiconductor
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271
Input/Output (I/O) Ports
14.5 Port D
Port D is an 6-bit general-purpose bidirectional I/O port. These pins are
open-drain when configured as output.
14.5.1 Port D Data Register
The port D data register contains a data latch for each of the six
port D pins.
NOTE:
Bits 5–1 of PTD are not available in the 32-pin low-profile quad flat pack.
Address:
Read:
Write:
$0003
Bit 7
6
0
0
5
4
3
2
1
Bit 0
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
10mA
sink
25mA
sink
25mA
sink
Unaffected by reset
Reset:
Additional
Function:
10mA
sink
10mA
sink
10mA
sink
Figure 14-8. Port D Data Register (PTD)
PTD[5:0] — Port D Data Bits
These read/write bits are software programmable. Data direction of
each port D pin is under control of the corresponding bit in data
direction register D. Reset has no effect on port D data.
The LED direct drive bit, PTDLDD, in the port option control register
(POCR) controls the drive options for PTD5–PTD2 pins. The infrared
LED drive bit, PTDILDD, in the POCR controls the drive options for
PTD1–PTD0 pins. (See 14.7 Port Options.)
Technical Data
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Input/Output (I/O) Ports
14.5.2 Data Direction Register D
Data direction register D determines whether each port D pin is an input
or an output. Writing a logic 1 to a DDRD bit enables the output buffer for
the corresponding port D pin; a logic 0 disables the output buffer.
Address:
Read:
$0007
Bit 7
6
0
0
0
0
Write:
Reset:
5
4
3
2
1
Bit 0
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
0
0
0
0
0
0
Figure 14-9. Data Direction Register D (DDRD)
DDRD[5:0] — Data Direction Register D Bits
These read/write bits control port D data direction. Reset clears
DDRD[5:0], configuring all port D pins as inputs.
1 = Corresponding port D pin configured as output
0 = Corresponding port D pin configured as input
Port D pins are open-drain when configured as output.
NOTE:
Avoid glitches on port D pins by writing to the port D data register before
changing data direction register D bits from 0 to 1.
NOTE:
For those devices packaged in a 32-pin low-profile quad flat pack,
PTD5–1 are not connected. DDRD5–1 should be set to a 1 to configure
PTD5–1 as outputs.
Figure 14-10 shows the port D I/O circuit logic.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
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Input/Output (I/O) Ports
READ DDRD ($0007)
INTERNAL DATA BUS
WRITE DDRD ($0007)
DDRDx
RESET
WRITE PTD ($0003)
PTDx
PTDx
READ PTD ($0003)
Figure 14-10. Port D I/O Circuit
When bit DDRDx is a logic 1, reading address $0003 reads the PTDx
data latch. When bit DDRDx is a logic 0, reading address $0003 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 14-4 summarizes
the operation of the port D pins.
Table 14-4. Port D Pin Functions
DDRD
Bit
PTD Bit
I/O Pin Mode
Accesses
to DDRD
Accesses to PTD
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRD[5:0]
Pin
PTD[5:0](3)
1
X
Output
DDRD[5:0]
PTD[5:0]
PTD[5:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
Technical Data
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Freescale Semiconductor
Input/Output (I/O) Ports
14.6 Port E
Port E is a 5-bit special function port that shares three of its pins with the
timer interface modules (TIMs) and two of its pins with the USB data pins
D+ and D–. PTE4 and PTE3 are open-drain when configured as output.
14.6.1 Port E Data Register
The port E data register contains a data latch for each of the five
port E pins.
Address:
Read:
$0008
Bit 7
6
5
0
0
0
Write:
Reset:
4
3
2
1
Bit 0
PTE4
PTE3
PTE2
PTE1
PTE0
Unaffected by reset
Alternative
D–
D+
T2CH01
T1CH01
TCLK
Additional
Function:
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Optional
pullup
Additional
Function:
External
interrupt
Function:
Open-drain Open-drain
= Unimplemented
Figure 14-11. Port E Data Register (PTE)
PTE[4:0] — Port E Data Bits
PTE[4:0] are read/write, software-programmable bits. Data direction
of each port E pin is under the control of the corresponding bit in data
direction register E.
The PTE4 and PTE3 pullup enable bits, PTE4P and PTE3P, in the
port option control register (POCR) enable 5kΩ pullups on PTE4 and
PTE3 if the respective pin is configured as an input and the USB
module is disabled. (See 14.7 Port Options.)
MC68HC908JB16 — Rev. 1.1
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Input/Output (I/O) Ports
The PTE[2:0] pullup enable bit, PTE20P, in the port option control
register (POCR) enables pullups on PTE2–PTE0, regardless of the
pin is configured as an input or an output. (See 14.7 Port Options.)
PTE4 pin functions as an external interrupt when PTE4IE=1 in the
IRQ option control register (IOCR) and USBEN=0 in the USB address
register (USB disabled). (See 15.9 IRQ Option Control Register.)
D– and D+ — USB Data Pins
D– and D+ are the differential data lines used by the USB module.
(See Section 11. Universal Serial Bus Module (USB).)
The USB module enable bit, USBEN, in the USB address register
(UADDR) controls the pin options for PTE4/D– and PTE3/D+. When
the USB module is enabled, PTE4/D– and PTE3/D+ function as USB
data pins D– and D+. When the USB module is disabled, PTE4/D–
and PTE3/D+ function as 10mA open-drain high current pins for PS/2
clock and data use.
The pullup enable bit, PULLEN, in the USB control register 3 (UCR3)
enables a 1.5kΩ pullup on D– pin when the USB module is enabled.
(See 11.8.8 USB Control Register 3.)
NOTE:
PTE4/D– pin has two programmable pullup resistors. One is used for
PTE4 when the USB module is disabled and another is used for D–
when the USB module is enabled.
T2CH01 and T1CH01 — Timer Channel I/O Bits
The PTE2/T2CH01 and PTE1/T1CH01 pins are the respective TIM2
and TIM1 input capture/output compare pins. The edge/level select
bits, ELSxB and ELSxA, determine whether the PTE2/T2CH01 and
PTE1/T1CH01 pins are timer channel I/O pins or general-purpose I/O
pins. (See Section 10. Timer Interface Module (TIM).)
TCLK — Timer Clock Input
The PTE0/TCLK pin is the external clock input for TIM1 and TIM2.
The prescaler select bits, PS[2:0], select PTE0/TCLK as the TIM
clock input. When not selected as the TIM clock, PTE0/TCLK is
available for general purpose I/O. (See Section 10. Timer Interface
Module (TIM).)
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Input/Output (I/O) Ports
NOTE:
Data direction register E (DDRE) does not affect the data direction of
port E pins that are being used by the TIM. However, the DDRE bits
always determine whether reading port E returns the states of the
latches or the states of the pins.
14.6.2 Data Direction Register E
Data direction register E determines whether each port E pin is an input
or an output. Writing a logic 1 to a DDRE bit enables the output buffer for
the corresponding port E pin; a logic 0 disables the output buffer.
Address:
Read:
$0009
Bit 7
6
5
0
0
0
0
0
0
Write:
Reset:
4
3
2
1
Bit 0
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
0
0
0
0
0
= Unimplemented
Figure 14-12. Data Direction Register E (DDRE)
DDRE[4:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE[4:0], configuring all port E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
NOTE:
Avoid glitches on port E pins by writing to the port E data register before
changing data direction register E bits from 0 to 1.
Figure 14-13 shows the port E I/O circuit logic.
MC68HC908JB16 — Rev. 1.1
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Technical Data
Input/Output (I/O) Ports
277
Input/Output (I/O) Ports
READ DDRE ($0009)
INTERNAL DATA BUS
WRITE DDRE ($0009)
DDREx
RESET
WRITE PTE ($0008)
PTEx
PTEx
READ PTE ($0008)
Figure 14-13. Port E I/O Circuit
When bit DDREx is a logic 1, reading address $0008 reads the PTEx
data latch. When bit DDREx is a logic 0, reading address $0008 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 14-3 summarizes
the operation of the port E pins.
Table 14-5. Port E Pin Functions
DDRE
Bit
PTE
Bit
I/O Pin Mode
Accesses
to DDRE
Accesses to PTE
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRE[4:0]
Pin
PTE[4:0](3)
1
X
Output
DDRE[4:0]
PTE[4:0]
PTE[4:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
14.7 Port Options
All pins of port A, port C, and port E have programmable pullup resistors.
Port D has programmable LED drive capability; PTD5–PTD2 each have
10mA high current sink, and PTD1–PTD0 each have 25mA high current
sink.
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Freescale Semiconductor
Input/Output (I/O) Ports
14.7.1 Port Option Control Register
The port option control register controls the pullup options for port A,
port C, and port E pins. It also controls the drive configuration on port D.
Address:
$001D
Bit 7
Read:
Write:
Reset:
PTE20P
0
R
6
5
PTDLDD PTDILDD
0
4
3
2
1
Bit 0
PTE4P
PTE3P
PCP
R
PAP
0
0
0
0
0
0
= Reserved
Figure 14-14. Port Option Control Register (POCR)
PTE20P — Pins PTE[2:0] Pullup Enable
This read/write bit controls the pullup option for the PTE2–PTE0 pins,
regardless whether the pins are input or output.
