FREESCALE MC908MR16CBE

MC68HC908MR32
MC68HC908MR16
Data Sheet
M68HC08
Microcontrollers
MC68HC908MR32/D
Rev. 6.0
11/2003
MOTOROLA.COM/SEMICONDUCTORS
深圳市南天星电子科技有限公司
专业代理飞思卡尔
(Freescale)
飞思卡尔主要产品
8 位微控制器
16 位微控制器
数字信号处理器与控制器
i.MX 应用处理器
基于 ARM®技术的 Kinetis MCU
32/64 位微控制器与处理器
模拟与电源管理器件
射频器件（LDMOS，收发器）
传感器（压力，加速度，磁场，
触摸，电池）
飞思卡尔产品主要应用
汽车电子
数据连接
消费电子
工业控制
医疗保健
电机控制
网络
智能能源
深圳市南天星电子科技有限公司
电话：0755－83040796
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网址：www.soustar.com.cn
地址：深圳市福田区福明路雷圳大厦 2306 室
MC68HC908MR32
MC68HC908MR16
Data Sheet
To provide the most up-to-date information, the revision of our documents on the
World Wide Web will be the most current. Your printed copy may be an earlier
revision. To verify you have the latest information available, refer to:
http://motorola.com/semiconductors
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.
Motorola and the Stylized M Logo are registered trademarks of Motorola, Inc.
DigitalDNA is a trademark of Motorola, Inc.
This product incorporates SuperFlash® technology licensed from SST.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
© Motorola, Inc., 2003
Data Sheet
3
Revision History
Revision History
Date
Revision
Level
August,
2001
3.0
October,
2001
4.0
December,
2001
5.0
Description
Figure 2-1. MC68HC908MR32 Memory Map — Added FLASH Block Protect
Register (FLBPR) at address location $FF7E
29
Figure A-1. MC68HC908MR16 Memory Map — Added FLASH Block Protect
Register (FLBPR) at address location $FF7E
306
3.3.3 Conversion Time — Reworked equations and text for clarity.
50
Figure 18-8. Monitor Mode Circuit — PTA7 and connecting circuitry added
279
Table 18-2. Monitor Mode Signal Requirements and Options — Switch locations
added to column headings for clarity
281
Section 16. Timer Interface A (TIMA) — Timer discrepancies corrected throughout
this section.
233
Section 17. Timer Interface B (TIMB) — Timer discrepancies corrected throughout
this section.
255
Reformatted to meet current publication standards
November,
2003
6.0
Throughout
2.8.2 FLASH Page Erase Operation — Procedure reworked for clarity
42
2.8.3 FLASH Mass Erase Operation — Procedure reworked for clarity
42
2.8.4 FLASH Program Operation — Procedure reworked for clarity
43
Figure 14-14. SIM Break Status Register (SBSR) — Clarified definition of SBSW
bit.
207
19.5 DC Electrical Characteristics — Corrected maximum value for monitor mode
entry voltage (on IRQ)
291
19.6 FLASH Memory Characteristics — Updated table entries
292
Data Sheet
4
Page
Number(s)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Revision History
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
List of Sections
Section 1. General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Section 2. Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Section 3. Analog-to-Digital Converter (ADC) . . . . . . . . . . . . . . . . . . . 47
Section 4. Clock Generator Module (CGM). . . . . . . . . . . . . . . . . . . . . . 59
Section 5. Configuration Register (CONFIG) . . . . . . . . . . . . . . . . . . . . 79
Section 6. Computer Operating Properly (COP) . . . . . . . . . . . . . . . . . 83
Section 7. Central Processor Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . 87
Section 8. External Interrupt (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Section 9. Low-Voltage Inhibit (LVI) . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Section 10. Input/Output (I/O) Ports (PORTS) . . . . . . . . . . . . . . . . . . 111
Section 11. Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . .125
Section 12. Pulse-Width Modulator for Motor
Control (PWMMC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
Section 13. Serial Communications Interface Module (SCI) . . . . . . . 169
Section 14. System Integration Module (SIM) . . . . . . . . . . . . . . . . . . 195
Section 15. Serial Peripheral Interface Module (SPI). . . . . . . . . . . . . 209
Section 16. Timer Interface A (TIMA) . . . . . . . . . . . . . . . . . . . . . . . . . 233
Section 17. Timer Interface B (TIMB) . . . . . . . . . . . . . . . . . . . . . . . . . 255
Section 18. Development Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Section 19. Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . 289
Section 20. Ordering Information and Mechanical
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Appendix A. MC68HC908MR16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
List of Sections
5
List of Sections
Data Sheet
6
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
List of Sections
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Table of Contents
Section 1. General Description
1.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.3
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.4
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.1
Power Supply Pins (VDD and VSS) . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.2
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.3
External Reset Pin (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.4
External Interrupt Pin (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.5
CGM Power Supply Pins (VDDA and VSSAD) . . . . . . . . . . . . . . . . . .
1.4.6
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . . . . . . .
1.4.7
Analog Power Supply Pins (VDDAD and VSSAD) . . . . . . . . . . . . . . . .
1.4.8
ADC Voltage Decoupling Capacitor Pin (VREFH) . . . . . . . . . . . . . . .
1.4.9
ADC Voltage Reference Low Pin (VREFL) . . . . . . . . . . . . . . . . . . . .
1.4.10
Port A Input/Output (I/O) Pins (PTA7–PTA0) . . . . . . . . . . . . . . . . . .
1.4.11
Port B I/O Pins (PTB7/ATD7–PTB0/ATD0) . . . . . . . . . . . . . . . . . . .
1.4.12
Port C I/O Pins (PTC6–PTC2 and PTC1/ATD9–PTC0/ATD8) . . . . .
1.4.13
Port D Input-Only Pins (PTD6/IS3–PTD4/IS1
and PTD3/FAULT4–PTD0/FAULT1) . . . . . . . . . . . . . . . . . . . . . .
1.4.14
PWM Pins (PWM6–PWM1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.15
PWM Ground Pin (PWMGND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.16
Port E I/O Pins (PTE7/TCH3A–PTE3/TCLKA
and PTE2/TCH1B–PTE0/TCLKB) . . . . . . . . . . . . . . . . . . . . . . . .
1.4.17
Port F I/O Pins (PTF5/TxD–PTF4/RxD
and PTF3/MISO–PTF0/SPSCK) . . . . . . . . . . . . . . . . . . . . . . . . .
22
24
24
24
24
25
25
25
25
25
25
25
25
26
26
26
26
26
Section 2. Memory
2.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.3
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4
I/O Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.6
Monitor ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.7
Random-Access Memory (RAM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Table of Contents
7
Table of Contents
2.8
2.8.1
2.8.2
2.8.3
2.8.4
2.8.5
2.8.6
2.8.7
2.8.8
FLASH Memory (FLASH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Block Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40
41
42
42
43
45
45
46
46
Section 3. Analog-to-Digital Converter (ADC)
3.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC Port I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conversion Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monotonicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.5
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.6
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.1
ADC Analog Power Pin (VDDAD). . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.2
ADC Analog Ground Pin (VSSAD) . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.3
ADC Voltage Reference Pin (VREFH) . . . . . . . . . . . . . . . . . . . . . . . .
3.6.4
ADC Voltage Reference Low Pin (VREFL) . . . . . . . . . . . . . . . . . . . .
3.6.5
ADC Voltage In (ADVIN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.6
ADC External Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.6.1
VREFH and VREFL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.6.2
ANx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.6.3
Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
52
52
52
52
53
53
53
53
53
53
3.7
3.7.1
3.7.2
3.7.3
3.7.4
54
54
56
56
57
I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC Data Register High. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC Data Register Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC Clock Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Sheet
8
47
49
49
50
50
50
52
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Table of Contents
MOTOROLA
Table of Contents
Section 4. Clock Generator Module (CGM)
4.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.1
Crystal Oscillator Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2
Phase-Locked Loop Circuit (PLL). . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2.1
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2.2
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2.3
Manual and Automatic PLL Bandwidth Modes . . . . . . . . . . . . . . .
4.3.2.4
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2.5
Special Programming Exceptions . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.3
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.4
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
61
61
61
62
62
64
65
65
66
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
4.4.6
4.4.7
4.4.8
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crystal Amplifier Input Pin (OSC1) . . . . . . . . . . . . . . . . . . . . . . . . . .
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . . . . . . . .
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . . . . . . .
PLL Analog Power Pin (VDDA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oscillator Enable Signal (SIMOSCEN) . . . . . . . . . . . . . . . . . . . . . . .
Crystal Output Frequency Signal (CGMXCLK). . . . . . . . . . . . . . . . .
CGM Base Clock Output (CGMOUT) . . . . . . . . . . . . . . . . . . . . . . . .
CGM CPU Interrupt (CGMINT). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
67
67
67
67
67
67
68
68
68
4.5
4.5.1
4.5.2
4.5.3
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLL Bandwidth Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLL Programming Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
68
69
70
72
4.6
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.7
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.8
4.8.1
4.8.2
4.8.3
4.8.4
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acquisition/Lock Time Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parametric Influences on Reaction Time . . . . . . . . . . . . . . . . . . . . .
Choosing a Filter Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reaction Time Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
74
74
75
75
76
Section 5. Configuration Register (CONFIG)
5.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.2
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.3
Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Table of Contents
9
Table of Contents
Section 6. Computer Operating Properly (COP)
6.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.2
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.3
6.3.1
6.3.2
6.3.3
6.3.4
6.3.5
6.3.6
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CGMXCLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset Vector Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COPD (COP Disable) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.5
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.6
Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.7
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.8
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
84
84
84
84
84
85
85
Section 7. Central Processor Unit (CPU)
7.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
7.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
7.3
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condition Code Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.4
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7.5
7.5.1
7.5.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7.6
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7.7
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.8
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
88
88
89
89
90
90
Section 8. External Interrupt (IRQ)
8.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
8.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
8.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
8.4
IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
8.5
IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
8.6
IRQ Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
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Section 9. Low-Voltage Inhibit (LVI)
9.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
9.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
9.3
9.3.1
9.3.2
9.3.3
9.3.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Polled LVI Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Forced Reset Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
False Reset Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LVI Trip Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4
LVI Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
9.5
LVI Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
9.6
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
9.7
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
107
108
108
108
109
Section 10. Input/Output (I/O) Ports (PORTS)
10.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
10.2 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
10.2.1
Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
10.2.2
Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
10.3 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
10.3.1
Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
10.3.2
Data Direction Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
10.4 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
10.4.1
Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
10.4.2
Data Direction Register C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
10.5
Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
10.6 Port E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
10.6.1
Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
10.6.2
Data Direction Register E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
10.7 Port F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.7.1
Port F Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.7.2
Data Direction Register F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Section 11. Power-On Reset (POR)
11.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
11.2
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
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Section 12. Pulse-Width Modulator for Motor Control (PWMMC)
12.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
12.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
12.3 Timebase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
12.3.1
Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
12.3.2
Prescaler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
12.4 PWM Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
12.4.1
Load Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
12.4.2
PWM Data Overflow and Underflow Conditions . . . . . . . . . . . . . . . 137
12.5 Output Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.5.1
Selecting Six Independent PWMs
or Three Complementary PWM Pairs . . . . . . . . . . . . . . . . . . . .
12.5.2
Dead-Time Insertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.5.3
Top/Bottom Correction with Motor Phase
Current Polarity Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.5.4
Output Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.5.5
PWM Output Port Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6 Fault Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.1
Fault Condition Input Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.1.1
Fault Pin Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.1.2
Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.1.3
Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.2
Software Output Disable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.6.3
Output Port Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
138
138
139
142
145
146
149
149
151
151
152
153
153
12.7
Initialization and the PWMEN Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
12.8
PWM Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
12.9 Control Logic Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.1
PWM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.2
PWM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.3
PWMx Value Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.4
PWM Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.5
PWM Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.6
Dead-Time Write-Once Register . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.7
PWM Disable Mapping Write-Once Register . . . . . . . . . . . . . . . . .
12.9.8
Fault Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.9
Fault Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.10
Fault Acknowledge Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12.9.11
PWM Output Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .
155
155
156
157
158
160
162
162
162
164
165
166
12.10 PWM Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
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Section 13. Serial Communications Interface Module (SCI)
13.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
13.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
13.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.1
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.2
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.3
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.4
Idle Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.5
Inversion of Transmitted Output . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.2.6
Transmitter Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3
Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.2
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.3
Data Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.4
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.5
Receiver Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.6
Receiver Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.3.3.7
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
171
172
173
174
174
174
175
175
176
176
176
176
176
180
180
180
181
13.4
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
13.5
SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . 181
13.6 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
13.6.1
PTF5/TxD (Transmit Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
13.6.2
PTF4/RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
13.7 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.1
SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.2
SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.3
SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.4
SCI Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.5
SCI Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.6
SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.7.7
SCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
182
182
185
187
188
191
192
192
Section 14. System Integration Module (SIM)
14.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
14.2 SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . . . . . . . . .
14.2.1
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.2.2
Clock Startup from POR or LVI Reset . . . . . . . . . . . . . . . . . . . . . .
14.2.3
Clocks in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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197
197
197
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14.3 Reset and System Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.3.1
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.3.2
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . . . . . . .
14.3.2.1
Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.3.2.2
Computer Operating Properly (COP) Reset . . . . . . . . . . . . . . . .
14.3.2.3
Illegal Opcode Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.3.2.4
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.3.2.5
Forced Monitor Mode Entry Reset (MENRST) . . . . . . . . . . . . . .
14.3.2.6
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . . . . . . .
198
198
199
199
200
201
201
201
201
14.4 SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
14.4.1
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . . . . . . . 202
14.4.2
SIM Counter and Reset States . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
14.5 Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.5.1
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.5.1.1
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.5.1.2
Software Interrupt (SWI) Instruction . . . . . . . . . . . . . . . . . . . . . .
14.5.2
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
202
202
204
205
205
14.6 Low-Power Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
14.6.1
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
14.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
14.7 SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.7.1
SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.7.2
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14.7.3
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . .
206
207
207
208
Section 15. Serial Peripheral Interface Module (SPI)
15.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
15.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
15.3
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
15.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
15.4.1
Master Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
15.4.2
Slave Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
15.5 Transmission Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.5.1
Clock Phase and Polarity Controls . . . . . . . . . . . . . . . . . . . . . . . . .
15.5.2
Transmission Format When CPHA = 0. . . . . . . . . . . . . . . . . . . . . .
15.5.3
Transmission Format When CPHA = 1. . . . . . . . . . . . . . . . . . . . . .
15.5.4
Transmission Initiation Latency . . . . . . . . . . . . . . . . . . . . . . . . . . .
214
214
215
216
217
15.6 Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
15.6.1
Overflow Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
15.6.2
Mode Fault Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
15.7
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
15.8
Resetting the SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Data Sheet
14
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Table of Contents
MOTOROLA
Table of Contents
15.9
Queuing Transmission Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
15.10 Low-Power Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
15.11 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11.1
MISO (Master In/Slave Out) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11.2
MOSI (Master Out/Slave In) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11.3
SPSCK (Serial Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11.4
SS (Slave Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11.5
VSS (Clock Ground) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
225
225
226
226
226
227
15.12 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.12.1
SPI Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.12.2
SPI Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . .
15.12.3
SPI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
227
227
229
232
Section 16. Timer Interface A (TIMA)
16.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
16.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
16.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.1
TIMA Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.2
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.3
Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.3.1
Unbuffered Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.4
Pulse-Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.4.1
Unbuffered PWM Signal Generation. . . . . . . . . . . . . . . . . . . . . .
16.3.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . .
16.3.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
237
237
238
239
239
239
240
241
242
242
16.4
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
16.5
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
16.6 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
16.6.1
TIMA Clock Pin (PTE3/TCLKA) . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
16.6.2
TIMA Channel I/O Pins (PTE4/TCH0A–PTE7/TCH3A) . . . . . . . . . 245
16.7 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.7.1
TIMA Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . .
16.7.2
TIMA Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.7.3
TIMA Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . .
16.7.4
TIMA Channel Status and Control Registers . . . . . . . . . . . . . . . . .
16.7.5
TIMA Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
245
245
247
248
248
252
Data Sheet
Table of Contents
15
Table of Contents
Section 17. Timer Interface B (TIMB)
17.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
17.2
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
17.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.1
TIMB Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.2
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.3
Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.3.1
Unbuffered Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.4
Pulse-Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.3.4.1
Unbuffered PWM Signal Generation. . . . . . . . . . . . . . . . . . . . . .
17.3.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . .
17.3.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
255
258
258
259
260
260
261
262
262
263
17.4
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
17.5
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
17.6 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
17.6.1
TIMB Clock Pin (PTE0/TCLKB) . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
17.6.2
TIMB Channel I/O Pins (PTE1/TCH0B–PTE2/TCH1B) . . . . . . . . . 265
17.7 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.7.1
TIMB Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . .
17.7.2
TIMB Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.7.3
TIMB Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . .
17.7.4
TIMB Channel Status and Control Registers . . . . . . . . . . . . . . . . .
17.7.5
TIMB Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
265
265
267
268
268
272
Section 18. Development Support
18.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
18.2 Break Module (BRK). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.1
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.1.1
Flag Protection During Break Interrupts . . . . . . . . . . . . . . . . . . .
18.2.1.2
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.1.3
TIM1 and TIM2 During Break Interrupts . . . . . . . . . . . . . . . . . . .
18.2.1.4
COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.2.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.2.2
Stop Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.3
Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.3.1
Break Status and Control Register . . . . . . . . . . . . . . . . . . . . . . .
18.2.3.2
Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.3.3
Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.2.3.4
Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Sheet
16
273
273
275
275
275
275
275
275
275
275
276
276
277
278
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Table of Contents
MOTOROLA
Table of Contents
18.3 Monitor ROM (MON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.1
Entering Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.2
Normal Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.3
Forced Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.4
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.5
Echoing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.6
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.7
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.1.8
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18.3.2
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
278
278
280
280
282
282
283
283
283
286
286
Section 19. Electrical Specifications
19.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
19.2
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
19.3
Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
19.4
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
19.5
DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
19.6
FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
19.7
Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
19.8
Serial Peripheral Interface Characteristics . . . . . . . . . . . . . . . . . . . . . . 294
19.9
TImer Interface Module Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 297
19.10 Clock Generation Module Component Specifications . . . . . . . . . . . . . 297
19.11 CGM Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
19.12 CGM Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . . . . 298
19.13 Analog-to-Digital Converter (ADC) Characteristics. . . . . . . . . . . . . . . . 299
Section 20. Ordering Information
and Mechanical Specifications
20.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
20.2
Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
20.3
64-Pin Plastic Quad Flat Pack (QFP) . . . . . . . . . . . . . . . . . . . . . . . . . . 302
20.4
56-Pin Shrink Dual In-Line Package (SDIP) . . . . . . . . . . . . . . . . . . . . . 303
Appendix A. MC68HC908MR16
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Table of Contents
17
Table of Contents
Data Sheet
18
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Table of Contents
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 1. General Description
1.1 Introduction
The MC68HC908MR32 is a member of the low-cost, high-performance M68HC08
Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the
enhanced M68HC08 central processor unit (CPU08) and are available with a
variety of modules, memory sizes and types, and package types.
The information contained in this document pertains to the MC68HC908MR16 with
the exceptions shown in Appendix A. MC68HC908MR16.
1.2 Features
Features include:
•
High-performance M68HC08 architecture
•
Fully upward-compatible object code with M6805, M146805, and M68HC05
Families
•
8-MHz internal bus frequency
•
On-chip FLASH memory with in-circuit programming capabilities of FLASH
program memory:
MC68HC908MR32 — 32 Kbytes
MC68HC908MR16 — 16 Kbytes
•
On-chip programming firmware for use with host personal computer
•
FLASH data security(1)
•
768 bytes of on-chip random-access memory (RAM)
•
12-bit, 6-channel center-aligned or edge-aligned pulse-width modulator
(PWMMC)
•
Serial peripheral interface module (SPI)
•
Serial communications interface module (SCI)
•
16-bit, 4-channel timer interface module (TIMA)
•
16-bit, 2-channel timer interface module (TIMB)
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading
or copying the FLASH difficult for unauthorized users.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
General Description
19
General Description
•
Clock generator module (CGM)
•
Low-voltage inhibit (LVI) module with software selectable trip points
•
10-bit, 10-channel analog-to-digital converter (ADC)
•
System protection features:
– Optional computer operating properly (COP) reset
– Low-voltage detection with optional reset
– Illegal opcode or address detection with optional reset
– Fault detection with optional PWM disabling
•
Available packages:
– 64-pin plastic quad flat pack (QFP)
– 56-pin shrink dual in-line package (SDIP)
•
Low-power design, fully static with wait mode
•
Master reset pin (RST) and power-on reset (POR)
•
Stop mode as an option
•
Break module (BRK) supports setting the in-circuit simulator (ICS) single
break point
Features of the CPU08 include:
•
Enhanced M68HC05 programming model
•
Extensive loop control functions
•
16 addressing modes (eight more than the M68HC05)
•
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
•
C language support
1.3 MCU Block Diagram
Figure 1-1 shows the structure of the MC68HC908MR32.
Data Sheet
20
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
General Description
MOTOROLA
PTA
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
OSC1
OSC2
CGMXFC
CLOCK GENERATOR
MODULE
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDAD
VSSAD(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VDDAD
VSSAD
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 1-1. MCU Block Diagram
General Description
MCU Block Diagram
21
Data Sheet — Rev. 6.0
VSS
VDD
ANALOG-TO-DIGITAL CONVERTER
MODULE
SERIAL COMMUNICATIONS INTERFACE
MODULE
DDRE
USER FLASH VECTOR SPACE — 46 BYTES
TIMER INTERFACE
MODULE B
PTF
MONITOR ROM — 240 BYTES
General Description
PTA7–PTA0
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
DDRB
CPU
REGISTERS
DDRF
MC68HC908MR32 • MC68HC908MR16
MOTOROLA
INTERNAL BUS
M68HC08 CPU
General Description
1.4 Pin Assignments
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
VSSAD
OSC2
OSC1
CGMXFC
VDDAD
62
61
60
59
58
57
56
55
54
53
52
51
50
PTB2/ATD2
1
49
RST
PTB0/ATD0
63
64
PTB1/ATD1
Figure 1-2 shows the 64-pin QFP pin assignments and Figure 1-3 shows the
56-pin SDIP pin assignments.
48
IRQ
VDDAD
9
40
VDD
VSSAD
10
39
PTE7/TCH3A
VREFL
11
38
PTE6/TCH2A
VREFH
12
37
PTE5/TCH1A
PTC2
13
36
PTE4/TCH0A
PTC3
14
35
PTE3/TCLKA
PTC4
15
34
PTE2/TCH1B
33
PTE1/TCH0B
PTE0/TCLKB 32
16
PTC6 17
PTC5
31
VSS
PWM6
41
30
8
PWM5
PTC1/ATD9
29
PTF0/SPSCK
PWMGND
42
28
7
PWM4
PTC0/ATD8
27
PTF1/SS
PWM3
43
26
6
PWM2
PTB7/ATD7
25
PTF2/MOSI
PWM1
44
24
5
PTD6/IS3
PTB6/ATD6
23
PTF3/MISO
PTD5/IS2
45
22
4
PTD4/IS1
PTB5/ATD5
21
PTF4/RxD
PTD3/FAULT4
46
20
3
PTD2/FAULT3
PTB4/ATD4
19
PTF5/TxD
PTD1/FAULT2
47
18
2
PTD0/FAULT1
PTB3/ATD3
Figure 1-2. 64-Pin QFP Pin Assignments
Data Sheet
22
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
General Description
MOTOROLA
General Description
Pin Assignments
PTA2
1
56
PTA1
PTA3
2
55
PTA0
PTA4
3
54
VSSA
PTA5
4
53
OSC2
PTA6
5
52
OSC1
PTA7
6
51
CGMXFC
PTB0/ATD0
7
50
VDDA
PTB1/ATD1
8
49
RST
PTB2/ATD2
9
48
IRQ
PTB3/ATD3
10
47
PTF5/TxD
PTB4/ATD4
11
46
PTF4/RxD
PTB5/ATD5
12
45
VSS
PTB6/ATD5
13
44
VDD
PTB7/ATD7
14
43
PTE7/TCH3A
PTC0/ATD8
15
42
PTE6/TCH2A
VDDAD
16
41
PTE5/TCH1A
VSSAD/VREFL
17
40
PTE4/TCH0A
VREFH
18
39
PTE3/TCLKA
PTC2
19
38
NC
PTC3
20
37
PWM6
PTC4
21
36
PWM5
PTC5
22
35
PWMGND
PTC6
23
34
PWM4
PTD0/FAULT1
24
33
PWM3
PTD1/FAULT2
25
32
PWM2
PTD2/FAULT3
26
31
PWM1
PTD3/FAULT4
27
30
PTD6/IS3
PTD4/IS1
28
29
PTD5/IS2
Note:
PTC1, PTE0, PTE1, PTE2, PTF0, PTF1, PTF2, and PTF3
are removed from this package.
Figure 1-3. 56-Pin SDIP Pin Assignments
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
General Description
23
General Description
1.4.1 Power Supply Pins (VDD and 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 C1 bypass capacitor
as close to the MCU as possible. Use a high-frequency-response ceramic
capacitor for C1. C2 is an optional bulk current bypass capacitor for use in
applications that require the port pins to source high-current levels.
MCU
VSS
VDD
C1
0.1 µF
+
C2
1–10 µF
VDD
Note: Component values shown represent typical applications.
Figure 1-4. Power Supply Bypassing
1.4.2 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator circuit. For
more detailed information, see Section 4. Clock Generator Module (CGM).
1.4.3 External Reset Pin (RST)
A logic 0 on the RST pin forces the MCU to a known startup state. RST is
bidirectional, allowing a reset of the entire system. It is driven low when any internal
reset source is asserted. See Section 14. System Integration Module (SIM).
1.4.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. See Section 8. External Interrupt
(IRQ).
Data Sheet
24
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
General Description
MOTOROLA
General Description
Pin Assignments
1.4.5 CGM Power Supply Pins (VDDA and VSSAD)
VDDA and VSSAD are the power supply pins for the analog portion of the clock
generator module (CGM). Decoupling of these pins should be per the digital
supply. See Section 4. Clock Generator Module (CGM).
1.4.6 External Filter Capacitor Pin (CGMXFC)
CGMXFC is an external filter capacitor connection for the CGM. See Section 4.
Clock Generator Module (CGM).
1.4.7 Analog Power Supply Pins (VDDAD and VSSAD)
VDDAD and VSSAD are the power supply pins for the analog-to-digital converter.
Decoupling of these pins should be per the digital supply. See Section 3.
Analog-to-Digital Converter (ADC).
1.4.8 ADC Voltage Decoupling Capacitor Pin (VREFH)
VREFH is the power supply for setting the reference voltage. Connect the VREFH pin
to the same voltage potential as VDDAD. See Section 3. Analog-to-Digital
Converter (ADC).
1.4.9 ADC Voltage Reference Low Pin (VREFL)
VREFL is the lower reference supply for the ADC. Connect the VREFL pin to the
same voltage potential as VSSAD. See Section 3. Analog-to-Digital Converter
(ADC).
1.4.10 Port A Input/Output (I/O) Pins (PTA7–PTA0)
PTA7–PTA0 are general-purpose bidirectional input/output (I/O) port pins. See
Section 10. Input/Output (I/O) Ports (PORTS).
1.4.11 Port B I/O Pins (PTB7/ATD7–PTB0/ATD0)
Port B is an 8-bit special function port that shares all eight pins with the
analog-to-digital converter (ADC). See Section 3. Analog-to-Digital Converter
(ADC) and Section 10. Input/Output (I/O) Ports (PORTS).
1.4.12 Port C I/O Pins (PTC6–PTC2 and PTC1/ATD9–PTC0/ATD8)
PTC6–PTC2 are general-purpose bidirectional I/O port pins (see Section 10.
Input/Output (I/O) Ports (PORTS)). PTC1/ATD9–PTC0/ATD8 are special
function port pins that are shared with the analog-to-digital converter (ADC). See
Section 3. Analog-to-Digital Converter (ADC) and Section 10. Input/Output
(I/O) Ports (PORTS).
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
General Description
25
General Description
1.4.13 Port D Input-Only Pins (PTD6/IS3–PTD4/IS1 and PTD3/FAULT4–PTD0/FAULT1)
PTD6/IS3–PTD4/IS1 are special function input-only port pins that also serve as
current sensing pins for the pulse-width modulator module (PWMMC).
PTD3/FAULT4–PTD0/FAULT1 are special function port pins that also serve as
fault pins for the PWMMC. See Section 12. Pulse-Width Modulator for Motor
Control (PWMMC) and Section 10. Input/Output (I/O) Ports (PORTS).
1.4.14 PWM Pins (PWM6–PWM1)
PWM6–PWM1 are dedicated pins used for the outputs of the pulse-width
modulator module (PWMMC). These are high-current sink pins. See Section 12.
Pulse-Width Modulator for Motor Control (PWMMC) and Section 19. Electrical
Specifications.
1.4.15 PWM Ground Pin (PWMGND)
PWMGND is the ground pin for the pulse-width modulator module (PWMMC). This
dedicated ground pin is used as the ground for the six high-current PWM pins. See
Section 12. Pulse-Width Modulator for Motor Control (PWMMC).
1.4.16 Port E I/O Pins (PTE7/TCH3A–PTE3/TCLKA and PTE2/TCH1B–PTE0/TCLKB)
Port E is an 8-bit special function port that shares its pins with the two timer
interface modules (TIMA and TIMB). See Section 16. Timer Interface A (TIMA),
Section 17. Timer Interface B (TIMB), and Section 10. Input/Output (I/O) Ports
(PORTS).
1.4.17 Port F I/O Pins (PTF5/TxD–PTF4/RxD and PTF3/MISO–PTF0/SPSCK)
Port F is a 6-bit special function port that shares two of its pins with the serial
communications interface module (SCI) and four of its pins with the serial
peripheral interface module (SPI). See Section 15. Serial Peripheral Interface
Module (SPI), Section 13. Serial Communications Interface Module (SCI), and
Section 10. Input/Output (I/O) Ports (PORTS).
Data Sheet
26
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
General Description
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 2. Memory
2.1 Introduction
The central processor unit (CPU08) can address 64 Kbytes of memory space. The
memory map, shown in Figure 2-1, includes:
•
32 Kbytes of FLASH
•
768 bytes of random-access memory (RAM)
•
46 bytes of user-defined vectors
•
240 bytes of monitor read-only memory (ROM)
2.2 Unimplemented Memory Locations
Some addresses are unimplemented. Accessing an unimplemented address can
cause an illegal address reset. In the memory map and in the input/output (I/O)
register summary, unimplemented addresses are shaded.
Some I/O bits are read only; the write function is unimplemented. Writing to a
read-only I/O bit has no effect on microcontroller unit (MCU) operation. In register
figures, the write function of read-only bits is shaded.
Similarly, some I/O bits are write only; the read function is unimplemented. Reading
of write-only I/O bits has no effect on MCU operation. In register figures, the read
function of write-only bits is shaded.
2.3 Reserved Memory Locations
Some addresses are reserved. Writing to a reserved address can have
unpredictable effects on MCU operation. In the memory map (Figure 2-1) and in
the I/O register summary (Figure 2-2) reserved addresses are marked with the
word reserved.
Some I/O bits are reserved. Writing to a reserved bit can have unpredictable effects
on MCU operation. In register figures, reserved bits are marked with the letter R.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
27
Memory
2.4 I/O Section
Addresses $0000–$005F, shown in Figure 2-2, contain most of the control, status,
and data registers. Additional I/O registers have these addresses:
•
$FE00, SIM break status register (SBSR)
•
$FE01, SIM reset status register (SRSR)
•
$FE03, SIM break flag control register (SBFCR)
•
$FE07, FLASH control register (FLCR)
•
$FE0C, Break address register high (BRKH)
•
$FE0D, Break address register low (BRKL)
•
$FE0E, Break status and control register (BRKSCR)
•
$FE0F, LVI status and control register (LVISCR)
•
$FF7E, FLASH block protect register (FLBPR)
•
$FFFF, COP control register (COPCTL)
2.5 Memory Map
Figure 2-1 shows the memory map for the MC68HC908MR32 while the memory
map for the MC68HC908MR16 is shown in Appendix A. MC68HC908MR16
Data Sheet
28
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Memory Map
$0000
↓
$005F
I/O REGISTERS — 96 BYTES
$0060
↓
$035F
RAM — 768 BYTES
$0360
↓
$7FFF
UNIMPLEMENTED — 31,904 BYTES
$8000
↓
$FDFF
FLASH — 32,256 BYTES
$FE00
SIM BREAK STATUS REGISTER (SBSR)
$FE01
SIM RESET STATUS REGISTER (SRSR)
$FE02
RESERVED
$FE03
SIM BREAK FLAG CONTROL REGISTER (SBFCR)
$FE04
RESERVED
$FE05
RESERVED
$FE06
RESERVED
$FE07
RESERVED
$FE08
FLASH CONTROL REGISTER (FLCR)
$FE09
UNIMPLEMENTED
$FE0A
UNIMPLEMENTED
$FE0B
UNIMPLEMENTED
$FE0C
SIM BREAK ADDRESS REGISTER HIGH (BRKH)
$FE0D
SIM BREAK ADDRESS REGISTER LOW (BRKL)
$FE0E
SIM BREAK FLAG CONTROL REGISTER (SBFCR)
$FE0F
LVI STATUS AND CONTROL REGISTER (LVISCR)
$FE10
↓
$FEFF
MONITOR ROM — 240 BYTES
$FF00
↓
$FF7D
UNIMPLEMENTED — 126 BYTES
$FF7E
FLASH BLOCK PROTECT REGISTER (FLBPR)
$FF7F
↓
$FFD1
UNIMPLEMENTED — 83 BYTES
$FFD2
↓
$FFFF
VECTORS — 46 BYTES
Figure 2-1. MC68HC908MR32 Memory Map
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
29
Memory
Addr.