1 = Configure PTE2–PTE0 to have internal pullups
0 = Disconnect PTE2–PTE0 internal pullups
PTDLDD — LED Direct Drive Control
This read/write bit controls the output current capability of
PTD5–PTD2 pins. When set, each port pin has 10mA current sink
limit. An LED can be connected directly between the port pin and VDD
without the need of a series resistor.
1 = PTD5–PTD2 configured for direct LED drive capability;
when a pin is set as an output, the pin is an open-drain pin with
10mA current sink limit
0 = PTD5–PTD2 configured as standard open-drain I/O port pins
PTDILDD — Infrared LED Drive Control
This read/write bit controls the output current capability of PTD1 and
PTD0 pins. When set, each port pin has 25mA current sink capability.
An infrared LED can be connected directly between the port pin and
VDD.
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Technical Data
Input/Output (I/O) Ports
279
Input/Output (I/O) Ports
1 = PTD1 and PTD0 configured for infrared LED drive capability;
when a pin is set as an output, the pin is an open-drain pin with
25mA current sink capability
0 = PTD1 and PTD0 configured as standard open-drain I/O port
pins
PTE4P — Pin PTE4 Pullup Enable
This read/write bit controls the pullup option for the PTE4 pin when the
pin is configured as an input and the USB module is disabled.
1 = Configure PTE4 to have internal pullup
0 = Disconnect PTE4 internal pullup
NOTE:
When the USB module is enabled, the pullup controlled by PTE4P is
disconnected; PTE4/D– pin functions as D– which has a 1.5kΩ
programmable pull-up resistor. (See 11.8.8 USB Control Register 3.)
PTE3P — Pin PTE3 Pullup Enable
This read/write bit controls the pullup option for the PTE3 pin when the
pin is configured as an input and the USB module is disabled.
1 = Configure PTE3 to have internal pullup
0 = Disconnect PTE3 internal pullup
PCP — Port C Pullup Enable
This read/write bit controls the pullup option for the PTC1 and PTC0
pins. When set, a pullup device is connected when a pin is configured
as an input.
1 = Configure port C to have internal pullups
0 = Disconnect port C internal pullups
PAP — Port A Pullup Enable
This read/write bit controls the pullup option for the PTA7–PTA0 pins.
When set, a pullup device is connected when a pin is configured as
an input.
1 = Configure port A to have internal pullups
0 = Disconnect port A internal pullups
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Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 15. External Interrupt (IRQ)
15.1 Contents
15.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
15.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
15.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282
15.5
IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
15.6
PTE4/D– Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
15.7
IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . . 285
15.8
IRQ Status and Control Register . . . . . . . . . . . . . . . . . . . . . . 286
15.9
IRQ Option Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . 287
15.2 Introduction
The IRQ module provides two external interrupt inputs: one dedicated
IRQ pin and one shared port pin, PTE4/D–.
15.3 Features
Features of the IRQ module include:
•
Two external interrupt pins, IRQ and PTE4/D–
•
IRQ interrupt control bits
•
Hysteresis buffer
•
Programmable edge-only or edge and level interrupt sensitivity
•
Automatic interrupt acknowledge
•
Low leakage IRQ pin for external RC wake up input
•
Selectable internal pullup resistor
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Technical Data
External Interrupt (IRQ)
281
External Interrupt (IRQ)
15.4 Functional Description
A logic 0 applied to the external interrupt pin can latch a CPU interrupt
request. Figure 15-1 shows the structure of the IRQ module.
Interrupt signals on the IRQ pin are latched into the IRQ latch. An
interrupt latch remains set until one of the following actions occurs:
•
Vector fetch — A vector fetch automatically generates an interrupt
acknowledge signal that clears the IRQ latch.
•
Software clear — Software can clear the interrupt latch by writing
to the acknowledge bit in the interrupt status and control register
(ISCR). Writing a logic 1 to the ACK bit clears the IRQ latch.
•
Reset — A reset automatically clears the interrupt latch.
The external interrupt pin is falling-edge-triggered and is softwareconfigurable to be either falling-edge or low-level-triggered. The MODE
bit in the ISCR controls the triggering sensitivity of the IRQ pin.
When the interrupt pin is edge-triggered only, the CPU interrupt request
remains set until a vector fetch, software clear, or reset occurs.
When the interrupt pin is both falling-edge and low-level-triggered, the
CPU interrupt request remains set until both of the following occur:
•
Vector fetch or software clear
•
Return of the interrupt pin to logic one
The vector fetch or software clear may occur before or after the interrupt
pin returns to logic 1. As long as the pin is low, the interrupt request
remains pending. A reset will clear the latch and the MODE control bit,
thereby clearing the interrupt even if the pin stays low.
When set, the IMASK bit in the ISCR mask all external interrupt
requests. A latched interrupt request is not presented to the interrupt
priority logic unless the IMASK bit is clear.
NOTE:
The interrupt mask (I) in the condition code register (CCR) masks all
interrupt requests, including external interrupt requests. (See 8.6
Exception Control.)
Technical Data
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External Interrupt (IRQ)
Freescale Semiconductor
External Interrupt (IRQ)
INTERNAL ADDRESS BUS
ACK
RESET
VECTOR
FETCH
DECODER
HIGH
VOLTAGE
DETECT
TO MODE
SELECT
LOGIC
TO CPU FOR
BIL/BIH
INSTRUCTIONS
VDD
IRQPD
"1"
INTERNAL
IRQF
PULLUP
D
DEVICE
IRQ
CLR
Q
SYNCHRONIZER
CK
IRQ
INTERRUPT
REQUEST
IRQ
FF
IMASK
MODE
TO PTE4 PULLUP
ENABLE CIRCUITRY
"1"
READ IOCR
D
PTE4
CLR
Q
PTE4IF
CK
PTE4IE
Figure 15-1. IRQ Module Block Diagram
Addr.
$001C
$001E
Register Name
Bit 7
6
5
4
3
2
IRQ Option Control Register Read:
(IOCR) Write:
0
0
0
0
0
PTE4IF
Reset:
0
0
0
0
0
0
IRQ Status and Control Register Read:
(ISCR) Write:
0
0
0
0
IRQF
0
Reset:
0
ACK
0
0
0
0
0
1
Bit 0
PTE4IE
IRQPD
0
0
IMASK
MODE
0
0
= Unimplemented
Figure 15-2. IRQ I/O Register Summary
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Technical Data
External Interrupt (IRQ)
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External Interrupt (IRQ)
15.5 IRQ Pin
The IRQ pin has a low leakage for input voltages ranging from 0V to
VDD; suitable for applications using RC discharge circuitry to wake up
the MCU.
A logic 0 on the IRQ pin can latch an interrupt request into the IRQ latch.
A vector fetch, software clear, or reset clears the IRQ latch.
If the MODE bit is set, the IRQ pin is both falling-edge-sensitive and lowlevel-sensitive. With MODE set, both of the following actions must occur
to clear IRQ:
•
Vector fetch or software clear — A vector fetch generates an
interrupt acknowledge signal to clear the latch. Software may
generate the interrupt acknowledge signal by writing a logic 1 to
the ACK bit in the interrupt status and control register (ISCR). The
ACK bit is useful in applications that poll the IRQ pin and require
software to clear the IRQ latch. Writing to the ACK bit prior to
leaving an interrupt service routine can also prevent spurious
interrupts due to noise. Setting ACK does not affect subsequent
transitions on the IRQ pin. A falling edge that occurs after writing
to the ACK bit latches another interrupt request. If the IRQ mask
bit, IMASK, is clear, the CPU loads the program counter with the
vector address at locations $FFF8 and $FFF9.
•
Return of the IRQ pin to logic one — As long as the IRQ pin is at
logic zero, IRQ remains active.
The vector fetch or software clear and the return of the IRQ pin to logic
one may occur in any order. The interrupt request remains pending as
long as the IRQ pin is at logic zero. A reset will clear the latch and the
MODE control bit, thereby clearing the interrupt even if the pin stays low.
If the MODE bit is clear, the IRQ pin is falling-edge-sensitive only. With
MODE clear, a vector fetch or software clear immediately clears the IRQ
latch.
The IRQF bit in the ISCR register can be used to check for pending
interrupts. The IRQF bit is not affected by the IMASK bit, which makes it
useful in applications where polling is preferred.
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Freescale Semiconductor
External Interrupt (IRQ)
Use the BIH or BIL instruction to read the logic level on the IRQ pin.
NOTE:
When using the level-sensitive interrupt trigger, avoid false interrupts by
masking interrupt requests in the interrupt routine.
An internal pullup resistor to VDD is connected to IRQ pin; this can be
disabled by setting the IRQPD bit in the IRQ option control register
($001C).