$0000
$0001
$0002
$0003
$0004
Register Name
Port A Data Register Read:
(PTA) Write:
See page 113. Reset:
Port B Data Register Read:
(PTB) Write:
See page 115. Reset:
Port C Data Register Read:
(PTC) Write:
See page 117. Reset:
Port D Data Register Read:
(PTD) Write:
See page 119. Reset:
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
PTB2
PTB1
PTB0
PTC2
PTC1
PTC0
Unaffected by reset
PTB7
$0006
0
R
$0007
$0008
Port E Data Register Read:
(PTE) Write:
See page 120. Reset:
Port F Data Register
(PTF) Write:
See page 122. Reset:
Unimplemented
$000B
Unimplemented
U = Unaffected
PTB3
PTC5
PTC4
PTC3
PTD6
PTD5
R
R
R
PTD4
PTD3
PTD2
PTD1
PTD0
R
R
R
R
R
Unaffected by reset
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
0
0
0
0
0
0
0
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
0
0
0
0
0
0
0
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
0
0
0
0
0
0
0
0
PTE7
PTE6
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
0
0
R
R
PTF2
PTF1
PTF0
0
R
Unimplemented
$000A
$000C
PTC6
0
Data Direction Register B
DDRB7
(DDRB) Write:
See page 115. Reset:
0
Read:
$0009
PTB4
Unaffected by reset
Data Direction Register A Read: DDRA7
(DDRA) Write:
See page 113. Reset:
0
Data Direction Register C Read:
(DDRC) Write:
See page 117. Reset:
PTB5
Unaffected by reset
Read:
$0005
PTB6
Unaffected by reset
PTF4
PTF3
Unaffected by reset
Data Direction Register E Read: DDRE7
(DDRE) Write:
See page 120. Reset:
0
X = Indeterminate
PTF5
R
DDRE6
DDRE5
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
0
0
0
0
0
0
0
Bold
= Buffered
= Reserved
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 1 of 8)
Data Sheet
30
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Memory Map
Addr.
Register Name
$000D
Data Direction Register F Read:
(DDRF) Write:
See page 122. Reset:
$000E
1
Bit 0
DDRF5
DDRF4
DDRF3
DDRF2
DDRF1
DDRF0
0
0
0
0
0
0
PS2
PS1
PS0
0
0
TRST
R
1
0
0
0
0
0
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
R
R
R
R
R
R
R
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
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 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
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
TIMA Counter Register High Read:
(TACNTH) Write:
See page 247. Reset:
Bit 15
TIMA Counter Register Low Read:
(TACNTL) Write:
See page 247. Reset:
TIMA Channel 0 Status/Control Read:
Register (TASC0) Write:
See page 249. Reset:
TIMA Channel 0 Register High Read:
(TACH0H) Write:
See page 252. Reset:
0
CH0F
0
Indeterminate after reset
TIMA Channel 0 Register Low
(TACH0L) Write:
See page 252. Reset:
Bit 7
TIMA Channel 1 Status/Control Read:
Register (TASC1) Write:
See page 252. Reset:
CH1F
TIMA Channel 1 Register High Read:
(TACH1H) Write:
See page 252. Reset:
TIMA Channel 1 Register Low Read:
(TACH1L) Write:
See page 252. Reset:
U = Unaffected
2
0
Read:
$0018
R
3
0
TIMA Counter Modulo Read:
Register Low (TAMODL) Write:
See page 248. Reset:
$0012
$0017
R
4
TSTOP
TIMA Counter Modulo
Register High (TAMODH) Write:
See page 248. Reset:
$0011
$0016
0
5
TOIE
Read:
$0015
0
TOF
$0010
$0014
6
TIMA Status/Control Register Read:
(TASC) Write:
See page 245. Reset:
$000F
$0013
Bit 7
X = Indeterminate
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
0
0
CH1IE
R
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
R
= Reserved
Bold
= Buffered
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 2 of 8)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
31
Memory
Addr.
$0019
Register Name
TIMA Channel 2 Status/Control Read:
Register (TASC2) Write:
See page 249. Reset:
TIMA Channel 2 Register High Read:
(TACH2H) Write:
See page 252. Reset:
$001A
TIMA Channel 2 Register Low Read:
(TACH2L) Write:
See page 252. Reset:
$001B
$001C
Bit 7
TIMA Channel 3 Status/Control Read:
Register (TASC3) Write:
See page 249. Reset:
Read:
$001D
$001E
TIMA Channel 3 Register High
(TACH3H) Write:
See page 252. Reset:
TIMA Channel 3 Register Low Read:
(TACH3L) Write:
See page 252. Reset:
$001F
$0020
Configuration Register Read:
(CONFIG) Write:
See page 80. Reset:
PWM Control Register 1 Read:
(PCTL1) Write:
See page 158. Reset:
6
5
4
3
2
1
Bit 0
CH2IE
MS2B
MS2A
ELS2B
ELS2A
TOV2
CH2MAX
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
CH2F
0
Indeterminate after reset
Bit 7
$0022
CH3F
0
$0023
$0024
U = Unaffected
Fault Status Register Read:
(FSR) Write:
See page 164. Reset:
Fault Acknowledge Register Read:
(FTACK) Write:
See page 165. Reset:
X = Indeterminate
Bit 4
Bit 3
0
CH3IE
R
MS3A
ELS3B
ELS3A
TOV3
CH3MAX
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
EDGE
BOTNEG
TOPNEG
INDEP
LVIRST
LVIPWR
STOPE
COPD
0
0
0
0
1
1
0
0
DISX
DISY
PWMINT
PWMF
ISENS1
ISENS0
LDOK
PWMEN
0
0
0
0
0
0
0
0
IPOL1
IPOL2
IPOL3
PRSC1
PRSC0
PWM Control Register 2
LDFQ1
(PCTL2) Write:
See page 160. Reset:
0
Fault Control Register Read:
(FCR) Write:
See page 162. Reset:
Bit 5
Indeterminate after reset
Read:
$0021
Bit 6
0
LDFQ0
0
0
0
0
0
0
0
FINT4
FMODE4
FINT3
FMODE3
FINT2
FMODE2
FINT1
FMODE1
0
0
0
0
0
0
0
0
FPIN4
FFLAG4
FPIN3
FFLAG3
FPIN2
FFLAG2
FPIN1
FFLAG1
U
0
U
0
U
0
U
0
0
0
DT6
DT5
DT4
DT3
DT2
DT1
FTACK4
0
R
0
FTACK3
0
= Reserved
FTACK2
0
0
Bold
= Buffered
FTACK1
0
0
0
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 3 of 8)
Data Sheet
32
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Memory Map
Addr.
$0025
Register Name
5
4
3
2
1
Bit 0
OUTCTL
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
0
0
0
0
0
0
0
0
0
PWM Counter Register High Read:
(PCNTH) Write:
See page 156. Reset:
0
0
0
0
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
PWM Counter Register Low Read:
(PCNTL) Write:
See page 156. Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
0
0
0
0
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
X
X
X
X
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
X
X
X
X
X
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
Bold
= Buffered
$0027
PWM Counter Modulo Register Read:
High (PMODH) Write:
See page 156. Reset:
Read:
$0029
6
PWM Output Control Register Read:
(PWMOUT) Write:
See page 166. Reset:
$0026
$0028
Bit 7
PWM Counter Modulo Register
Low (PMODL) Write:
See page 156. Reset:
$002A
$002B
$002C
PWM 1 Value Register High Read:
(PVAL1H) Write:
See page 157. Reset:
PWM 1 Value Register Low Read:
(PVAL1L) Write:
See page 157. Reset:
PWM 2 Value Register High Read:
(PVAL2H) Write:
See page 157. Reset:
Read:
$002D
$002E
$002F
$0030
U = Unaffected
PWM 2 Value Register Low
(PVAL2L) Write:
See page 157. Reset:
PWM 3 Value Register High Read:
(PVAL3H) Write:
See page 157. Reset:
PWM 3 Value Register Low Read:
(PVAL3L) Write:
See page 157. Reset:
PWM 4 Value Register High Read:
(PVAL4H) Write:
See page 157. Reset:
X = Indeterminate
0
R
= Reserved
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 4 of 8)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
33
Memory
Addr.
Register Name
PWM 4 Value Register Low Read:
(PVAL4L) Write:
See page 157. Reset:
$0031
PWM 5 Value Register High Read:
(PMVAL5H) Write:
See page 157. Reset:
$0032
PWM 5 Value Register Low Read:
(PVAL5L) Write:
See page 157. Reset:
$0033
PWM 6 Value Register High Read:
(PVAL6H) Write:
See page 157. Reset:
$0034
Read:
PWM 6 Value Register Low
(PMVAL6L) Write:
See page 157. Reset:
$0035
Dead-Time Write-Once Read:
Register (DEADTM) Write:
See page 162. Reset:
$0036
$0037
PWM Disable Mapping Read:
Write-Once Register (DISMAP) Write:
See page 149. Reset:
$0038
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
0
0
0
0
0
0
0
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
ORIE
NEIE
FEIE
PEIE
SCI Control Register 1 Read: LOOPS
(SCC1) Write:
See page 183. Reset:
0
Read:
$0039
$003A
$003B
$003C
U = Unaffected
SCI Control Register 2
SCTIE
(SCC2) Write:
See page 185. Reset:
0
SCI Control Register 3 Read:
(SCC3) Write:
See page 187. Reset:
R8
U
SCI Status Register 1 Read:
(SCS1) Write:
See page 188. Reset:
SCI Status Register 2 Read:
(SCS2) Write:
See page 191. Reset:
X = Indeterminate
0
0
R
R
U
0
0
0
0
0
0
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
R
R
R
R
R
R
R
R
1
1
0
0
0
0
0
0
0
0
0
0
0
0
BKF
RPF
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
Bold
= Buffered
R
0
R
T8
= Reserved
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 5 of 8)
Data Sheet
34
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Memory Map
Addr.
Register Name
SCI Data Register Read:
(SCDR) Write:
See page 192. Reset:
$003D
SCI Baud Rate Register Read:
(SCBR) Write:
See page 192. Reset:
$003E
IRQ Status/Control Register Read:
(ISCR) Write:
See page 105. Reset:
$003F
Read:
ADC Data Register High
Right Justified Mode (ADRH) Write:
See page 56. Reset:
ADC Data Register Low Read:
Right Justified Mode (ADRL) Write:
See page 56. Reset:
$0042
ADC Clock Register Read:
(ADCLK) Write:
See page 57. Reset:
$0043
5
4
3
2
1
Bit 0
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
SCR2
SCR1
SCR0
0
0
IMASK1
MODE1
Unaffected by reset
0
0
R
R
0
Read:
SPI Status and Control
Register (SPSCR) Write:
See page 229. Reset:
$0045
SPI Data Register Read:
(SPDR) Write:
See page 232. Reset:
$0046
$0047
↓
$0050
0
SCP1
SCP0
0
0
0
0
0
0
0
0
0
IRQF
0
R
R
R
R
0
0
0
0
0
0
0
0
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
R
ACK1
0
0
1
1
1
1
1
0
0
0
0
0
0
AD9
AD8
R
R
R
R
R
R
R
R
Unaffected by reset
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
R
R
R
R
R
R
R
R
Unaffected by reset
0
ADIV2
ADIV1
ADIV0
ADICLK
MODE1
MODE0
0
0
0
0
0
0
1
0
0
R
SPMSTR
CPOL
CPHA
SPWOM
SPE
SPTIE
0
0
0
MODFEN
SPR1
SPR0
SPI Control Register Read: SPRIE
(SPCR) Write:
See page 228. Reset:
0
$0044
$0051
6
ADC Status and Control Read: COCO
R
Register (ADSCR) Write:
See page 54. Reset:
0
$0040
$0041
Bit 7
SPRF
R
0
ERRIE
1
0
1
OVRF
MODF
SPTE
R
R
R
R
0
0
0
0
1
0
0
0
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
PS2
PS1
PS0
0
0
0
Unaffected by reset
Unimplemented
TIMB Status/Control Register Read:
(TBSC) Write:
See page 265. Reset:
U = Unaffected
X = Indeterminate
TOF
0
0
R
TOIE
TSTOP
0
1
= Reserved
0
0
TRST
R
0
0
Bold
= Buffered
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 6 of 8)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
35
Memory
Addr.
Register Name
$0052
$0053
$0054
$0055
Bit 7
6
5
4
3
2
1
Bit 0
TIMB Counter Register High Read:
(TBCNTH) Write:
See page 267. Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
TIMB Counter Register Low Read:
(TBCNTL) Write:
See page 267. Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
1
1
1
1
1
1
1
1
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 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
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
TIMB Counter Modulo Register Read:
High (TBMODH) Write:
See page 268. Reset:
TIMB Counter Modulo Register Read:
Low (TBMODL) Write:
See page 268. Reset:
Read:
$0056
TIMB Channel 0 Status/Control
Register (TBSC0) Write:
See page 269. Reset:
TIMB Channel 0 Register High Read:
(TBCH0H) Write:
See page 272. Reset:
$0057
TIMB Channel 0 Register Low Read:
(TBCH0L) Write:
See page 272. Reset:
$0058
$0059
TIMB Channel 1 Status/Control Read:
Register (TBSC1) Write:
See page 269. Reset:
Read:
$005A
$005B
TIMB Channel 1 Register High
(TBCH1H) Write:
See page 272. Reset:
TIMB Channel 1 Register Low Read:
(TBCH1L) Write:
See page 272. Reset:
$005C
$005D
U = Unaffected
PLL Control Register Read:
(PCTL) Write:
See page 69. Reset:
PLL Bandwidth Control Read:
Register (PBWC) Write:
See page 71. Reset:
X = Indeterminate
CH0F
0
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
CH1F
0
0
CH1IE
R
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
1
1
1
1
R
R
R
R
1
1
1
1
0
0
0
0
R
R
R
R
0
0
0
0
0
Bold
= Buffered
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
PLLIE
0
AUTO
0
R
PLLF
R
PLLON
BCS
1
0
ACQ
XLD
0
LOCK
R
0
0
= Reserved
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 7 of 8)
Data Sheet
36
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Memory Map
Addr.
Register Name
PLL Programming Register Read:
(PPG) Write:
See page 72. Reset:
$005E
$005F
Unimplemented
$FE00
SIM Break Status Register Read:
(SBSR) Write:
See page 207. Reset:
SIM Reset Status Register Read:
(SRSR) Write:
See page 207. Reset:
$FE01
Read:
SIM Break Flag Control
Register (SBFCR) Write:
See page 208. Reset:
$FE03
FLASH Control Register
(FLCR)
See page 41.
$FE08
Read:
Break Address Register High Read:
(BRKH) Write:
See page 276. Reset:
Break Address Register Low Read:
(BRKL) Write:
See page 276. Reset:
$FE0D
Break Status and Control Read:
Register (BRKSCR) Write:
See page 276. Reset:
$FE0E
6
5
4
3
2
1
Bit 0
MUL7
MUL6
MUL5
MUL4
VRS7
VRS6
VRS5
VRS4
0
1
1
0
0
1
1
0
R
R
R
R
R
R
BW
R
0
POR
PIN
COP
ILOP
ILAD
MENRST
LVI
0
R
R
R
R
R
R
R
R
1
0
0
0
0
0
0
0
BCFE
R
R
R
R
R
R
R
0
0
0
0
HVEN
MASS
ERASE
PGM
0
0
0
0
0
0
0
0
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
0
0
0
R
R
R
R
R
0
Write:
Reset:
$FE0C
Bit 7
0
Read: LVIOUT
$FE0F
$FF7E
LVI Status and Control Register
(LVISCR) Write:
See page 109. Reset:
FLASH Block Protect Register Read:
(FLBPR) Write:
See page 45. Reset:
$FFFF
U = Unaffected
0
0
TRPSEL
R
R
0
0
0
0
0
0
0
0
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
0
0
0
0
0
0
0
0
COP Control Register Read:
(COPCTL) Write:
See page 85. Reset:
X = Indeterminate
Low byte of reset vector
Clear COP counter
Unaffected by reset
R
= Reserved
Bold
= Buffered
= Unimplemented
Figure 2-2. Control, Status, and Data Registers Summary (Sheet 8 of 8)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
37
Memory
Table 2-1 is a list of vector locations.
Table 2-1. Vector Addresses
Priority
Low
Address
Vector
$FFD2
SCI transmit vector (high)
$FFD3
SCI transmit vector (low)
$FFD4
SCI receive vector (high)
$FFD5
SCI receive vector (low)
$FFD6
SCI error vector (high)
$FFD7
SCI error vector (low)
$FFD8
SPI transmit vector (high)(1)
$FFD9
SPI transmit vector (low)(1)
$FFDA
SPI receive vector (high)(1)
$FFDB
SPI receive vector (low)(1)
$FFDC
A/D vector (high)
$FFDD
A/D vector (low)
$FFDE
TIMB overflow vector (high)
$FFDF
TIMB overflow vector (low)
$FFE0
TIMB channel 1 vector (high)
$FFE1
TIMB channel 1 vector (low)
$FFE2
TIMB channel 0 vector (high)
$FFE3
TIMB channel 0 vector (low)
$FFE4
TIMA overflow vector (high)
$FFE5
TIMA overflow vector (low)
$FFE6
TIMA channel 3 vector (high)
$FFE7
TIMA channel 3 vector (low)
$FFE8
TIMA channel 2 vector (high)
$FFE9
TIMA channel 2 vector (low)
$FFEA
TIMA channel 1 vector (high)
$FFEB
TIMA channel 1 vector (low)
$FFEC
TIMA channel 0 vector (high)
$FFED
TIMA channel 0 vector (low)
1. The SPI module is not available in the 56-pin SDIP package.
Data Sheet
38
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
Monitor ROM
Table 2-1. Vector Addresses (Continued)
High
Priority
Address
Vector
$FFEE
PWMMC vector (high)
$FFEF
PWMMC vector (low)
$FFF0
FAULT 4 (high)
$FFF1
FAULT 4 (low)
$FFF2
FAULT 3 (high)
$FFF3
FAULT 3 (low)
$FFF4
FAULT 2 (high)
$FFF5
FAULT 2 (low)
$FFF6
FAULT 1 (high)
$FFF7
FAULT 1 (low)
$FFF8
PLL vector (high)
$FFF9
PLL vector (low)
$FFFA
IRQ vector (high)
$FFFB
IRQ vector (low)
$FFFC
SWI vector (high)
$FFFD
SWI vector (low)
$FFFE
Reset vector (high)
$FFFF
Reset vector (low)
2.6 Monitor ROM
The 240 bytes at addresses $FE10–$FEFF are reserved ROM addresses that
contain the instructions for the monitor functions. See 18.3 Monitor ROM (MON).
2.7 Random-Access Memory (RAM)
Addresses $0060–$035F are RAM locations. The location of the stack RAM is
programmable. The 16-bit stack pointer allows the stack to be anywhere in the
64-Kbyte memory space.
NOTE:
For correct operation, the stack pointer must point only to RAM locations.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
39
Memory
Within page zero are 160 bytes of RAM. Because the location of the stack RAM is
programmable, all page zero RAM locations can be used for input/output (I/O)
control and user data or code. When the stack pointer is moved from its reset
location at $00FF, direct addressing mode instructions can access efficiently all
page zero RAM locations. Page zero RAM, therefore, provides ideal locations for
frequently accessed global variables.
Before processing an interrupt, the central processor unit (CPU) uses five bytes of
the stack to save the contents of the CPU registers.
NOTE:
For M68HC05 and M1468HC05 compatibility, the H register is not stacked.
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.
2.8 FLASH Memory (FLASH)
The FLASH memory is an array of 32,256 bytes with an additional 46 bytes of user
vectors and one byte of block protection.
NOTE:
An erased bit reads as a 1 and a programmed bit reads as a 0.
Program and erase operations are facilitated through control bits in a memory
mapped register. Details for these operations appear later in this section.
Memory in the FLASH array is organized into two rows per page. The page size is
128 bytes per page. The minimum erase page size is 128 bytes. Programming is
performed on a row basis, 64 bytes at a time.
The address ranges for the user memory and vectors are:
•
$8000–$FDFF, user memory
•
$FF7E, block protect register (FLBPR)
•
$FE08, FLASH control register (FLCR)
•
$FFD2–$FFFF, reserved for user-defined interrupt and reset vectors
Programming tools are available from Motorola. Contact a local Motorola
representative for more information.
NOTE:
A security feature prevents viewing of the FLASH contents.(1)
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Data Sheet
40
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
FLASH Memory (FLASH)
2.8.1 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase
operations.
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 2-3. FLASH Control Register (FLCR)
HVEN — High-Voltage Enable Bit
This read/write bit enables the charge pump to drive high voltages for program
and erase operations in the array. HVEN can only be set if either PGM = 1 or
ERASE = 1 and the proper sequence for program or erase 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
Setting this read/write bit configures the 32-Kbyte FLASH array for mass erase
operation. Mass erase is disabled if any FLASH block is protected
1 = MASS erase operation selected
0 = MASS erase operation unselected
ERASE — Erase Control Bit
This read/write bit configures the memory for erase operation. ERASE is
interlocked with the PGM bit such that both bits cannot be equal to 1 or set to 1
at the same time.
1 = Erase operation selected
0 = Erase operation unselected
PGM — Program Control Bit
This read/write bit configures the memory for program operation. PGM is
interlocked with the ERASE bit such that both bits cannot be equal to 1 or set
to 1 at the same time.
1 = Program operation selected
0 = Program operation unselected
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
41
Memory
2.8.2 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (128 bytes) of FLASH memory.
1. Set the ERASE bit and clear the MASS bit in the FLASH control register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH location within the address range of the block
to be erased.
4. Wait for a time, tNVS (minimum 10 µs).
5. Set the HVEN bit.
6. Wait for a time, tErase (minimum 1 ms or 4 ms).
7. Clear the ERASE bit.
8. Wait for a time, tNVH (minimum 5 µs).
9. Clear the HVEN bit.
10. After time, tRCV (typical 1 µs), 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 shown, other unrelated operations may occur between the steps.
In applications that require more than 1000 program/erase cycles, use the 4 ms
page erase specification to get improved long-term reliability. Any application can
use this 4 ms page erase specification. However, in applications where a FLASH
location will be erased and reprogrammed less than 1000 times, and speed is
important, use the 1 ms page erase specification to get a shorter cycle time.
2.8.3 FLASH Mass Erase Operation
Use this step-by-step procedure to erase the entire FLASH memory.
1. Set both the ERASE bit and the MASS bit in the FLASH control register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH address(1) within the FLASH memory address
range.
4. Wait for a time, tNVS (minimum 10 µs).
5. Set the HVEN bit.
6. Wait for a time, tMErase (minimum 4 ms).
7. Clear the ERASE and MASS bits.
NOTE:
Mass erase is disabled whenever any block is protected (FLBPR does not equal
$FF).
1. When in monitor mode, with security sequence failed (see 18.3.2 Security), write to the FLASH
block protect register instead of any FLASH address.
Data Sheet
42
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
FLASH Memory (FLASH)
8. Wait for a time, tNVHL (minimum 100 µs).
9. Clear the HVEN bit.
10. After time, tRCV (typical 1 µs), 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 shown, other unrelated operations may occur between the steps.
2.8.4 FLASH Program Operation
Use the following step-by-step procedure to program a row of FLASH memory.
Figure 2-4 shows a flowchart of the programming algorithm.
NOTE:
Only bytes which are currently $FF may be programmed.
1. Set the PGM bit. This configures the memory for program operation and
enables the latching of address and data for programming.
2. Read the FLASH block protect register.
3. Write any data to any FLASH location within the address range desired.
4. Wait for a time, tNVS (minimum 10 µs).
5. Set the HVEN bit.
6. Wait for a time, tPGS (minimum 5 µs).
7. Write data to the FLASH address being programmed(1).
8. Wait for time, tPROG (minimum 30 µs).
9. Repeat step 7 and 8 until all desired bytes within the row are programmed.
10. Clear the PGM bit(1).
11. Wait for time, tNVH (minimum 5 µs).
12. Clear the HVEN bit.
13. After time, tRCV (typical 1 µs), the memory can be accessed in read mode
again.
NOTE:
The COP register at location $FFFF should not be written between steps 5-12,
when the HVEN bit is set. Since this register is located at a valid FLASH address,
unpredictable behavior may occur if this location is written while HVEN is set.
This program sequence is repeated throughout the memory until all data is
programmed.
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 shown, other unrelated operations may occur between the steps. Do not
exceed tPROG maximum, see 19.6 FLASH Memory Characteristics.
1. The time between each FLASH address change, or the time between the last FLASH address
programmed to clearing PGM bit, must not exceed the maximum programming time, tPROG
maximum.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
43
Memory
ALGORITHM FOR PROGRAMMING
A ROW (64 BYTES) OF FLASH MEMORY
1
2
3
SET PGM BIT
READ THE FLASH BLOCK PROTECT REGISTER
WRITE ANY DATA TO ANY FLASH ADDRESS
WITHIN THE ROW ADDRESS RANGE DESIRED
4
WAIT FOR A TIME, tNVS
5
SET HVEN BIT
6
7
WAIT FOR A TIME, tPGS
WRITE DATA TO THE FLASH ADDRESS
TO BE PROGRAMMED
8
WAIT FOR A TIME, tPROG
COMPLETED
PROGRAMMING
THIS ROW?
YES
NO
10
11
CLEAR PGM BIT
WAIT FOR A TIME, tNVH
Note:
The time between each FLASH address change (step 7 to step 7), or
the time between the last FLASH address programmed
to clearing PGM bit (step 7 to step 10)
must not exceed the maximum programming
time, tPROG max.
12
13
This row program algorithm assumes the row/s
to be programmed are initially erased.
CLEAR HVEN BIT
WAIT FOR A TIME, tRCV
END OF PROGRAMMING
Figure 2-4. FLASH Programming Flowchart
Data Sheet
44
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Memory
FLASH Memory (FLASH)
2.8.5 FLASH Block 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 for protecting a block of
memory from unintentional erase or program operations due to system
malfunction. This protection is done by using 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
at 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:
In performing a program or erase operation, the FLASH block protect register must
be read after setting the PGM or ERASE bit and before asserting the HVEN bit
When the FLBPR is programmed with all 0s, the entire memory is protected from
being programmed and erased. When all the bits are erased (all 1s), the entire
memory is accessible for program and erase.
When bits within the FLBPR are programmed, they lock a block of memory, whose
address ranges are shown in 2.8.6 FLASH Block Protect Register. Once the
FLBPR is programmed with a value other than $FF, any erase or program of the
FLBPR or the protected block of FLASH memory is prohibited. Mass erase is
disabled whenever any block is protected (FLBPR does not equal $FF). The
FLBPR itself can be erased or programmed only with an external voltage, VTST,
present on the IRQ pin. This voltage also allows entry from reset into the monitor
mode.
2.8.6 FLASH Block Protect Register
The FLASH block protect register (FLBPR) is implemented as a byte within the
FLASH memory, and therefore can be written only during a programming
sequence of the FLASH memory. The value in this register determines the starting
location of the protected range within the FLASH memory.
Address:
Read:
Write:
Reset:
$FF7E
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
U = Unaffected by reset. Initial value from factory is 1.
Write to this register by a programming sequence to the FLASH memory.
Figure 2-5. FLASH Block Protect Register (FLBPR)
BPR[7:0] — FLASH Block Protect Bits
These eight bits represent bits [14:7] of a 16-bit memory address. Bit 15 is 1 and
bits [6:0] are 0s.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Memory
45
Memory
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 XX00 and XX80 (128 bytes page boundaries)
within the FLASH memory.
16-BIT MEMORY ADDRESS
START ADDRESS OF FLASH
BLOCK PROTECT
1
FLBPR VALUE
0
0
0
0
0
0
0
Figure 2-6. FLASH Block Protect Start Address
Refer to Table 2-2 for examples of the protect start address.
Table 2-2. Examples of Protect Start Address
BPR[7:0]
Start of Address of Protect Range
$00
The entire FLASH memory is protected.
$01 (0000 0001)
$8080 (1000 0000 1000 0000)
$02 (0000 0010)
$8100 (1000 0001 0000 0000)
and so on...
$FE (1111 1110)
$FF00 (1111 1111 0000 0000)
$FF
The entire FLASH memory is not protected.
Note: The end address of the protected range is always $FFFF.
2.8.7 Wait Mode
Putting the MCU into wait mode while the FLASH is in read mode does not affect
the operation of the FLASH memory directly, but there will not be any memory
activity since the CPU is inactive.
The WAIT instruction should not be executed while performing a program or erase
operation on the FLASH. Otherwise, the operation will discontinue, and the FLASH
will be on standby mode.
2.8.8 Stop Mode
Putting the MCU into stop mode while the FLASH is in read mode does not affect
the operation of the FLASH memory directly, but there will not be any memory
activity since the CPU is inactive.
The STOP instruction should not be executed while performing a program or erase
operation on the FLASH, otherwise the operation will discontinue, and the FLASH
will be on standby mode
NOTE:
Standby mode is the power-saving mode of the FLASH module in which all internal
control signals to the FLASH are inactive and the current consumption of the
FLASH is at a minimum.
Data Sheet
46
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Memory
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 3. Analog-to-Digital Converter (ADC)
3.1 Introduction
This section describes the 10-bit analog-to-digital converter (ADC).
3.2 Features
Features of the ADC module include:
•
10 channels with multiplexed input
•
Linear successive approximation
•
10-bit resolution, 8-bit accuracy
•
Single or continuous conversion
•
Conversion complete flag or conversion complete interrupt
•
Selectable ADC clock
•
Left or right justified result
•
Left justified sign data mode
•
High impedance buffered ADC input
3.3 Functional Description
Ten ADC channels are available for sampling external sources at pins
PTC1/ATD9:PTC0/ATD8 and PTB7/ATD7:PTB0/ATD0. To achieve the best
possible accuracy, these pins are implemented as input-only pins when the
analog-to-digital (A/D) feature is enabled. An analog multiplexer allows the single
ADC to select one of the 10 ADC channels as ADC voltage IN (ADCVIN). ADCVIN
is converted by the successive approximation algorithm. When the conversion is
completed, the ADC places the result in the ADC data register (ADRH and ADRL)
and sets a flag or generates an interrupt. See Figure 3-2.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
47
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
CLOCK GENERATOR
MODULE
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
OSC1
OSC2
CGMXFC
TIMER INTERFACE
MODULE B
DDRF
USER FLASH VECTOR SPACE — 46 BYTES
MOTOROLA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MONITOR ROM — 240 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 3-1. Block Diagram Highlighting ADC Block and Pins
Analog-to-Digital Converter (ADC)
Data Sheet
48
INTERNAL BUS
M68HC08 CPU
Analog-to-Digital Converter (ADC)
Functional Description
INTERNAL
DATA BUS
PTB/Cx
ADC CHANNEL x
READ PTB/PTC
DISABLE
ADC DATA REGISTERS
INTERRUPT
LOGIC
AIEN
CONVERSION
COMPLETE
ADC VOLTAGE IN
ADVIN
ADC
CHANNEL
SELECT
ADCH[4:0]
COCO
ADC CLOCK
CGMXCLK
CLOCK
GENERATOR
BUS CLOCK
ADIV[2:0]
ADICLK
Figure 3-2. ADC Block Diagram
3.3.1 ADC Port I/O Pins
PTC1/ATD9:PTC0/ATD8 and PTB7/ATD7:PTB0/ATD0 are general-purpose I/O
pins that are shared with the ADC channels.
The channel select bits define which ADC channel/port pin will be used as the input
signal. The ADC overrides the port logic when that port is selected by the ADC
multiplexer. The remaining ADC channels/port pins are controlled by the port logic
and can be used as general-purpose input/output (I/O) pins. Writes to the port
register or DDR will not have any effect on the port pin that is selected by the ADC.
Read of a port pin which is in use by the ADC will return a 0.
3.3.2 Voltage Conversion
When the input voltage to the ADC equals VREFH, the ADC converts the signal to
$3FF (full scale). If the input voltage equals VREFL, the ADC converts it to $000.
Input voltages between VREFH and VREFL are straight-line linear conversions. All
other input voltages will result in $3FF if greater than VREFH and $000 if less than
VREFL.
NOTE:
Input voltage should not exceed the analog supply voltages. See
19.13 Analog-to-Digital Converter (ADC) Characteristics.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
49
Analog-to-Digital Converter (ADC)
3.3.3 Conversion Time
Conversion starts after a write to the ADSCR. A conversion is between 16 and 17
ADC clock cycles, therefore:
16 to17 ADC Cycles
Conversion time =
ADC Frequency
Number of Bus Cycles = Conversion Time x CPU Bus Frequency
The ADC conversion time is determined by the clock source chosen and the divide
ratio selected. The clock source is either the bus clock or CGMXCLK and is
selectable by ADICLK located in the ADC clock register. For example, if
CGMXCLK is 4 MHz and is selected as the ADC input clock source, the ADC input
clock divide-by-4 prescale is selected and the CPU bus frequency is 8 MHz:
Conversion Time =
16 to 17 ADC Cycles
= 16 to 17 µs
4 MHz/4
Number of bus cycles = 16 µs x 8 MHz = 128 to 136 cycles
NOTE:
The ADC frequency must be between fADIC minimum and fADIC maximum to meet
A/D specifications. See 19.13 Analog-to-Digital Converter (ADC)
Characteristics.
Since an ADC cycle may be comprised of several bus cycles (eight, 136 minus 128,
in the previous example) and the start of a conversion is initiated by a bus cycle
write to the ADSCR, from zero to eight additional bus cycles may occur before the
start of the initial ADC cycle. This results in a fractional ADC cycle and is
represented as the 17th cycle.
3.3.4 Continuous Conversion
In continuous conversion mode, the ADC data registers ADRH and ADRL will be
filled with new data after each conversion. Data from the previous conversion will
be overwritten whether that data has been read or not. Conversions will continue
until the ADCO bit is cleared. The COCO bit is set after each conversion and will
stay set until the next read of the ADC data register.
When a conversion is in process and the ADSCR is written, the current conversion
data should be discarded to prevent an incorrect reading.
3.3.5 Result Justification
The conversion result may be formatted in four different ways:
1. Left justified
2. Right justified
3. Left Justified sign data mode
4. 8-bit truncation mode
Data Sheet
50
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MOTOROLA
Analog-to-Digital Converter (ADC)
Functional Description
All four of these modes are controlled using MODE0 and MODE1 bits located in
the ADC clock register (ADCR).
Left justification will place the eight most significant bits (MSB) in the corresponding
ADC data register high, ADRH. This may be useful if the result is to be treated as
an 8-bit result where the two least significant bits (LSB), located in the ADC data
register low, ADRL, can be ignored. However, ADRL must be read after ADRH or
else the interlocking will prevent all new conversions from being stored.
Right justification will place only the two MSBs in the corresponding ADC data
register high, ADRH, and the eight LSBs in ADC data register low, ADRL. This
mode of operation typically is used when a 10-bit unsigned result is desired.
Left justified sign data mode is similar to left justified mode with one exception. The
MSB of the 10-bit result, AD9 located in ADRH, is complemented. This mode of
operation is useful when a result, represented as a signed magnitude from
mid-scale, is needed. Finally, 8-bit truncation mode will place the eight MSBs in
ADC data register low, ADRL. The two LSBs are dropped. This mode of operation
is used when compatibility with 8-bit ADC designs are required. No interlocking
between ADRH and ADRL is present.
NOTE:
Quantization error is affected when only the most significant eight bits are used as
a result. See Figure 3-3.
8-BIT 10-BIT
RESULT RESULT
IDEAL 8-BIT CHARACTERISTIC
WITH QUANTIZATION = ±1/2
10-BIT TRUNCATED
TO 8-BIT RESULT
003
00B
00A
009
002
IDEAL 10-BIT CHARACTERISTIC
WITH QUANTIZATION = ±1/2
008
007
006
005
001
004
WHEN TRUNCATION IS USED,
ERROR FROM IDEAL 8-BIT = 3/8 LSB
DUE TO NON-IDEAL QUANTIZATION.
003
002
001
000
000
1/2
2 1/2
1 1/2
1/2
4 1/2
3 1/2
6 1/2
5 1/2
8 1/2
7 1/2
1 1/2
9 1/2
2 1/2
INPUT VOLTAGE
REPRESENTED AS 10-BIT
INPUT VOLTAGE
REPRESENTED AS 8-BIT
Figure 3-3. 8-Bit Truncation Mode Error
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
51
Analog-to-Digital Converter (ADC)
3.3.6 Monotonicity
The conversion process is monotonic and has no missing codes.
3.4 Interrupts
When the AIEN bit is set, the ADC module is capable of generating a CPU interrupt
after each ADC conversion. A CPU interrupt is generated if the COCO bit is at 0.
The COCO bit is not used as a conversion complete flag when interrupts are
enabled.
3.5 Wait Mode
The WAIT instruction can put the MCU in low power-consumption standby mode.
The ADC continues normal operation during wait mode. Any enabled CPU interrupt
request from the ADC can bring the MCU out of wait mode. If the ADC is not
required to bring the MCU out of wait mode, power down the ADC by setting
ADCH[4:0] in the ADC status and control register before executing the WAIT
instruction.
3.6 I/O Signals
The ADC module has 10 input signals that are shared with port B and port C.
3.6.1 ADC Analog Power Pin (VDDAD)
The ADC analog portion uses VDDAD as its power pin. Connect the VDDAD pin to
the same voltage potential as VDD. External filtering may be necessary to ensure
clean VDDAD for good results.
NOTE:
Route VDDAD carefully for maximum noise immunity and place bypass capacitors
as close as possible to the package.
3.6.2 ADC Analog Ground Pin (VSSAD)
The ADC analog portion uses VSSAD as its ground pin. Connect the VSSAD pin to
the same voltage potential as VSS.
3.6.3 ADC Voltage Reference Pin (VREFH)
VREFH is the power supply for setting the reference voltage VREFH. Connect the
VREFH pin to the same voltage potential as VDDAD. There will be a finite current
associated with VREFH. See Section 19. Electrical Specifications.
NOTE:
Data Sheet
52
Route VREFH carefully for maximum noise immunity and place bypass capacitors
as close as possible to the package.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MOTOROLA
Analog-to-Digital Converter (ADC)
I/O Signals
3.6.4 ADC Voltage Reference Low Pin (VREFL)
VREFL is the lower reference supply for the ADC. Connect the VREFL pin to the
same voltage potential as VSSAD. A finite current will be associated with VREFL.
See Section 19. Electrical Specifications.
NOTE:
In the 56-pin shrink dual in-line package (SDIP), VREFL and VSSAD are tied
together.
3.6.5 ADC Voltage In (ADVIN)
ADVIN is the input voltage signal from one of the 10 ADC channels to the ADC
module.
3.6.6 ADC External Connections
This section describes the ADC external connections: VREFH and VREFL, ANx, and
grounding.
3.6.6.1 VREFH and VREFL
Both ac and dc current are drawn through the VREFH and VREFL loop. The AC
current is in the form of current spikes required to supply charge to the capacitor
array at each successive approximation step. The current flows through the
internal resistor string. The best external component to meet both these current
demands is a capacitor in the 0.01 µF to 1 µF range with good high frequency
characteristics. This capacitor is connected between VREFH and VREFL and must
be placed as close as possible to the package pins. Resistance in the path is not
recommended because the dc current will cause a voltage drop which could result
in conversion errors.
3.6.6.2 ANx
Empirical data shows that capacitors from the analog inputs to VREFL improve ADC
performance. 0.01-µF and 0.1-µF capacitors with good high-frequency
characteristics are sufficient. These capacitors must be placed as close as possible
to the package pins.
3.6.6.3 Grounding
In cases where separate power supplies are used for analog and digital power, the
ground connection between these supplies should be at the VSSAD pin. This should
be the only ground connection between these supplies if possible. The VSSA pin
makes a good single point ground location. Connect the VREFL pin to the same
potential as VSSAD at the single point ground location.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
53
Analog-to-Digital Converter (ADC)
3.7 I/O Registers
These I/O registers control and monitor operation of the ADC:
•
ADC status and control register, ADSCR
•
ADC data registers, ADRH and ARDL
•
ADC clock register, ADCLK
3.7.1 ADC Status and Control Register
This section describes the function of the ADC status and control register
(ADSCR). Writing ADSCR aborts the current conversion and initiates a new
conversion.
Address: $0040
Bit 7
6
5
4
3
2
1
Bit 0
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
0
0
0
1
1
1
1
1
R
= Reserved
Read:
COCO
Write:
R
Reset:
Figure 3-4. ADC Status and Control Register (ADSCR)
COCO — Conversions Complete Bit
In non-interrupt mode (AIEN = 0), COCO is a read-only bit that is set at the end
of each conversion. COCO will stay set until cleared by a read of the ADC data
register. Reset clears this bit.
In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end
of a conversion. It always reads as a 0.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled
(AIEN = 1)
NOTE:
The write function of the COCO bit is reserved. When writing to the ADSCR
register, always have a 0 in the COCO bit position.
AIEN — ADC Interrupt Enable Bit
When this bit is set, an interrupt is generated at the end of an ADC conversion.
The interrupt signal is cleared when the data register is read or the status/control
register is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
ADCO — ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the ADR
register at the end of each conversion. Only one conversion is allowed when this
bit is cleared. Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
Data Sheet
54
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MOTOROLA
Analog-to-Digital Converter (ADC)
I/O Registers
ADCH[4:0] — ADC Channel Select Bits
ADCH4, ADCH3, ADCH2, ADCH1, and ADCH0 form a 5-bit field which is
used to select one of 10 ADC channels. The ADC channels are detailed in
Table 3-1.
NOTE:
Take care to prevent switching noise from corrupting the analog signal when
simultaneously using a port pin as both an analog and digital input.
The ADC subsystem is turned off when the channel select bits are all set to 1.
This feature allows for reduced power consumption for the MCU when the ADC
is not used.
NOTE:
Recovery from the disabled state requires one conversion cycle to stabilize.
The voltage levels supplied from internal reference nodes as specified in
Table 3-1 are used to verify the operation of the ADC both in production test and
for user applications.
Table 3-1. Mux Channel Select
ADCH4
0
0
0
0
0
0
0
0
0
ADCH3
0
0
0
0
0
0
0
0
1
ADCH2
0
0
0
0
1
1
1
1
0
ADCH1
0
0
1
1
0
0
1
1
0
ADCH0
0
1
0
1
0
1
0
1
0
Input Select
PTB0/ATD0
PTB1/ATD1
PTB2/ATD2
PTB3/ATD3
PTB4/ATD4
PTB5/ATD5
PTB6/ATD6
PTB7/ATD7
PTC0/ATD8
0
1
0
0
1
PTC1/ATD9(1)
0
1
0
1
0
0
0
0
0
0
1
1
1
1
1
1
0
0
1
1
1
1
0
1
0
0
1
1
0
1
0
1
0
1
0
Unused(2)
Ø
Ø
Ø
Ø
Ø
Ø
1
1
0
1
0
Unused(2)
1
1
0
1
1
Reserved(3)
1
1
1
0
0
1
1
1
0
1
Unused(2)
VREFH
1
1
1
1
0
VREFL
1
1
1
1
1
ADC power off
1. ATD9 is not available in the 56-pin SDIP package.
2. Used for factory testing.
3. If any unused channels are selected, the resulting ADC conversion will be unknown.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
55
Analog-to-Digital Converter (ADC)
3.7.2 ADC Data Register High
In left justified mode, this 8-bit result register holds the eight MSBs of the 10-bit
result. This register is updated each time an ADC single channel conversion
completes. Reading ADRH latches the contents of ADRL until ADRL is read. Until
ADRL is read, all subsequent ADC results will be lost.
Address:
$0041
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Write:
R
R
R
R
R
R
R
R
R
= Reserved
Reset:
Unaffected by reset
Figure 3-5. ADC Data Register High (ADRH) Left Justified Mode
In right justified mode, this 8-bit result register holds the two MSBs of the 10-bit
result. All other bits read as 0. This register is updated each time a single channel
ADC conversion completes. Reading ADRH latches the contents of ADRL until
ADRL is read. Until ADRL is read, all subsequent ADC results will be lost.
Address:
$0041
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
AD9
AD8
Write:
R
R
R
R
R
R
R
R
Reset:
Unaffected by reset
R
= Reserved
Figure 3-6. ADC Data Register High (ADRH) Right Justified Mode
3.7.3 ADC Data Register Low
In left justified mode, this 8-bit result register holds the two LSBs of the 10-bit result.
All other bits read as 0. This register is updated each time a single channel ADC
conversion completes. Reading ADRH latches the contents of ADRL until ADRL is
read. Until ADRL is read, all subsequent ADC results will be lost.
Address:
$0042
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AD1
AD0
0
0
0
0
0
0
Write:
R
R
R
R
R
R
R
R
R
= Reserved
Reset:
Unaffected by reset
Figure 3-7. ADC Data Register Low (ADRL) Left Justified Mode
Data Sheet
56
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MOTOROLA
Analog-to-Digital Converter (ADC)
I/O Registers
In right justified mode, this 8-bit result register holds the eight LSBs of the 10-bit
result. This register is updated each time an ADC conversion completes. Reading
ADRH latches the contents of ADRL until ADRL is read. Until ADRL is read, all
subsequent ADC results will be lost.
Address:
$0042
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
Unaffected by reset
R
= Reserved
Figure 3-8. ADC Data Register Low (ADRL) Right Justified Mode
In 8-bit mode, this 8-bit result register holds the eight MSBs of the 10-bit result. This
register is updated each time an ADC conversion completes. In 8-bit mode, this
register contains no interlocking with ADRH.
Address:
$0042
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Write:
R
R
R
R
R
R
R
R
Reset:
Unaffected by reset
R
= Reserved
Figure 3-9. ADC Data Register Low (ADRL) 8-Bit Mode
3.7.4 ADC Clock Register
This register selects the clock frequency for the ADC, selecting between modes of
operation.
Address:
Read:
Write:
Reset:
$0043
Bit 7
6
5
4
3
2
1
ADIV2
ADIV1
ADIV0
ADICLK
MODE1
MODE0
0
0
0
0
0
0
1
0
R
= Reserved
Bit 0
0
R
0
Figure 3-10. ADC Clock Register (ADCLK)
ADIV2:ADIV0 — ADC Clock Prescaler Bits
ADIV2, ADIV1, and ADIV0 form a 3-bit field which selects the divide ratio used
by the ADC to generate the internal ADC clock. Table 3-2 shows the available
clock configurations.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Analog-to-Digital Converter (ADC)
Data Sheet
57
Analog-to-Digital Converter (ADC)
Table 3-2. ADC Clock Divide Ratio
ADIV2
ADIV1
ADIV0
ADC Clock Rate
0
0
0
ADC input clock ÷ 1
0
0
1
ADC input clock ÷ 2
0
1
0
ADC input clock ÷ 4
0
1
1
ADC input clock ÷ 8
1
X
X
ADC input clock ÷ 16
X = don’t care
ADICLK — ADC Input Clock Select Bit
ADICLK selects either bus clock or CGMXCLK as the input clock source to
generate the internal ADC clock. Reset selects CGMXCLK as the ADC clock
source.
If the external clock (CGMXCLK) is equal to or greater than 1 MHz, CGMXCLK
can be used as the clock source for the ADC. If CGMXCLK is less than 1 MHz,
use the PLL-generated bus clock as the clock source. As long as the internal
ADC clock is at fADIC, correct operation can be guaranteed. See 19.13
Analog-to-Digital Converter (ADC) Characteristics.
1 = Internal bus clock
0 = External clock, CGMXCLK
CGMXCLK or bus frequency
fADIC =
ADIV[2:0]
MODE1:MODE0 — Modes of Result Justification Bits
MODE1:MODE0 selects among four modes of operation. The manner in which
the ADC conversion results will be placed in the ADC data registers is controlled
by these modes of operation. Reset returns right-justified mode.
00 = 8-bit truncation mode
01 = Right justified mode
10 = Left justified mode
11 = Left justified sign data mode
Data Sheet
58
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Analog-to-Digital Converter (ADC)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 4. Clock Generator Module (CGM)
4.1 Introduction
This section describes the clock generator module (CGM, version A). The CGM
generates the crystal clock signal, CGMXCLK, which operates at the frequency of
the crystal. The CGM also generates the base clock signal, CGMOUT, from which
the system integration module (SIM) derives the system clocks.
CGMOUT is based on either the crystal clock divided by two or the phase-locked
loop (PLL) clock, CGMVCLK, divided by two. The PLL is a frequency generator
designed for use with crystals or ceramic resonators. The PLL can generate an
8-MHz bus frequency without using a 32-MHz external clock.
4.2 Features
Features of the CGM include:
•
PLL with output frequency in integer multiples of the crystal reference
•
Programmable hardware voltage-controlled oscillator (VCO) for low-jitter
operation
•
Automatic bandwidth control mode for low-jitter operation
•
Automatic frequency lock detector
•
Central processor unit (CPU) interrupt on entry or exit from locked condition
4.3 Functional Description
The CGM consists of three major submodules:
1. Crystal oscillator circuit — The crystal oscillator circuit generates the
constant crystal frequency clock, CGMXCLK.
2. Phase-locked loop (PLL) — The PLL generates the programmable VCO
frequency clock, CGMVCLK.
3. Base clock selector circuit — This software-controlled circuit selects either
CGMXCLK divided by two or the VCO clock, CGMVCLK, divided by two as
the base clock, CGMOUT. The SIM derives the system clocks from
CGMOUT.
Figure 4-1 shows the structure of the CGM.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
59
Clock Generator Module (CGM)
CRYSTAL OSCILLATOR
OSC2
CGMXCLK
CLOCK
SELECT
CIRCUIT
OSC1
A
÷2
CGMOUT
B S*
TO SIM
TO SIM
*WHEN S = 1, CGMOUT = B
SIMOSCEN
CGMRDV
CGMRCLK
VDDA
BCS
CGMXFC
USER MODE
VSS
PTC2
VRS[7:4]
MONITOR MODE
PHASE
DETECTOR
VOLTAGE
CONTROLLED
OSCILLATOR
LOOP
FILTER
PLL ANALOG
LOCK
DETECTOR
LOCK
AUTO
CGMINT
INTERRUPT
CONTROL
BANDWIDTH
CONTROL
ACQ
PLLIE
PLLF
MUL[7:4]
CGMVDV
CGMVCLK
FREQUENCY
DIVIDER
Figure 4-1. CGM Block Diagram
Addr.
Register Name
Bit 7
$005C
PLL Control Register Read:
(PCTL) Write:
See page 69. Reset:
$005D
PLL Bandwidth Control Register Read:
(PBWC) Write:
See page 71. Reset:
$005E
PLL Programming Register Read:
(PPG) Write:
See page 72. Reset:
PLLIE
0
AUTO
6
PLLF
R
0
LOCK
R
5
4
PLLON
BCS
1
0
ACQ
XLD
3
2
1
Bit 0
1
1
1
1
R
R
R
R
1
1
1
1
0
0
0
0
R
R
R
R
0
0
0
0
0
0
0
0
MUL7
MUL6
MUL5
MUL4
VRS7
VRS6
VRS5
VRS4
1
1
0
0
1
1
0
0
R
= Reserved
Figure 4-2. CGM I/O Register Summary
Data Sheet
60
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Functional Description
4.3.1 Crystal Oscillator Circuit
The crystal oscillator circuit consists of an inverting amplifier and an external
crystal. The OSC1 pin is the input to the amplifier and the OSC2 pin is the output.
The SIMOSCEN signal from the system integration module (SIM) enables the
crystal oscillator circuit.
The CGMXCLK signal is the output of the crystal oscillator circuit and runs at a rate
equal to the crystal frequency. CGMXCLK is then buffered to produce CGMRCLK,
the PLL reference clock.
CGMXCLK can be used by other modules which require precise timing for
operation. The duty cycle of CGMXCLK is not guaranteed to be 50 percent and
depends on external factors, including the crystal and related external
components.
An externally generated clock also can feed the OSC1 pin of the crystal oscillator
circuit. Connect the external clock to the OSC1 pin and let the OSC2 pin float.
4.3.2 Phase-Locked Loop Circuit (PLL)
The PLL is a frequency generator that can operate in either acquisition mode or
tracking mode, depending on the accuracy of the output frequency. The PLL can
change between acquisition and tracking modes either automatically or manually.
4.3.2.1 PLL Circuits
The PLL consists of these circuits:
• Voltage-controlled oscillator (VCO)
• Modulo VCO frequency divider
• Phase detector
• Loop filter
• Lock detector
The operating range of the VCO is programmable for a wide range of frequencies
and for maximum immunity to external noise, including supply and CGMXFC noise.
The VCO frequency is bound to a range from roughly one-half to twice the
center-of-range frequency, fVRS. Modulating the voltage on the CGMXFC pin
changes the frequency within this range. By design, fVRS is equal to the nominal
center-of-range frequency, fNOM, (4.9152 MHz) times a linear factor, L or (L) fNOM.
CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK.
CGMRCLK runs at a frequency, fRCLK, and is fed to the PLL through a buffer. The
buffer output is the final reference clock, CGMRDV, running at a frequency,
fRDV = fRCLK.
The VCO’s output clock, CGMVCLK, running at a frequency, fVCLK, is fed back
through a programmable modulo divider. The modulo divider reduces the VCO
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
61
Clock Generator Module (CGM)
clock by a factor, N. The divider’s output is the VCO feedback clock, CGMVDV,
running at a frequency, fVDV = fVCLK/N. (See 4.3.2.4 Programming the PLL for
more information.)
The phase detector then compares the VCO feedback clock, CGMVDV, with the
final reference clock, CGMRDV. 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 CGMXFC based on the width and
direction of the correction pulse. The filter can make fast or slow corrections
depending on its mode, described in 4.3.2.2 Acquisition and Tracking Modes.
The value of the external capacitor and the reference frequency determines the
speed of the corrections and the stability of the PLL.
The lock detector compares the frequencies of the VCO feedback clock, CGMVDV,
and the final reference clock, CGMRDV. Therefore, the speed of the lock detector
is directly proportional to the final reference frequency, fRDV. The circuit determines
the mode of the PLL and the lock condition based on this comparison.
4.3.2.2 Acquisition and Tracking Modes
The PLL filter is manually or automatically configurable into one of two operating
modes:
1. Acquisition mode — In acquisition mode, the filter can make large frequency
corrections to the VCO. This mode is used at PLL startup or when the PLL
has suffered a severe noise hit and the VCO frequency is far off the desired
frequency. When in acquisition mode, the ACQ bit is clear in the PLL
bandwidth control register. See 4.5.2 PLL Bandwidth Control Register.
2. Tracking mode — In tracking mode, the filter makes only small corrections
to the frequency of the VCO. PLL jitter is much lower in tracking mode, but
the response to noise is also slower. The PLL enters tracking mode when
the VCO frequency is nearly correct, such as when the PLL is selected as
the base clock source. See 4.3.3 Base Clock Selector Circuit. The PLL is
automatically in tracking mode when not in acquisition mode or when the
ACQ bit is set.
4.3.2.3 Manual and Automatic PLL Bandwidth Modes
The PLL can change the bandwidth or operational mode of the loop filter manually
or automatically.
In automatic bandwidth control mode (AUTO = 1), the lock detector automatically
switches between acquisition and tracking modes. Automatic bandwidth control
mode also is used to determine when the VCO clock, CGMVCLK, is safe to use as
the source for the base clock, CGMOUT. See 4.5.2 PLL Bandwidth Control
Register. If PLL interrupts are enabled, the software can wait for a PLL interrupt
request and then check the LOCK bit. If interrupts are disabled, software can poll
the LOCK bit continuously (during PLL startup, usually) or at periodic intervals. In
either case, when the LOCK bit is set, the VCO clock is safe to use as the source
Data Sheet
62
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Functional Description
for the base clock. See 4.3.3 Base Clock Selector Circuit. If the VCO is selected
as the source for the base clock and the LOCK bit is clear, the PLL has suffered a
severe noise hit and the software must take appropriate action, depending on the
application. See 4.6 Interrupts for information and precautions on using interrupts.
These conditions apply when the PLL is in automatic bandwidth control mode:
•
The ACQ bit (see 4.5.2 PLL Bandwidth Control Register) is a read-only
indicator of the mode of the filter. For more information, see 4.3.2.2
Acquisition and Tracking Modes.
•
The ACQ bit is set when the VCO frequency is within a certain tolerance,
∆TRK, and is cleared when the VCO frequency is out of a certain tolerance,
∆UNT. For more information, see 4.8 Acquisition/Lock Time
Specifications.
•
The LOCK bit is a read-only indicator of the locked state of the PLL.
•
The LOCK bit is set when the VCO frequency is within a certain tolerance,
∆Lock, and is cleared when the VCO frequency is out of a certain tolerance,
∆UNL. For more information, see 4.8 Acquisition/Lock Time
Specifications.
•
CPU interrupts can occur if enabled (PLLIE = 1) when the PLL’s lock
condition changes, toggling the LOCK bit. For more information, see 4.5.1
PLL Control Register.
The PLL also may operate in manual mode (AUTO = 0). Manual mode is used by
systems that do not require an indicator of the lock condition for proper operation.
Such systems typically operate well below fBUSMAX and require fast startup. These
conditions apply when in manual mode:
•
ACQ is a writable control bit that controls the mode of the filter. Before
turning on the PLL in manual mode, the ACQ bit must be clear.
•
Before entering tracking mode (ACQ = 1), software must wait a given time,
tACQ (see 4.8 Acquisition/Lock Time Specifications), after turning on the
PLL by setting PLLON in the PLL control register (PCTL).
•
Software must wait a given time, tAL, after entering tracking mode before
selecting the PLL as the clock source to CGMOUT (BCS = 1).
•
The LOCK bit is disabled.
•
CPU interrupts from the CGM are disabled.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
63
Clock Generator Module (CGM)
4.3.2.4 Programming the PLL
Use this 9-step procedure to program the PLL. Table 4-1 lists the variables used
and their meaning.
Table 4-1. Variable Definitions
Variable
Definition
fBUSDES
Desired bus clock frequency
fVCLKDES
Desired VCO clock frequency
fRCLK
Chosen reference crystal frequency
fVCLK
Calculated VCO clock frequency
fBUS
Calculated bus clock frequency
fNOM
Nominal VCO center frequency
fVRS
Shifted FCO center frequency
1. Choose the desired bus frequency, fBUSDES.
Example: fBUSDES = 8 MHz
2. Calculate the desired VCO frequency, fVCLKDES.
fVCLKDES = 4 x fBUSDES
Example: fVCLKDES = 4 x 8 MHz = 32 MHz
3. Using a reference frequency, fRCLK, equal to the crystal frequency, calculate
the VCO frequency multiplier, N. Round the result to the nearest integer.
fVCLKDES
N=
fRCLK
Example: N =
32 MHz
= 8 MHz
4 MHz
4. Calculate the VCO frequency, fVCLK.
fVCLK = N x fRCLK
Example: fVCLK = 8 x 4 MHz = 32 MHz
5. Calculate the bus frequency, fBUS, and compare fBUS with fBUSDES.
fBUS =
Example: N =
fVCLK
4
32 MHz
= 8 MHz
4 MHz
6. If the calculated fBUS is not within the tolerance limits of the application,
select another fBUSDES or another fRCLK.
Data Sheet
64
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Functional Description
7. Using the value 4.9152 MHz for fNOM, calculate the VCO linear range
multiplier, L. The linear range multiplier controls the frequency range of the
PLL.
fVCLK
)
L = round ( f
NOM
Example: L =
32 MHz
= 7 MHz
4.9152 MHz
8. Calculate the VCO center-of-range frequency, fVRS. The center-or-range
frequency is the midpoint between the minimum and maximum frequencies
attainable by the PLL.
fVRS = L x fNOM
Example: fVRS = 7 x 4.9152 MHz = 34.4 MHz
For proper operation,
fVRS – fVCLK | ≤
CAUTION:
fNOM
2
Exceeding the recommended maximum bus frequency or VCO frequency can
crash the MCU.
9. Program the PLL registers accordingly:
a. In the upper four bits of the PLL programming register (PPG), program
the binary equivalent of N.
b. In the lower four bits of the PLL programming register (PPG), program
the binary equivalent of L.
4.3.2.5 Special Programming Exceptions
The programming method described in 4.3.2.4 Programming the PLL does not
account for possible exceptions. A value of 0 for N or L is meaningless when used
in the equations given. To account for these exceptions:
•
A 0 value for N is interpreted exactly the same as a value of 1.
•
A 0 value for L disables the PLL and prevents its selection as the source for
the base clock. See 4.3.3 Base Clock Selector Circuit.
4.3.3 Base Clock Selector Circuit
This circuit is used to select either the crystal clock, CGMXCLK, or the VCO clock,
CGMVCLK, as the source of the base clock, CGMOUT. The two input clocks go
through a transition control circuit that waits up to three CGMXCLK cycles and
three CGMVCLK cycles to change from one clock source to the other. During this
time, CGMOUT is held in stasis. The output of the transition control circuit is then
divided by two to correct the duty cycle. Therefore, the bus clock frequency, which
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
65
Clock Generator Module (CGM)
is one-half of the base clock frequency, is one-fourth the frequency of the selected
clock (CGMXCLK or CGMVCLK).
The BCS bit in the PLL control register (PCTL) selects which clock drives
CGMOUT. The VCO clock cannot be selected as the base clock source if the PLL
is not turned on. The PLL cannot be turned off if the VCO clock is selected. The
PLL cannot be turned on or off simultaneously with the selection or deselection of
the VCO clock. The VCO clock also cannot be selected as the base clock source
if the factor L is programmed to a 0. This value would set up a condition
inconsistent with the operation of the PLL, so that the PLL would be disabled and
the crystal clock would be forced as the source of the base clock.
4.3.4 CGM External Connections
In its typical configuration, the CGM requires seven external components. Five of
these are for the crystal oscillator and two are for the PLL.
The crystal oscillator is normally connected in a Pierce oscillator configuration, as
shown in Figure 4-3. Figure 4-3 shows only the logical representation of the
internal components and may not represent actual circuitry.
SIMOSCEN
CGMXCLK
OSC1
OSC2
VSS
CGMXFC
VDDA
VDD
CF
RS *
CBYP
RB
X1
C1
*RS can be 0 (shorted) when used with
higher frequency crystals. Refer to
manufacturer’s data.
C2
Figure 4-3. CGM External Connections
The oscillator configuration uses five components:
1. Crystal, X1
2. Fixed capacitor, C1
3. Tuning capacitor, C2 (can also be a fixed capacitor)
4. Feedback resistor, RB
5. Series resistor, RS (optional)
Data Sheet
66
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
I/O Signals
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.
Figure 4-3 also shows the external components for the PLL:
NOTE:
•
Bypass capacitor, CBYP
•
Filter capacitor, CF
Routing should be done with great care to minimize signal cross talk and noise.
(See 4.8 Acquisition/Lock Time Specifications for routing information and more
information on the filter capacitor’s value and its effects on PLL performance.)
4.4 I/O Signals
This section describes the CGM input/output (I/O) signals.
4.4.1 Crystal Amplifier Input Pin (OSC1)
The OSC1 pin is an input to the crystal oscillator amplifier.
4.4.2 Crystal Amplifier Output Pin (OSC2)
The OSC2 pin is the output of the crystal oscillator inverting amplifier.
4.4.3 External Filter Capacitor Pin (CGMXFC)
The CGMXFC pin is required by the loop filter to filter out phase corrections. A
small external capacitor is connected to this pin.
NOTE:
To prevent noise problems, CF should be placed as close to the CGMXFC pin as
possible, with minimum routing distances and no routing of other signals across the
CF connection.
4.4.4 PLL Analog Power Pin (VDDA)
VDDA is a power pin used by the analog portions of the PLL. Connect the VDDA pin
to the same voltage potential as the VDD pin.
NOTE:
Route VDDA carefully for maximum noise immunity and place bypass capacitors as
close as possible to the package.
4.4.5 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal comes from the system integration module (SIM) and
enables the oscillator and PLL.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
67
Clock Generator Module (CGM)
4.4.6 Crystal Output Frequency Signal (CGMXCLK)
CGMXCLK 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 4-3
shows only the logical relation of CGMXCLK to OSC1 and OSC2 and may not
represent the actual circuitry. The duty cycle of CGMXCLK is unknown and may
depend on the crystal and other external factors. Also, the frequency and amplitude
of CGMXCLK can be unstable at startup.
4.4.7 CGM Base Clock Output (CGMOUT)
CGMOUT is the clock output of the CGM. This signal goes to the SIM, which
generates the MCU clocks. CGMOUT is a 50 percent duty cycle clock running at
twice the bus frequency. CGMOUT is software programmable to be either the
oscillator output, CGMXCLK, divided by two or the VCO clock, CGMVCLK, divided
by two.
4.4.8 CGM CPU Interrupt (CGMINT)
CGMINT is the interrupt signal generated by the PLL lock detector.
4.5 CGM Registers
These registers control and monitor operation of the CGM:
•
PLL control register (PCTL) — see 4.5.1 PLL Control Register
•
PLL bandwidth control register (PBWC) — see 4.5.2 PLL Bandwidth
Control Register
•
PLL programming register (PPG) — see 4.5.3 PLL Programming Register
Figure 4-4 is a summary of the CGM registers.
Data Sheet
68
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
CGM Registers
Addr.
$005C
$005D
$005E
Register Name
Bit 7
PLL Control Register
(PCTL)
See page 69.
PLL Bandwidth Control Register
(PBWC)
See page 71.
PLL Programming Register
(PPG)
See page 72.
Read:
6
5
4
PLLON
BCS
PLLF
PLLIE
Write:
R
Reset:
0
Read:
0
1
0
ACQ
XLD
LOCK
AUTO
Write:
R
Reset:
3
2
1
Bit 0
1
1
1
1
R
R
R
R
1
1
1
1
0
0
0
0
R
R
R
R
0
0
0
0
0
0
0
0
MUL7
MUL6
MUL5
MUL4
VRS7
VRS6
VRS5
VRS4
0
1
1
0
0
1
1
0
Read:
Write:
Reset:
R
= Reserved
Notes:
1. When AUTO = 0, PLLIE is forced to logic 0 and is read-only.
2. When AUTO = 0, PLLF and LOCK read as logic 0.
3. When AUTO = 1, ACQ is read-only.
4. When PLLON = 0 or VRS[7:4] = $0, BCS is forced to logic 0 and is read-only.
5. When PLLON = 1, the PLL programming register is read-only.
6. When BCS = 1, PLLON is forced set and is read-only.
Figure 4-4. CGM I/O Register Summary
4.5.1 PLL Control Register
The PLL control register (PCTL) contains the interrupt enable and flag bits, the
on/off switch, and the base clock selector bit.
Address:
$005C
Bit 7
Read:
Write:
Reset:
6
PLLF
PLLIE
R
0
0
R
= Reserved
5
4
PLLON
BCS
1
0
3
2
1
Bit 0
1
1
1
1
R
R
R
R
1
1
1
1
Figure 4-5. PLL Control Register (PCTL)
PLLIE — PLL Interrupt Enable Bit
This read/write bit enables the PLL to generate an interrupt request when the
LOCK bit toggles, setting the PLL flag, PLLF. When the AUTO bit in the PLL
bandwidth control register (PBWC) is clear, PLLIE cannot be written and reads
as logic 0. Reset clears the PLLIE bit.
1 = PLL interrupts enabled
0 = PLL interrupts disabled
PLLF — PLL Interrupt Flag
This read-only bit is set whenever the LOCK bit toggles. PLLF generates an
interrupt request if the PLLIE bit also is set. PLLF always reads as logic 0 when
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
69
Clock Generator Module (CGM)
the AUTO bit in the PLL bandwidth control register (PBWC) is clear. Clear the
PLLF bit by reading the PLL control register. Reset clears the PLLF bit.
1 = Change in lock condition
0 = No change in lock condition
NOTE:
Do not inadvertently clear the PLLF bit. Any read or read-modify-write operation on
the PLL control register clears the PLLF bit.
PLLON — PLL On Bit
This read/write bit activates the PLL and enables the VCO clock, CGMVCLK.
PLLON cannot be cleared if the VCO clock is driving the base clock, CGMOUT
(BCS = 1). See 4.3.3 Base Clock Selector Circuit. Reset sets this bit so that
the loop can stabilize as the MCU is powering up.
1 = PLL on
0 = PLL off
BCS — Base Clock Select Bit
This read/write bit selects either the crystal oscillator output, CGMXCLK, or the
VCO clock, CGMVCLK, as the source of the CGM output, CGMOUT. CGMOUT
frequency is one-half the frequency of the selected clock. BCS cannot be set
while the PLLON bit is clear. After toggling BCS, it may take up to three
CGMXCLK and three CGMVCLK cycles to complete the transition from one
source clock to the other. During the transition, CGMOUT is held in stasis. See
4.3.3 Base Clock Selector Circuit. Reset clears the BCS bit.
1 = CGMVCLK divided by two drives CGMOUT
0 = CGMXCLK divided by two drives CGMOUT
NOTE:
PLLON and BCS have built-in protection that prevents the base clock selector
circuit from selecting the VCO clock as the source of the base clock if the PLL is
off. Therefore, PLLON cannot be cleared when BCS is set, and BCS cannot be set
when PLLON is clear. If the PLL is off (PLLON = 0), selecting CGMVCLK requires
two writes to the PLL control register. See 4.3.3 Base Clock Selector Circuit.
PCTL[3:0] — Unimplemented Bits
These bits provide no function and always read as logic 1s.