15.6 PTE4/D– Pin
The PTE4 pin is configured as an interrupt input to trigger the IRQ
interrupt when the following conditions are satisfied:
•
The USB module is disabled (USBEN = 0)
•
PTE4 pin configured for external interrupt input (PTE4IE = 1)
Setting PTE4IE configures the PTE4 pin to an input pin with an internal
pullup device. The PTE4 interrupt is "ORed" with the IRQ input to trigger
the IRQ interrupt (see Figure 15-1 . IRQ Module Block Diagram).
Therefore, the IRQ status and control register affects both the IRQ pin
and the PTE4 pin. An interrupt on PTE4 also sets the PTE4 interrupt flag,
PTE4IF, in the IRQ option control register (IOCR).
15.7 IRQ Module During Break Interrupts
The system integration module (SIM) controls whether the IRQ latch can
be cleared during the break state. The BCFE bit in the break flag control
register (BFCR) enables software to clear the latches during the break
state. (See Section 8. System Integration Module (SIM).)
To allow software to clear the IRQ latch during a break interrupt, write a
logic 1 to the BCFE bit. If a latch is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect the latches during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), writing to the ACK bit in the
IRQ status and control register during the break state has no effect on
the IRQ latch.
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Freescale Semiconductor
Technical Data
External Interrupt (IRQ)
285
External Interrupt (IRQ)
15.8 IRQ Status and Control Register
The IRQ status and control register (ISCR) controls and monitors
operation of the IRQ module. The ISCR has the following functions:
•
Shows the state of the IRQ flag
•
Clears the IRQ latch
•
Masks IRQ interrupt request
•
Controls triggering sensitivity of the IRQ pin.
Address:
Read:
$001E
Bit 7
6
5
4
3
2
0
0
0
0
IRQF
0
Write:
Reset:
ACK
0
0
0
0
0
0
1
Bit 0
IMASK
MODE
0
0
= Unimplemented
Figure 15-3. IRQ Status and Control Register (ISCR)
IRQF — IRQ Flag
This read-only status bit is high when the IRQ interrupt is pending.
1 = IRQ interrupt pending
0 = IRQ interrupt not pending
ACK — IRQ Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ latch. ACK always
reads as logic 0. Reset clears ACK.
IMASK — IRQ Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ interrupt requests.
Reset clears IMASK.
1 = IRQ interrupt requests disabled
0 = IRQ interrupt requests enabled
MODE — IRQ Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ pin.
Reset clears MODE.
1 = IRQ pin interrupt requests on falling edges and low levels
0 = IRQ pin interrupt requests on falling edges only
Technical Data
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External Interrupt (IRQ)
Freescale Semiconductor
External Interrupt (IRQ)
15.9 IRQ Option Control Register
The IRQ option control register controls and monitors the external
interrupt function available on the PTE4 pin. It also disables/enables the
pullup resistor on the IRQ pin.
•
Controls pullup option on IRQ pin
•
Enables PTE4 pin for external interrupts to IRQ
•
Shows the state of the PTE4 interrupt flag
Address:
Read:
$001C
Bit 7
6
5
4
3
2
0
0
0
0
0
PTE4IF
0
0
0
0
0
0
Write:
Reset:
1
Bit 0
PTE4IE
IRQPD
0
0
= Unimplemented
Figure 15-4. IRQ Option Control Register (IOCR)
PTE4IF — PTE4 Interrupt Flag
This read-only status bit is high when a falling edge on PTE4 pin is
detected. PTE4IF bit clears when the IOCR is read.
1 = Falling edge on PTE4 is detected and PTE4IE is set
0 = Falling edge on PTE4 is not detected or PTE4IE is clear
PTE4IE — PTE4 Interrupt Enable
This read/write bit enables or disables the interrupt function on the
PTE4 pin to trigger the IRQ interrupt. Setting the PTE4IE bit and
clearing the USBEN bit in the USB address register configure the
PTE4 pin for interrupt function to the IRQ interrupt. Setting PTE4IE
also enables the internal pullup on PTE4 pin.
1 = PTE4 interrupt enabled; triggers IRQ interrupt
0 = PTE4 interrupt disabled
IRQPD — IRQ Pullup Disable
This read/write bit controls the pullup option for the IRQ pin.
1 = Internal pullup is disconnected
0 = Internal pull-up is connected between IRQ pin and VDD
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Freescale Semiconductor
Technical Data
External Interrupt (IRQ)
287
External Interrupt (IRQ)
Technical Data
288
MC68HC908JB16 — Rev. 1.1
External Interrupt (IRQ)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 16. Keyboard Interrupt Module (KBI)
16.1 Contents
16.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
16.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
16.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
16.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291
16.6
Keyboard Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
16.7 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
16.7.1 Keyboard Status and Control Register. . . . . . . . . . . . . . . . 294
16.7.2 Keyboard Interrupt Enable Register . . . . . . . . . . . . . . . . . . 295
16.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
16.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
16.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
16.9
Keyboard Module During Break Interrupts . . . . . . . . . . . . . . . 296
16.2 Introduction
The keyboard interrupt module (KBI) provides eight independently
maskable external interrupts which are accessible via PTA0–PTA7 pins.
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Technical Data
Keyboard Interrupt Module (KBI)
289
Keyboard Interrupt Module (KBI)
16.3 Features
Features of the keyboard interrupt module include:
Addr.
•
Eight keyboard interrupt pins with separate keyboard interrupt
enable bits and one keyboard interrupt mask
•
Hysteresis buffers
•
Programmable edge-only or edge- and level-interrupt sensitivity
•
Exit from low-power modes
Register Name
Bit 7
6
5
4
3
2
Read:
Keyboard Status and Control
$0016
Register Write:
(KBSCR)
Reset:
0
0
0
0
KEYF
0
$0017
Read:
Keyboard Interrupt Enable
Register Write:
(KBIER)
Reset:
ACKK
1
Bit 0
IMASKK
MODEK
0
0
0
0
0
0
0
0
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 16-1. I/O Register Summary
16.4 Pin Name Conventions
The KBI share eight I/O pins with eight port A I/O pins. The full name of
the I/O pins are listed in Table 16-1. The generic pin name appear in the
text that follows.
Table 16-1. Pin Name Conventions
Full MCU Pin Name
KBI
Generic Pin Name
Pin Selected for KBI Function by
KBIEx Bit in KBIER
PTA7/KBA7–PTA0/KBA0
KBA7–KBA0
KBIE7–KBIE0
Technical Data
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Freescale Semiconductor
Keyboard Interrupt Module (KBI)
16.5 Functional Description
INTERNAL BUS
KBA0
ACKK
VREG
.
KBIE0
TO PULLUP ENABLE
D
.
CLR
VECTOR FETCH
DECODER
KEYF
RESET
Q
SYNCHRONIZER
CK
.
KEYBOARD
INTERRUPT FF
KBA7
Keyboard
Interrupt
Request
IMASKK
MODEK
KBIE7
TO PULLUP ENABLE
Figure 16-2. Keyboard Module Block Diagram
Writing to the KBIE7–KBIE0 bits in the keyboard interrupt enable register
independently enables or disables each port A pin as a keyboard
interrupt pin. Enabling a keyboard interrupt pin also enables its internal
pullup device. A logic 0 applied to an enabled keyboard interrupt pin
latches a keyboard interrupt request.
A keyboard interrupt is latched when one or more keyboard pins goes
low after all were high. The MODEK bit in the keyboard status and
control register controls the triggering mode of the keyboard interrupt.
•
If the keyboard interrupt is edge-sensitive only, a falling edge on a
keyboard pin does not latch an interrupt request if another
keyboard pin is already low.To prevent losing an interrupt request
on one pin because another pin is still low, software can disable
the latter pin while it is low.
•
If the keyboard interrupt is falling edge- and low level-sensitive, an
interrupt request is present as long as any keyboard pin is low.
If the MODEK bit is set, the keyboard interrupt pins are both falling edgeand low level-sensitive, and both of the following actions must occur to
clear a keyboard interrupt request:
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Freescale Semiconductor
Technical Data
Keyboard Interrupt Module (KBI)
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Keyboard Interrupt Module (KBI)
•
Vector fetch or software clear — A vector fetch generates an
interrupt acknowledge signal to clear the interrupt request.
Software may generate the interrupt acknowledge signal by
writing a logic 1 to the ACKK bit in the keyboard status and control
register (KBSCR). The ACKK bit is useful in applications that poll
the keyboard interrupt pins and require software to clear the
keyboard interrupt request. Writing to the ACKK bit prior to leaving
an interrupt service routine also can prevent spurious interrupts
due to noise. Setting ACKK does not affect subsequent transitions
on the keyboard interrupt pins. A falling edge that occurs after
writing to the ACKK bit latches another interrupt request. If the
keyboard interrupt mask bit, IMASKK, is clear, the CPU loads the
program counter with the vector address at locations $FFE0 and
$FFE1.
•
Return of all enabled keyboard interrupt pins to logic 1 — As long
as any enabled keyboard interrupt pin is at logic 0, the keyboard
interrupt remains set.
The vector fetch or software clear and the return of all enabled keyboard
interrupt pins to logic 1 may occur in any order.
If the MODEK bit is clear, the keyboard interrupt pin is falling-edgesensitive only. With MODEK clear, a vector fetch or software clear
immediately clears the keyboard interrupt request.
Reset clears the keyboard interrupt request and the MODEK bit, clearing
the interrupt request even if a keyboard interrupt pin stays at logic 0.
The keyboard flag bit (KEYF) in the keyboard status and control register
can be used to see if a pending interrupt exists. The KEYF bit is not
affected by the keyboard interrupt mask bit (IMASKK) which makes it
useful in applications where polling is preferred.
To determine the logic level on a keyboard interrupt pin, use the data
direction register to configure the pin as an input and read the data
register.
NOTE:
Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction
register. However, the data direction register bit must be a logic 0 for
software to read the pin.
Technical Data
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Freescale Semiconductor
Keyboard Interrupt Module (KBI)
16.6 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the pullup
device to reach a logic 1. Therefore, a false interrupt can occur as soon
as the pin is enabled.
To prevent a false interrupt on keyboard initialization:
1. Mask keyboard interrupts by setting the IMASKK bit in the
keyboard status and control register.
2. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
3. Write to the ACKK bit in the keyboard status and control register
to clear any false interrupts.
4. Clear the IMASKK bit.
An interrupt signal on an edge-triggered pin can be acknowledged
immediately after enabling the pin. An interrupt signal on an edge- and
level-triggered interrupt pin must be acknowledged after a delay that
depends on the external load.
Another way to avoid a false interrupt:
1. Configure the keyboard pins as outputs by setting the appropriate
DDRA bits in data direction register A.
2. Write logic 1s to the appropriate port A data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
16.7 I/O Registers
These registers control and monitor operation of the keyboard module:
•
Keyboard status and control register (KBSCR)
•
Keyboard interrupt enable register (KBIER)
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Freescale Semiconductor
Technical Data
Keyboard Interrupt Module (KBI)
293
Keyboard Interrupt Module (KBI)
16.7.1 Keyboard Status and Control Register
•
Flags keyboard interrupt requests
•
Acknowledges keyboard interrupt requests
•
Masks keyboard interrupt requests
•
Controls keyboard interrupt triggering sensitivity
Address:
Read:
$0016
Bit 7
6
5
4
3
2
0
0
0
0
KEYF
0
Write:
Reset:
ACKK
0
0
0
0
0
0
1
Bit 0
IMASKK
MODEK
0
0
= Unimplemented
Figure 16-3. Keyboard Status and Control Register (KBSCR)
KEYF — Keyboard Flag Bit
This read-only bit is set when a keyboard interrupt is pending. Reset
clears the KEYF bit.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
ACKK — Keyboard Acknowledge Bit
Writing a logic 1 to this write-only bit clears the keyboard interrupt
request. ACKK always reads as logic 0. Reset clears ACKK.
IMASKK — Keyboard Interrupt Mask Bit
Writing a logic 1 to this read/write bit prevents the output of the
keyboard interrupt mask from generating interrupt requests. Reset
clears the IMASKK bit.
1 = Keyboard interrupt requests masked
0 = Keyboard interrupt requests not masked
MODEK — Keyboard Triggering Sensitivity Bit
This read/write bit controls the triggering sensitivity of the keyboard
interrupt pins. Reset clears MODEK.
1 = Keyboard interrupt requests on falling edges and low levels
0 = Keyboard interrupt requests on falling edges only
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Freescale Semiconductor
Keyboard Interrupt Module (KBI)
16.7.2 Keyboard Interrupt Enable Register
The keyboard interrupt enable register enables or disables each port A
pin to operate as a keyboard interrupt pin.
Address: $0017
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
0
0
0
0
0
0
0
0
Figure 16-4. Keyboard Interrupt Enable Register (KBIER)
KBIE7–KBIE0 — Keyboard Interrupt Enable Bits
Each of these read/write bits enables the corresponding keyboard
interrupt pin to latch interrupt requests. Reset clears the keyboard
interrupt enable register.
1 = PTAx/KBAx pin enabled as keyboard interrupt pin
0 = PTAx/KBAx not enabled as keyboard interrupt pin
16.8 Low-Power Modes
The WAIT and STOP instructions put the MCU in low-power
consumption standby modes.
16.8.1 Wait Mode
The keyboard module remains active in wait mode. Clearing the
IMASKK bit in the keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of wait mode.
16.8.2 Stop Mode
The keyboard module remains active in stop mode. Clearing the
IMASKK bit in the keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of stop mode.
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Technical Data
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295
Keyboard Interrupt Module (KBI)
16.9 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard
interrupt latch can be cleared during the break state. The BCFE bit in the
break flag control register (BFCR) enables software to clear status bits
during the break state.
To allow software to clear the keyboard interrupt latch during a break
interrupt, write a logic 1 to the BCFE bit. If a latch is cleared during the
break state, it remains cleared when the MCU exits the break state.
To protect the latch during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), writing to the keyboard
acknowledge bit (ACKK) in the keyboard status and control register
during the break state has no effect. (See 16.7.1 Keyboard Status and
Control Register.)
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Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 17. Computer Operating Properly (COP)
17.1 Contents
17.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
17.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .298
17.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.4.1 OSCDCLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299
17.4.2 STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.4.3 COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299
17.4.4 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.4.5 Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
17.4.6 Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
17.4.7 COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
17.4.8 COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . 300
17.5
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
17.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301
17.7
Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301
17.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
17.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
17.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
17.9
COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . . 302
17.2 Introduction
The computer operating properly (COP) module contains a free-running
counter that generates a reset if allowed to overflow. The COP module
helps software recover from runaway code. Prevent a COP reset by
clearing the COP counter periodically. The COP module can be disabled
through the COPD bit in the CONFIG register.
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Computer Operating Properly (COP)
17.3 Functional Description
Figure 17-1 shows the structure of the COP module.
RESET STATUS REGISTER
COP TIMEOUT
CLEAR STAGES 5–12
STOP INSTRUCTION
INTERNAL RESET SOURCES
RESET VECTOR FETCH
RESET CIRCUIT
12-BIT COP PRESCALER
CLEAR ALL STAGES
OSCDCLK
COPCTL WRITE
COP CLOCK
6-BIT COP COUNTER
COPEN (FROM SIM)
COP DISABLE
(COPD FROM CONFIG)
RESET
COPCTL WRITE
CLEAR
COP COUNTER
COP RATE SEL
(COPRS FROM CONFIG)
Figure 17-1. COP Block Diagram
The COP counter is a free-running 6-bit counter preceded by a 12-bit
prescaler counter. If not cleared by software, the COP counter overflows
and generates an asynchronous reset after 218 – 24 or 213 – 24
OSCDCLK cycles, depending on the state of the COP rate select bit,
COPRS, in configuration register 1. With a 218 – 24 OSCDCLK cycle
overflow option, a 24MHz OSCDCLK (12MHz crystal) gives a COP
timeout period of 10.92ms. Writing any value to location $FFFF before
an overflow occurs prevents a COP reset by clearing the COP counter
and stages 12 through 5 of the prescaler.
NOTE:
Service the COP immediately after reset and before entering or after
exiting stop mode to guarantee the maximum time before the first COP
counter overflow.
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Freescale Semiconductor
Computer Operating Properly (COP)
A COP reset pulls the RST pin low for 32 OSCDCLK cycles and sets the
COP bit in the SIM reset status register (SRSR).
In monitor mode, the COP is disabled if the RST pin or the IRQ is held
at VTST. During the break state, VTST on the RST pin disables the COP.
NOTE:
Place COP clearing instructions in the main program and not in an
interrupt subroutine. Such an interrupt subroutine could keep the COP
from generating a reset even while the main program is not working
properly.
17.4 I/O Signals
The following paragraphs describe the signals shown in Figure 17-1.
17.4.1 OSCDCLK
OSCDCLK is the crystal oscillator clock doubler output signal. Its
frequency is two times the crystal frequency.
17.4.2 STOP Instruction
The STOP instruction clears the COP prescaler.
17.4.3 COPCTL Write
Writing any value to the COP control register (COPCTL) (see 17.5 COP
Control Register) clears the COP counter and clears bits 12 through 5
of the prescaler. Reading the COP control register returns the low byte
of the reset vector.
17.4.4 Power-On Reset
The power-on reset (POR) circuit clears the COP prescaler 4096
OSCDCLK cycles after power-up.
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Technical Data
Computer Operating Properly (COP)
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Computer Operating Properly (COP)
17.4.5 Internal Reset
An internal reset clears the COP prescaler and the COP counter.
17.4.6 Reset Vector Fetch
A reset vector fetch occurs when the vector address appears on the data
bus. A reset vector fetch clears the COP prescaler.
17.4.7 COPD (COP Disable)
The COPD signal reflects the state of the COP disable bit (COPD) in the
CONFIG register. (See Figure 17-2.)
17.4.8 COPRS (COP Rate Select)
The COPRS signal reflects the state of the COP rate select bit (COPRS)
in the CONFIG register. (See Figure 17-2.)