4.5.2 PLL Bandwidth Control Register
The PLL bandwidth control register (PBWC):
Data Sheet
70
•
Selects automatic or manual (software-controlled) bandwidth control mode
•
Indicates when the PLL is locked
•
In automatic bandwidth control mode, indicates when the PLL is in
acquisition or tracking mode
•
In manual operation, forces the PLL into acquisition or tracking mode
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
CGM Registers
Address: $005D
Bit 7
Read:
Write:
Reset:
6
LOCK
AUTO
R
0
0
R
= Reserved
5
4
ACQ
XLD
0
0
3
2
1
Bit 0
0
0
0
0
R
R
R
R
0
0
0
0
Figure 4-6. PLL Bandwidth Control Register (PBWC)
AUTO — Automatic Bandwidth Control Bit
This read/write bit selects automatic or manual bandwidth control. When
initializing the PLL for manual operation (AUTO = 0), clear the ACQ bit before
turning on the PLL. Reset clears the AUTO bit.
1 = Automatic bandwidth control
0 = Manual bandwidth control
LOCK — Lock Indicator Bit
When the AUTO bit is set, LOCK is a read-only bit that becomes set when the
VCO clock, CGMVCLK, is locked (running at the programmed frequency).
When the AUTO bit is clear, LOCK reads as logic 0 and has no meaning. Reset
clears the LOCK bit.
1 = VCO frequency correct or locked
0 = VCO frequency incorrect or unlocked
ACQ — Acquisition Mode Bit
When the AUTO bit is set, ACQ is a read-only bit that indicates whether the PLL
is in acquisition mode or tracking mode. When the AUTO bit is clear, ACQ is a
read/write bit that controls whether the PLL is in acquisition or tracking mode.
In automatic bandwidth control mode (AUTO = 1), the last-written value from
manual operation is stored in a temporary location and is recovered when
manual operation resumes. Reset clears this bit, enabling acquisition mode.
1 = Tracking mode
0 = Acquisition mode
XLD — Crystal Loss Detect Bit
When the VCO output, CGMVCLK, is driving CGMOUT, this read/write bit can
indicate whether the crystal reference frequency is active or not. To check the
status of the crystal reference, follow these steps:
1. Write a logic 1 to XLD.
2. Wait N × 4 cycles. (N is the VCO frequency multiplier.)
3. Read XLD.
The crystal loss detect function works only when the BCS bit is set, selecting
CGMVCLK to drive CGMOUT. When BCS is clear, XLD always reads as logic 0.
1 = Crystal reference is not active.
0 = Crystal reference is active.
PBWC[3:0] — Reserved for Test
These bits enable test functions not available in user mode. To ensure software
portability from development systems to user applications, software should write
0s to PBWC[3:0] whenever writing to PBWC.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
71
Clock Generator Module (CGM)
4.5.3 PLL Programming Register
The PLL programming register (PPG) contains the programming information for
the modulo feedback divider and the programming information for the hardware
configuration of the VCO.
Address: $005E
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
MUL7
MUL6
MUL5
MUL4
VRS7
VRS6
VRS5
VRS4
0
1
1
0
0
1
1
0
Figure 4-7. PLL Programming Register (PPG)
MUL[7:4] — Multiplier Select Bits
These read/write bits control the modulo feedback divider that selects the VCO
frequency multiplier, N. See 4.3.2.1 PLL Circuits and 4.3.2.4 Programming
the PLL. A value of $0 in the multiplier select bits configures the modulo
feedback divider the same as a value of $1. Reset initializes these bits to $6 to
give a default multiply value
of 6.
Table 4-2. VCO Frequency Multiplier (N) Selection
NOTE:
MUL7:MUL6:MUL5:MUL4
VCO Frequency Multiplier (N)
0000
1
0001
1
0010
2
0011
3
1101
13
1110
14
1111
15
The multiplier select bits have built-in protection that prevents them from being
written when the PLL is on (PLLON = 1).
VRS[7:4] — VCO Range Select Bits
These read/write bits control the hardware center-of-range linear multiplier L,
which controls the hardware center-of-range frequency fVRS. See 4.3.2.1 PLL
Circuits, 4.3.2.4 Programming the PLL and 4.5.1 PLL Control Register.
VRS[7:4] cannot be written when the PLLON bit in the PLL control register
Data Sheet
72
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Interrupts
(PCTL) is set. See 4.3.2.5 Special Programming Exceptions. A value of $0 in
the VCO range select bits disables the PLL and clears the BCS bit in the PCTL.
See 4.3.3 Base Clock Selector Circuit and 4.3.2.5 Special Programming
Exceptions for more information.
Reset initializes the bits to $6 to give a default range multiply
value of 6.
NOTE:
The VCO range select bits have built-in protection that prevents them from being
written when the PLL is on (PLLON = 1) and prevents selection of the VCO clock
as the source of the base clock (BCS = 1) if the VCO range select bits are all clear.
The VCO range select bits must be programmed correctly. Incorrect programming
may result in failure of the PLL to achieve lock.
4.6 Interrupts
When the AUTO bit is set in the PLL bandwidth control register (PBWC), the PLL
can generate a CPU interrupt request every time the LOCK bit changes state. The
PLLIE bit in the PLL control register (PCTL) enables CPU interrupts from the PLL.
PLLF, the interrupt flag in the PCTL, becomes set whether interrupts are enabled
or not. When the AUTO bit is clear, CPU interrupts from the PLL are disabled and
PLLF reads as logic 0.
Software should read the LOCK bit after a PLL interrupt request to see if the
request was due to an entry into lock or an exit from lock. When the PLL enters
lock, the VCO clock, CGMVCLK, divided by two can be selected as the CGMOUT
source by setting BCS in the PCTL. When the PLL exits lock, the VCO clock
frequency is corrupt, and appropriate precautions should be taken. If the
application is not frequency-sensitive, interrupts should be disabled to prevent PLL
interrupt service routines from impeding software performance or from exceeding
stack limitations.
NOTE:
Software can select the CGMVCLK divided by two as the CGMOUT source even
if the PLL is not locked (LOCK = 0). Therefore, software should make sure the PLL
is locked before setting the BCS bit.
4.7 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
The WAIT instruction does not affect the CGM. Before entering wait mode,
software can disengage and turn off the PLL by clearing the BCS and PLLON bits
in the PLL control register (PCTL). Less power-sensitive applications can
disengage the PLL without turning it off. Applications that require the PLL to wake
the MCU from wait mode also can deselect the PLL output without turning off the
PLL.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
73
Clock Generator Module (CGM)
4.8 Acquisition/Lock Time Specifications
The acquisition and lock times of the PLL are, in many applications, the most
critical PLL design parameters. Proper design and use of the PLL ensures the
highest stability and lowest acquisition/lock times.
4.8.1 Acquisition/Lock Time Definitions
Typical control systems refer to the acquisition time or lock time as the reaction
time, within specified tolerances, of the system to a step input. In a PLL, the step
input occurs when the PLL is turned on or when it suffers a noise hit. The tolerance
is usually specified as a percent of the step input or when the output settles to the
desired value plus or minus a percent of the frequency change. Therefore, the
reaction time is constant in this definition, regardless of the size of the step input.
For example, consider a system with a 5 percent acquisition time tolerance. If a
command instructs the system to change from 0 Hz to 1 MHz, the acquisition time
is the time taken for the frequency to reach 1 MHz ± 50 kHz. Fifty kHz = 5% of the
1-MHz step input. If the system is operating at 1 MHz and suffers a –100-kHz noise
hit, the acquisition time is the time taken to return from 900 kHz to 1 MHz ±5 kHz.
Five kHz = 5% of the 100-kHz step input.
Other systems refer to acquisition and lock times as the time the system takes to
reduce the error between the actual output and the desired output to within
specified tolerances. Therefore, the acquisition or lock time varies according to the
original error in the output. Minor errors may not even be registered. Typical PLL
applications prefer to use this definition because the system requires the output
frequency to be within a certain tolerance of the desired frequency regardless of
the size of the initial error.
The discrepancy in these definitions makes it difficult to specify an acquisition or
lock time for a typical PLL. Therefore, the definitions for acquisition and lock times
for this module are:
Data Sheet
74
•
Acquisition time, tACQ, is the time the PLL takes to reduce the error between
the actual output frequency and the desired output frequency to less than
the tracking mode entry tolerance, ∆TRK. Acquisition time is based on an
initial frequency error,
(fDES – fORIG)/fDES, of not more than ±100 percent. In automatic bandwidth
control mode (see 4.3.2.3 Manual and Automatic PLL Bandwidth
Modes), acquisition time expires when the ACQ bit becomes set in the PLL
bandwidth control register (PBWC).
•
Lock time, tLock, is the time the PLL takes to reduce the error between the
actual output frequency and the desired output frequency to less than the
lock mode entry tolerance, ∆Lock. Lock time is based on an initial frequency
error, (fDES – fORIG)/fDES, of not more than ±100 percent. In automatic
bandwidth control mode, lock time expires when the LOCK bit becomes set
in the PLL bandwidth control register (PBWC). See 4.3.2.3 Manual and
Automatic PLL Bandwidth Modes.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
Obviously, the acquisition and lock times can vary according to how large the
frequency error is and may be shorter or longer in many cases.
4.8.2 Parametric Influences on Reaction Time
Acquisition and lock times are designed to be as short as possible while still
providing the highest possible stability. These reaction times are not constant,
however. Many factors directly and indirectly affect the acquisition time.
The most critical parameter which affects the reaction times of the PLL is the
reference frequency, fRDV. This frequency is the input to the phase detector and
controls how often the PLL makes corrections. For stability, the corrections must
be small compared to the desired frequency, so several corrections are required to
reduce the frequency error. Therefore, the slower the reference the longer it takes
to make these corrections. This parameter is also under user control via the choice
of crystal frequency, fXCLK.
Another critical parameter is the external filter capacitor. The PLL modifies the
voltage on the VCO by adding or subtracting charge from this capacitor. Therefore,
the rate at which the voltage changes for a given frequency error (thus change in
charge) is proportional to the capacitor size. The size of the capacitor also is related
to the stability of the PLL. If the capacitor is too small, the PLL cannot make small
enough adjustments to the voltage and the system cannot lock. If the capacitor is
too large, the PLL may not be able to adjust the voltage in a reasonable time. See
4.8.3 Choosing a Filter Capacitor.
Also important is the operating voltage potential applied to VDDA. The power supply
potential alters the characteristics of the PLL. A fixed value is best. Variable
supplies, such as batteries, are acceptable if they vary within a known range at very
slow speeds. Noise on the power supply is not acceptable, because it causes small
frequency errors which continually change the acquisition time of the PLL.
Temperature and processing also can affect acquisition time because the electrical
characteristics of the PLL change. The part operates as specified as long as these
influences stay within the specified limits. External factors, however, can cause
drastic changes in the operation of the PLL. These factors include noise injected
into the PLL through the filter capacitor filter, capacitor leakage, stray impedances
on the circuit board, and even humidity or circuit board contamination.
4.8.3 Choosing a Filter Capacitor
As described in 4.8.2 Parametric Influences on Reaction Time, the external filter
capacitor, CF, is critical to the stability and reaction time of the PLL. The PLL is also
dependent on reference frequency and supply voltage. The value of the capacitor
must, therefore, be chosen with supply potential and reference frequency in mind.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
75
Clock Generator Module (CGM)
For proper operation, the external filter capacitor must be chosen according to this
equation:
 V DDA
C F = C FACT  ---------------
 f RDV 
For acceptable values of CFACT, see 4.8 Acquisition/Lock Time Specifications.
For the value of VDDA, choose the voltage potential at which the MCU is operating.
If the power supply is variable, choose a value near the middle of the range of
possible supply values.
This equation does not always yield a commonly available capacitor size, so round
to the nearest available size. If the value is between two different sizes, choose the
higher value for better stability. Choosing the lower size may seem attractive for
acquisition time improvement, but the PLL can become unstable. Also, always
choose a capacitor with a tight tolerance (±20 percent or better) and low
dissipation.
4.8.4 Reaction Time Calculation
The actual acquisition and lock times can be calculated using the equations here.
These equations yield nominal values under these conditions:
•
Correct selection of filter capacitor, CF, see 4.8.3 Choosing a Filter
Capacitor
•
Room temperature operation
•
Negligible external leakage on CGMXFC
•
Negligible noise
The K factor in the equations is derived from internal PLL parameters. KACQ is the
K factor when the PLL is configured in acquisition mode, and KTRK is the K factor
when the PLL is configured in tracking mode. See 4.3.2.2 Acquisition and
Tracking Modes.
 V DDA
8
t ACQ =  ---------------  ---------------

f
K
 RDV  ACQ
 V DDA
4
t AL =  ---------------  --------------

K
f
 RDV  TRK
t Lock = t ACQ + t AL
NOTE:
The inverse proportionality between the lock time and the reference frequency.
In automatic bandwidth control mode, the acquisition and lock times are quantized
into units based on the reference frequency. See 4.3.2.3 Manual and Automatic
PLL Bandwidth Modes A certain number of clock cycles, nACQ, is required to
ascertain that the PLL is within the tracking mode entry tolerance, ∆TRK, before
Data Sheet
76
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
exiting acquisition mode. A certain number of clock cycles, nTRK, is required to
ascertain that the PLL is within the lock mode entry tolerance, ∆Lock. Therefore, the
acquisition time, tACQ, is an integer multiple of nACQ/fRDV, and the acquisition to
lock time, tAL, is an integer multiple of nTRK/fRDV. Also, since the average frequency
over the entire measurement period must be within the specified tolerance, the
total time usually is longer than tLock as calculated in the previous example.
In manual mode, it is usually necessary to wait considerably longer than tLock
before selecting the PLL clock (see 4.3.3 Base Clock Selector Circuit) because
the factors described in 4.8.2 Parametric Influences on Reaction Time may slow
the lock time considerably.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Clock Generator Module (CGM)
Data Sheet
77
Clock Generator Module (CGM)
Data Sheet
78
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Clock Generator Module (CGM)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 5. Configuration Register (CONFIG)
5.1 Introduction
This section describes the configuration register (CONFIG). This register contains
bits that configure these options:
•
Resets caused by the low-voltage inhibit (LVI) module
•
Power to the LVI module
•
Computer operating properly (COP) module
•
Top-side pulse-width modulator (PWM) polarity
•
Bottom-side PWM polarity
•
Edge-aligned versus center-aligned PWMs
•
Six independent PWMs versus three complementary PWM pairs
5.2 Functional Description
The configuration register (CONFIG) 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 microcontroller unit (MCU), it is recommended that this register
be written immediately after reset. The configuration register is located at $001F
and may be read at anytime.
NOTE:
On a FLASH device, the options are one-time writeable by the user after each
reset. The registers are not in the FLASH memory but are special registers
containing one-time writeable latches after each reset. Upon a reset, the
configuration register defaults to predetermined settings as shown in Figure 5-1.
If the LVI module and the LVI reset signal are enabled, a reset occurs when VDD
falls to a voltage, VLVRx, and remains at or below that level for at least nine
consecutive central processor unit (CPU) cycles. Once an LVI reset occurs, the
MCU remains in reset until VDD rises to a voltage, VLVRX.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Configuration Register (CONFIG)
Data Sheet
79
Configuration Register (CONFIG)
5.3 Configuration Register
Address:
Read:
Write:
Reset:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
EDGE
BOTNEG
TOPNEG
INDEP
LVIRST
LVIPWR
STOPE
COPD
0
0
0
0
1
1
0
0
Figure 5-1. Configuration Register (CONFIG)
EDGE — Edge-Align Enable Bit
EDGE determines if the motor control PWM will operate in edge-aligned mode
or center-aligned mode. See Section 12. Pulse-Width Modulator for Motor
Control (PWMMC).
1 = Edge-aligned mode enabled
0 = Center-aligned mode enabled
BOTNEG — Bottom-Side PWM Polarity Bit
BOTNEG determines if the bottom-side PWMs will have positive or negative
polarity. See Section 12. Pulse-Width Modulator for Motor Control
(PWMMC).
1 = Negative polarity
0 = Positive polarity
TOPNEG — Top-Side PWM Polarity Bit
TOPNEG determines if the top-side PWMs will have positive or negative
polarity. See Section 12. Pulse-Width Modulator for Motor Control
(PWMMC).
1 = Negative polarity
0 = Positive polarity
INDEP — Independent Mode Enable Bit
INDEP determines if the motor control PWMs will be six independent PWMs or
three complementary PWM pairs. See Section 12. Pulse-Width Modulator for
Motor Control (PWMMC).
1 = Six independent PWMs
0 = Three complementary PWM pairs
LVIRST — LVI Reset Enable Bit
LVIRST enables the reset signal from the LVI module. See
Section 9. Low-Voltage Inhibit (LVI).
1 = LVI module resets enabled
0 = LVI module resets disabled
LVIPWR — LVI Power Enable Bit
LVIPWR enables the LVI module. See Section 9. Low-Voltage Inhibit (LVI).
1 = LVI module power enabled
0 = LVI module power disabled
Data Sheet
80
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Configuration Register (CONFIG)
MOTOROLA
Configuration Register (CONFIG)
Configuration Register
STOPE — Stop Enable Bit
Writing a 0 or a 1 to bit 1 has no effect on MCU operation. Bit 1 operates the
same as the other bits within this write-once register operate.
1 = STOP mode enabled
0 = STOP mode disabled
COPD — COP Disable Bit
COPD disables the COP module. See Section 6. Computer Operating
Properly (COP).
1 = COP module disabled
0 = COP module enabled
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Configuration Register (CONFIG)
Data Sheet
81
Configuration Register (CONFIG)
Data Sheet
82
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Configuration Register (CONFIG)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 6. Computer Operating Properly (COP)
6.1 Introduction
This section describes the computer operating properly module, a free-running
counter that generates a reset if allowed to overflow. The computer operating
properly (COP) module helps software recover from runaway code. Prevent a COP
reset by periodically clearing the COP counter.
6.2 Functional Description
Figure 6-1 shows the structure of the COP module. A summary of the input/output
(I/O) register is shown in Figure 6-2.
SIM
CLEAR BITS 12–4
13-BIT SIM COUNTER
CLEAR ALL BITS
CGMXCLK
SIM RESET CIRCUIT
SIM RESET STATUS REGISTER
INTERNAL RESET SOURCES(1)
RESET VECTOR FETCH
COPCTL WRITE
COP MODULE
6-BIT COP COUNTER
COPD (FROM CONFIG)
RESET
COPCTL WRITE
CLEAR
COP COUNTER
Note 1. See 14.3.2 Active Resets from Internal Sources.
Figure 6-1. COP Block Diagram
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Computer Operating Properly (COP)
Data Sheet
83
Computer Operating Properly (COP)
Addr.
Register Name
Bit 7
COP Control Register
(COPCTL)
See page 85.
$FFFF
6
5
4
3
Read:
Low byte of reset vector
Write:
Clear COP counter
Reset:
Unaffected by reset
2
1
Bit 0
Figure 6-2. COP I/O Register Summary
The COP counter is a free-running, 6-bit counter preceded by the 13-bit system
integration module (SIM) counter. If not cleared by software, the COP counter
overflows and generates an asynchronous reset after 218–24 CGMXCLK cycles.
With a 4.9152-MHz crystal, the COP timeout period is 53.3 ms. Writing any value
to location $FFFF before overflow occurs clears the COP counter and prevents
reset.
A COP reset pulls the RST pin low for 32 CGMXCLK cycles and sets the COP bit
in the SIM reset status register (SRSR). See 14.7.2 SIM Reset Status Register.
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.
6.3 I/O Signals
This section describes the signals shown in Figure 6-1.
6.3.1 CGMXCLK
CGMXCLK is the crystal oscillator output signal. CGMXCLK frequency is equal to
the crystal frequency.
6.3.2 COPCTL Write
Writing any value to the COP control register (COPCTL) (see 6.4 COP Control
Register) clears the COP counter and clears bits 12–4 of the SIM counter.
Reading the COP control register returns the reset vector.
6.3.3 Power-On Reset
The power-on reset (POR) circuit in the SIM clears the SIM counter 4096
CGMXCLK cycles after power-up.
6.3.4 Internal Reset
An internal reset clears the SIM counter and the COP counter.
Data Sheet
84
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Computer Operating Properly (COP)
MOTOROLA
Computer Operating Properly (COP)
COP Control Register
6.3.5 Reset Vector Fetch
A reset vector fetch occurs when the vector address appears on the data bus. A
reset vector fetch clears the SIM counter.
6.3.6 COPD (COP Disable)
The COPD signal reflects the state of the COP disable bit (COPD) in the
configuration register (CONFIG). See Section 5. Configuration Register
(CONFIG).
6.4 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:
Clear COP counter
Reset:
Unaffected by reset
2
1
Bit 0
Figure 6-3. COP Control Register (COPCTL)
6.5 Interrupts
The COP does not generate CPU interrupt requests.
6.6 Monitor Mode
The COP is disabled in monitor mode when VHI is present on the IRQ pin or on the
RST pin.
6.7 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
The COP continues to operate during wait mode.
6.8 Stop Mode
Stop mode turns off the CGMXCLK 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.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Computer Operating Properly (COP)
Data Sheet
85
Computer Operating Properly (COP)
Data Sheet
86
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Computer Operating Properly (COP)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 7. Central Processor Unit (CPU)
7.1 Introduction
This section describes the central processor unit (CPU08, version A). The
M68HC08 CPU is an enhanced and fully object-code-compatible version of the
M68HC05 CPU. The CPU08 Reference Manual, Motorola document order number
CPU08RM/AD, contains a description of the CPU instruction set, addressing
modes, and architecture.
7.2 Features
Features of the CPU08 include:
•
Fully upward, object-code compatibility with M68HC05 Family
•
16-bit stack pointer with stack manipulation instructions
•
16-bit index register with X-register manipulation instructions
•
8-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 wait mode
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
Data Sheet
87
Central Processor Unit (CPU)
7.3 CPU Registers
Figure 7-1 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 7-1. CPU Registers
7.3.1 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 7-2. Accumulator (A)
Data Sheet
88
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
CPU Registers
7.3.2 Index Register
The 16-bit index register allows indexed addressing of a 64-Kbyte 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 7-3. Index Register (H:X)
7.3.3 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 7-4. Stack Pointer (SP)
NOTE:
The location of the stack is arbitrary and may be relocated anywhere in
random-access memory (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.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
Data Sheet
89
Central Processor Unit (CPU)
7.3.4 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
Bit
0
1
Read:
Write:
Reset:
Loaded with vector from $FFFE and $FFFF
Figure 7-5. Program Counter (PC)
7.3.5 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 1. The following paragraphs describe the functions of the condition
code register.
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
Read:
Write:
Reset:
X = Indeterminate
Figure 7-6. 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
Data Sheet
90
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
CPU Registers
H — Half-Carry Flag
The CPU sets the half-carry flag when a carry occurs between accumulator bits
3 and 4 during an add-without-carry (ADD) or add-with-carry (ADC) operation.
The half-carry flag is required for binary-coded decimal (BCD) arithmetic
operations. The DAA instruction uses the states of the H and C flags to
determine the appropriate correction factor.
1 = Carry between bits 3 and 4
0 = No carry between bits 3 and 4
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
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
Data Sheet
91
Central Processor Unit (CPU)
7.4 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the instruction
set.
Refer to the CPU08 Reference Manual (Motorola document order number
CPU08RM/AD) for a description of the instructions and addressing modes and
more detail about the architecture of the CPU.
7.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby
modes.
7.5.1 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
7.5.2 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.
7.6 CPU During Break Interrupts
If a break module is present on the MCU, the CPU starts a break interrupt by:
•
Loading the instruction register with the SWI instruction
•
Loading the program counter with $FFFC:$FFFD or with $FEFC:$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.
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.
Data Sheet
92
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
Instruction Set Summary
7.7 Instruction Set Summary
Table 7-1 provides a summary of the M68HC08 instruction set.
ADC #opr
ADC opr
ADC opr
ADC opr,X
ADC opr,X
ADC ,X
ADC opr,SP
ADC opr,SP
V H I N Z C
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
ff
ee ff
A7
ii
2
– – – – – – IMM
AF
ii
2
IMM
DIR
EXT
IX2
0 – – –
IX1
IX
SP1
SP2
A4
B4
C4
D4
E4
F4
9EE4
9ED4
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
0
DIR
INH
INH
– – IX1
IX
SP1
38 dd
48
58
68 ff
78
9E68 ff
4
1
1
4
3
5
C
DIR
INH
INH
– – IX1
IX
SP1
37 dd
47
57
67 ff
77
9E67 ff
4
1
1
4
3
5
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)
A ← (A) & (M)
ASL opr
ASLA
ASLX
ASL opr,X
ASL ,X
ASL opr,SP
A ← (A) + (M)
Logical AND
Arithmetic Shift Left
(Same as LSL)
C
b7
ASR opr
ASRA
ASRX
ASR opr,X
ASR opr,X
ASR opr,SP
Arithmetic Shift Right
BCC rel
Branch if Carry Bit Clear
b0
b7
2
3
4
4
3
2
4
5
2
3
4
4
3
2
4
5
ADD #opr
ADD opr
ADD opr
ADD opr,X
ADD opr,X
ADD ,X
ADD opr,SP
ADD opr,SP
AND #opr
AND opr
AND opr
AND opr,X
AND opr,X
AND ,X
AND opr,SP
AND opr,SP
ff
ee ff
Cycles
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 1 of 7)
b0
PC ← (PC) + 2 + rel ? (C) = 0
Mn ← 0
ff
ee ff
– – – – – – 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
BCLR n, opr
Clear Bit n in M
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
Data Sheet
93
Central Processor Unit (CPU)
V H I N Z C
PC ← (PC) + 2 + rel ? (N ⊕ V) = 0
BGE opr
Branch if Greater Than or Equal To
(Signed Operands)
BGT opr
Branch if Greater Than (Signed
Operands)
BHCC rel
Branch if Half Carry Bit Clear
PC ← (PC) + 2 + rel ? (H) = 0
BHCS rel
Branch if Half Carry Bit Set
BHI rel
Branch if Higher
BHS rel
Cycles
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 2 of 7)
– – – – – – REL
90
rr
3
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 0 – – – – – – REL
92
rr
3
– – – – – – REL
28
rr
3
PC ← (PC) + 2 + rel ? (H) = 1
– – – – – – REL
29
rr
PC ← (PC) + 2 + rel ? (C) | (Z) = 0
– – – – – – REL
22
rr
3
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
(A) & (M)
IMM
DIR
EXT
0 – – – IX2
IX1
IX
SP1
SP2
A5
B5
C5
D5
E5
F5
9EE5
9ED5
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
93
rr
3
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)
BLO rel
Branch if Lower (Same as BCS)
BLS rel
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 1 – – – – – – REL
3
PC ← (PC) + 2 + rel ? (C) = 1
– – – – – – REL
25
rr
3
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
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
BRCLR n,opr,rel Branch if Bit n in M Clear
BRN rel
Data Sheet
94
Branch Never
PC ← (PC) + 3 + rel ? (Mn) = 0
PC ← (PC) + 2
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
Instruction Set Summary
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
PC ← (PC) + 2; push (PCL)
SP ← (SP) – 1; push (PCH)
SP ← (SP) – 1
PC ← (PC) + rel
– – – – – – REL
AD
rr
4
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 3 + rel ? (X) – (M) = $00
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 2 + rel ? (A) – (M) = $00
PC ← (PC) + 4 + rel ? (A) – (M) = $00
DIR
IMM
– – – – – – IMM
IX1+
IX+
SP1
31
41
51
61
71
9E61
dd rr
ii rr
ii rr
ff rr
rr
ff rr
5
4
4
5
4
6
Description
V H I N Z C
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
Cycles
Operand
PC ← (PC) + 3 + rel ? (Mn) = 1
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
– – – – – DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
Operation
Effect
on CCR
Address
Mode
Source
Form
Opcode
Table 7-1. Instruction Set Summary (Sheet 3 of 7)
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 dd
4F
5F
8C
6F ff
7F
9E6F ff
(A) – (M)
IMM
DIR
EXT
IX2
– – IX1
IX
SP1
SP2
A1
B1
C1
D1
E1
F1
9EE1
9ED1
M ← (M) = $FF – (M)
A ← (A) = $FF – (M)
X ← (X) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
INH
0 – – 1 IX1
IX
SP1
33 dd
43
53
63 ff
73
9E63 ff
(H:X) – (M:M + 1)
– – IMM
DIR
CLR opr
CLRA
CLRX
CLRH
CLR opr,X
CLR ,X
CLR opr,SP
CMP #opr
CMP opr
CMP opr
CMP opr,X
CMP opr,X
CMP ,X
CMP opr,SP
CMP opr,SP
Clear
Compare A with 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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
65
75
ii
dd
hh ll
ee ff
ff
ff
ee ff
ii ii+1
dd
3
1
1
1
3
2
4
2
3
4
4
3
2
4
5
4
1
1
4
3
5
3
4
Data Sheet
95
Central Processor Unit (CPU)
Compare X with M
DAA
Decimal Adjust A
DBNZ opr,rel
DBNZA rel
DBNZX rel
Decrement and Branch if Not Zero
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
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
LDA #opr
LDA opr
LDA opr
LDA opr,X
LDA opr,X
LDA ,X
LDA opr,SP
LDA opr,SP
Data Sheet
96
Exclusive OR M with A
Increment
Jump
Jump to Subroutine
Load A from M
(X) – (M)
(A)10
IMM
DIR
EXT
IX2
– – IX1
IX
SP1
SP2
A3
B3
C3
D3
E3
F3
9EE3
9ED3
U – – INH
72
A ← (A) – 1 or M ← (M) – 1 or X ← (X) – 1
PC ← (PC) + 3 + rel ? (result) ≠ 0
DIR
PC ← (PC) + 2 + rel ? (result) ≠ 0
INH
PC ← (PC) + 2 + rel ? (result) ≠ 0
– – – – – – INH
PC ← (PC) + 3 + rel ? (result) ≠ 0
IX1
PC ← (PC) + 2 + rel ? (result) ≠ 0
IX
PC ← (PC) + 4 + rel ? (result) ≠ 0
SP1
3B
4B
5B
6B
7B
9E6B
ii
dd
hh ll
ee ff
ff
ff
ee ff
Cycles
V H I N Z C
CPX #opr
CPX opr
CPX opr
CPX ,X
CPX opr,X
CPX opr,X
CPX opr,SP
CPX opr,SP
EOR #opr
EOR opr
EOR opr
EOR opr,X
EOR opr,X
EOR ,X
EOR opr,SP
EOR opr,SP
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 4 of 7)
2
3
4
4
3
2
4
5
2
dd rr
rr
rr
ff rr
rr
ff rr
5
3
3
5
4
6
M ← (M) – 1
A ← (A) – 1
X ← (X) – 1
M ← (M) – 1
M ← (M) – 1
M ← (M) – 1
DIR
INH
– – – INH
IX1
IX
SP1
A ← (H:A)/(X)
H ← Remainder
– – – – INH
52
A ← (A ⊕ M)
IMM
DIR
EXT
IX2
0 – – –
IX1
IX
SP1
SP2
A8
B8
C8
D8
E8
F8
9EE8
9ED8
M ← (M) + 1
A ← (A) + 1
X ← (X) + 1
M ← (M) + 1
M ← (M) + 1
M ← (M) + 1
DIR
INH
INH
– – – IX1
IX
SP1
3C dd
4C
5C
6C ff
7C
9E6C ff
PC ← Jump Address
DIR
EXT
– – – – – – IX2
IX1
IX
BC
CC
DC
EC
FC
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
A ← (M)
IMM
DIR
EXT
0 – – – IX2
IX1
IX
SP1
SP2
A6
B6
C6
D6
E6
F6
9EE6
9ED6
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
3A dd
4A
5A
6A ff
7A
9E6A ff
4
1
1
4
3
5
7
ii
dd
hh ll
ee ff
ff
ff
ee ff
ff
ee ff
2
3
4
4
3
2
4
5
4
1
1
4
3
5
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
Instruction Set Summary
LDHX #opr
LDHX opr
LDX #opr
LDX opr
LDX opr
LDX opr,X
LDX opr,X
LDX ,X
LDX opr,SP
LDX opr,SP
LSL opr
LSLA
LSLX
LSL opr,X
LSL ,X
LSL opr,SP
V H I N Z C
Load H:X from M
H:X ← (M:M + 1)
IMM
0 – – – DIR
45
55
X ← (M)
IMM
DIR
EXT
IX2
0 – – – IX1
IX
SP1
SP2
AE
BE
CE
DE
EE
FE
9EEE
9EDE
0
DIR
INH
– – INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E68 ff
4
1
1
4
3
5
C
DIR
INH
INH
– – 0 IX1
IX
SP1
34 dd
44
54
64 ff
74
9E64 ff
4
1
1
4
3
5
Load X from M
Logical Shift Left
(Same as ASL)
LSR opr
LSRA
LSRX
LSR opr,X
LSR ,X
LSR opr,SP
Logical Shift Right
MOV opr,opr
MOV opr,X+
MOV #opr,opr
MOV X+,opr
Move
MUL
Unsigned multiply
Cycles
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 5 of 7)
C
b7
b0
0
b7
b0
(M)Destination ← (M)Source
H:X ← (H:X) + 1 (IX+D, DIX+)
0 – – –
DD
DIX+
IMD
IX+D
X:A ← (X) × (A)
– 0 – – – 0 INH
M ← –(M) = $00 – (M)
A ← –(A) = $00 – (A)
X ← –(X) = $00 – (X)
M ← –(M) = $00 – (M)
M ← –(M) = $00 – (M)
DIR
INH
INH
– – IX1
IX
SP1
4E
5E
6E
7E
ii jj
dd
3
4
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
2
4
5
ff
ee ff
dd dd
dd
ii dd
dd
42
5
4
4
4
5
30 dd
40
50
60 ff
70
9E60 ff
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
A ← (A) | (M)
IMM
DIR
EXT
IX2
0 – – – IX1
IX
SP1
SP2
AA
BA
CA
DA
EA
FA
9EEA
9EDA
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
ff
ee ff
Data Sheet
97
Central Processor Unit (CPU)
ROL opr
ROLA
ROLX
ROL opr,X
ROL ,X
ROL opr,SP
V H I N Z C
Rotate Left through Carry
C
b7
b0
Cycles
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 6 of 7)
DIR
INH
– – INH
IX1
IX
SP1
39 dd
49
59
69 ff
79
9E69 ff
4
1
1
4
3
5
DIR
INH
INH
– – IX1
IX
SP1
36 dd
46
56
66 ff
76
9E66 ff
4
1
1
4
3
5
ROR opr
RORA
RORX
ROR opr,X
ROR ,X
ROR opr,SP
Rotate Right through Carry
RSP
Reset Stack Pointer
SP ← $FF
– – – – – – INH
9C
1
RTI
Return from Interrupt
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
RTS
Return from Subroutine
SP ← SP + 1; Pull (PCH)
SP ← SP + 1; Pull (PCL)
– – – – – – INH
81
4
A ← (A) – (M) – (C)
IMM
DIR
EXT
– – IX2
IX1
IX
SP1
SP2
A2
B2
C2
D2
E2
F2
9EE2
9ED2
C
b7
b0
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
M ← (A)
DIR
EXT
IX2
0 – – – IX1
IX
SP1
SP2
B7
C7
D7
E7
F7
9EE7
9ED7
(M:M + 1) ← (H:X)
0 – – – DIR
35
I ← 0; Stop Oscillator
– – 0 – – – INH
8E
M ← (X)
DIR
EXT
IX2
0 – – – 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
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
Data Sheet
98
Store X in M
Subtract
A ← (A) – (M)
ff
ee ff
dd
hh ll
ee ff
ff
ff
ee ff
3
4
4
3
2
4
5
dd
4
1
ff
ee ff
ff
ee ff
3
4
4
3
2
4
5
2
3
4
4
3
2
4
5
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
MOTOROLA
Central Processor Unit (CPU)
Opcode Map
V H I N Z C
Cycles
Description
Operand
Operation
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-1. Instruction Set Summary (Sheet 7 of 7)
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
(A) – $00 or (X) – $00 or (M) – $00
DIR
INH
0 – – – INH
IX1
IX
SP1
H:X ← (SP) + 1
– – – – – – INH
95
2
A ← (X)
– – – – – – INH
9F
1
(SP) ← (H:X) – 1
– – – – – – INH
94
2
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
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
&
|
⊕
()
–( )
#
«
←
?
:
—
– – 1 – – – INH
83
9
3D dd
4D
5D
6D ff
7D
9E6D ff
3
1
1
3
2
4
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
7.8 Opcode Map
See Table 7-2.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Central Processor Unit (CPU)
Data Sheet
99
MSB
0
1
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
Branch
REL
DIR
INH
2
3
4
Read-Modify-Write
INH
IX1
5
6
SP1
IX
9E6
7
Control
INH
INH
8
9
Register/Memory
IX2
SP2
IMM
DIR
EXT
A
B
C
D
9ED
4
SUB
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
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
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
1
2
3
4
6
7
8
9
MOTOROLA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Central Processor Unit (CPU)
5
A
B
C
D
E
F
3
BRA
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
2
4
1
NEG
NEGA
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
2
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
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
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
2
5
3
NEG
NEG
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
3
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
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
1
2
SUB
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
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
2
2
MSB
3
0
3
3
SUB
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
2
4
SUB
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
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
3
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
1
Central Processor Unit (CPU)
Data Sheet
100
Table 7-2. Opcode Map
Bit Manipulation
DIR
DIR
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 8. External Interrupt (IRQ)
8.1 Introduction
This section describes the external interrupt (IRQ) module, which supports external
interrupt functions.
8.2 Features
Features of the IRQ module include:
•
A dedicated external interrupt pin, IRQ
•
Hysteresis buffers
8.3 Functional Description
A logic 0 applied to any of the external interrupt pins can latch a CPU interrupt
request. Figure 8-1 shows the structure of the IRQ module.
ACK1
VDD
D
CLR
Q
CK
IRQ
SYNCHRONIZER
IRQ
INTERRUPT
REQUEST
HIGH
VOLTAGE
DETECT
TO MODE
SELECT
LOGIC
IRQ
LATCH
IMASK1
MODE1
Figure 8-1. IRQ Module Block Diagram
Addr.
$003F
Register Name
IRQ Status/Control Register
(ISCR)
See page 105.
Bit 7
6
5
4
Read:
0
0
0
0
Write:
R
R
R
R
0
0
0
Reset:
0
R
3
IRQF
0
2
0
ACK1
0
1
Bit 0
IMASK1
MODE1
0
0
= Reserved
Figure 8-2. IRQ I/O Register Summary
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
External Interrupt (IRQ)
Data Sheet
101
External Interrupt (IRQ)
Interrupt signals on the IRQ pin are latched into the IRQ1 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 latch that caused the vector fetch.
•
Software clear — Software can clear an interrupt latch by writing to the
appropriate acknowledge bit in the interrupt status and control register
(ISCR). Writing a logic 1 to the ACK1 bit clears the IRQ1 latch.
•
Reset — A reset automatically clears both interrupt latches.
The external interrupt pins are falling-edge-triggered and are software-configurable
to be both falling-edge and low-level-triggered. The MODE1 bit in the ISCR
controls the triggering sensitivity of the IRQ pin.
When the interrupt pin is edge-triggered only, the interrupt latch remains set until a
vector fetch, software clear, or reset occurs.
When the interrupt pin is both falling-edge and low-level-triggered, the interrupt
latch remains set until both of these occur:
•
Vector fetch, software clear, or reset
•
Return of the interrupt pin to logic 1
The vector fetch or software clear can occur before or after the interrupt pin returns
to logic 1. As long as the pin is low, the interrupt request remains pending.
When set, the IMASK1 bit in the ISCR masks all external interrupt requests. A
latched interrupt request is not presented to the interrupt priority logic unless the
IMASK bit is clear.
NOTE:
Data Sheet
102
The interrupt mask (I) in the condition code register (CCR) masks all interrupt
requests, including external interrupt requests. (See Figure 8-3.)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
External Interrupt (IRQ)
MOTOROLA
External Interrupt (IRQ)
Functional Description
FROM RESET
YES
I BIT SET?
NO
INTERRUPT?
YES
NO
STACK CPU REGISTERS
SET I BIT
LOAD PC WITH INTERRUPT VECTOR
FETCH NEXT
INSTRUCTION
SWI
INSTRUCTION?
YES
NO
RTI
INSTRUCTION?
YES
UNSTACK CPU REGISTERS
NO
EXECUTE INSTRUCTION
Figure 8-3. IRQ Interrupt Flowchart
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
External Interrupt (IRQ)
Data Sheet
103
External Interrupt (IRQ)
8.4 IRQ Pin
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 MODE1 bit is set, the IRQ pin is both falling-edge-sensitive and low-levelsensitive. With MODE1 set, both of these actions must occur to clear the IRQ1
latch:
•
Vector fetch, software clear, or reset — A vector fetch generates an interrupt
acknowledge signal to clear the latch. Software can generate the interrupt
acknowledge signal by writing a logic 1 to the ACK1 bit in the interrupt status
and control register (ISCR). The ACK1 bit is useful in applications that poll
the IRQ pin and require software to clear the IRQ1 latch. Writing to the ACK1
bit can also prevent spurious interrupts due to noise. Setting ACK1 does not
affect subsequent transitions on the IRQ pin. A falling edge that occurs after
writing to the ACK1 bit latches another interrupt request. If the IRQ1 mask
bit, IMASK1, is clear, the CPU loads the program counter with the vector
address at locations $FFFA and $FFFB.
•
Return of the IRQ pin to logic 1 — As long as the IRQ pin is at logic 0, the
IRQ1 latch remains set.
8.5 IRQ Pin
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 MODE1 bit is set, the IRQ pin is both falling-edge-sensitive and low-levelsensitive. With MODE1 set, both of these actions must occur to clear the IRQ1
latch:
•
Vector fetch, software clear, or reset — A vector fetch generates an interrupt
acknowledge signal to clear the latch. Software can generate the interrupt
acknowledge signal by writing a logic 1 to the ACK1 bit in the interrupt status
and control register (ISCR). The ACK1 bit is useful in applications that poll
the IRQ pin and require software to clear the IRQ1 latch. Writing to the ACK1
bit can also prevent spurious interrupts due to noise. Setting ACK1 does not
affect subsequent transitions on the IRQ pin. A falling edge that occurs after
writing to the ACK1 bit latches another interrupt request. If the IRQ1 mask
bit, IMASK1, is clear, the CPU loads the program counter with the vector
address at locations $FFFA and $FFFB.
•
Return of the IRQ pin to logic 1 — As long as the IRQ pin is at logic 0, the
IRQ1 latch remains set.
The vector fetch or software clear and the return of the IRQ pin to logic 1 can occur
in any order. The interrupt request remains pending as long as the IRQ pin is at
logic 0.
Data Sheet
104
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
External Interrupt (IRQ)
MOTOROLA
External Interrupt (IRQ)
IRQ Status and Control Register
If the MODE1 bit is clear, the IRQ pin is falling-edge-sensitive only. With MODE1
clear, a vector fetch or software clear immediately clears the IRQ1 latch.
Use the branch if IRQ pin high (BIH) or branch if IRQ pin low (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.
8.6 IRQ Status and Control Register
The IRQ status and control register (ISCR) has these functions:
•
Clears the IRQ interrupt latch
•
Masks IRQ interrupt requests
•
Controls triggering sensitivity of the IRQ interrupt pin
Address:
$003F
Bit 7
6
5
4
Read:
0
0
0
0
Write:
R
R
R
R
Reset:
0
0
0
0
R
= Reserved
3
IRQF
0
2
0
ACK1
0
1
Bit 0
IMASK1
MODE1
0
0
Figure 8-4. IRQ Status and Control Register (ISCR)
ACK1 — IRQ Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ latch. ACK1 always reads
as logic 0. Reset clears ACK1.
IMASK1 — IRQ Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ interrupt requests. Reset
clears IMASK1.
1 = IRQ interrupt requests disabled
0 = IRQ interrupt requests enabled
MODE1 — IRQ Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ pin. Reset clears
MODE1.
1 = IRQ interrupt requests on falling edges and low levels
0 = IRQ interrupt requests on falling edges only
IRQF — IRQ Flag
This read-only bit acts as a status flag, indicating an IRQ event occurred.
1 = External IRQ event occurred.
0 = External IRQ event did not occur.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
External Interrupt (IRQ)
Data Sheet
105
External Interrupt (IRQ)
Data Sheet
106
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
External Interrupt (IRQ)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 9. Low-Voltage Inhibit (LVI)
9.1 Introduction
This section describes the low-voltage inhibit (LVI) module, which monitors the
voltage on the VDD pin and can force a reset when the VDD voltage falls to the LVI
trip voltage.
9.2 Features
Features of the LVI module include:
•
Programmable LVI reset
•
Programmable power consumption
•
Digital filtering of VDD pin level
•
Selectable LVI trip voltage
9.3 Functional Description
Figure 9-1 shows the structure of the LVI module. The LVI is enabled out of reset.
The LVI module contains a bandgap reference circuit and comparator. The LVI
power bit, LVIPWR, enables the LVI to monitor VDD voltage. The LVI reset bit,
LVIRST, enables the LVI module to generate a reset when VDD falls below a
voltage, VLVRX, and remains at or below that level for nine or more consecutive
CGMXCLK. VLVRX and VLVHX are determined by the TRPSEL bit in the LVISCR
(see Figure 9-2). LVIPWR and LVIRST are in the configuration register (CONFIG).
See Section 5. Configuration Register (CONFIG).
Once an LVI reset occurs, the MCU remains in reset until VDD rises above a
voltage, VLVRX + VLVHX. VDD must be above VLVRX + VLVHX for only one CPU cycle
to bring the MCU out of reset. See 14.3.2.6 Low-Voltage Inhibit (LVI) Reset. The
output of the comparator controls the state of the LVIOUT flag in the LVI status
register (LVISCR).
An LVI reset also drives the RST pin low to provide low-voltage protection to
external peripheral devices. See 19.5 DC Electrical Characteristics.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Low-Voltage Inhibit (LVI)
Data Sheet
107
Low-Voltage Inhibit (LVI)
VDD
LVIPWR
FROM CONFIG
FROM CONFIG
CPU CLOCK
LOW VDD
DETECTOR
VDD > LVItrip = 0
LVIRST
VDD
DIGITAL FILTER
LVI RESET
VDD < LVItrip = 1
TRPSEL
ANLGTRIP
FROM LVISCR
LVIOUT
Figure 9-1. LVI Module Block Diagram
Addr.
$FE0F
Register Name
Bit 7
LVI Status and Control Register Read: LVIOUT
(LVISCR) Write:
R
See page 109. Reset:
0
R
6
0
R
0
5
TRPSEL
0
4
3
2
1
Bit 0
0
0
0
0
0
R
R
R
R
R
0
0
0
0
0
= Reserved
Figure 9-2. LVI I/O Register Summary
9.3.1 Polled LVI Operation
In applications that can operate at VDD levels below VLVRX, software can monitor
VDD by polling the LVIOUT bit. In the configuration register, the LVIPWR bit must
be 1 to enable the LVI module, and the LVIRST bit must be 0 to disable LVI resets.
See Section 5. Configuration Register (CONFIG). TRPSEL in the LVISCR
selects VLVRX.
9.3.2 Forced Reset Operation
In applications that require VDD to remain above VLVRX, enabling LVI resets allows
the LVI module to reset the MCU when VDD falls to the VLVRX level and remains at
or below that level for nine or more consecutive CPU cycles. In the CONFIG
register, the LVIPWR and LVIRST bits must be 1s to enable the LVI module and to
enable LVI resets. TRPSEL in the LVISCR selects VLVRX.
9.3.3 False Reset Protection
The VDD pin level is digitally filtered to reduce false resets due to power supply
noise. In order for the LVI module to reset the MCU, VDD must remain at or below
VLVRX for nine or more consecutive CPU cycles. VDD must be above VLVRX +
VLVHX for only one CPU cycle to bring the MCU out of reset. TRPSEL in the
LVISCR selects VLVRX + VLVHX.
Data Sheet
108
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Low-Voltage Inhibit (LVI)
MOTOROLA
Low-Voltage Inhibit (LVI)
LVI Status and Control Register
9.3.4 LVI Trip Selection
The TRPSEL bit allows the user to chose between 5 percent and 10 percent
tolerance when monitoring the supply voltage. The 10 percent option is enabled
out of reset. Writing a 1 to TRPSEL will enable 5 percent option.
NOTE:
The microcontroller is guaranteed to operate at a minimum supply voltage. The trip
point (VLVR1 or VLVR2) may be lower than this. See 19.5 DC Electrical
Characteristics.
9.4 LVI Status and Control Register
The LVI status register (LVISCR) flags VDD voltages below the VLVRX level.
Address:
$FE0F
Bit 7
6
5
Read:
LVIOUT
0
Write:
R
R
Reset:
0
0
R
= Reserved
TRPSEL
0
4
3
2
1
Bit 0
0
0
0
0
0
R
R
R
R
R
0
0
0
0
0
Figure 9-3. LVI Status and Control Register (LVISCR)
LVIOUT — LVI Output Bit
This read-only flag becomes set when the VDD voltage falls below the VLVRX
voltage for 32 to 40 CGMXCLK cycles. See Table 9-1. Reset clears the LVIOUT
bit.
Table 9-1. LVIOUT Bit Indication
VDD
LVIOUT
At Level:
For Number of CGMXCLK Cycles:
VDD > VLVRX + VLVHX
Any
0
VDD < VLVRX
< 32 CGMXCLK cycles
0
VDD < VLVRX
Between 32 & 40 CGMXCLK cycles
0 or 1
VDD < VLVRX
> 40 CGMXCLK cycles
1
VLVRX < VDD < VLVRX + VLVHX
Any
Previous value
TRPSEL — LVI Trip Select Bit
This bit selects the LVI trip point. Reset clears this bit.
1 = 5 percent tolerance. The trip point and recovery point are determined by
VLVR1 and VLVH1, respectively.
0 = 10 percent tolerance. The trip point and recovery point are determined by
VLVR2 and VLVH2, respectively.
NOTE:
If LVIRST and LVIPWR are 0s, note that when changing the tolerance, LVI reset
will be generated if the supply voltage is below the trip point.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Low-Voltage Inhibit (LVI)
Data Sheet
109
Low-Voltage Inhibit (LVI)
9.5 LVI Interrupts
The LVI module does not generate interrupt requests.
9.6 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
With the LVIPWR bit in the configuration register programmed to 1, the LVI module
is active after a WAIT instruction.
With the LVIRST bit in the configuration register programmed to 1, the LVI module
can generate a reset and bring the MCU out of wait mode.
9.7 Stop Mode
If enabled, the LVI module remains active in stop mode. If enabled to generate
resets, the LVI module can generate a reset and bring the MCU out of stop mode.
Data Sheet
110
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Low-Voltage Inhibit (LVI)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 10. Input/Output (I/O) Ports (PORTS)
10.1 Introduction
Thirty-seven bidirectional input-output (I/O) pins and seven input pins form six
parallel ports. All I/O pins are programmable as inputs or outputs.
When using the 56-pin package version:
NOTE:
•
Set the data direction register bits in DDRC such that bit 1 is written to a
logic 1 (along with any other output bits on port C).
•
Set the data direction register bits in DDRE such that bits 0, 1, and 2 are
written to a logic 1 (along with any other output bits on port E).
•
Set the data direction register bits in DDRF such that bits 0, 1, 2, and 3 are
written to a logic 1 (along with any other output bits on port F).
Connect any unused I/O pins to an appropriate logic level, either VDD or VSS.
Although PWM6–PWM1 do not require termination for proper operation,
termination reduces excess current consumption and the possibility of electrostatic
damage.
Addr.
Register Name
$0000
Port A Data Register
(PTA)
See page 113.
$0001
$0002
$0003
Port B Data Register
(PTB)
See page 115.
Port C Data Register
(PTC)
See page 117.
Port D Data Register
(PTD)
See page 119.
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
PTB2
PTB1
PTB0
PTC2
PTC1
PTC0
Read:
Write:
Reset:
Unaffected by reset
Read:
PTB7
PTB6
PTB5
PTB4
PTB3
Write:
Reset:
Unaffected by reset
Read:
0
Write:
R
PTC6
PTC5
Reset:
PTC4
PTC3
Unaffected by reset
Read:
0
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Write:
R
R
R
R
R
R
R
R
Reset:
Unaffected by reset
R
= Reserved
Figure 10-1. I/O Port Register Summary
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
111
Input/Output (I/O) Ports (PORTS)
Addr.
Register Name
$0004
Data Direction Register A
(DDRA)
See page 113.
$0005
$0006
Data Direction Register B
(DDRB)
See page 115.
Data Direction Register C
(DDRC)
See page 117.
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
DDRB7
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
Reset:
0
0
0
0
0
0
0
0
Read:
0
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
Write:
R
Reset:
0
0
0
0
0
0
0
0
PTE2
PTE1
PTE0
PTF2
PTF1
PTF0
Read:
Write:
Reset:
Read:
Write:
$0007
$0008
$0009
Unimplemented
Port E Data Register
(PTE)
See page 120.
Port F Data Register
(PTF)
See page 122.
$000A
Unimplemented
$000B
Unimplemented
$000C
Data Direction Register E
(DDRE)
See page 120.
$000D
Data Direction Register F
(DDRF)
See page 122.
Read:
PTE7
PTE6
PTE5
PTE4
PTE3
Write:
Reset:
Unaffected by reset
Read:
0
0
Write:
R
R
PTF5
Reset:
PTF4
PTF3
Unaffected by reset
Read:
DDRE7
DDRE6
DDRE5
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
Reset:
0
0
0
0
0
0
0
0
Read:
0
0
DDRF5
DDRF4
DDRF3
DDRF2
DDRF1
DDRF0
Write:
R
R
0
0
0
0
0
0
Write:
Reset:
R
= Reserved
Figure 10-1. I/O Port Register Summary (Continued)
Data Sheet
112
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port A
10.2 Port A
Port A is an 8-bit, general-purpose, bidirectional I/O port.
10.2.1 Port A Data Register
The port A data register (PTA) 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
Reset:
Unaffected by reset
Figure 10-2. 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.
10.2.2 Data Direction Register A
Data direction register A (DDRA) 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
Figure 10-3. 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.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
113
Input/Output (I/O) Ports (PORTS)
Figure 10-4 shows the port A I/O logic.
READ DDRA ($0004)
INTERNAL DATA BUS
WRITE DDRA ($0004)
DDRAx
RESET
WRITE PTA ($0000)
PTAx
PTAx
READ PTA ($0000)
Figure 10-4. Port A I/O Circuit
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 10-1 summarizes the operation of the port A pins.
Table 10-1. 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]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Data Sheet
114
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port B
10.3 Port B
Port B is an 8-bit, general-purpose, bidirectional I/O port that shares its pins with
the analog-to-digital convertor (ADC) module.
10.3.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the eight port B
pins.
Address:
Read:
Write:
$0001
Bit 7
6
5
4
3
2
1
Bit 0
PTB7
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
Figure 10-5. Port B Data Register (PTB)
PTB[7:0] — Port B Data Bits
These read/write bits are software-programmable. Data direction of each port B
pin is under the control of the corresponding bit in data direction register B.
Reset has no effect on port B data.
10.3.2 Data Direction Register B
Data direction register B (DDRB) determines whether each port B pin is an input or
an output. Writing a logic 1 to a DDRB bit enables the output buffer for the
corresponding port B pin; a logic 0 disables the output buffer.
Address:
Read:
Write:
Reset:
$0005
Bit 7
6
5
4
3
2
1
Bit 0
DDRB7
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
0
0
0
0
0
0
0
0
Figure 10-6. Data Direction Register B (DDRB)
DDRB[7:0] — Data Direction Register B Bits
These read/write bits control port B data direction. Reset clears DDRB[7:0],
configuring all port B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
NOTE:
Avoid glitches on port B pins by writing to the port B data register before changing
data direction register B bits from 0 to 1.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
115
Input/Output (I/O) Ports (PORTS)
Figure 10-7 shows the port B I/O logic.
READ DDRB ($0005)
INTERNAL DATA BUS
WRITE DDRB ($0005)
DDRBx
RESET
WRITE PTB ($0001)
PTBx
PTBx
READ PTB ($0001)
Figure 10-7. Port B I/O Circuit
When bit DDRBx is a logic 1, reading address $0001 reads the PTBx data latch.
When bit DDRBx is a logic 0, reading address $0001 reads the voltage level on the
pin. The data latch can always be written, regardless of the state of its data
direction bit. Table 10-2 summarizes the operation of the port B pins.
Table 10-2. Port B Pin Functions
DDRB
Bit
PTB Bit
Accesses
to DDRB
I/O Pin Mode
Accesses to PTB
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRB[7:0]
Pin
PTB[7:0](3)
1
X
Output
DDRB[7:0]
PTB[7:0]
PTB[7:0]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Data Sheet
116
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port C
10.4 Port C
Port C is a 7-bit, general-purpose, bidirectional I/O port that shares two of its pins
with the analog-to-digital convertor module (ADC).
10.4.1 Port C Data Register
The port C data register (PTC) contains a data latch for each of the seven port C
pins.
Address:
$0002
Bit 7
Read:
0
Write:
R
6
5
4
3
2
1
Bit 0
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Reset:
Unaffected by reset
R
= Reserved
Figure 10-8. Port C Data Register (PTC)
PTC[6:0] — 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.
10.4.2 Data Direction Register C
Data direction register C (DDRC) 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:
$0006
Bit 7
6
5
4
3
2
1
Bit 0
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
0
0
0
0
0
0
Read:
0
Write:
R
Reset:
0
0
R
= Reserved
Figure 10-9. Data Direction Register C (DDRC)
DDRC[6:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC[6:0],
configuring all port C pins as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
117
Input/Output (I/O) Ports (PORTS)
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 10-10 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 10-10. Port C I/O Circuit
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 10-3 summarizes the operation of the port C pins.
Table 10-3. 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[6:0]
Pin
PTC[6:0](3)
1
X
Output
DDRC[6:0]
PTC[6:0]
PTC[6:0]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Data Sheet
118
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port D
10.5 Port D
Port D is a 7-bit, input-only port that shares its pins with the pulse width modulator
for motor control module (PMC).
The port D data register (PTD) contains a data latch for each of the seven port pins.
Address:
$0003
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Write:
R
R
R
R
R
R
R
R
Reset:
Unaffected by reset
R
= Reserved
Figure 10-11. Port D Data Register (PTD)
PTD[6:0] — Port D Data Bits
These read/write bits are software programmable. Reset has no effect on port D
data.
INTERNAL DATA BUS
Figure 10-12 shows the port D input logic.
READ PTD ($0003)
PTDx
Figure 10-12. Port D Input Circuit
Reading address $0003 reads the voltage level on the pin. Table 10-4 summarizes
the operation of the port D pins.
Table 10-4. Port D Pin Functions
PTD Bit
(1)
X
Pin Mode
(2)
Input, Hi-Z
Accesses to PTD
Read
Write
Pin
PTD[6:0](3)
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
119
Input/Output (I/O) Ports (PORTS)
10.6 Port E
Port E is an 8-bit, special function port that shares five of its pins with the timer
interface module (TIM) and two of its pins with the serial communications interface
module (SCI).
10.6.1 Port E Data Register
The port E data register (PTE) contains a data latch for each of the eight port E
pins.
Address:
Read:
Write:
$0008
Bit 7
6
5
4
3
2
1
Bit 0
PTE7
PTE6
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
Reset:
Unaffected by reset
Figure 10-13. Port E Data Register (PTE)
PTE[7:0] — Port E Data Bits
PTE[7:0] 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.
NOTE:
Data direction register E (DDRE) does not affect the data direction of port E pins
that are being used by the TIMA or TIMB. However, the DDRE bits always
determine whether reading port E returns the states of the latches or the states of
the pins.
10.6.2 Data Direction Register E
Data direction register E (DDRE) 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:
Write:
Reset:
$000C
Bit 7
6
5
4
3
2
1
Bit 0
DDRE7
DDRE6
DDRE5
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
0
0
0
0
0
0
0
0
Figure 10-14. Data Direction Register E (DDRE)
DDRE[7:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears DDRE[7:0],
configuring all port E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
Data Sheet
120
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port E
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 10-15 shows the port E I/O logic.
READ DDRE ($000C)
INTERNAL DATA BUS
WRITE DDRE ($000C)
RESET
DDREx
WRITE PTE ($0008)
PTEx
PTEx
READ PTE ($0008)
Figure 10-15. 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 10-5 summarizes the operation of the port E pins.
Table 10-5. 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[7:0]
Pin
PTE[7:0](3)
1
X
Output
DDRE[7:0]
PTE[7:0]
PTE[7:0]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
121
Input/Output (I/O) Ports (PORTS)
10.7 Port F
Port F is a 6-bit, special function port that shares four of its pins with the serial
peripheral interface module (SPI) and two pins with the serial communications
interface (SCI).
10.7.1 Port F Data Register
The port F data register (PTF) contains a data latch for each of the six port F pins.
Address:
$0009
Bit 7
6
Read:
0
0
Write:
R
R
R
= Reserved
5
4
3
2
1
Bit 0
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
Reset:
Unaffected by reset
Figure 10-16. Port F Data Register (PTF)
PTF[5:0] — Port F Data Bits
These read/write bits are software programmable. Data direction of each port F
pin is under the control of the corresponding bit in data direction register F.
Reset has no effect on PTF[5:0].
NOTE:
Data direction register F (DDRF) does not affect the data direction of port F pins
that are being used by the SPI or SCI module. However, the DDRF bits always
determine whether reading port F returns the states of the latches or the states of
the pins.
10.7.2 Data Direction Register F
Data direction register F (DDRF) determines whether each port F pin is an input or
an output. Writing a logic 1 to a DDRF bit enables the output buffer for the
corresponding port F pin; a logic 0 disables the output buffer.
Address:
$000D
Bit 7
6
Read:
0
0
Write:
R
R
Read:
R
5
4
3
2
1
Bit 0
DDRF5
DDRF4
DDRF3
DDRF2
DDRF1
DDRF0
0
0
0
0
0
0
= Reserved
Figure 10-17. Data Direction Register F (DDRF)
DDRF[5:0] — Data Direction Register F Bits
These read/write bits control port F data direction. Reset clears DDRF[5:0],
configuring all port F pins as inputs.
1 = Corresponding port F pin configured as output
0 = Corresponding port F pin configured as input
Data Sheet
122
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Port F
NOTE:
Avoid glitches on port F pins by writing to the port F data register before changing
data direction register F bits from 0 to 1.
Figure 10-18 shows the port F I/O logic.
READ DDRF ($000D)
INTERNAL DATA BUS
WRITE DDRF ($000D)
RESET
DDRFx
WRITE PTF ($0009)
PTFx
PTFx
READ PTF ($0009)
Figure 10-18. Port F I/O Circuit
When bit DDRFx is a logic 1, reading address $0009 reads the PTFx data latch.
When bit DDRFx is a logic 0, reading address $0009 reads the voltage level on the
pin. The data latch can always be written, regardless of the state of its data
direction bit. Table 10-6 summarizes the operation of the port F pins.
Table 10-6. Port F Pin Functions
DDRF
Bit
PTF
Bit
I/O Pin Mode
Accesses
to DDRF
Accesses to PTF
Read/Write
Read
Write
0
X(1)
Input, Hi-Z(2)
DDRF[6:0]
Pin
PTF[6:0](3)
1
X
Output
DDRF[6:0]
PTF[6:0]
PTF[6:0]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Input/Output (I/O) Ports (PORTS)
Data Sheet
123
Input/Output (I/O) Ports (PORTS)
Data Sheet
124
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Input/Output (I/O) Ports (PORTS)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 11. Power-On Reset (POR)
11.1 Introduction
This section describes the power-on reset (POR) module.
11.2 Functional Description
The POR module provides a known, stable signal to the microcontroller unit (MCU)
at power-on. This signal tracks VDD until the MCU generates a feedback signal to
indicate that it is properly initialized. At this time, the POR drives its output low.
The POR is not a brown-out detector, low-voltage detector, or glitch detector. VDD
at the POR must go completely to 0 to reset the microcontroller unit (MCU). To
detect power-loss conditions, use a low-voltage inhibit module (LVI) or other
suitable circuit.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Power-On Reset (POR)
Data Sheet
125
Power-On Reset (POR)
Data Sheet
126
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Power-On Reset (POR)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 12. Pulse-Width Modulator for Motor Control (PWMMC)
12.1 Introduction
This section describes the pulse-width modulator for motor control (PWMMC,
version A). The PWM module can generate three complementary PWM pairs or six
independent PWM signals. These PWM signals can be center-aligned or
edge-aligned. A block diagram of the PWM module is shown in Figure 12-2.
A12-bit timer PWM counter is common to all six channels. PWM resolution is one
clock period for edge-aligned operation and two clock periods for center-aligned
operation. The clock period is dependent on the internal operating frequency (fOP)
and a programmable prescaler. The highest resolution for edge-aligned operation
is 125 ns (fOP = 8 MHz). The highest resolution for center-aligned operation is
250 ns (fOP = 8 MHz).
When generating complementary PWM signals, the module features automatic
dead-time insertion to the PWM output pairs and transparent toggling of PWM data
based upon sensed motor phase current polarity.
A summary of the PWM registers is shown in Figure 12-3.
12.2 Features
Features of the PWMMC include:
•
Three complementary PWM pairs or six independent PWM signals
•
Edge-aligned PWM signals or center-aligned PWM signals
•
PWM signal polarity control
•
20-mA current sink capability on PWM pins
•
Manual PWM output control through software
•
Programmable fault protection
•
Complementary mode featuring:
– Dead-time insertion
– Separate top/bottom pulse width correction via current sensing or
programmable software bits
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
127
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
CLOCK GENERATOR
MODULE
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
OSC1
OSC2
CGMXFC
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
USER FLASH VECTOR SPACE — 46 BYTES
TIMER INTERFACE
MODULE B
DDRF
MONITOR ROM — 240 BYTES
MOTOROLA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
USER RAM — 768 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 12-1. Block Diagram Highlighting PWMMC Block and Pins
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
128
INTERNAL BUS
M68HC08 CPU
Pulse-Width Modulator for Motor Control (PWMMC)
Features
8
CPU BUS
PWM1 PIN
PWM CHANNELS 3 AND 4
FAULT PROTECTION
PWM2 PIN
OUTPUT CONTROL
CONTROL LOGIC BLOCK
PWM CHANNELS 1 AND 2
PWM3 PIN
PWM4 PIN
PWM5 PIN
PWM CHANNELS 5 AND 6
PWM6 PIN
4
12
FAULT
INTERRUPT
PINS
TIMEBASE
3
COIL CURRENT
POLARITY PINS
Figure 12-2. PWM Module Block Diagram
Addr.
Register Name
$0020
PWM Control Register 1
(PCTL1)
See page 158.
$0021
$0022
$0023
PWM Control Register 2
(PCTL2)
See page 160.
Fault Control Register
(FCR)
See page 162.
Fault Status Register
(FSR)
See page 164.
Bit 7
6
5
4
3
2
1
Bit 0
DISX
DISY
PWMINT
PWMF
ISENS1
ISENS0
LDOK
PWMEN
0
0
0
0
0
0
0
0
LDFQ1
LDFQ0
IPOL1
IPOL2
IPOL3
PRSC1
PRSC0
0
0
0
0
0
0
0
0
FINT4
FMODE4
FINT3
FMODE3
FINT2
FMODE2
FINT1
FMODE1
Reset:
0
0
0
0
0
0
0
0
Read:
FPIN4
FFLAG4
FPIN3
FFLAG3
FPIN2
FFLAG2
FPIN1
FFLAG1
U
0
U
0
U
0
U
0
Bold
= Buffered
Read:
Write:
Reset:
Read:
0
Write:
Reset:
Read:
Write:
Write:
Reset:
R
= Reserved
X = Indeterminate
Figure 12-3. Register Summary (Sheet 1 of 3)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
129
Pulse-Width Modulator for Motor Control (PWMMC)
Addr.
Register Name
Fault Acknowledge Register
(FTACK)
See page 165.
$0024
PWM Output Control
Register (PWMOUT)
See page 166.
$0025
PWM Counter Register High
(PCNTH)
See page 156.
$0026
PWM Counter Register Low
(PCNTL)
See page 156.
$0027
$0028
$0029
PWM Counter Modulo Register
High (PMODH)
See page 156.
PWM Counter Modulo Register
Low (PMODL)
See page 156.
$002A
$002B
$002C
$002D
PWM 1 Value Register High
(PVAL1H)
See page 157.
PWM 1 Value Register Low
(PVAL1L)
See page 157.
PWM 2 Value Register High
(PVAL2H)
See page 157.