Address:
Read:
Write:
Reset:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
LVIDR
LVI5OR3
URSTD
LVID
SSREC
COPRS
STOP
COPD
0*
0*
0*
0*
0
0
0
0
* LVIDR, LVI5OR3, URSTD, and LVID, are reset by POR or LVI reset only.
Figure 17-2. Configuration Register (CONFIG)
COPRS — COP Rate Select Bit
COPRS selects the COP timeout period. Reset clears COPRS.
1 = COP timeout period is 213 – 24 OSCDCLK cycles
0 = COP timeout period is 218 – 24 OSCDCLK cycles
COPD — COP Disable Bit
COPD disables the COP module.
1 = COP module disabled
0 = COP module enabled
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Freescale Semiconductor
Computer Operating Properly (COP)
17.5 COP Control Register
The COP control register is located at address $FFFF and overlaps the
reset vector. Writing any value to $FFFF clears the COP counter and
starts a new timeout period. Reading location $FFFF returns the low
byte of the reset vector.
Address:
$FFFF
Bit 7
6
5
4
3
Read:
Low byte of reset vector
Write:
Clears COP counter (any value)
Reset:
Unaffected by reset
2
1
Bit 0
Figure 17-3. COP Control Register (COPCTL)
17.6 Interrupts
The COP does not generate CPU interrupt requests.
17.7 Monitor Mode
When monitor mode is entered with VTST on the IRQ pin, the COP is
disabled as long as VTST remains on the IRQ pin or the RST pin. When
monitor mode is entered by having blank reset vectors and not having
VTST on the IRQ pin, the COP is automatically disabled until a POR
occurs.
17.8 Low-Power Modes
The WAIT and STOP instructions put the MCU in low powerconsumption standby modes.
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Computer Operating Properly (COP)
301
Computer Operating Properly (COP)
17.8.1 Wait Mode
The COP remains active during wait mode. To prevent a COP reset
during wait mode, periodically clear the COP counter in a CPU interrupt
routine.
17.8.2 Stop Mode
Stop mode turns off the OSCDCLK input to the COP and clears the COP
prescaler. Service the COP immediately before entering or after exiting
stop mode to ensure a full COP timeout period after entering or exiting
stop mode.
To prevent inadvertently turning off the COP with a STOP instruction, a
configuration option is available that disables the STOP instruction.
When the STOP bit in the configuration register has the STOP
instruction is disabled, execution of a STOP instruction results in an
illegal opcode reset.
17.9 COP Module During Break Mode
The COP is disabled during a break interrupt when VTST is present on
the RST pin.
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Technical Data — MC68HC908JB16
Section 18. Low-Voltage Inhibit (LVI)
18.1 Contents
18.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
18.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
18.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304
18.4.1 Low VDD Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304
18.4.2 Low VREG Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
18.5
LVI Control and Configuration . . . . . . . . . . . . . . . . . . . . . . . . 305
18.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
18.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
18.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
18.2 Introduction
This section describes the low-voltage inhibit (LVI) module, which
monitors the voltage on the VDD pin and VREG pin. and can force a reset
when the VDD or VREG voltage falls below the LVI trip falling voltage.
18.3 Features
Features of the LVI module include:
•
Independent voltage monitoring circuits for VDD and VREG
•
Independent LVI circuit disable for VDD and VREG
•
Selectable LVI trip voltage for VDD
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Technical Data
Low-Voltage Inhibit (LVI)
303
Low-Voltage Inhibit (LVI)
VDD
LVID
LOW VDD
VDD > VLVR = 0
DETECTOR
VDD < VLVR = 1
LVI5OR3
LVI RESET
VREG
LVIDR
LOW VREG
VDD > VLVRR = 0
DETECTOR
VDD < VLVRR = 1
Figure 18-1. LVI Module Block Diagram
18.4 Functional Description
Figure 18-1 shows the structure of the LVI module. The LVI is enabled
out of reset. The LVI module contains independent bandgap reference
circuit and comparator for monitoring the VDD voltage and the VREG
voltage. An LVI reset performs a MCU internal reset and drives the RST
pin low to provide low-voltage protection to external peripheral devices.
18.4.1 Low VDD Detector
The low VDD detector circuit monitors the VDD voltage and forces a LVI
reset when the VDD voltage falls below the trip voltage. The LVI5OR3 bit
in the configuration register (CONFIG) selects the trip point voltage. The
VDD LVI circuit can be disabled by the setting the LVID bit in CONFIG.
See 8.4.2.5 Low-Voltage Inhibit (LVI) Reset for details of the
interaction between the SIM and the LVI.
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Freescale Semiconductor
Low-Voltage Inhibit (LVI)
18.4.2 Low VREG Detector
The low VREG detector circuit monitors the VREG voltage and forces a
LVI reset when the VREG voltage falls below the trip voltage. The VREG
LVI circuit can be disabled by the setting the LVIDR bit in CONFIG.
NOTE:
There is no LVI circuit for VREGA.
18.5 LVI Control and Configuration
Three bits in the configuration register (CONFIG) control the operation
of the LVI module.
Address:
Read:
Write:
Reset:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
LVIDR
LVI5OR3
URSTD
LVID
SSREC
COPRS
STOP
COPD
0*
0*
0*
0*
0
0
0
0
= Unimplemented
* LVIDR, LVI5OR3, URSTD, and LVID bits are reset by POR (power-on reset) or LVI reset only.
Figure 18-2. Configuration Register (CONFIG)
LVIDR — LVI Disable Bit for VREG
LVIDR disables the LVI circuit for VREG.
1 = LVI circuit for VREG disabled
0 = LVI circuit for VREG enabled
LVI5OR3 — LVI Trip Point Voltage Select Bit for VDD
LVI5OR3 selects the trip point voltage of the LVI circuit for VDD. See
Section 20. Electrical Specifications for the trip voltage tolerances.
1 = LVI trips at 3.3V
0 = LVI trips at 2.4V
LVID — LVI Disable Bit for VDD
LVID disables the LVI circuit for VDD.
1 = LVI circuit for VDD disabled
0 = LVI circuit for VDD enabled
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Technical Data
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305
Low-Voltage Inhibit (LVI)
18.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low powerconsumption standby modes.
18.6.1 Wait Mode
If enabled, the LVI module remains active in wait mode.
18.6.2 Stop Mode
If enabled, the LVI module remains active in stop mode.
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Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 19. Break Module (BRK)
19.1 Contents
19.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
19.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
19.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308
19.4.1 Flag Protection During Break Interrupts . . . . . . . . . . . . . . . 310
19.4.2 CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .310
19.4.3 TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . 310
19.4.4 COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 310
19.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
19.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
19.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
19.6 Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
19.6.1 Break Status and Control Register. . . . . . . . . . . . . . . . . . . 311
19.6.2 Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . 312
19.6.3 SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 312
19.6.4 SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 314
19.2 Introduction
This section describes the break module. The break module can
generate a break interrupt that stops normal program flow at a defined
address to enter a background program.
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Technical Data
Break Module (BRK)
307
Break Module (BRK)
19.3 Features
Features of the break module include:
•
Accessible input/output (I/O) registers during the break interrupt
•
CPU-generated break interrupts
•
Software-generated break interrupts
•
COP disabling during break interrupts
19.4 Functional Description
When the internal address bus matches the value written in the break
address registers, the break module issues a breakpoint signal to the
CPU. The CPU then loads the instruction register with a software
interrupt instruction (SWI) after completion of the current CPU
instruction. The program counter vectors to $FFFC and $FFFD
($FEFC and $FEFD in monitor mode).
The following events can cause a break interrupt to occur:
•
A CPU-generated address (the address in the program counter)
matches the contents of the break address registers.
•
Software writes a logic 1 to the BRKA bit in the break status and
control register.
When a CPU-generated address matches the contents of the break
address registers, the break interrupt begins after the CPU completes its
current instruction. A return-from-interrupt instruction (RTI) in the break
routine ends the break interrupt and returns the MCU to normal
operation. Figure 19-1 shows the structure of the break module.
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Break Module (BRK)
Freescale Semiconductor
Break Module (BRK)
IAB15–IAB8
BREAK ADDRESS REGISTER HIGH
8-BIT COMPARATOR
IAB15–IAB0
BREAK
CONTROL
8-BIT COMPARATOR
BREAK ADDRESS REGISTER LOW
IAB7–IAB0
Figure 19-1. Break Module Block Diagram
Addr.
Register Name
Read:
SIM Break Status Register
$FE00
Write:
(SBSR)
Reset:
$FE03
$FE0C
$FE0D
Read:
SIM Break Flag Control
Write:
Register (SBFCR)
Reset:
Read:
Break Address Register
Write:
High (BRKH)
Reset:
Read:
Break Address Register
Write:
Low (BRKL)
Reset:
Read:
Break Status and Control
$FE0E
Write:
Register (BRKSCR)
Reset:
Note: Writing a logic 0 clears SBSW.