PWM 2 Value Register Low
(PVAL2L)
See page 157.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
DT6
DT5
DT4
DT3
DT2
DT1
FTACK4
Write:
Reset:
0
Read:
0
FTACK3
FTACK2
FTACK1
0
0
0
0
0
0
0
OUTCTL
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
Write:
Reset:
0
0
0
0
0
0
0
0
Read:
0
0
0
0
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
0
0
0
0
0
0
0
0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset:
0
0
0
0
0
0
0
0
Read:
0
0
0
0
Bit 11
Bit 10
Bit 9
Bit 8
Write:
Write:
Write:
Reset:
0
0
0
0
X
X
X
X
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
X
X
X
X
X
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bold
= Buffered
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
R
= Reserved
X = Indeterminate
Figure 12-3. Register Summary (Sheet 2 of 3)
Data Sheet
130
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Features
Addr.
$002E
$002F
$0030
$0031
$0032
$0033
$0034
$0035
$0036
$0037
Register Name
PWM 3 Value Register High
(PVAL3H)
See page 157.
PWM 3 Value Register Low
(PVAL3L)
See page 157.
PWM 4 Value Register High
(PVAL4H)
See page 157.
PWM 4 Value Register Low
(PVAL4L)
See page 157.
PWM 5 Value Register High
(PVAL5H)
See page 157.
PWM 5 Value Register Low
(PVAL5L)
See page 157.
PWM 6 Value Register High
(PVAL6H)
See page 157.
PWM 6 Value Register Low
(PMVAL6L)
See page 157.
Dead-Time Write-Once
Register (DEADTM)
See page 162.
PWM Disable Mapping
Write-Once Register
(DISMAP) See page 162.
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Bold
= Buffered
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
R
= Reserved
X = Indeterminate
Figure 12-3. Register Summary (Sheet 3 of 3)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
131
Pulse-Width Modulator for Motor Control (PWMMC)
12.3 Timebase
This section provides a discussion of the timebase.
12.3.1 Resolution
In center-aligned mode, a 12-bit up/down counter is used to create the PWM
period. Therefore, the PWM resolution in center-aligned mode is two clocks
(highest resolution is 250 ns @ fOP = 8 MHz) as shown in Figure 12-4. The
up/down counter uses the value in the timer modulus register to determine its
maximum count. The PWM period will equal:
[(timer modulus) x (PWM clock period) x 2].
UP/DOWN COUNTER
MODULUS = 4
PERIOD = 8 X (PWM CLOCK PERIOD)
PWM = 0
PWM = 1
PWM = 2
PWM = 3
PWM = 4
Figure 12-4. Center-Aligned PWM (Positive Polarity)
Data Sheet
132
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Timebase
For edge-aligned mode, a 12-bit up-only counter is used to create the PWM period.
Therefore, the PWM resolution in edge-aligned mode is one clock (highest
resolution is125 ns @ fOP = 8 MHz) as shown in Figure 12-5. Again, the timer
modulus register is used to determine the maximum count. The PWM period will
equal:
(timer modulus) x (PWM clock period)
Center-aligned operation versus edge-aligned operation is determined by the
option EDGE. See 5.2 Functional Description.
UP-ONLY COUNTER
MODULUS = 4
PERIOD = 4 X (PWM
CLOCK PERIOD)
PWM = 0
PWM = 1
PWM = 2
PWM = 3
PWM = 4
Figure 12-5. Edge-Aligned PWM (Positive Polarity)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
133
Pulse-Width Modulator for Motor Control (PWMMC)
12.3.2 Prescaler
To permit lower PWM frequencies, a prescaler is provided which will divide the
PWM clock frequency by 1, 2, 4, or 8. Table 12-1 shows how setting the prescaler
bits in PWM control register 2 affects the PWM clock frequency. This prescaler is
buffered and will not be used by the PWM generator until the LDOK bit is set and
a new PWM reload cycle begins.
Table 12-1. PWM Prescaler
Prescaler Bits
PRSC1 and PRSC0
PWM Clock Frequency
00
fOP
01
fOP/2
10
fOP/4
11
fOP/8
12.4 PWM Generators
Pulse-width modulator (PWM) generators are discussed in this subsection.
12.4.1 Load Operation
To help avoid erroneous pulse widths and PWM periods, the modulus, prescaler,
and PWM value registers are buffered. New PWM values, counter modulus values,
and prescalers can be loaded from their buffers into the PWM module every one,
two, four, or eight PWM cycles. LDFQ1 and LDFQ0 in PWM control register 2 are
used to control this reload frequency, as shown in Table 12-2. When a reload cycle
arrives, regardless of whether an actual reload occurs (as determined by the LDOK
bit), the PWM reload flag bit in PWM control register 1 will be set. If the PWMINT
bit in PWM control register 1 is set, a CPU interrupt request will be generated when
PWMF is set. Software can use this interrupt to calculate new PWM parameters in
real time for the PWM module.
Table 12-2. PWM Reload Frequency
Data Sheet
134
Reload Frequency Bits
LDFQ1 and LDFQ0
PWM Reload Frequency
00
Every PWM cycle
01
Every 2 PWM cycles
10
Every 4 PWM cycles
11
Every 8 PWM cycles
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
PWM Generators
For ease of software, the LDFQx bits are buffered. When the LDFQx bits are
changed, the reload frequency will not change until the previous reload cycle is
completed. See Figure 12-6.
NOTE:
When reading the LDFQx bits, the value is the buffered value (for example, not
necessarily the value being acted upon).
RELOAD
RELOAD
RELOAD
RELOAD RELOADRELOADRELOAD
CHANGE RELOAD
FREQUENCY TO
EVERY 4 CYCLES
CHANGE RELOAD
FREQUENCY TO
EVERY CYCLE
Figure 12-6. Reload Frequency Change
PWMINT enables CPU interrupt requests as shown in Figure 12-7. When this bit
is set, CPU interrupt requests are generated when the PWMF bit is set. When the
PWMINT bit is clear, PWM interrupt requests are inhibited. PWM reloads will still
occur at the reload rate, but no interrupt requests will be generated.
READ PWMF AS 1,
WRITE PWMF AS 0
OR
RESET
VDD
RESET
PWMF
CPU INTERRUPT
REQUEST
D
LATCH
PWM RELOAD
CK
PWMINT
Figure 12-7. PWM Interrupt Requests
To prevent a partial reload of PWM parameters from occurring while the software
is still calculating them, an interlock bit controlled from software is provided. This
bit informs the PWM module that all the PWM parameters have been calculated,
and it is “okay” to use them. A new modulus, prescaler, and/or PWM value cannot
be loaded into the PWM module until the LDOK bit in PWM control register 1 is set.
When the LDOK bit is set, these new values are loaded into a second set of
registers and used by the PWM generator at the beginning of the next PWM reload
cycle as shown in Figure 12-8, Figure 12-9, Figure 12-10, and Figure 12-11. After
these values are loaded, the LDOK bit is cleared.
NOTE:
When the PWM module is enabled (via the PWMEN bit), a load will occur if the
LDOK bit is set. Even if it is not set, an interrupt will occur if the PWMINT bit is set.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
135
Pulse-Width Modulator for Motor Control (PWMMC)
To prevent this, the software should clear the PWMINT bit before enabling the
PWM module.
LDFQ1:LDFQ0 = 00 (RELOAD EVERY CYCLE)
UP/DOWN
COUNTER
LDOK = 1
MODULUS = 3
PWM VALUE = 1
PWMF SET
LDOK = 0
MODULUS = 3
PWM VALUE = 2
PWMF SET
LDOK = 1
MODULUS = 3
PWM VALUE = 2
PWMF SET
LDOK = 0
MODULUS = 3
PWM VALUE = 1
PWMF SET
PWM
Figure 12-8. Center-Aligned PWM Value Loading
LDFQ1:LDFQ0 = 00 (RELOAD EVERY CYCLE)
UP/DOWN
COUNTER
LDOK = 1
MODULUS = 2
PWM VALUE = 1
PWMF SET
LDOK = 1
MODULUS = 3
PWM VALUE = 1
PWMF SET
LDOK = 1
LDOK = 1
LDOK = 0
MODULUS = 2 MODULUS = 1 MODULUS = 2
PWMVALUE = 1 PWM VALUE = 1 PWM VALUE = 1
PWMF SET
PWMF SET
PWMF SET
PWM
Figure 12-9. Center-Aligned Loading of Modulus
LDFQ1:LDFQ0 = 00 (RELOAD EVERY CYCLE)
UP-ONLY
COUNTER
LDOK = 1
LDOK = 0
LDOK = 1
LDOK = 0
LDOK = 0
MODULUS = 3 MODULUS = 3
MODULUS = 3
MODULUS = 3 MODULUS = 3
PWM VALUE = 1 PWM VALUE = 2 PWM VALUE = 2 PWM VALUE = 1 PWM VALUE = 1
PWMF SET
PWMF SET
PWMF SET
PWMF SET
PWMF SET
PWM
Figure 12-10. Edge-Aligned PWM Value Loading
Data Sheet
136
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
PWM Generators
LDFQ1:LDFQ0 = 00 (RELOAD EVERY CYCLE)
UP-ONLY
COUNTER
LDOK = 1
MODULUS = 3
PWM VALUE = 2
PWMF SET
LDOK = 1
MODULUS = 4
PWM VALUE = 2
PWMF SET
LDOK = 1
MODULUS = 2
PWM VALUE = 2
PWMF SET
LDOK = 0
MODULUS = 1
PWM VALUE = 2
PWMF SET
PWM
Figure 12-11. Edge-Aligned Modulus Loading
12.4.2 PWM Data Overflow and Underflow Conditions
The PWM value registers are 16-bit registers. Although the counter is only 12 bits,
the user may write a 16-bit signed value to a PWM value register. As shown in
Figure 12-4 and Figure 12-5, if the PWM value is less than or equal to zero, the
PWM will be inactive for the entire period. Conversely, if the PWM value is greater
than or equal to the timer modulus, the PWM will be active for the entire period.
Refer to Table 12-3.
NOTE:
The terms “active” and “inactive” refer to the asserted and negated states of the
PWM signals and should not be confused with the high-impedance state of the
PWM pins.
Table 12-3. PWM Data Overflow and Underflow Conditions
PWMVALxH:PWMVALxL
Condition
PWM Value Used
$0000–$0FFF
Normal
Per register contents
$1000–$7FFF
Overflow
$FFF
$8000–$FFFF
Underflow
$000
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
137
Pulse-Width Modulator for Motor Control (PWMMC)
12.5 Output Control
This subsection discusses output control.
12.5.1 Selecting Six Independent PWMs or Three Complementary PWM Pairs
The PWM outputs can be configured as six independent PWM channels or three
complementary channel pairs. The option INDEP determines which mode is used
(see 5.2 Functional Description). If complementary operation is chosen, the
PWM pins are paired as shown in Figure 12-12. Operation of one pair is then
determined by one PWM value register. This type of operation is meant for use in
motor drive circuits such as the one in Figure 12-13.
When complementary operation is used, two additional features are provided:
•
Dead-time insertion
•
Separate top/bottom pulse width correction to correct for distortions caused
by the motor drive characteristics
If independent operation is chosen, each PWM has its own PWM value register.
PWM1 PIN
PWM VALUE REGISTER
PWMS 1 AND 2
PWM VALUE REGISTER
OUTPUT CONTROL
POLARITY & DEAD-TIME INSERTION
PWM2 PIN
PWMS 3 AND 4
PWM3 PIN
PWM4 PIN
PWM5 PIN
PWM VALUE REGISTER
PWMS 5 AND 6
PWM6 PIN
Figure 12-12. Complementary Pairing
Data Sheet
138
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Output Control
PWM
1
PWM
3
PWM
5
TO
AC
MOTOR
INPUTS
PWM
2
PWM
4
PWM
6
Figure 12-13. Typical AC Motor Drive
12.5.2 Dead-Time Insertion
As shown in Figure 12-13, in complementary mode, each PWM pair can be used
to drive top-side/bottom-side transistors.
When controlling dc-to-ac inverters such as this, the top and bottom PWMs in one
pair should never be active at the same time. In Figure 12-13, if PWM1 and PWM2
were on at the same time, large currents would flow through the two transistors as
they discharge the bus capacitor. The IGBTs could be weakened or destroyed.
Simply forcing the two PWMs to be inversions of each other is not always sufficient.
Since a time delay is associated with turning off the transistors in the motor drive,
there must be a dead-time between the deactivation of one PWM and the activation
of the other.
A dead-time can be specified in the dead-time write-once register. This 8-bit value
specifies the number of CPU clock cycles to use for the dead-time. The dead-time
is not affected by changes in the PWM period caused by the prescaler.
Dead-time insertion is achieved by feeding the top PWM outputs of the PWM
generator into dead-time generators, as shown in Figure 12-14. Current sensing
determines which PWM value of a PWM generator pair to use for the top PWM in
the next PWM cycle. See 12.5.3 Top/Bottom Correction with Motor Phase
Current Polarity Sensing. When output control is enabled, the odd OUT bits,
rather than the PWM generator outputs, are fed into the dead-time generators. See
12.5.5 PWM Output Port Control.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
139
Pulse-Width Modulator for Motor Control (PWMMC)
PREDT (TOP)
OUTX
SELECT
DEAD-TIME
POSTDT (TOP)
MUX
PWMPAIR56
(TOP)
PWM (TOP)
PREDT (TOP)
OUTX
SELECT
PWM1
BOTTOM
(PWM2)
PWM2
TOP
(PWM3)
BOTTOM
(PWM4)
POLARITY/OUTPUT DRIVE
PWM (TOP)
TOP
(PWM1)
FAULT
DEAD-TIME
POSTDT (TOP)
MUX
PWMPAIR34
(TOP)
TOP/BOTTOM
GENERATION
DEAD-TIME
6
CURRENT SENSING
PWMGEN<1:6>
PWM GENERATOR
PREDT (TOP)
OUTX
SELECT
DEAD-TIME
POSTDT (TOP)
DEAD-TIME
PWM (TOP)
DEAD-TIME
MUX
PWMPAIR12
(TOP)
TOP/BOTTOM
GENERATION
OUT2
OUT4
OUT6
TOP/BOTTOM
GENERATION
OUTCTL
OUT5
OUT3
OUT1
OUTPUT CONTROL
(OUTCTL)
PWM3
PWM4
TOP
(PWM5)
PWM5
BOTTOM
(PWM6)
PWM6
Figure 12-14. Dead-Time Generators
Whenever an input to a dead-time generator transitions, a dead-time is inserted
(for example, both PWMs in the pair are forced to their inactive state). The bottom
PWM signal is generated from the top PWM and the dead-time. In the case of
output control enabled, the odd OUTx bits control the top PWMs, the even OUTx
bits control the bottom PWMs with respect to the odd OUTx bits (see Table 12-6).
Figure 12-15 shows the effects of the dead-time insertion.
As seen in Figure 12-15, some pulse width distortion occurs when the dead-time
is inserted. The active pulse widths are reduced. For example, in Figure 12-15,
when the PWM value register is equal to two, the ideal waveform (with no
dead-time) has pulse widths equal to four. However, the actual pulse widths shrink
to two after a dead-time of two was inserted. In this example, with the prescaler set
to divide by one and center-aligned operation selected, this distortion can be
compensated for by adding or subtracting half the dead-time value to or from the
PWM register value. This correction is further described in 12.5.3 Top/Bottom
Correction with Motor Phase Current Polarity Sensing.
Further examples of dead-time insertion are shown in Figure 12-16 and Figure
12-17. Figure 12-16 shows the effects of dead-time insertion at the duty cycle
Data Sheet
140
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Output Control
boundaries (near 0 percent and 100 percent duty cycles). Figure 12-17 shows the
effects of dead-time insertion on pulse widths smaller than the dead-time.
UP/DOWN COUNTER
MODULUS = 4
PWM VALUE = 2
PWM VALUE = 2
PWM VALUE = 3
PWM1 W/
NO DEAD-TIME
PWM2 W/
NO DEAD-TIME
PWM1 W/
DEAD-TIME = 2
2
PWM2 W/
DEAD-TIME = 2
2
2
2
2
2
Figure 12-15. Effects of Dead-Time Insertion
UP/DOWN COUNTER
MODULUS = 3
PWM VALUE = 1
PWM VALUE = 1
PWM VALUE = 3
PWM VALUE = 3
PWM1 W/
NO DEAD-TIME
PWM2 W/
NO DEAD-TIME
PWM1 W/
DEAD-TIME = 2
PWM2 W/
DEAD-TIME = 2
2
2
2
2
Figure 12-16. Dead-Time at Duty Cycle Boundaries
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
141
Pulse-Width Modulator for Motor Control (PWMMC)
UP/DOWN COUNTER
MOUDULUS = 3
PWM VALUE = 2
PWM VALUE = 3
PWM VALUE = 2
PWM VALUE = 1
PWM1 W/
NO DEAD-TIME
PWM2 W/
NO DEAD-TIME
PWM1 W/
DEAD-TIME = 3
PWM2 W/
DEAD-TIME = 3
3
3
3
3
3
3
Figure 12-17. Dead-Time and Small Pulse Widths
12.5.3 Top/Bottom Correction with Motor Phase Current Polarity Sensing
Ideally, when complementary pairs are used, the PWM pairs are inversions of each
other, as shown in Figure 12-18. When PWM1 is active, PWM2 is inactive, and
vice versa. In this case, the motor terminal voltage is never allowed to float and is
strictly controlled by the PWM waveforms.
UP/DOWN COUNTER
MODULUS = 4
PWM1
PWM VALUE = 1
PWM2
PWM3
PWM VALUE = 2
PWM4
PWM5
PWM VALUE = 3
PWM6
Figure 12-18. Ideal Complementary Operation (Dead-Time = 0)
Data Sheet
142
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Output Control
However, when dead-time is inserted, the motor voltage is allowed to float
momentarily during the dead-time interval, creating a distortion in the motor current
waveform. This distortion is aggravated by dissimilar turn-on and turn-off delays of
each of the transistors.
For a typical motor drive inverter as shown in Figure 12-13, for a given top/bottom
transistor pair, only one of the transistors will be effective in controlling the output
voltage at any given time depending on the direction of the motor current for that
pair. To achieve distortion correction, one of two different correction factors must
be added to the desired PWM value, depending on whether the top or bottom
transistor is controlling the output voltage. Therefore, the software is responsible
for calculating both compensated PWM values and placing them in an odd/even
PWM register pair. By supplying the PWM module with information regarding which
transistor (top or bottom) is controlling the output voltage at any given time (for
instance, the current polarity for that motor phase), the PWM module selects either
the odd or even numbered PWM value register to be used by the PWM generator.
Current sensing or programmable software bits are then used to determine which
PWM value to use. If the current sensed at the motor for that PWM pair is positive
(voltage on current pin ISx is low) or bit IPOLx in PWM control register 2 is low, the
top PWM value is used for the PWM pair. Likewise, if the current sensed at the
motor for that PWM pair is negative (voltage on current pin ISx is high) or bit IPOLx
in PWM control register 2 is high, the bottom PWM value is used. See Table 12-4.
NOTE:
This text assumes the user will provide current sense circuitry which causes the
voltage at the corresponding input pin to be low for positive current and high for
negative current. See Figure 12-19 for current convention. In addition, it assumes
the top PWMs are PWMs 1, 3, and 5 while the bottom PWMs are PWMs 2, 4, and 6.
Table 12-4. Current Sense Pins
Current
Sense Pin
or Bit
Voltage
on Current
Sense Pin
or IPOLx Bit
PWM Value
Register Used
PWMs
Affected
IS1 or IPOL1
Logic 0
PWM value register 1
PWMs 1 and 2
IS1 or IPOL1
Logic 1
PWM value register 2
PWMs 1 and 2
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
143
Pulse-Width Modulator for Motor Control (PWMMC)
I+
I-
Figure 12-19. Current Convention
To allow for correction based on different current sensing methods or correction
controlled by software, the ISENS1 and ISENS0 bits in PWM control register 1 are
provided to choose the correction method. These bits provide correction according
to Table 12-5.
Table 12-5. Correction Methods
Current Correction Bits
ISENS1 and ISENS0
Correction Method
00
01
Bits IPOL1, IPOL2, and IPOL3 used for correction
10
Current sensing on pins IS1, IS2, and IS3 occurs during the
dead-time.
11
Current sensing on pins IS1, IS2, and IS3 occurs at the half
cycle in center-aligned mode and at the end of the cycle in
edge-aligned mode.
If correction is to be done in software or is not necessary, setting
ISENS1:ISENS0 = 00 or = 01 causes the correction to be based on bits IPOL1,
IPOL2, and IPOL3 in PWM control register 2. If correction is not required, the user
can initialize the IPOLx bits and then only load one PWM value register per PWM
pair.
To allow the user to use a current sense scheme based upon sensed phase
voltage during dead-time, setting ISENS1:ISENS0 = 10 causes the polarity of the
Ix pin to be latched when both the top and bottom PWMs are off (for example,
during the dead-time). At the 0 percent and 100 percent duty cycle boundaries,
there is no dead-time so no new current value is sensed.
To accommodate other current sensing schemes, setting ISENS1:ISENS0 = 11
causes the polarity of the current sense pin to be latched half-way into the PWM
cycle in center-aligned mode and at the end of the cycle in edge-aligned mode.
Therefore, even at 0 percent and 100 percent duty cycle, the current is sensed.
Data Sheet
144
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Output Control
Distortion correction is only available in complementary mode. At the beginning of
the PWM period, the PWM uses this latched current value or polarity bit to decide
whether the top PWM value or bottom PWM value is used. Figure 12-20 shows an
example of top/bottom correction for PWMs 1 and 2.
NOTE:
The IPOLx bits and the values latched on the ISx pins are buffered so that only one
PWM register is used per PWM cycle. If the IPOLx bits or the current sense values
change during a PWM period, this new value will not be used until the next PWM
period. The ISENSx bits are NOT buffered; therefore, changing the current sensing
method could affect the present PWM cycle.
When the PWM is first enabled by setting PWMEN, PWM value registers 1, 3,
and 5 will be used if the ISENSx bits are configured for current sensing correction.
This is because no current will have previously been sensed.
PWM VALUE REG. 2 = 2
PWM VALUE REG. 1 = 1
IS1 POSITIVE
PWM = 1
IS1 POSITIVE
PWM = 1
IS1 NEGATIVE
PWM = 2
IS1 NEGATIVE
PWM = 2
PWM1
PWM2
Figure 12-20. Top/Bottom Correction for PWMs 1 and 2
12.5.4 Output Polarity
The output polarity of the PWMs is determined by two options: TOPNEG and
BOTNEG. The top polarity option, TOPNEG, controls the polarity of PWMs 1, 3,
and 5. The bottom polarity option, BOTNEG, controls the polarity of PWMs 2, 4,
and 6. Positive polarity means that when the PWM is active, the PWM output is
high. Conversely, negative polarity means that when the PWM is active, PWM
output is low. See Figure 12-21.
NOTE:
Both bits are found in the CONFIG register, which is a write-once register. This
reduces the chances of the software inadvertently changing the polarity of the
PWM signals and possibly damaging the motor drive hardware.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
145
Pulse-Width Modulator for Motor Control (PWMMC)
CENTER-ALIGNED POSITIVE POLARITY
EDGE-ALIGNED POSITIVE POLARITY
UP-ONLY COUNTER
MODULUS = 4
UP/DOWN COUNTER
MODULUS = 4
PWM <= 0
PWM <= 0
PWM = 1
PWM = 1
PWM = 2
PWM = 2
PWM = 3
PWM = 3
PWM >= 4
PWM >= 4
CENTER-ALIGNED NEGATIVE POLARITY
EDGE-ALIGNED NEGATIVE POLARITY
UP-ONLY COUNTER
MODULUS = 4
UP/DOWN COUNTER
MODULUS = 4
PWM <= 0
PWM = 1
PWM <= 0
PWM = 2
PWM = 1
PWM = 3
PWM = 2
PWM >= 4
PWM = 3
PWM >= 4
Figure 12-21. PWM Polarity
12.5.5 PWM Output Port Control
Conditions may arise in which the PWM pins need to be individually controlled.
This is made possible by the PWM output control register (PWMOUT) shown in
Figure 12-22.
Address:
$0025
Bit 7
Read:
0
Write:
Reset:
0
6
5
4
3
2
1
Bit 0
OUTCTL
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
0
0
0
0
0
0
0
= Unimplemented
Figure 12-22. PWM Output Control Register (PWMOUT)
Data Sheet
146
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Output Control
If the OUTCTL bit is set, the PWM pins can be controlled by the OUTx bits. These
bits behave according to Table 12-6.
Table 12-6. OUTx Bits
OUTx Bit
Complementary Mode
Independent Mode
OUT1
1 — PWM1 is active.
0 — PWM1 is inactive.
1 — PWM1 is active.
0 — PWM1 is inactive.
OUT2
1 — PWM2 is complement of PWM 1.
0 — PWM2 is inactive.
1 — PWM2 is active.
0 — PWM2 is inactive.
OUT3
1 — PWM3 is active.
0 — PWM3 is inactive.
1 — PWM3 is active.
0 — PWM3 is inactive.
OUT4
1 — PWM4 is complement of PWM 3.
0 — PWM4 is inactive.
1 — PWM4 is active.
0 — PWM4 is inactive.
OUT5
1 — PWM5 is active.
0 — PWM5 is inactive.
1 — PWM5 is active.
0 — PWM5 is inactive.
OUT6
1 — PWM 6 is complement of PWM 5.
0 — PWM6 is inactive.
1 — PWM6 is active.
0 — PWM6 is inactive.
When OUTCTL is set, the polarity options TOPPOL and BOTPOL will still affect the
outputs. In addition, if complementary operation is in use, the PWM pairs will not
be allowed to be active simultaneously, and dead-time will still not be violated.
When OUTCTL is set and complementary operation is in use, the odd OUTx bits
are inputs to the dead-time generators as shown in Figure 12-15. Dead-time is
inserted whenever the odd OUTx bit toggles as shown in Figure 12-23. Although
dead-time is not inserted when the even OUTx bits change, there will be no
dead-time violation as shown in Figure 12-24.
Setting the OUTCTL bit does not disable the PWM generator and current sensing
circuitry. They continue to run, but are no longer controlling the output pins. In
addition, OUTCTL will control the PWM pins even when PWMEN = 0. When
OUTCTL is cleared, the outputs of the PWM generator become the inputs to the
dead-time and output circuitry at the beginning of the next PWM cycle.
NOTE:
To avoid an unexpected dead-time occurrence, it is recommended that the OUTx
bits be cleared prior to entering and prior to exiting individual PWM output control
mode.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
147
Pulse-Width Modulator for Motor Control (PWMMC)
UP/DOWN COUNTER
MODULUS = 4
DEAD-TIME = 2
PWM VALUE = 3
OUTCTL
OUT1
OUT2
PWM1
PWM2
PWM1/PWM2
DEAD-TIME
2
2
2
DEAD-TIME INSERTED AS PART OF DEAD-TIME INSERTED DUE
NORMAL PWM OPERATION AS
TO SETTING OF OUT1 BIT
CONTROLLED BY CURRENT
SENSING AND PWM GENERATOR
DEAD-TIME INSERTED
DUE TO CLEARING OF
OUT1 BIT
Figure 12-23. Dead-Time Insertion During OUTCTL = 1
UP/DOWN COUNTER
MODULUS = 4
DEAD-TIME = 2
PWM VALUE = 3
OUTCTL
OUT1
OUT2
PWM1
PWM2
PWM1/PWM2
DEAD-TIME
2
2
DEAD-TIME INSERTED BECAUSE
WHEN OUTCTL WAS SET, THE
STATE OF OUT1 WAS SUCH THAT
PWM1 WAS DIRECTED TO TOGGLE
2
2
DEAD-TIME INSERTED
BECAUSE OUT1 TOGGLES,
DIRECTING PWM1 TO
TOGGLE
NO DEAD-TIME INSERTED
BECAUSE OUT1 IS NOT
TOGGLING
Figure 12-24. Dead-Time Insertion During OUTCTL = 1
Data Sheet
148
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Fault Protection
12.6 Fault Protection
Conditions may arise in the external drive circuitry which require that the PWM
signals become inactive immediately, such as an overcurrent fault condition.
Furthermore, it may be desirable to selectively disable PWM(s) solely with
software.
One or more PWM pins can be disabled (forced to their inactive state) by applying
a logic high to any of the four external fault pins or by writing a logic high to either
of the disable bits (DISX and DISY in PWM control register 1). Figure 12-26 shows
the structure of the PWM disabling scheme. While the PWM pins are disabled, they
are forced to their inactive state. The PWM generator continues to run — only the
output pins are disabled.
To allow for different motor configurations and the controlling of more than one
motor, the PWM disabling function is organized as two banks, bank X and bank Y.
Bank information combines with information from the disable mapping register to
allow selective PWM disabling. Fault pin 1, fault pin 2, and PWM disable bit X
constitute the disabling function of bank X. Fault pin 3, fault pin 4, and PWM disable
bit Y constitute the disabling function of bank Y. Figure 12-25 and Figure 12-27
show the disable mapping write-once register and the decoding scheme of the
bank which selectively disables PWM(s). When all bits of the disable mapping
register are set, any disable condition will disable all PWMs.
A fault can also generate a CPU interrupt. Each fault pin has its own interrupt
vector.
Address: $0037
Read:
Write:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Reset:
Figure 12-25. PWM Disable Mapping Write-Once Register (DISMAP)
12.6.1 Fault Condition Input Pins
A logic high level on a fault pin disables the respective PWM(s) determined by the
bank and the disable mapping register. Each fault pin incorporates a filter to assist
in rejecting spurious faults. All of the external fault pins are software-configurable
to re-enable the PWMs either with the fault pin (automatic mode) or with software
(manual mode). Each fault pin has an associated FMODE bit to control the PWM
re-enabling method. Automatic mode is selected by setting the FMODEx bit in the
fault control register. Manual mode is selected when FMODEx is clear.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
149
Pulse-Width Modulator for Motor Control (PWMMC)
DISX
CYCLE START
SOFTWARE X DISABLE
S
Q
R
FMODE2
TWO
SAMPLE
FILTER
FAULT
PIN2
AUTO
MODE
FPIN2
LOGIC HIGH FOR FAULT
ONE
SHOT
BANK X
DISABLE
FAULT PIN 2 DISABLE
S
Q FFLAG2
R
S
Q
R
MANUAL
MODE
CLEAR BY WRITING 1 TO FTACK4
INTERRUPT REQUEST
FINT2
The example is of fault pin 2 with DISX. Fault pin 4 with DISY is logically similar and affects BANK Y disable.
Note: In manual mode (FMODE = 0), faults 2 and 4 may be cleared only if a logic level low at the input of the fault
pin is present.
CYCLE START
FMODE1
FAULT PIN 1 DISABLE
AUTO
MODE
FPIN1
LOGIC HIGH FOR FAULT
FAULT
PIN1
TWO
SAMPLE
FILTER
ONE
SHOT
S
R
Q FFLAG1
S
Q
BANK X DISABLE
R
MANUAL
MODE
CLEAR BY WRITING 1 TO FTACK1
FINT1
INTERRUPT REQUEST
The example is of fault pin 1. Fault pin 3 is logically similar and affects BANK Y disable.
Note: In manual mode (FMODE = 0), faults 1 and 3 may be cleared regardless of the logic level at the input of the fault pin.
Figure 12-26. PWM Disabling Scheme
Data Sheet
150
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Fault Protection
BIT 7
DISABLE
PWM PIN 1
BIT 6
BANK X
DISABLE
BIT 5
DISABLE
PWM PIN 2
BIT 4
DISABLE
PWM PIN 3
BIT 3
BANK Y
DISABLE
DISABLE
PWM PIN 4
BIT 2
BIT 1
DISABLE
PWM PIN 5
BIT 0
DISABLE
PWM PIN 6
Figure 12-27. PWM Disabling Decode Scheme
12.6.1.1 Fault Pin Filter
Each fault pin incorporates a filter to assist in determining a genuine fault condition.
After a fault pin has been logic low for one CPU cycle, a rising edge (logic high) will
be synchronously sampled once per CPU cycle for two cycles. If both samples are
detected logic high, the corresponding FPIN bit and FFLAG bit will be set. The
FPIN bit will remain set until the corresponding fault pin is logic low and
synchronously sampled once in the following CPU cycle.
12.6.1.2 Automatic Mode
In automatic mode, the PWM(s) are disabled immediately once a filtered fault
condition is detected (logic high). The PWM(s) remain disabled until the filtered
fault condition is cleared (logic low) and a new PWM cycle begins as shown in
Figure 12-28. Clearing the corresponding FFLAGx event bit will not enable the
PWMs in automatic mode.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
151
Pulse-Width Modulator for Motor Control (PWMMC)
FILTERED FAULT PIN
PWM(S) ENABLED
PWM(S) DISABLED (INACTIVE)
PWM(S) ENABLED
Figure 12-28. PWM Disabling in Automatic Mode
The filtered fault pin’s logic state is reflected in the respective FPINx bit. Any write
to this bit is overwritten by the pin state. The FFLAGx event bit is set with each
rising edge of the respective fault pin after filtering has been applied. To clear the
FFLAGx bit, the user must write a 1 to the corresponding FTACKx bit.
If the FINTx bit is set, a fault condition resulting in setting the corresponding FFLAG
bit will also latch a CPU interrupt request. The interrupt request latch is not cleared
until one of these actions occurs:
•
The FFLAGx bit is cleared by writing a 1 to the corresponding FTACKx bit.
•
The FINTx bit is cleared. This will not clear the FFLAGx bit.
•
A reset automatically clears all four interrupt latches.
If prior to a vector fetch, the interrupt request latch is cleared by one of the actions
listed, a CPU interrupt will no longer be requested. A vector fetch does not alter the
state of the PWMs, the FFLAGx event flag, or FINTx.
NOTE:
If the FFLAGx or FINTx bits are not cleared during the interrupt service routine, the
interrupt request latch will not be cleared.
12.6.1.3 Manual Mode
In manual mode, the PWM(s) are disabled immediately once a filtered fault
condition is detected (logic high). The PWM(s) remain disabled until software
clears the corresponding FFLAGx event bit and a new PWM cycle begins. In
manual mode, the fault pins are grouped in pairs, each pair sharing common
functionality. A fault condition on pins 1 and 3 may be cleared, allowing the PWM(s)
to enable at the start of a PWM cycle regardless of the logic level at the fault pin.
See Figure 12-29. A fault condition on pins 2 and 4 can only be cleared, allowing
the PWM(s) to enable, if a logic low level at the fault pin is present at the start of a
PWM cycle. See Figure 12-30.