Bit 7
6
5
4
3
2
R
R
R
R
R
R
1
SBSW
Note
Bit 0
R
0
BCFE
R
R
R
R
R
R
R
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
BRKE
BRKA
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R
= Reserved
0
= Unimplemented
Figure 19-2. Break Module I/O Register Summary
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Break Module (BRK)
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Break Module (BRK)
19.4.1 Flag Protection During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables
software to clear status bits during the break state.
19.4.2 CPU During Break Interrupts
The CPU starts a break interrupt by:
•
Loading the instruction register with the SWI instruction
•
Loading the program counter with $FFFC and $FFFD
($FEFC and $FEFD in monitor mode)
The break interrupt begins after completion of the CPU instruction in
progress. If the break address register match occurs on the last cycle of
a CPU instruction, the break interrupt begins immediately.
19.4.3 TIM During Break Interrupts
A break interrupt stops the timer counters.
19.4.4 COP During Break Interrupts
The COP is disabled during a break interrupt when VTST is present on
the RST pin.
19.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low powerconsumption standby modes.
19.5.1 Wait Mode
If enabled, the break module is active in wait mode. In the break routine,
the user can subtract one from the return address on the stack if SBSW
is set (see Section 8. System Integration Module (SIM)). Clear the
SBSW bit by writing logic 0 to it.
Technical Data
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Freescale Semiconductor
Break Module (BRK)
19.5.2 Stop Mode
A break interrupt causes exit from stop mode and sets the SBSW bit in
the break status register.
19.6 Break Module Registers
These registers control and monitor operation of the break module:
•
Break status and control register (BRKSCR)
•
Break address register high (BRKH)
•
Break address register low (BRKL)
•
SIM break status register (SBSR)
•
SIM break flag control register (SBFCR)
19.6.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module
enable and status bits.
Address:
Read:
Write:
Reset:
$FE0E
Bit 7
6
BRKE
BRKA
0
0
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 19-3. Break Status and Control Register (BRKSCR)
BRKE — Break Enable Bit
This read/write bit enables breaks on break address register matches.
Clear BRKE by writing a logic 0 to bit 7. Reset clears the BRKE bit.
1 = Breaks enabled on 16-bit address match
0 = Breaks disabled on 16-bit address match
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Break Module (BRK)
311
Break Module (BRK)
BRKA — Break Active Bit
This read/write status and control bit is set when a break address
match occurs. Writing a logic 1 to BRKA generates a break interrupt.
Clear BRKA by writing a logic 0 to it before exiting the break routine.
Reset clears the BRKA bit.
1 = (When read) Break address match
0 = (When read) No break address match
19.6.2 Break Address Registers
The break address registers (BRKH and BRKL) contain the high and low
bytes of the desired breakpoint address. Reset clears the break address
registers.
Address:
Read:
Write:
Reset:
$FE0C
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Figure 19-4. Break Address Register High (BRKH)
Address:
Read:
Write:
Reset:
$FE0D
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Figure 19-5. Break Address Register Low (BRKL)
19.6.3 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a
break caused an exit from wait mode. The flag is useful in applications
requiring a return to wait mode after exiting from a break interrupt.
Technical Data
312
MC68HC908JB16 — Rev. 1.1
Break Module (BRK)
Freescale Semiconductor
Break Module (BRK)
Address:
Read:
Write:
$FE00
Bit 7
6
5
4
3
2
R
R
R
R
R
R
Reset:
1
SBSW
Note
Bit 0
R
0
Note: Writing a logic 0 clears SBSW.
R
= Reserved
Figure 19-6. SIM Break Status Register (SBSR)
SBSW — SIM Break Stop/Wait Bit
This status bit is useful in applications requiring a return to wait or stop
mode after exiting from a break interrupt. Clear SBSW by writing a
logic 0 to it. Reset clears SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting one from it. The
following code is an example.
; This code works if the H register has been pushed onto the stack in the break
; service routine software. This code should be executed at the end of the break
; service routine software.
HIBYTE
EQU
5
LOBYTE
EQU
6
;
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
; See if wait mode or stop mode was exited by
; break.
TST
LOBYTE,SP
;If RETURNLO is not zero,
BNE
DOLO
;then just decrement low byte.
DEC
HIBYTE,SP
;Else deal with high byte, too.
DOLO
DEC
LOBYTE,SP
;Point to WAIT/STOP opcode.
RETURN
PULH
RTI
;Restore H register.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Break Module (BRK)
313
Break Module (BRK)
19.6.4 SIM Break Flag Control Register
The SIM break flag control register (SBFCR) contains a bit that enables
software to clear status bits while the MCU is in a break state.
Address:
Read:
Write:
Reset:
$FE03
Bit 7
6
5
4
3
2
1
Bit 0
BCFE
R
R
R
R
R
R
R
0
R
= Reserved
Figure 19-7. SIM Break Flag Control Register (SBFCR)
BCFE — Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
Technical Data
314
MC68HC908JB16 — Rev. 1.1
Break Module (BRK)
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 20. Electrical Specifications
20.1 Contents
20.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
20.3
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . 316
20.4
Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . . 317
20.5
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
20.6
DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 318
20.7
Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
20.8
Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
20.9
TImer Interface Module Characteristics . . . . . . . . . . . . . . . . . 320
20.10 USB DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 320
20.11 USB Low-Speed Source Electrical Characteristics . . . . . . . . 321
20.12 USB Signaling Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
20.13 CGM Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 322
20.14 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . 324
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Electrical Specifications
315
Electrical Specifications
20.2 Introduction
This section contains electrical and timing specifications.
20.3 Absolute Maximum Ratings
Maximum ratings are the extreme limits to which the MCU can be
exposed without permanently damaging it.
NOTE:
This device is not guaranteed to operate properly at the maximum
ratings. Refer to 20.6 DC Electrical Characteristics for guaranteed
operating conditions.
Characteristic(1)
Symbol
Value
Unit
Supply voltage
VDD
–0.3 to +6.0
V
Input voltage
PTE4/D–, PTE3/D+
Others
VIN
VSS – 1.0 to VDD + 0.3
VSS – 0.3 to VDD + 0.3
V
Mode entry voltage, IRQ pin
VTST
VSS –0.3 to +8
V
I
± 25
mA
Storage temperature
TSTG
–55 to +150
°C
Maximum current out of VSS /VSS
IMVSS
100
mA
Maximum current into VDD /VDDA
IMVDD
100
mA
Maximum current per pin
excluding VDD and VSS
Notes:
1. Voltages referenced to VSS
NOTE:
This device contains circuitry to protect the inputs against damage due
to high static voltages or electric fields; however, it is advised that normal
precautions be taken to avoid application of any voltage higher than
maximum-rated voltages to this high-impedance circuit. For proper
operation, it is recommended that VIN and VOUT be constrained to the
range VSS ≤ (VIN or VOUT) ≤ VDD. Reliability of operation is enhanced if
unused inputs are connected to an appropriate logic voltage level (for
example, either VSS or VDD).
Technical Data
316
MC68HC908JB16 — Rev. 1.1
Electrical Specifications
Freescale Semiconductor
Electrical Specifications
20.4 Functional Operating Range
Characteristic
Operating temperature range
Operating voltage range
Symbol
Value
Unit
TA
0 to 70
°C
VDD
4.0 to 5.5
V
20.5 Thermal Characteristics
Characteristic
Symbol
Value
Unit
Thermal Resistance
LQFP (32 pins)
SOIC (28 pins)
θJA
95
70
°C/W
I/O pin power dissipation
PI/O
User-Determined
W
PD
PD = (IDD × VDD) +
(IDDA × VDDA) + PI/O =
K/(TJ + 273 °C)
W
Power dissipation
(1)
Constant(2)
K
Average junction temperature
Maximum junction temperature
PD x (TA + 273 °C)
+ PD2 × θJA
W/°C
TJ
TA + (PD × θJA)
°C
TJM
100
°C
Notes:
1. Power dissipation is a function of temperature.
2. K is a constant unique to the device. K can be determined for a known TA and measure PD.
With this value of K, PD and TJ can be determined for any value of TA.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Electrical Specifications
317
Electrical Specifications
20.6 DC Electrical Characteristics
Characteristic(1)
Symbol
Min
Typ(2)
Max
Unit
VREG
VREGA0
3.0
2.9
3.3
3.3
3.6
3.7
V
Output high voltage (ILoad = –2.0 mA)
PTA0–PTA7, PTC0–PTC1, PTE0–PTE2
VOH
VDD –0.8
—
—
V
Output low voltage
(ILoad = 1.6 mA) All I/O pins
(ILoad = 25 mA) PTD0–PTD1 in ILDD mode
(ILoad = 10 mA) PTE3–PTE4 with USB is disabled
VOL
—
—
—
—
—
—
0.4
0.5
0.4
Input high voltage
OSC1
All ports, IRQ, RST
VIH
0.7 × VREG
0.7 × VDD
—
—
VREG
VDD
V
Input low voltage
OSC1
All ports, IRQ, RST
VIL
VSS
VSS
—
—
0.3 × VREG
0.3 × VDD
V
Output low current (VOL = 2.0 V)
PTD2–PTD5 in LDD mode
IOL
10
13
20
mA
—
—
—
—
—
7.0
6.5
3.0
2.5
60
8.5
8.0
5.0
4.0
100
mA
mA
mA
mA
µA
Regulator output voltage
V
VDD supply current, VDD = 5.25V, fOP = 6MHz
Run, with low speed USB(3)
Run, with USB suspended(3)
Wait, with low speed USB(4)
Wait, with USB suspended(4)
Stop (0 °C to 70°C)(5)
IDD
I/O ports Hi-Z leakage current
IIL
—
—
± 10
µA
Input current
IIN
—
—
±1
µA
Capacitance
Ports (as input or output)
COut
CIn
—
—
—
—
12
8
pF
POR re-arm voltage(6)
VPOR
0
—
100
mV
POR rise-time ramp rate(7)
RPOR
0.035
—
—
V/ms
Monitor mode entry voltage
VTST
VDD + 2.5
8
V
Pullup resistors
Port A, port C, PTE0–PTE2, RST, IRQ (to VDD)
PTE3–PTE4 with USB module disabled (to VDD)
D– with USB module enabled (to VREG)
RPU
VDD LVI trip point voltage (LVI5OR3 = 0)
VDD LVI trip point voltage (LVI5OR3 = 1)
VLVR
VREG LVI trip point voltage
Technical Data
318
20
4
1.1
35
5
1.5
50
6
2.0
2.0
2.4
2.8
2.8
3.3
3.8
2.0
2.2
2.6
kΩ
V
MC68HC908JB16 — Rev. 1.1
Electrical Specifications
Freescale Semiconductor
Electrical Specifications
Notes:
1. VDD = 4.0 to 5.5 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
3. Run (operating) IDD measured using external square wave clock source (fXCLK = 12MHz). All inputs 0.2 V from rail. No dc
loads. Less than 100 pF on all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly
affects run IDD. Measured with all modules enabled.
4. Wait IDD measured using external square wave clock source (fXCLK = 12MHz); all inputs 0.2 V from rail; no dc loads; less
than 100 pF on all outputs. CL = 20 pF on OSC2; 15 kΩ ± 5% termination resistors on D+ and D– pins; all ports configured
as inputs; OSC2 capacitance linearly affects wait IDD
5. STOP IDD measured with USB in suspend mode; OSC1 grounded; no port pins sourcing current.
6. Maximum is highest voltage that POR is guaranteed.
7. If minimum VDD is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VDD is reached.
20.7 Control Timing
Characteristic(1)
Symbol
Min
Max
Unit
Internal operating frequency(2)
fOP
—
6
MHz
RST input pulse width low(3)
tIRL
125
—
ns
Notes:
1. VDD = 4.0 to 5.5 Vdc; VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
20.8 Oscillator Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
Crystal frequency(1)
fXCLK
1
12
12
MHz
External clock
Reference frequency(1), (2)
fXCLK
dc
12
12
MHz
Crystal load capacitance(3)
CL
—
—
—
Crystal fixed capacitance(3)
C1
—
2 × CL
—
Crystal tuning capacitance(3)
C2
—
2 × CL
—
Feedback bias resistor
RB
—
10 MΩ
—
Series resistor(3), (4)
RS
—
—
—
Notes:
1. The USB module is designed to operate with fXCLK = 12 MHz.
2. No more than 10% duty cycle deviation from 50%.
3. Consult crystal vendor data sheet.
4. Not required for high-frequency crystals.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Electrical Specifications
319
Electrical Specifications
20.9 TImer Interface Module Characteristics
Characteristic
Input capture pulse width
Input clock pulse width
Symbol
Min
Max
Unit
tTIH, tTIL
1/fOP
—
ns
tTCH, tTCL
(1/fOP) + 5
—
ns
20.10 USB DC Electrical Characteristics
Characteristic(1)
Symbol
Conditions
Min
Hi-Z state data line leakage
ILO
0 V<VIN<3.3
V
–10
Voltage input high (driven)
VIH
2.0
Voltage input high (floating)
VIHZ
2.7
Voltage input low
VIL
Differential input sensitivity
VDI
|(D+) – (D–)|
0.2
Differential common mode range
VCM
Includes VDI
Range
0.8
Static output low
VOL
RL of 1.425 K
to 3.6 V
Static output high
VOH
RL of 14.25 K
to GND
Output signal crossover voltage
VCRS
Regulator bypass capacitor
CREGBYPASS
Regulator bulk capacitor
CREGBULK
Typ
+10
µA
3.6
V
0.8
V
V
—
0.1
4.7
Unit
V
2.8
1.3
Max
2.5
V
0.3
V
3.6
V
2.0
V
µF
µF
Notes:
1. VDD = 4.0 to 5.5 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
Technical Data
320
MC68HC908JB16 — Rev. 1.1
Electrical Specifications
Freescale Semiconductor
Electrical Specifications
20.11 USB Low-Speed Source Electrical Characteristics
Characteristic(1)
Symbol
Conditions
Min
Typ
Max
Unit
Internal operating frequency
fOP
—
—
6
—
MHz
Transition time(2)
Rise time
tR
CL = 200 pF
CL = 600 pF
CL = 200 pF
CL = 600 pF
75
—
300
ns
75
—
tRFM
tR/tF
80
—
120
%
tDRATE
1.5 Mbs ± 1.5%
1.4775
676.8
1.500
666.0
1.5225
656.8
Mbs
ns
Source differential driver jitter
To next transition
For paired transitions
tDDJ1
tDDJ2
CL = 600 pF
Measured at
crossover point
–25
–10
—
—
25
10
ns
Receiver data jitter tolerance
To next transition
For paired transitions
tDJR1
tDJR2
CL = 600 pF
Measured at
crossover point
–75
–45
—
—
75
45
ns
Source SEO interval of EOP
tLEOPT
Measured at
crossover point
1.25
—
1.50
µs
Fall time
Rise/Fall time matching
Low speed data rate
tF
Source jitter for differential transition
to SE0 transition(3)
Receiver SEO interval of EOP
Must reject as EOP
Must accept
Width of SEO interval during
differential transition
300
Measured at
crossover point
tLEOPR1
tLEOPR2
tLST
Measured at
crossover point
Measured at
crossover point
667
ns
210
670
—
—
—
—
ns
—
—
210
ns
Notes:
1. All voltages are measured from local ground, unless otherwise specified. All timings use a capacitive load of 50 pF, unless
otherwise specified. Low-speed timings have a 1.5kΩ pullup to 2.8 V on the D– data line.
2. Transition times are measured from 10% to 90% of the data signal. The rising and falling edges should be smoothly transitioning (monotonic). Capacitive loading includes 50 pF of tester capacitance.
3. The two transitions are a (nominal) bit time apart.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Electrical Specifications
321
Electrical Specifications
20.12 USB Signaling Levels
Signaling Levels
Bus State
Transmit
Receive
Differential 1
D+ > VOH (min) and D– < VOL (max)
(D+) – (D–) > 200 mV
Differential 0
D– > VOH (min) and D– < VOL (max)
(D–) – (D+) > 200 mV
Single-ended 0 (SE0)
D+ and D– < VOL (max)
D+ and D– < VIL (max)
Data J state (low speed)
Differential 0
Differential 0
Data K state (low speed)
Differential 1
Differential 1
Idle state (low speed)
NA
D– > VIHZ (min) and D+ < VIL (max)
Resume state
Differential 1
Differential 1
Start of packet (SOP)
Data lines switch from Idle to K State
End of packet (EOP)
SE0 for approximately 2 bit times(1)
followed by a J state for 1 bit time
SE0 for ≥ 1 bit time(2) followed by a
J state for 1 bit time
Reset
NA
D+ and D– < VIL (max) for ≥ 8µs
Notes:
1. The width of EOP is defined in bit times relative to the speed of transmission.
2. The width of EOP is defined in bit times relative to the device type receiving the EOP. The bit time is approximate.
20.13 CGM Electrical Characteristics
Characteristic(1)
Condition
CGM power supply
CGM supply current
Both PLLs enabled
One PLL enabled
CGM regulator output voltage
Symbol
Min
Typ(2)
Max
Unit
VDDA
4.0
5
5.5
V
IDDA
—
—
6
3
10
5
mA
mA
VREGA0
2.9
3.3
3.7
V
CGM output high voltage
(ILoad = –2.0 mA)
VOH
VREGA0 –0.8
—
—
V
CGM output low voltage
(ILoad = 1.6 mA)
VOL
—
—
0.4
V
COUT
—
—
12
pF
tR/tF
—
—
8
ns
RL
2
—
—
kΩ
CGM output equivalent
capacitance
CGM output rise and fall time
Output resistive load
RL = 2kΩ
CL = 10pF
10% to 90%
Technical Data
322
MC68HC908JB16 — Rev. 1.1
Electrical Specifications
Freescale Semiconductor
Electrical Specifications
Characteristic(1)
Condition
Output capacitive load
Symbol
Min
Typ(2)
Max
Unit
CL
—
—
10
pF
—
MHz
PLL frequency list
Rx LO 1
Rx LO 2
Rx LO 3
Rx LO 4
Rx LO 5
—
26.54
26.59
26.64
26.69
26.74
PLL output signal frequency
accuracy
Exclude crystal
OSC tolerance
—
±100
±4
—
Hz
ppm
PLL output signal phase
noise level
At ±1kHz offset
from carrier
—
–40
—
dBc/Hz
26
—
28
MHz
channel to
channel(3)
—
10
—
ms
Wait/stop mode to
active(4)
—
20
—
ms
Duration for Lock bit detection
Within ±10% final
frequency(5)
—
10
—
ms
PLL stop duration
PLL module from
active to disable
mode.