The function of the fault control and event bits is the same as in automatic mode
except that the PWMs are not re-enabled until the FFLAGx event bit is cleared by
writing to the FTACKx bit and the filtered fault condition is cleared (logic low).
Data Sheet
152
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Fault Protection
FILTERED FAULT PIN 1 OR 3
PWM(S) ENABLED
PWM(S) DISABLED
PWM(S) ENABLED
FFLAGX CLEARED
Figure 12-29. PWM Disabling in Manual Mode (Example 1)
FILTERED FAULT PIN 2 OR 4
PWM(S) ENABLED
PWM(S) DISABLED
PWM(S) ENABLED
FFLAGX CLEARED
Figure 12-30. PWM Disabling in Manual Mode (Example 2)
12.6.2 Software Output Disable
Setting PWM disable bit DISX or DISY in PWM control register 1 immediately
disables the corresponding PWM pins as determined by the bank and disable
mapping register. The PWM pin(s) remain disabled until the PWM disable bit is
cleared and a new PWM cycle begins as shown in Figure 12-31. Setting a PWM
disable bit does not latch a CPU interrupt request, and there are no event flags
associated with the PWM disable bits.
12.6.3 Output Port Control
When operating the PWMs using the OUTx bits (OUTCTL = 1), fault protection
applies as described in this section. Due to the absence of periodic PWM cycles,
fault conditions are cleared upon each CPU cycle and the PWM outputs are
re-enabled, provided all fault clearing conditions are satisfied.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
153
Pulse-Width Modulator for Motor Control (PWMMC)
DISABLE BIT
PWM(S) ENABLED
PWM(S) DISABLED
PWM(S) ENABLED
Figure 12-31. PWM Software Disable
12.7 Initialization and the PWMEN Bit
For proper operation, all registers should be initialized and the LDOK bit should be
set before enabling the PWM via the PWMEN bit. When the PWMEN bit is first set,
a reload will occur immediately, setting the PWMF flag and generating an interrupt
if PWMINT is set. In addition, in complementary mode, PWM value registers 1, 3,
and 5 will be used for the first PWM cycle if current sensing is selected.
NOTE:
If the LDOK bit is not set when PWMEN is set after a RESET, the prescaler and
PWM values will be 0, but the modulus will be unknown. If the LDOK bit is not set
after the PWMEN bit has been cleared then set (without a RESET), the modulus
value that was last loaded will be used.
If the dead-time register (DEADTM) is changed after PWMEN or OUTCTL is set,
an improper dead-time insertion could occur. However, the dead-time can never be
shorter than the specified value.
Because of the equals-comparator architecture of this PWM, the modulus = 0 case
is considered illegal. Therefore, the modulus register is not reset, and a modulus
value of 0 will result in waveforms inconsistent with the other modulus waveforms.
See 12.9.2 PWM Counter Modulo Registers.
When PWMEN is set, the PWM pins change from high impedance to outputs. At
this time, assuming no fault condition is present, the PWM pins will drive according
to the PWM values, polarity, and dead-time. See the timing diagram in Figure
12-32.
Data Sheet
154
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
PWM Operation in Wait Mode
CPU CLOCK
PWMEN
DRIVE ACCORDING TO PWM
VALUE, POLARITY, AND DEAD-TIME
PWM PINS
HI-Z IF OUTCTL = 0
HI-Z IF OUTCTL = 0
Figure 12-32. PWMEN and PWM Pins
When the PWMEN bit is cleared, this will occur:
•
PWM pins will be three-stated unless OUTCTL = 1.
•
PWM counter is cleared and will not be clocked.
•
Internally, the PWM generator will force its outputs to 0 to avoid glitches
when the PWMEN is set again.
When PWMEN is cleared, these features remain active:
NOTE:
•
All fault circuitry
•
Manual PWM pin control via the PWMOUT register
•
Dead-time insertion when PWM pins change via the PWMOUT register
The PWMF flag and pending CPU interrupts are NOT cleared when PWMEN = 0.
12.8 PWM Operation in Wait Mode
When the microcontroller is put in low-power wait mode via the WAIT instruction,
all clocks to the PWM module will continue to run. If an interrupt is issued from the
PWM module (via a reload or a fault), the microcontroller will exit wait mode.
Clearing the PWMEN bit before entering wait mode will reduce power consumption
in wait mode because the counter, prescaler divider, and LDFQ divider will no
longer be clocked. In addition, power will be reduced because the PWMs will no
longer toggle.
12.9 Control Logic Block
This subsection provides a description of the control logic block.
12.9.1 PWM Counter Registers
The PWM counter registers (PCNTH and PCNTL) display the 12-bit up/down or
up-only counter. When the high byte of the counter is read, the lower byte is
latched. PCNTL will hold this latched value until it is read. See Figure 12-33 and
Figure 12-34.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
155
Pulse-Width Modulator for Motor Control (PWMMC)
Address:
Read:
$0026
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 12-33. PWM Counter Register High (PCNTH)
Address:
Read:
$0027
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
Figure 12-34. PWM Counter Register Low (PCNTL)
12.9.2 PWM Counter Modulo Registers
The PWM counter modulus registers (PMODH and PMODL) hold a 12-bit unsigned
number that determines the maximum count for the up/down or up-only counter. In
center-aligned mode, the PWM period will be twice the modulus (assuming no
prescaler). In edge-aligned mode, the PWM period will equal the modulus. See
Figure 12-35 and Figure 12-36.
Address:
Read:
$0028
Bit 7
6
5
4
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented
3
2
1
Bit 0
Bit 11
Bit 10
Bit 9
Bit 8
X
X
X
X
X = Indeterminate
Figure 12-35. PWM Counter Modulo Register High (PMODH)
Address:
Read:
Write:
Reset:
$0029
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
X
X
X
X
X
X = Indeterminate
Figure 12-36. PWM Counter Modulo Register Low (PMODL)
Data Sheet
156
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
To avoid erroneous PWM periods, this value is buffered and will not be used by the
PWM generator until the LDOK bit has been set and the next PWM load cycle
begins.
NOTE:
When reading this register, the value read is the buffer (not necessarily the value
the PWM generator is currently using).
Because of the equals-comparator architecture of this PWM, the modulus = 0 case
is considered illegal. Therefore, the modulus register is not reset, and a modulus
value of 0 will result in waveforms inconsistent with the other modulus waveforms.
If a modulus of 0 is loaded, the counter will continually count down from $FFF. This
operation will not be tested or guaranteed (the user should consider it illegal).
However, the dead-time constraints and fault conditions will still be guaranteed.
12.9.3 PWMx Value Registers
Each of the six PWMs has a 16-bit PWM value register.
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
Bold
= Buffered
Figure 12-37. PWMx Value Registers High (PVALxH)
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Bold
= Buffered
Figure 12-38. PWMx Value Registers Low (PVALxL)
The 16-bit signed value stored in this register determines the duty cycle of the
PWM. The duty cycle is defined as: (PWM value/modulus) x 100.
Writing a number less than or equal to 0 causes the PWM to be off for the entire
PWM period. Writing a number greater than or equal to the 12-bit modulus causes
the PWM to be on for the entire PWM period.
If the complementary mode is selected, the PWM pairs share PWM value registers.
To avoid erroneous PWM pulses, this value is buffered and will not be used by the
PWM generator until the LDOK bit has been set and the next PWM load cycle
begins.
NOTE:
When reading these registers, the value read is the buffer (not necessarily the
value the PWM generator is currently using).
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
157
Pulse-Width Modulator for Motor Control (PWMMC)
12.9.4 PWM Control Register 1
PWM control register 1 (PCTL1) controls PWM enabling/disabling, the loading of
new modulus, prescaler, PWM values, and the PWM correction method. In
addition, this register contains the software disable bits to force the PWM outputs
to their inactive states (according to the disable mapping register).
Address:
Read:
Write:
Reset:
$0020
Bit 7
6
5
4
3
2
1
Bit 0
DISX
DISY
PWMINT
PWMF
ISENS1
ISENS0
LDOK
PWMEN
0
0
0
0
0
0
0
0
Figure 12-39. PWM Control Register 1 (PCTL1)
DISX — Software Disable Bit for Bank X Bit
This read/write bit allows the user to disable one or more PWM pins in bank X.
The pins that are disabled are determined by the disable mapping write-once
register.
1 = Disable PWM pins in bank X.
0 = Re-enable PWM pins at beginning of next PWM cycle.
DISY — Software Disable Bit for Bank Y Bit
This read/write bit allows the user to disable one or more PWM pins in bank Y.
The pins that are disabled are determined by the disable mapping write-once
register.
1 = Disable PWM pins in bank Y.
0 = Re-enable PWM pins at beginning of next PWM cycle.
PWMINT — PWM Interrupt Enable Bit
This read/write bit allows the user to enable and disable PWM CPU interrupts.
If set, a CPU interrupt will be pending when the PWMF flag is set.
1 = Enable PWM CPU interrupts.
0 = Disable PWM CPU interrupts.
NOTE:
When PWMINT is cleared, pending CPU interrupts are inhibited.
PWMF — PWM Reload Flag
This read/write bit is set at the beginning of every reload cycle regardless of the
state of the LDOK bit. This bit is cleared by reading PWM control register 1 with
the PWMF flag set, then writing a logic 0 to PWMF. If another reload occurs
before the clearing sequence is complete, then writing logic 0 to PWMF has no
effect.
1 = New reload cycle began.
0 = New reload cycle has not begun.
NOTE:
Data Sheet
158
When PWMF is cleared, pending PWM CPU interrupts are cleared (not including
fault interrupts).
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
ISENS1 and ISENS0 — Current Sense Correction Bits
These read/write bits select the top/bottom correction scheme as shown in
Table 12-7.
Table 12-7. Correction Methods
Current Correction Bits
ISENS1 and ISENS0
Correction Method
00
01
Bits IPOL1, IPOL2, and IPOL3 are used for correction.
10
Current sensing on pins IS1, IS2, and IS3 occurs during the
dead-time.
11
Current sensing on pins IS1, IS2, and IS3 occurs at the half
cycle in center-aligned mode and at the end of the cycle in
edge-aligned mode.
1. The polarity of the ISx pin is latched when both the top and bottom PWMs are off. At
the 0% and 100% duty cycle boundaries, there is no dead-time, so no new current
value is sensed.
2. Current is sensed even with 0% and 100% duty cycle.
NOTE:
The ISENSx bits are not buffered. Changing the current sensing method can affect
the present PWM cycle.
LDOK— Load OK Bit
This read/write bit loads the prescaler bits of the PMCTL2 register and the entire
PMMODH/L and PWMVALH/L registers into a set of buffers. The buffered
prescaler divisor, PWM counter modulus value, and PWM pulse will take effect
at the next PWM load. Set LDOK by reading it when it is logic 0 and then writing
a logic 1 to it. LDOK is automatically cleared after the new values are loaded or
can be manually cleared before a reload by writing a 0 to it. Reset clears LDOK.
1 = Load prescaler, modulus, and PWM values.
0 = Do not load new modulus, prescaler, and PWM values.
NOTE:
The user should initialize the PWM registers and set the LDOK bit before enabling
the PWM.
A PWM CPU interrupt request can still be generated when LDOK is 0.
PWMEN — PWM Module Enable Bit
This read/write bit enables and disables the PWM generator and the PWM pins.
When PWMEN is clear, the PWM generator is disabled and the PWM pins are
in the high-impedance state (unless OUTCTL = 1).
When the PWMEN bit is set, the PWM generator and PWM pins are activated.
For more information, see 12.7 Initialization and the PWMEN Bit.
1 = PWM generator and PWM pins enabled
0 = PWM generator and PWM pins disabled
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
159
Pulse-Width Modulator for Motor Control (PWMMC)
12.9.5 PWM Control Register 2
PWM control register 2 (PCTL2) controls the PWM load frequency, the PWM
correction method, and the PWM counter prescaler. For ease of software and to
avoid erroneous PWM periods, some of these register bits are buffered. The PWM
generator will not use the prescaler value until the LDOK bit has been set, and a
new PWM cycle is starting. The correction bits are used at the beginning of each
PWM cycle (if the ISENSx bits are configured for software correction). The load
frequency bits are not used until the current load cycle is complete.
See Figure 12-40.
NOTE:
The user should initialize this register before enabling the PWM.
Address:
Read:
Write:
Reset:
$0021
Bit 7
6
5
LDFQ1
LDFQ0
0
0
0
0
= Unimplemented
4
3
2
1
Bit 0
IPOL1
IPOL2
IPOL3
PRSC1
PRSC0
0
0
0
0
0
Bold
= Buffered
Figure 12-40. PWM Control Register 2 (PCTL2)
LDFQ1 and LDFQ0 — PWM Load Frequency Bits
These buffered read/write bits select the PWM CPU load frequency according
to Table 12-8.
NOTE:
When reading these bits, the value read is the buffer value (not necessarily the
value the PWM generator is currently using).
The LDFQx bits take effect when the current load cycle is complete regardless of
the state of the load okay bit, LDOK.
Table 12-8. PWM Reload Frequency
NOTE:
Data Sheet
160
Reload Frequency Bits
LDFQ1 and LDFQ0
PWM Reload Frequency
00
Every PWM cycle
01
Every 2 PWM cycles
10
Every 4 PWM cycles
11
Every 8 PWM cycles
Reading the LPFQx bit reads the buffered values and not necessarily the values
currently in effect.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
IPOL1 — Top/Bottom Correction Bit for PWM Pair 1 (PWMs 1 and 2)
This buffered read/write bit selects which PWM value register is used if
top/bottom correction is to be achieved without current sensing.
1 = Use PWM value register 2.
0 = Use PWM value register 1.
NOTE:
When reading this bit, the value read is the buffer value (not necessarily the value
the output control block is currently using).
The IPOLx bits take effect at the beginning of the next load cycle, regardless of the
state of the load okay bit, LDOK.
IPOL2 — Top/Bottom Correction Bit for PWM Pair 2 (PWMs 3 and 4)
This buffered read/write bit selects which PWM value register is used if
top/bottom correction is to be achieved without current sensing.
1 = Use PWM value register 4.
0 = Use PWM value register 3.
NOTE:
When reading this bit, the value read is the buffer value (not necessarily the value
the output control block is currently using).
IPOL3 — Top/Bottom Correction Bit for PWM Pair 3 (PWMs 5 and 6)
This buffered read/write bit selects which PWM value register is used if
top/bottom correction is to be achieved without current sensing.
1 = Use PWM value register 6.
0 = Use PWM value register 5.
NOTE:
When reading this bit, the value read is the buffer value (not necessarily the value
the output control block is currently using).
PRSC1 and PRSC0 — PWM Prescaler Bits
These buffered read/write bits allow the PWM clock frequency to be modified as
shown in Table 12-9.
NOTE:
When reading these bits, the value read is the buffer value (not necessarily the
value the PWM generator is currently using).
Table 12-9. PWM Prescaler
Prescaler Bits
PRSC1 and PRSC0
PWM Clock Frequency
00
fOP
01
fOP/2
10
fOP/4
11
fOP/8
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
161
Pulse-Width Modulator for Motor Control (PWMMC)
12.9.6 Dead-Time Write-Once Register
The dead-time write-once register (DEADTM) holds an 8-bit value which specifies
the number of CPU clock cycles to use for the dead-time when complementary
PWM mode is selected. After this register is written for the first time, it cannot be
rewritten unless a reset occurs. Dead-time is not affected by changes to the
prescaler value.
Address:
Read:
Write:
Reset:
$0036
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Figure 12-41. Dead-Time Write-Once Register (DEADTM)
12.9.7 PWM Disable Mapping Write-Once Register
The PWM disable mapping write-once register (DISMAP) holds an 8-bit value
which determines which PWM pins will be disabled if an external fault or software
disable occurs. For a further description of disable mapping, see 12.6 Fault
Protection. After this register is written for the first time, it cannot be rewritten
unless a reset occurs.
Address:
Read:
Write:
Reset:
$0037
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Figure 12-42. PWM Disable Mapping
Write-Once Register (DISMAP)
12.9.8 Fault Control Register
The fault control register (FCR) controls the fault-protection circuitry.
Address: $0022
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
FINT4
FMODE4
FINT3
FMODE3
FINT2
FMODE2
FINT1
FMODE1
0
0
0
0
0
0
0
0
Figure 12-43. Fault Control Register (FCR)
Data Sheet
162
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
FINT4 — Fault 4 Interrupt Enable Bit
This read/write bit allows the CPU interrupt caused by faults on fault pin 4 to be
enabled. The fault protection circuitry is independent of this bit and will always
be active. If a fault is detected, the PWM pins will still be disabled according to
the disable mapping register.
1 = Fault pin 4 will cause CPU interrupts.
0 = Fault pin 4 will not cause CPU interrupts.
FMODE4 — Fault Mode Selection for Fault Pin 4 Bit
(automatic versus manual mode)
This read/write bit allows the user to select between automatic and manual
mode faults. For further descriptions of each mode, see 12.6 Fault Protection.
1 = Automatic mode
0 = Manual mode
FINT3 — Fault 3 Interrupt Enable Bit
This read/write bit allows the CPU interrupt caused by faults on fault pin 3 to be
enabled. The fault protection circuitry is independent of this bit and will always
be active. If a fault is detected, the PWM pins will still be disabled according to
the disable mapping register.
1 = Fault pin 3 will cause CPU interrupts.
0 = Fault pin 3 will not cause CPU interrupts.
FMODE3 — Fault Mode Selection for Fault Pin 3 Bit
(automatic versus manual mode)
This read/write bit allows the user to select between automatic and manual
mode faults. For further descriptions of each mode, see 12.6 Fault Protection.
1 = Automatic mode
0 = Manual mode
FINT2 — Fault 2 Interrupt Enable Bit
This read/write bit allows the CPU interrupt caused by faults on fault pin 2 to be
enabled. The fault protection circuitry is independent of this bit and will always
be active. If a fault is detected, the PWM pins will still be disabled according to
the disable mapping register.
1 = Fault pin 2 will cause CPU interrupts.
0 = Fault pin 2 will not cause CPU interrupts.
FMODE2 — Fault Mode Selection for Fault Pin 2 Bit
(automatic versus manual mode)
This read/write bit allows the user to select between automatic and manual
mode faults. For further descriptions of each mode, see 12.6 Fault Protection.
1 = Automatic mode
0 = Manual mode
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
163
Pulse-Width Modulator for Motor Control (PWMMC)
FINT1 — Fault 1 Interrupt Enable Bit
This read/write bit allows the CPU interrupt caused by faults on fault pin 1 to be
enabled. The fault protection circuitry is independent of this bit and will always
be active. If a fault is detected, the PWM pins will still be disabled according to
the disable mapping register.
1 = Fault pin 1 will cause CPU interrupts.
0 = Fault pin 1 will not cause CPU interrupts.
FMODE1 — Fault Mode Selection for Fault Pin 1 Bit
(automatic versus manual mode)
This read/write bit allows the user to select between automatic and manual
mode faults. For further descriptions of each mode, see 12.6 Fault Protection.
1 = Automatic mode
0 = Manual mode
12.9.9 Fault Status Register
The fault status register (FSR) is a read-only register that indicates the current fault
status.
Address:
Read:
$0023
Bit 7
6
5
4
3
2
1
Bit 0
FPIN4
FFLAG4
FPIN3
FFLAG3
FPIN2
FFLAG2
FPIN1
FFLAG1
U
0
U
0
U
0
U
0
Write:
Reset:
= Unimplemented
U = Unaffected
Figure 12-44. Fault Status Register (FSR)
FPIN4 — State of Fault Pin 4 Bit
This read-only bit allows the user to read the current state of fault
pin 4.
1 = Fault pin 4 is at logic 1.
0 = Fault pin 4 is at logic 0.
FFLAG4 — Fault Event Flag 4
The FFLAG4 event bit is set within two CPU cycles after a rising edge on fault
pin 4. To clear the FFLAG4 bit, the user must write a 1 to the FTACK4 bit in the
fault acknowledge register.
1 = A fault has occurred on fault pin 4.
0 = No new fault on fault pin 4
FPIN3 — State of Fault Pin 3 Bit
This read-only bit allows the user to read the current state of fault
pin 3.
1 = Fault pin 3 is at logic 1.
0 = Fault pin 3 is at logic 0.
Data Sheet
164
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
FFLAG3 — Fault Event Flag 3
The FFLAG3 event bit is set within two CPU cycles after a rising edge on fault
pin 3. To clear the FFLAG3 bit, the user must write a 1 to the FTACK3 bit in the
fault acknowledge register.
1 = A fault has occurred on fault pin 3.
0 = No new fault on fault pin 3.
FPIN2 — State of Fault Pin 2 Bit
This read-only bit allows the user to read the current state of fault pin 2.
1 = Fault pin 2 is at logic 1.
0 = Fault pin 2 is at logic 0.
FFLAG2 — Fault Event Flag 2
The FFLAG2 event bit is set within two CPU cycles after a rising edge on fault
pin 2. To clear the FFLAG2 bit, the user must write a 1 to the FTACK2 bit in the
fault acknowledge register.
1 = A fault has occurred on fault pin 2.
0 = No new fault on fault pin 2
FPIN1 — State of Fault Pin 1 Bit
This read-only bit allows the user to read the current state of fault pin 1.
1 = Fault pin 1 is at logic 1.
0 = Fault pin 1 is at logic 0.
FFLAG1 — Fault Event Flag 1
The FFLAG1 event bit is set within two CPU cycles after a rising edge on fault
pin 1. To clear the FFLAG1 bit, the user must write a 1 to the FTACK1 bit in the
fault acknowledge register.
1 = A fault has occurred on fault pin 1.
0 = No new fault on fault pin 1.
12.9.10 Fault Acknowledge Register
The fault acknowledge register (FTACK) is used to acknowledge and clear the
FFLAGs. In addition, it is used to monitor the current sensing bits to test proper
operation.
Address: $0024
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
DT6
DT5
DT4
DT3
DT2
DT1
FTACK4
Write:
Reset:
0
0
FTACK3
0
0
FTACK2
0
0
FTACK1
0
0
= Unimplemented
Figure 12-45. Fault Acknowledge Register (FTACK)
FTACK4 — Fault Acknowledge 4 Bit
The FTACK4 bit is used to acknowledge and clear FFLAG4. This bit will always
read 0. Writing a 1 to this bit will clear FFLAG4. Writing a 0 will have no effect.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
165
Pulse-Width Modulator for Motor Control (PWMMC)
FTACK3 — Fault Acknowledge 3 Bit
The FTACK3 bit is used to acknowledge and clear FFLAG3. This bit will always
read 0. Writing a 1 to this bit will clear FFLAG3. Writing a 0 will have no effect.
FTACK2 — Fault Acknowledge 2 Bit
The FTACK2 bit is used to acknowledge and clear FFLAG2. This bit will always
read 0. Writing a 1 to this bit will clear FFLAG2. Writing a 0 will have no effect.
FTACK1 — Fault Acknowledge 1 Bit
The FTACK1 bit is used to acknowledge and clear FFLAG1. This bit will always
read 0. Writing a 1 to this bit will clear FFLAG1. Writing a 0 will have no effect.
DT6 — Dead-Time 6 Bit
Current sensing pin IS3 is monitored immediately before dead-time ends due to
the assertion of PWM6.
DT5 — Dead-Time 5 Bit
Current sensing pin IS3 is monitored immediately before dead-time ends due to
the assertion of PWM5.
DT4 — Dead-Time 4 Bit
Current sensing pin IS2 is monitored immediately before dead-time ends due to
the assertion of PWM4.
DT3 — Dead-Time 3 Bit
Current sensing pin IS2 is monitored immediately before dead-time ends due to
the assertion of PWM3.
DT2 — Dead-Time 2 Bit
Current sensing pin IS1 is monitored immediately before dead-time ends due to
the assertion of PWM2.
DT1 — Dead-Time 1 Bit
Current sensing pin IS1 is monitored immediately before dead-time ends due to
the assertion of PWM1.
12.9.11 PWM Output Control Register
The PWM output control register (PWMOUT) is used to manually control the PWM
pins.
Address: $0025
Bit 7
Read:
0
Write:
Reset:
0
6
5
4
3
2
1
Bit 0
OUTCTL
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
0
0
0
0
0
0
0
= Unimplemented
Figure 12-46. PWM Output Control Register (PWMOUT)
Data Sheet
166
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
PWM Glossary
OUTCTL— Output Control Enable Bit
This read/write bit allows the user to manually control the PWM pins. When set,
the PWM generator is no longer the input to the dead-time and output circuitry.
The OUTx bits determine the state of the PWM pins. Setting the OUTCTL bit
does not disable the PWM generator. The generator continues to run, but is no
longer the input to the PWM dead-time and output circuitry. When OUTCTL is
cleared, the outputs of the PWM generator immediately become the inputs to
the dead-time and output circuitry.
1 = PWM outputs controlled manually
0 = PWM outputs determined by PWM generator
OUT6–OUT1— PWM Pin Output Control Bits
These read/write bits control the PWM pins according to Table 12-10.
Table 12-10. OUTx Bits
OUTx Bit
Complementary Mode
Independent Mode
OUT1
1 — PWM1 is active.
0 — PWM1 is inactive.
1 — PWM1 is active.
0 — PWM1 is inactive.
OUT2
1 — PWM2 is complement of PWM 1.
0 — PWM2 is inactive.
1 — PWM2 is active.
0 — PWM2 is inactive.
OUT3
1 — PWM3 is active.
0 — PWM3 is inactive.
1 — PWM3 is active.
0 — PWM3 is inactive.
OUT4
1 — PWM4 is complement of PWM 3.
0 — PWM4 is inactive.
1 — PWM4 is active.
0 — PWM4 is inactive.
OUT5
1 — PWM5 is active.
0 — PWM5 is inactive.
1 — PWM5 is active.
0 — PWM5 is inactive.
OUT6
1 — PWM 6 is complement of PWM 5.
0 — PWM6 is inactive.
1 — PWM6 is active.
0 — PWM6 is inactive.
12.10 PWM Glossary
CPU cycle — One internal bus cycle (1/fOP)
PWM clock cycle (or period) — One tick of the PWM counter (1/fOP with no
prescaler). See Figure 12-47.
PWM cycle (or period)
•
Center-aligned mode: The time it takes the PWM counter to count up and
count down (modulus * 2/fOP assuming no prescaler). See Figure 12-47.
•
Edge-aligned mode: The time it takes the PWM counter to count up
(modulus/fOP). See Figure 12-47.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
167
Pulse-Width Modulator for Motor Control (PWMMC)
Center-Aligned Mode
PWM CLOCK CYCLE
PWM CYCLE (OR PERIOD)
Edge-Aligned Mode
PWM
CLOCK
CYCLE
PWM CYCLE (OR PERIOD)
Figure 12-47. PWM Clock Cycle and PWM Cycle Definitions
PWM Load Frequency — Frequency at which new PWM parameters get loaded
into the PWM. See Figure 12-48.
LDFQ1:LDFQ0 = 01 — Reload Every Two Cycles
PWM LOAD CYCLE
(1/PWM LOAD FREQUENCY)
RELOAD NEW
MODULUS,
PRESCALER, &
PWM VALUES IF
LDOK = 1
RELOAD NEW
MODULUS,
PRESCALER, &
PWM VALUES IF
LDOK = 1
Figure 12-48. PWM Load Cycle/Frequency Definition
Data Sheet
168
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Pulse-Width Modulator for Motor Control (PWMMC)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 13. Serial Communications Interface Module (SCI)
13.1 Introduction
This section describes the serial communications interface module (SCI,
version D), which allows high-speed asynchronous communications with
peripheral devices and other microcontroller units (MCUs).
13.2 Features
Features of the SCI module include:
•
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
•
Separate receiver and transmitter
•
Programmable transmitter output polarity
•
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
169
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
CLOCK GENERATOR
MODULE
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
OSC1
OSC2
CGMXFC
TIMER INTERFACE
MODULE B
DDRF
USER FLASH VECTOR SPACE — 46 BYTES
MOTOROLA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MONITOR ROM — 240 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 13-1. Block Diagram Highlighting SCI Block and Pins
Serial Communications Interface Module (SCI)
Data Sheet
170
INTERNAL BUS
M68HC08 CPU
Serial Communications Interface Module (SCI)
Functional Description
13.3 Functional Description
Figure 13-2 shows the structure of the SCI module. The SCI allows full-duplex,
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.
INTERNAL BUS
ERROR
INTERRUPT
CONTROL
RECEIVE
SHIFT REGISTER
PTF4/RxD
SCI DATA
REGISTER
RECEIVER
INTERRUPT
CONTROL
TRANSMITTER
INTERRUPT
CONTROL
SCI DATA
REGISTER
TRANSMIT
SHIFT REGISTER
PTF5/TxD
TXINV
SCTIE
R8
TCIE
T8
SCRIE
ILIE
TE
SCTE
RE
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
fOP
÷4
PRESCALER
BAUD RATE
GENERATOR
÷ 16
PEN
PTY
DATA SELECTION
CONTROL
Figure 13-2. SCI Module Block Diagram
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
171
Serial Communications Interface Module (SCI)
Addr.
$0038
$0039
$003A
$003B
$003C
Register Name
SCI Control Register 1
(SCC1)
See page 183.
SCI Control Register 2
(SCC2)
See page 185.
SCI Control Register 3
(SCC3)
See page 187.
SCI Status Register 1
(SCS1)
See page 188.
SCI Status Register 2
(SCS2)
See page 191.
SCI Data Register
(SCDR)
See page 192.
$003D
$003E
SCI Baud Rate Register
(SCBR)
See page 192.
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
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
Reset:
0
0
0
0
0
0
0
0
Read:
R8
0
0
Write:
R
R
R
ORIE
NEIE
FEIE
PEIE
Read:
Write:
Reset:
Read:
Write:
T8
Reset:
U
U
0
0
0
0
0
0
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
R
R
R
R
R
R
R
R
Reset:
1
1
0
0
0
0
0
0
Read:
0
0
0
0
0
0
BKF
RPF
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
SCR2
SCR1
SCR0
0
0
0
Reset:
Unaffected by reset
Read:
0
0
Write:
R
R
Reset:
0
0
R
SCP1
SCP0
0
0
0
R
0
= Reserved
U = Unaffected
Figure 13-3. SCI I/O Register Summary
13.3.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format illustrated
in Figure 13-4.
8-BIT DATA FORMAT
BIT M IN SCC1 CLEAR
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
POSSIBLE
PARITY
BIT
BIT 6
9-BIT DATA FORMAT
BIT M IN SCC1 SET
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
STOP
BIT
BIT 7
NEXT
START
BIT
POSSIBLE
PARITY
BIT
BIT 6
BIT 7
BIT 8
STOP
BIT
NEXT
START
BIT
Figure 13-4. SCI Data Formats
Data Sheet
172
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
Functional Description
13.3.2 Transmitter
Figure 13-5 shows the structure of the SCI transmitter.
INTERNAL BUS
BAUD
DIVIDER
÷ 16
SCI DATA REGISTER
SCP1
SCP0
11-BIT
TRANSMIT
SHIFT REGISTER
SCR2
H
SCR1
8
7
6
5
4
3
2
START
PRESCALER
STOP
fOP
÷4
1
0
L
PTF5/TxD
MSB
SCR0
TXINV
T8
TRANSMITTER CPU
INTERRUPT REQUEST
BREAK
ALL 0s
PARITY
GENERATION
PREAMBLE
ALL 1s
PTY
SHIFT ENABLE
PEN
LOAD FROM SCDR
M
TRANSMITTER
CONTROL LOGIC
SCTE
SCTE
SCTIE
TC
TCIE
SBK
LOOPS
SCTIE
ENSCI
TC
TE
TCIE
Figure 13-5. SCI Transmitter
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
173
Serial Communications Interface Module (SCI)
13.3.2.1 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).
13.3.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character out to the
PTF5/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 1 to the enable SCI bit (ENSCI) in SCI control
register 1 (SCC1).
2. Enable the transmitter by writing a 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 1s. After the preamble shifts out, control
logic transfers the SCDR data into the transmit shift register. A 0 start bit
automatically goes into the least significant bit (LSB) position of the transmit shift
register. A 1 stop bit goes into the most significant bit (MSB) 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 PTF5/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 E pins.
13.3.2.3 Break Characters
Writing a 1 to the send break bit, SBK, in SCC2 loads the transmit shift register with
a break character. A break character contains all 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 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.
Data Sheet
174
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
Functional Description
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
13.3.2.4 Idle Characters
An idle character contains all 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 PTF5/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.
NOTE:
When a break sequence is followed immediately by an idle character, this SCI
design exhibits a condition in which the break character length is reduced by one
half bit time. In this instance, the break sequence will consist of a valid start bit,
eight or nine data bits (as defined by the M bit in SCC1) of logic 0 and one half data
bit length of logic 0 in the stop bit position followed immediately by the idle
character. To ensure a break character of the proper length is transmitted, always
queue up a byte of data to be transmitted while the final break sequence is in
progress.
When queueing an idle character, return the TE bit to 1 before the stop bit of the
current character shifts out to the PTF5/TxD pin. Setting TE after the stop bit
appears on PTF5/TxD causes data previously written to the SCDR to be lost.
A good time to toggle the TE bit is when the SCTE bit becomes set and just before
writing the next byte to the SCDR.
13.3.2.5 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 1. See 13.7.1 SCI Control Register 1.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
175
Serial Communications Interface Module (SCI)
13.3.2.6 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.
13.3.3 Receiver
Figure 13-6 shows the structure of the SCI receiver.
13.3.3.1 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).
13.3.3.2 Character Reception
During an SCI reception, the receive shift register shifts characters in from the
PTF4/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.
13.3.3.3 Data Sampling
The receiver samples the PTF4/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 these times (see Figure 13-7):
Data Sheet
176
•
After every start bit
•
After the receiver detects a data bit change from 1 to 0 (after the majority of
data bit samples at RT8, RT9, and RT10 return a valid 1 and the majority of
the next RT8, RT9, and RT10 samples return a valid 0)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
Functional Description
INTERNAL BUS
SCR2
SCR1
SCP0
SCR0
BAUD
PRESCALER DIVIDER
fOP
DATA
RECOVERY
PTF4/RxD
H
11-BIT
RECEIVE SHIFT REGISTER
8
7
6
5
ALL 1s
M
WAKE
ILTY
PEN
PTY
4
3
2
1
0
L
ALL 0s
RPF
CPU INTERRUPT REQUEST
ERROR CPU INTERRUPT REQUEST
BKF
STOP
÷ 16
MSB
÷4
SCI DATA REGISTER
START
SCP1
SCRF
WAKEUP
LOGIC
PARITY
CHECKING
IDLE
ILIE
RWU
IDLE
R8
ILIE
SCRF
SCRIE
OR
ORIE
NF
NEIE
FE
FEIE
PE
PEIE
SCRIE
OR
ORIE
NF
NEIE
FE
FEIE
PE
PEIE
Figure 13-6. SCI Receiver Block Diagram
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
177
Serial Communications Interface Module (SCI)
START BIT
LSB
PTF4/RxD
START BIT
QUALIFICATION
SAMPLES
START BIT
VERIFICATION
DATA
SAMPLING
RT4
RT3
RT2
RT16
RT1
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT CLOCK
STATE
RT1
RT
CLOCK
RT CLOCK
RESET
Figure 13-7. Receiver Data Sampling
To locate the start bit, data recovery logic does an asynchronous search for a 0
preceded by three 1s. When the falling edge of a possible start bit occurs, the RT
clock begins to count to 16.