—
—
1
ms
PLL output sideband
noise level(6)
At offset >4kHz
At offset >42.5kHz
—
–40
–50
—
dBc
PLL output channel
intermodulation products(7)
At offset >42.5kHz
—
–50
—
dBc
VCO frequency range
PLL lock duration
Notes:
1. VDDA = 4.0 to 5.5 Vdc, VSSA = 0 Vdc, TA = TL to TH, with the pre-defined programming setting for the PLL
(see 13.10 Pre-Defined VCO Output Frequency Settings) and under steady state condition, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
3. Defined as the total time for PLL module switching from channel-to-channel and the frequency is stable with ±60ppm. The
reference frequency should be greater than 32kHz.
4. Defined as the total time for PLL module active from wait/stop mode to the frequency is stable with ±60ppm error. The
reference frequency should be greater than 32kHz.
5. Defined as the total time for PLL Lock bit setup from un-lock to lock state with the frequency is stable with ±10% error. The
reference frequency should be greater than 32kHz.
6. Side-band component generate from reference frequency modulation on carrier.
7. Noise component generate from adjacent channel carrier when both PLLs are enable.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Electrical Specifications
323
Electrical Specifications
20.14 FLASH Memory Characteristics
Characteristic
RAM data retention voltage
Symbol
Min
Max
Unit
VRDR
1.3
—
V
FLASH block size
—
512
Bytes
FLASH programming size
—
64
Bytes
FLASH read bus clock frequency
fRead(1)
32 k
8.4 M
Hz
FLASH block erase time
tErase(2)
10
—
ms
FLASH mass erase time
tMErase(3)
200
—
ms
FLASH PGM/ERASE to HVEN set up time
tnvs
5
—
µs
FLASH high-voltage hold time
tnvh
5
—
µs
FLASH high-voltage hold time (mass erase)
tnvhl
100
—
µs
FLASH program hold time
tpgs
10
—
µs
FLASH program time
tProg
20
40
µs
FLASH return to read time
trcv(4)
1
—
µs
FLASH cumulative program hv period
tHV(5)
—
8
ms
FLASH row erase endurance(6)
—
10k
—
Cycles
FLASH row program endurance(7)
—
10k
—
Cycles
FLASH data retention time(8)
—
10
—
Years
Notes:
1. fRead is defined as the frequency range for which the FLASH memory can be read.
2. If the page erase time is longer than tErase (Min), there is no erase-disturb, but it reduced the endurance of the FLASH
memory.
3. If the mass erase time is longer than tMErase (Min), there is no erase-disturb, but it reduces the endurance of the FLASH
memory.
4. trcv is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by clearing
HVEN to logic 0.
5. tHV is defined as the cumulative high voltage programming time to the same row before next erase.
6. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase / program cycles.
7. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase / program cycles.
8. The FLASH is guaranteed to retain data over the entire operating temperature range for at least the minimum time
specified.
Technical Data
324
MC68HC908JB16 — Rev. 1.1
Electrical Specifications
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 21. Mechanical Specifications
21.1 Contents
21.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
21.3
32-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . . 326
21.4
28-Pin Small Outline Integrated Circuit (SOIC) . . . . . . . . . . . 327
21.2 Introduction
This section gives the dimensions for:
•
32-pin low-profile quad flat pack (case #873A)
•
28-pin small outline integrated circuit package (case #751F)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Mechanical Specifications
325
Mechanical Specifications
A
–T–, –U–, –Z–
21.3 32-Pin Low-Profile Quad Flat Pack (LQFP)
4X
A1
32
0.20 (0.008) AB T–U Z
25
1
–U–
–T–
B
V
AE
P
B1
DETAIL Y
17
8
V1
AE
DETAIL Y
9
4X
–Z–
9
0.20 (0.008) AC T–U Z
S1
S
DETAIL AD
G
–AB–
0.10 (0.004) AC
AC T–U Z
–AC–
BASE
METAL
ÉÉ
ÉÉ
ÉÉ
ÉÉ
F
8X
M_
R
M
N
D
J
0.20 (0.008)
SEATING
PLANE
SECTION AE–AE
W
K
X
DETAIL AD
Q_
GAUGE PLANE
H
0.250 (0.010)
C E
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE –AB– IS LOCATED AT BOTTOM
OF LEAD AND IS COINCIDENT WITH THE LEAD
WHERE THE LEAD EXITS THE PLASTIC BODY AT
THE BOTTOM OF THE PARTING LINE.
4. DATUMS –T–, –U–, AND –Z– TO BE DETERMINED
AT DATUM PLANE –AB–.
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE –AC–.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS
0.250 (0.010) PER SIDE. DIMENSIONS A AND B
DO INCLUDE MOLD MISMATCH AND ARE
DETERMINED AT DATUM PLANE –AB–.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. DAMBAR PROTRUSION SHALL
NOT CAUSE THE D DIMENSION TO EXCEED
0.520 (0.020).
8. MINIMUM SOLDER PLATE THICKNESS SHALL BE
0.0076 (0.0003).
9. EXACT SHAPE OF EACH CORNER MAY VARY
FROM DEPICTION.
DIM
A
A1
B
B1
C
D
E
F
G
H
J
K
M
N
P
Q
R
S
S1
V
V1
W
X
MILLIMETERS
MIN
MAX
7.000 BSC
3.500 BSC
7.000 BSC
3.500 BSC
1.400
1.600
0.300
0.450
1.350
1.450
0.300
0.400
0.800 BSC
0.050
0.150
0.090
0.200
0.500
0.700
12_ REF
0.090
0.160
0.400 BSC
1_
5_
0.150
0.250
9.000 BSC
4.500 BSC
9.000 BSC
4.500 BSC
0.200 REF
1.000 REF
INCHES
MIN
MAX
0.276 BSC
0.138 BSC
0.276 BSC
0.138 BSC
0.055
0.063
0.012
0.018
0.053
0.057
0.012
0.016
0.031 BSC
0.002
0.006
0.004
0.008
0.020
0.028
12_ REF
0.004
0.006
0.016 BSC
1_
5_
0.006
0.010
0.354 BSC
0.177 BSC
0.354 BSC
0.177 BSC
0.008 REF
0.039 REF
Figure 21-1. 32-Pin LQFP (Case #873A)
Technical Data
326
MC68HC908JB16 — Rev. 1.1
Mechanical Specifications
Freescale Semiconductor
Mechanical Specifications
21.4 28-Pin Small Outline Integrated Circuit (SOIC)
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE
DAMBAR PROTRUSION SHALL BE 0.13
(0.005) TOTAL IN EXCESS OF D DIMENSION
AT MAXIMUM MATERIAL CONDITION.
-A15
28
14X
-B1
P
0.010 (0.25)
M
B
M
14
28X
D
0.010 (0.25)
M
T A
S
B
M
S
R
X 45
C
26X
-T-
G
SEATING
PLANE
K
F
J
DIM
A
B
C
D
F
G
J
K
M
P
R
MILLIMETERS
MIN
MAX
17.80
18.05
7.40
7.60
2.35
2.65
0.35
0.49
0.41
0.90
1.27 BSC
0.23
0.32
0.13
0.29
0°
8°
10.01
10.55
0.25
0.75
INCHES
MIN
MAX
0.701
0.711
0.292
0.299
0.093
0.104
0.014
0.019
0.016
0.035
0.050 BSC
0.009
0.013
0.005
0.011
0°
8°
0.395
0.415
0.010
0.029
Figure 21-2. 28-Pin SOIC (Case #751F)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Mechanical Specifications
327
Mechanical Specifications
Technical Data
328
MC68HC908JB16 — Rev. 1.1
Mechanical Specifications
Freescale Semiconductor
Technical Data — MC68HC908JB16
Section 22. Ordering Information
22.1 Contents
22.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
22.3
MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
22.2 Introduction
This section contains ordering numbers for the MC68HC908JB16.
22.3 MC Order Numbers
Table 22-1. MC Order Numbers
Package
Operating
Temperature Range
MC68HC908JB16DW
28-pin SOIC
0 °C to +70 °C
MC68HC908JB16FA
32-pin LQFP
0 °C to +70 °C
MC Order Number
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Technical Data
Ordering Information
329
Ordering Information
Technical Data
330
MC68HC908JB16 — Rev. 1.1
Ordering Information
Freescale Semiconductor
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Rev. 1.1
MC68HC908JB16/D
August 1, 2005
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