To verify the start bit and to detect noise, data recovery logic takes samples at RT3,
RT5, and RT7. Table 13-1 summarizes the results of the start bit verification
samples.
Table 13-1. 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
If start bit verification is not successful, the RT clock is reset and a new search for
a start bit begins.
Data Sheet
178
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
Functional Description
To determine the value of a data bit and to detect noise, recovery logic takes
samples at RT8, RT9, and RT10. Table 13-2 summarizes the results of the data
bit samples.
Table 13-2. Data Bit Recovery
NOTE:
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
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 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 13-3 summarizes the results of the stop bit samples.
Table 13-3. 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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
179
Serial Communications Interface Module (SCI)
13.3.3.4 Framing Errors
If the data recovery logic does not detect a 1 where the stop bit should be in an
incoming character, it sets the framing error bit, FE, in SCS1. The FE flag is set at
the same time that the SCRF bit is set. A break character that has no stop bit also
sets the FE bit.
13.3.3.5 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
PTF4/RxD pin can bring the receiver out of the standby state:
NOTE:
•
Address mark — An address mark is a 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 PTF4/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 full bit, SCRF. The idle line type
bit, ILTY, determines whether the receiver begins counting 1s as idle
character bits after the start bit or after the stop bit.
Clearing the WAKE bit after the PTF4/RxD pin has been idle can cause the receiver
to wake up immediately.
13.3.3.6 Receiver Interrupts
These sources can generate CPU interrupt requests from the SCI receiver:
Data Sheet
180
•
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
1s shifted in from the PTF4/RxD pin. The idle line interrupt enable bit, ILIE,
in SCC2 enables the IDLE bit to generate CPU interrupt requests.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
Wait Mode
13.3.3.7 Error Interrupts
These 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.
• Framing error (FE) — The FE bit in SCS1 is set when a 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.
13.4 Wait Mode
The WAIT and STOP instructions put the MCU in low power-consumption standby
modes.
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.
13.5 SCI During Break Module Interrupts
The system integration module (SIM) controls whether status bits in other modules
can be cleared during interrupts generated by the break module. 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 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 0 to the BCFE bit. With BCFE
at 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 0. After the
break, doing the second step clears the status bit.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
181
Serial Communications Interface Module (SCI)
13.6 I/O Signals
Port F shares two of its pins with the SCI module. The two SCI input/output (I/O)
pins are:
•
PTF5/TxD — Transmit data
•
PTF4/RxD — Receive data
13.6.1 PTF5/TxD (Transmit Data)
The PTF5/TxD pin is the serial data output from the SCI transmitter. The SCI
shares the PTF5/TxD pin with port F. When the SCI is enabled, the PTF5/TxD pin
is an output regardless of the state of the DDRF5 bit in data direction register F
(DDRF).
13.6.2 PTF4/RxD (Receive Data)
The PTF4/RxD pin is the serial data input to the SCI receiver. The SCI shares the
PTF4/RxD pin with port F. When the SCI is enabled, the PTF4/RxD pin is an input
regardless of the state of the DDRF4 bit in data direction register F (DDRF).
13.7 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)
13.7.1 SCI Control Register 1
SCI control register 1 (SCC1):
Data Sheet
182
•
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
Address: $0038
Read:
Write:
Reset:
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 13-8. SCI Control Register 1 (SCC1)
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the PTF4/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.
M — Mode (Character Length) Bit
This read/write bit determines whether SCI characters are eight or nine bits
long. See Table 13-4. 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 1 (address
mark) in the most significant bit (MSB) position of a received character or an idle
condition on the PTF4/RxD pin. Reset clears the WAKE bit.
1 = Address mark wakeup
0 = Idle line wakeup
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
183
Serial Communications Interface Module (SCI)
ILTY — Idle Line Type Bit
This read/write bit determines when the SCI starts counting 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 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 13-4. When
enabled, the parity function inserts a parity bit in the most significant bit position.
See Figure 13-4. Reset clears the PEN bit.
1 = Parity function enabled
0 = Parity function disabled
PTY — Parity Bit
This read/write bit determines whether the SCI generates and checks for odd
parity or even parity. See Table 13-4. 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 13-4. Character Format Selection
Control Bits
Data Sheet
184
Character Format
M
PEN: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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
13.7.2 SCI Control Register 2
SCI control register 2 (SCC2):
•
Enables these 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
•
Enables the transmitter
•
Enables the receiver
•
Enables SCI wakeup
•
Transmits SCI break characters
Address: $0039
Read:
Write:
Reset:
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 13-9. 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. Setting the SCTIE bit in SCC3 enables SCTE 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. Setting the SCRIE bit in SCC3 enables the SCRF bit to generate 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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
185
Serial Communications Interface Module (SCI)
TE — Transmitter Enable Bit
Setting this read/write bit begins the transmission by sending a preamble of 10
or 11 1s from the transmit shift register to the PTF5/TxD pin. If software clears
the TE bit, the transmitter completes any transmission in progress before the
PTF5/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
SBK — Send Break Bit
Setting and then clearing this read/write bit transmits a break character followed
by a 1. The 1 after the break character guarantees recognition of a valid start
bit. If SBK remains set, the transmitter continuously transmits break characters
with no 1s between them. Reset clears the SBK bit.
1 = Transmit break characters
0 = No break characters being transmitted
NOTE:
Data Sheet
186
Do not toggle the SBK bit immediately after setting the SCTE bit. Toggling SBK too
early causes the SCI to send a break character instead of a preamble.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
13.7.3 SCI Control Register 3
SCI control register 3 (SCC3):
•
Stores the ninth SCI data bit received and the ninth SCI data bit to be
transmitted
•
Enables SCI receiver full (SCRF)
•
Enables SCI transmitter empty (SCTE)
•
Enables the following interrupts:
– Receiver overrun interrupts
– Noise error interrupts
– Framing error interrupts
– Parity error interrupts
Address:
$003A
Bit 7
6
Read:
R8
Write:
R
Reset:
U
U
R
= Reserved
T8
5
4
0
0
R
R
0
0
3
2
1
Bit 0
ORIE
NEIE
FEIE
PEIE
0
0
0
0
U = Unaffected
Figure 13-10. SCI Control Register 3 (SCC3)
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 eight 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.
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
187
Serial Communications Interface Module (SCI)
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 13.7.4 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
13.7.4 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: $003B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
R
R
R
R
R
R
R
R
Reset:
1
1
0
0
0
0
0
0
R
= Reserved
Figure 13-11. 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
Data Sheet
188
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
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 cleared automatically
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 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 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 13-12 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 flag-clearing sequence reads byte 3 in the SCDR instead of
byte 2.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
189
Serial Communications Interface Module (SCI)
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 13-12. Flag Clearing Sequence
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 flag-clearing 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 PTF4/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 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
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
Data Sheet
190
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
13.7.5 SCI Status Register 2
SCI status register 2 (SCS2) contains flags to signal these conditions:
•
Break character detected
•
Incoming data
Address:
$003C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
BKF
RPF
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 13-13. SCI Status Register 2 (SCS2)
BKF — Break Flag
This clearable, read-only bit is set when the SCI detects a break character on
the PTF4/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 PTF4/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
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
191
Serial Communications Interface Module (SCI)
13.7.6 SCI Data Register
The SCI data register (SCDR) is the buffer between the internal data bus and the
receive and transmit shift registers. Reset has no effect on data in the SCI data
register.
Address:
$003D
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 13-14. SCI Data Register (SCDR)
R7/T7:R0/T0 — Receive/Transmit Data Bits
Reading address $003D accesses the read-only received data bits, R7:R0.
Writing to address $003D writes the data to be transmitted, T7:T0. Reset has no
effect on the SCI data register.
13.7.7 SCI Baud Rate Register
The baud rate register (SCBR) selects the baud rate for both the receiver and the
transmitter.
Address:
$003E
Bit 7
6
Read:
0
0
Write:
R
R
Reset:
0
0
R
= Reserved
5
4
SCP1
SCP0
0
0
3
0
R
2
1
Bit 0
SCR2
SCR1
SCR0
0
0
0
0
Figure 13-15. 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
13-5. Reset clears SCP1 and SCP0.
Table 13-5. SCI Baud Rate Prescaling
Data Sheet
192
SCP1:SCP0
Prescaler Divisor (PD)
00
1
01
3
10
4
11
13
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Serial Communications Interface Module (SCI)
I/O Registers
SCR2–SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in Table 13-6.
Reset clears SCR2–SCR0.
Table 13-6. SCI Baud Rate Selection
SCR2:SCR1: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:
f OP
Baud rate = -----------------------------------64 × PD × BD
where:
fOP = internal operating frequency
PD = prescaler divisor
BD = baud rate divisor
Table 13-7 shows the SCI baud rates that can be generated with a 4.9152-MHz
crystal with the CGM set for an fOP of 7.3728 MHz and the CGM set for an fOP of
4.9152 MHz.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Communications Interface Module (SCI)
Data Sheet
193
Serial Communications Interface Module (SCI)
Table 13-7. SCI Baud Rate Selection Examples
SCP1:SCP0
Prescaler
Divisor (PD)
SCR2:SCR1:SCR0
Baud Rate
Divisor (BD)
Baud Rate
(fOP = 7.3728 MHz)
Baud Rate
(fOP = 4.9152 MHz)
00
1
000
1
115,200
76,800
00
1
001
2
57,600
38,400
00
1
010
4
28,800
19,200
00
1
011
8
14,400
9600
00
1
100
16
7200
4800
00
1
101
32
3600
2400
00
1
110
64
1800
1200
00
1
111
128
900
600
01
3
000
1
38,400
25,600
01
3
001
2
19,200
12,800
01
3
010
4
9600
6400
01
3
011
8
4800
3200
01
3
100
16
2400
1600
01
3
101
32
1200
800
01
3
110
64
600
400
01
3
111
128
300
200
10
4
000
1
28,800
19,200
10
4
001
2
14,400
9600
10
4
010
4
7200
4800
10
4
011
8
3600
2400
10
4
100
16
1800
1200
10
4
101
32
900
600
10
4
110
64
450
300
10
4
111
128
225
150
11
13
000
1
8861.5
5907.7
11
13
001
2
4430.7
2953.8
11
13
010
4
2215.4
1476.9
11
13
011
8
1107.7
738.5
11
13
100
16
553.8
369.2
11
13
101
32
276.9
184.6
11
13
110
64
138.5
92.3
11
13
111
128
69.2
46.2
Data Sheet
194
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Communications Interface Module (SCI)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 14. System Integration Module (SIM)
14.1 Introduction
This section describes the system integration module (SIM). Together with the
central processor unit (CPU), the SIM controls all microcontroller unit (MCU)
activities.
A block diagram of the SIM is shown in Figure 14-1.
The SIM is a system state controller that coordinates CPU and exception timing.
The SIM is responsible for:
•
Bus clock generation and control for CPU and peripherals:
– Wait/reset/break entry and recovery
– Internal clock control
•
Master reset control, including power-on reset (POR) and computer
operating properly (COP) timeout
•
Interrupt control:
– Acknowledge timing
– Arbitration control timing
– Vector address generation
•
CPU enable/disable timing
•
Modular architecture expandable to 128 interrupt sources
Table 14-1 shows the internal signal names used in this section.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
195
System Integration Module (SIM)
MODULE WAIT
WAIT
CONTROL
CPU WAIT (FROM CPU)
SIMOSCEN (TO CGM)
SIM
COUNTER
COP CLOCK
CGMXCLK (FROM CGM)
CGMOUT (FROM CGM)
÷2
CLOCK
CONTROL
RESET
PIN LOGIC
CLOCK GENERATORS
INTERNAL CLOCKS
LVI (FROM LVI MODULE)
POR CONTROL
MASTER
RESET
CONTROL
RESET PIN CONTROL
SIM RESET STATUS REGISTER
ILLEGAL OPCODE (FROM CPU)
ILLEGAL ADDRESS (FROM ADDRESS
MAP DECODERS)
COP (FROM COP MODULE)
RESET
INTERRUPT SOURCES
INTERRUPT CONTROL
AND PRIORITY DECODE
CPU INTERFACE
Figure 14-1. SIM Block Diagram
Table 14-1. Signal Name Conventions
Signal Name
CGMXCLK
Buffered version of OSC1 from clock generator module (CGM)
CGMVCLK
Phase-locked loop (PLL) circuit output
CGMOUT
PLL-based or OSC1-based clock output from CGM module (bus clock = CGMOUT divided by two)
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
Data Sheet
196
Description
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
SIM Bus Clock Control and Generation
14.2 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, CGMOUT,
as shown in Figure 14-2. This clock can come from either an external oscillator or
from the on-chip phase-locked loop (PLL) circuit. See Section 4. Clock Generator
Module (CGM).
CGMXCLK
OSC1
CLOCK
SELECT
CIRCUIT
CGMVCLK
÷2
A
CGMOUT
B S*
*When S = 1,
CGMOUT = B
BUS CLOCK
GENERATORS
÷2
SIM
BCS
PLL
SIM COUNTER
PTC2
MONITOR MODE
USER MODE
CGM
Figure 14-2. CGM Clock Signals
14.2.1 Bus Timing
In user mode, the internal bus frequency is either the crystal oscillator output
(CGMXCLK) divided by four or the PLL output (CGMVCLK) divided by four. See
Section 4. Clock Generator Module (CGM).
14.2.2 Clock Startup from POR or LVI Reset
When the power-on reset (POR) module or the low-voltage inhibit (LVI) module
generates a reset, the clocks to the CPU and peripherals are inactive and held in
an inactive phase until after the 4096 CGMXCLK cycle POR timeout has
completed. The RST pin is driven low by the SIM during this entire period. The
internal bus (IBUS) clocks start upon completion of the timeout.
14.2.3 Clocks in Wait 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.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
197
System Integration Module (SIM)
14.3 Reset and System Initialization
The MCU has these reset sources:
•
Power-on reset module (POR)
•
External reset pin (RST)
•
Computer operating properly (COP) module
•
Low-voltage inhibit (LVI) module
•
Illegal opcode
•
Illegal address
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 14.4 SIM Counter), but an external
reset does not. Each of the resets sets a corresponding bit in the SIM reset status
register (SRSR). See 14.7.2 SIM Reset Status Register.
14.3.1 External Pin Reset
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
CGMXCLK cycles, assuming that neither the POR nor the LVI was the source of
the reset. See Table 14-2 for details. Figure 14-3 shows the relative timing.
Table 14-2. PIN Bit Set Timing
Reset Type
Number of Cycles Required to Set PIN
POR/LVI
4163 (4096 + 64 + 3)
All others
67 (64 + 3)
CGMOUT
RST
IAB
PC
VECT H
VECT L
Figure 14-3. External Reset Timing
Data Sheet
198
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
Reset and System Initialization
14.3.2 Active Resets from Internal Sources
All internal reset sources actively pull the RST pin low for 32 CGMXCLK cycles to
allow resetting of external peripherals. The internal reset signal (IRST) continues
to be asserted for an additional 32 cycles (see Figure 14-5). An internal reset can
be caused by an illegal address, illegal opcode, COP timeout, LVI, or POR. (See
Figure 14-4.)
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
LVI
POR
INTERNAL RESET
Figure 14-4. Sources of Internal Reset
NOTE:
For LVI or POR resets, the SIM cycles through 4096 CGMXCLK cycles during
which the SIM forces the RST pin low. The internal reset signal then follows the
sequence from the falling edge of RST, as shown in Figure 14-5.
IRST
RST PULLED LOW BY MCU
RST
32 CYCLES
32 CYCLES
CGMXCLK
IAB
VECTOR HIGH
Figure 14-5. Internal Reset Timing
The COP reset is asynchronous to the bus clock.
The active reset feature allows the part to issue a reset to peripherals and other
chips within a system built around the MCU.
14.3.2.1 Power-On Reset (POR)
When power is first applied to the MCU, the power-on reset (POR) module
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 CGMXCLK cycles.
Sixty-four CGMXCLK cycles later, the CPU and memories are released from reset
to allow the reset vector sequence to occur.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
199
System Integration Module (SIM)
OSC1
PORRST
4096
CYCLES
32
CYCLES
32
CYCLES
CGMXCLK
CGMOUT
RST
$FFFE
IAB
$FFFF
Figure 14-6. POR Recovery
At power-on, these events occur:
•
A POR pulse is generated.
•
The internal reset signal is asserted.
•
The SIM enables CGMOUT.
•
Internal clocks to the CPU and modules are held inactive for 4096
CGMXCLK 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.
14.3.2.2 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 $FFFF clears the COP counter and bits 12–4 of the SIM counter. The SIM
counter output, which occurs at least every 213–24 CGMXCLK cycles, drives the
COP counter. The COP should be serviced as soon as possible out of reset to
guarantee the maximum amount of time before the first timeout.
The COP module is disabled if the RST pin or the IRQ pin is held at VHI while the
MCU is in monitor mode. The COP module can be disabled only through
combinational logic conditioned with the high voltage signal on the RST or the IRQ
Data Sheet
200
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
SIM Counter
pin. This prevents the COP from becoming disabled as a result of external noise.
During a break state, VHI on the RST pin disables the COP module.
14.3.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An illegal
instruction sets the ILOP bit in the SIM reset status register (SRSR) and causes a
reset.
Because the MC68HC908MR32 has stop mode disabled, execution of the STOP
instruction will cause an illegal opcode reset.
14.3.2.4 Illegal Address Reset
An opcode fetch from addresses other than FLASH or RAM addresses generates
an illegal address reset (unimplemented locations within memory map). The SIM
verifies that the CPU is fetching an opcode prior to asserting the ILAD bit in the SIM
reset status register (SRSR) and resetting the MCU. A data fetch from an
unmapped address does not generate a reset.
14.3.2.5 Forced Monitor Mode Entry Reset (MENRST)
The MENRST module monitors the reset vector fetches and will assert an internal
reset if it detects that the reset vectors are erased ($FF). When the MCU comes
out of reset, it is forced into monitor mode.
14.3.2.6 Low-Voltage Inhibit (LVI) Reset
The low-voltage inhibit (LVI) module asserts its output to the SIM when the VDD
voltage falls to the VLVRX voltage and remains at or below that level for at least nine
consecutive CPU cycles (see 19.5 DC Electrical Characteristics). 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 CGMXCLK cycles. Sixty-four
CGMXCLK 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.
14.4 SIM Counter
The SIM counter is used by the power-on reset (POR) module 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 (COP) module. The
SIM counter overflow supplies the clock for the COP module. The SIM counter is
13 bits long and is clocked by the falling edge of CGMXCLK.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
201
System Integration Module (SIM)
14.4.1 SIM Counter During Power-On Reset
The power-on reset (POR) module detects power applied to the MCU. At
power-on, the POR circuit asserts the signal PORRST. Once the SIM is initialized,
it enables the clock generation (CGM) module to drive the bus clock state machine.
14.4.2 SIM Counter and Reset States
External reset has no effect on the SIM counter. The SIM counter is free-running
after all reset states. For counter control and internal reset recovery sequences,
see 14.3.2 Active Resets from Internal Sources.
14.5 Exception Control
Normal, sequential program execution can be changed in three different ways:
1. Interrupts:
a. Maskable hardware CPU interrupts
b. Non-maskable software interrupt instruction (SWI)
2. Reset
3. Break interrupts
14.5.1 Interrupts
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 return-from-interrupt (RTI) instruction recovers the CPU register
contents from the stack so that normal processing can resume. Figure 14-7 shows
interrupt entry timing. Figure 14-9 shows interrupt recovery timing.
MODULE
INTERRUPT
I BIT
IAB
IDB
DUMMY
DUMMY
SP
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 14-7. Interrupt Entry
Data Sheet
202
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
Exception Control
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). See Figure 14-8.
FROM RESET
BREAK
OR SWI
I BIT SET?
INTERRUPT?
YES
NO
YES
I BIT SET?
NO
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 14-8. Interrupt Processing
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
203
System Integration Module (SIM)
MODULE
INTERRUPT
I BIT
IAB
SP – 4
IDB
SP – 3
CCR
SP – 2
A
SP – 1
X
SP
PC
PC + 1
PC – 1[7:0] PC – 1[15:8] OPCODE
OPERAND
R/W
Figure 14-9. Interrupt Recovery
14.5.1.1 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 14-10 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
load-accumulator-from- memory (LDA) instruction is executed.
CLI
LDA#$FF
INT1
BACKGROUND ROUTINE
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
INT2
PSHH
INT2 INTERRUPT SERVICE ROUTINE
PULH
RTI
Figure 14-10. 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:
Data Sheet
204
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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
Low-Power Mode
register or uses the indexed addressing mode, software should save the H register
and then restore it prior to exiting the routine.
14.5.1.2 Software Interrupt (SWI) Instruction
The software interrupt (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.
14.5.2 Reset
All reset sources always have equal and highest priority and cannot be arbitrated.
14.6 Low-Power Mode
Executing the WAIT instruction puts the MCU in a low power-consumption mode
for standby situations. The SIM holds the CPU in a non-clocked state. WAIT clears
the interrupt mask (I) in the condition code register, allowing interrupts to occur.
14.6.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks continue to
run. Figure 14-11 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. 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. If the COP disable bit, COPD, in the
configuration register is logic 0, then the computer operating properly module
(COP) is enabled and remains active in wait mode.
IAB
WAIT ADDR
IDB
WAIT ADDR + 1
PREVIOUS DATA
NEXT OPCODE
SAME
SAME
SAME
SAME
R/W
Note: Previous data can be operand data or the WAIT opcode, depending on the
last instruction.
Figure 14-11. Wait Mode Entry Timing
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
205
System Integration Module (SIM)
Figure 14-12 and Figure 14-13 show the timing for wait recovery.
IAB
IDB
$6E0B
$A6
$A6
$6E0C
$A6
$00FF
$01
$0B
$00FE
$00FD
$00FC
$6E
EXITSTOPWAIT
Note: EXITSTOPWAIT = RST pin OR CPU interrupt
Figure 14-12. Wait Recovery from Interrupt
32
CYCLES
IAB
IDB
32
CYCLES
$6E0B
$A6
$A6
RST VCT H RST VCT L
$A6
RST
CGMXCLK
Figure 14-13. Wait Recovery from Internal Reset
14.6.2 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.
The SIM disables the clock generator module outputs (CGMOUT and CGMXCLK)
in stop mode, stopping the CPU and peripherals. Stop recovery time is hard wired
at the normal delay of 4096 CGMXCLK cycles.
It is important to note that when using the PWM generator, its outputs will stop
toggling when stop mode is entered. The PWM module must be disabled before
entering stop mode to prevent external inverter failure.
14.7 SIM Registers
This subsection describes the SIM registers.
Data Sheet
206
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
System Integration Module (SIM)
SIM Registers
14.7.1 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a break
caused an exit from wait mode.
Address:
$FE00
BIt 7
6
5
4
3
2
R
R
R
R
R
R
Read:
Write:
1
Bit 0
SBSW
R
Note(1)
Reset:
0
R
= Reserved
Note 1. Writing a logic 0 clears SBSW.
Figure 14-14. SIM Break Status Register (SBSR)
SBSW — SIM Break Stop/Wait
This status bit is useful in applications requiring a return to wait mode after
exiting from a break interrupt. Clear SBSW by writing a logic 0 to it. Reset clears
SBSW.
1 = Wait mode was exited by break interrupt.
0 = 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.
14.7.2 SIM Reset Status Register
The SIM reset status register (SRSR) contains six flags that show the source of the
last reset. Clear the SIM reset status register by reading it. A power-on reset sets
the POR bit and clears all other bits in the register.
Address: $FE01
BIt 7
6
5
4
3
2
1
Bit 0
Read:
POR
PIN
COP
ILOP
ILAD
MENRST
LVI
0
Write:
R
R
R
R
R
R
R
R
Reset:
1
0
0
0
0
0
0
0
R
= Reserved
Figure 14-15. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
PIN — External Reset Bit
1 = Last reset caused by external reset pin (RST)
0 = POR or read of SRSR
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
System Integration Module (SIM)
Data Sheet
207
System Integration Module (SIM)
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
MENRST — Forced Monitor Mode Entry Reset Bit
1 = Last reset caused by the MENRST circuit
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
14.7.3 SIM Break Flag Control Register
The SIM break 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 14-16. 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
Data Sheet
208
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
System Integration Module (SIM)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 15. Serial Peripheral Interface Module (SPI)
15.1 Introduction
The serial peripheral interface (SPI) module allows full-duplex, synchronous, serial
communications with peripheral devices.
15.2 Features
Features of the SPI module include:
•
Full-duplex operation
•
Master and slave modes
•
Double-buffered operation with separate transmit and receive registers
•
Four master mode frequencies (maximum = bus frequency ÷ 2)
•
Maximum slave mode frequency = bus frequency
•
Serial clock with programmable polarity and phase
•
Two separately enabled interrupts with central processor unit (CPU)
service:
– SPRF (SPI receiver full)
– SPTE (SPI transmitter empty)
•
Mode fault error flag with CPU interrupt capability
•
Overflow error flag with CPU interrupt capability
•
Programmable wired-OR mode
•
I2C (inter-integrated circuit) compatibility
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
209
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
CLOCK GENERATOR
MODULE
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
OSC1
OSC2
CGMXFC
TIMER INTERFACE
MODULE B
DDRF
USER FLASH VECTOR SPACE — 46 BYTES
MOTOROLA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MONITOR ROM — 240 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 15-1. Block Diagram Highlighting SPI Block and Pins
Serial Peripheral Interface Module (SPI)
Data Sheet
210
INTERNAL BUS
M68HC08 CPU
Serial Peripheral Interface Module (SPI)
Pin Name Conventions
15.3 Pin Name Conventions
The generic names of the SPI input/output (I/O) pins are:
•
SS, slave select
•
SPSCK, SPI serial clock
•
MOSI, master out/slave in
•
MISO, master in/slave out
SPI pins are shared by parallel I/O ports or have alternate functions. The full name
of an SPI pin reflects the name of the shared port pin or the name of an alternate
pin function. The generic pin names appear in the text that follows. Table 15-1
shows the full names of the SPI I/O pins.
Table 15-1. Pin Name Conventions
Generic Pin Names:
Full Pin Names:
MISO
MOSI
SPSCK
SS
PTF3/MISO
PTF2/MOSI
PTF0/SPSCK
PTF1/SS
15.4 Functional Description
Figure 15-3 shows the structure of the SPI module and Figure 15-2 shows the
locations and contents of the SPI I/O registers.
The SPI module allows full-duplex, synchronous, serial communication between
the microcontroller unit (MCU) and peripheral devices, including other MCUs.
Software can poll the SPI status flags or SPI operation can be interrupt-driven. All
SPI interrupts can be serviced by the CPU.
Addr.
$0044
$0045
$0046
Register Name
SPI Control Register Read:
(SPCR) Write:
See page 228. Reset:
SPI Status and Control Read:
Register (SPSCR) Write:
See page 229. Reset:
SPI Data Register Read:
(SPDR) Write:
See page 232. Reset:
Bit 7
6
5
4
3
2
1
Bit 0
SPRIE
R
SPMSTR
CPOL
CPHA
SPWOM
SPE
SPTIE
0
0
1
0
1
0
0
0
OVRF
MODF
SPTE
R
R
R
MODFEN
SPR1
SPR0
SPRF
R
ERRIE
0
0
0
0
1
0
0
0
R7
R6
R5
R4
R3
R2
R1
R0
T7
T6
T5
T4
T3
T2
T1
T0
Unaffected by reset
R
= Reserved
Figure 15-2. SPI I/O Register Summary
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
211
Serial Peripheral Interface Module (SPI)
INTERNAL BUS
TRANSMIT DATA REGISTER
CGMOUT ÷ 2
(FROM SIM)
SHIFT REGISTER
7
6
5
4
3
2
1
MISO
0
÷2
CLOCK
DIVIDER
MOSI
÷8
RECEIVE DATA REGISTER
÷ 32
PIN
CONTROL
LOGIC
÷ 128
SPMSTR
SPE
CLOCK
SELECT
SPR1
SPSCK
M
CLOCK
LOGIC
S
SS
SPR0
SPMSTR
CPHA
CPOL
SPWOM
TRANSMITTER CPU INTERRUPT REQUEST
MODFEN
ERRIE
SPI
CONTROL
SPTIE
RECEIVER/ERROR CPU INTERRUPT REQUEST
SPRIE
SPE
SPRF
SPTE
OVRF
MODF
Figure 15-3. SPI Module Block Diagram
Data Sheet
212
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Functional Description
15.4.1 Master Mode
The SPI operates in master mode when the SPI master bit, SPMSTR, is set.
NOTE:
Configure the SPI modules as master or slave before enabling them. Enable the
master SPI before enabling the slave SPI. Disable the slave SPI before disabling
the master SPI. See 15.12.1 SPI Control Register.
Only a master SPI module can initiate transmissions. Software begins the
transmission from a master SPI module by writing to the SPI data register. If the
shift register is empty, the byte immediately transfers to the shift register, setting
the SPI transmitter empty bit, SPTE. The byte begins shifting out on the MOSI pin
under the control of the serial clock. See Figure 15-4.
MASTER MCU
SHIFT REGISTER
SLAVE MCU
MISO
MISO
MOSI
MOSI
SPSCK
BAUD RATE
GENERATOR
SS
SHIFT REGISTER
SPSCK
VDD
SS
Figure 15-4. Full-Duplex Master-Slave Connections
The SPR1 and SPR0 bits control the baud rate generator and determine the speed
of the shift register. See 15.12.2 SPI Status and Control Register. Through the
SPSCK pin, the baud-rate generator of the master also controls the shift register of
the slave peripheral.
As the byte shifts out on the MOSI pin of the master, another byte shifts in from the
slave on the master’s MISO pin. The transmission ends when the receiver full bit,
SPRF, becomes set. At the same time that SPRF becomes set, the byte from the
slave transfers to the receive data register. In normal operation, SPRF signals the
end of a transmission. Software clears SPRF by reading the SPI status and control
register with SPRF set and then reading the SPI data register. Writing to the SPI
data register clears the SPTE bit.
15.4.2 Slave Mode
The SPI operates in slave mode when the SPMSTR bit is clear. In slave mode the
SPSCK pin is the input for the serial clock from the master MCU. Before a data
transmission occurs, the SS pin of the slave SPI must be at logic 0. SS must remain
low until the transmission is complete. See 15.6.2 Mode Fault Error.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
213
Serial Peripheral Interface Module (SPI)
In a slave SPI module, data enters the shift register under the control of the serial
clock from the master SPI module. After a byte enters the shift register of a slave
SPI, it transfers to the receive data register, and the SPRF bit is set. To prevent an
overflow condition, slave software then must read the receive data register before
another full byte enters the shift register.
The maximum frequency of the SPSCK for an SPI configured as a slave is the bus
clock speed (which is twice as fast as the fastest master SPSCK clock that can be
generated). The frequency of the SPSCK for an SPI configured as a slave does not
have to correspond to any SPI baud rate. The baud rate only controls the speed of
the SPSCK generated by an SPI configured as a master. Therefore, the frequency
of the SPSCK for an SPI configured as a slave can be any frequency less than or
equal to the bus speed.
When the master SPI starts a transmission, the data in the slave shift register
begins shifting out on the MISO pin. The slave can load its shift register with a new
byte for the next transmission by writing to its transmit data register. The slave must
write to its transmit data register at least one bus cycle before the master starts the
next transmission. Otherwise, the byte already in the slave shift register shifts out
on the MISO pin. Data written to the slave shift register during a transmission
remains in a buffer until the end of the transmission.
When the clock phase bit (CPHA) is set, the first edge of SPSCK starts a
transmission. When CPHA is clear, the falling edge of SS starts a transmission.
See 15.5 Transmission Formats.
NOTE:
If the write to the data register is late, the SPI transmits the data already in the shift
register from the previous transmission.
SPSCK must be in the proper idle state before the slave is enabled to prevent
SPSCK from appearing as a clock edge.
15.5 Transmission Formats
During an SPI transmission, data is simultaneously transmitted (shifted out serially)
and received (shifted in serially). A serial clock synchronizes shifting and sampling
on the two serial data lines. A slave select line allows selection of an individual
slave SPI device; slave devices that are not selected do not interfere with SPI bus
activities. On a master SPI device, the slave select line can optionally be used to
indicate multiple-master bus contention.
15.5.1 Clock Phase and Polarity Controls
Software can select any of four combinations of serial clock (SPSCK) phase and
polarity using two bits in the SPI control register (SPCR). The clock polarity is
specified by the CPOL control bit, which selects an active high or low clock and has
no significant effect on the transmission format.
Data Sheet
214
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Transmission Formats
The clock phase (CPHA) control bit selects one of two fundamentally different
transmission formats. The clock phase and polarity should be identical for the
master SPI device and the communicating slave device. In some cases, the phase
and polarity are changed between transmissions to allow a master device to
communicate with peripheral slaves having different requirements.
NOTE:
Before writing to the CPOL bit or the CPHA bit, disable the SPI by clearing the SPI
enable bit (SPE).
15.5.2 Transmission Format When CPHA = 0
Figure 15-5 shows an SPI transmission in which CPHA is logic 0. The figure should
not be used as a replacement for data sheet parametric information.Two
waveforms are shown for SPSCK: one for CPOL = 0 and another for CPOL = 1.
The diagram may be interpreted as a master or slave timing diagram since the
serial clock (SPSCK), master in/slave out (MISO), and master out/slave in (MOSI)
pins are directly connected between the master and the slave. The MISO signal is
the output from the slave, and the MOSI signal is the output from the master. The
SS line is the slave select input to the slave. The slave SPI drives its MISO output
only when its slave select input (SS) is at logic 0, so that only the selected slave
drives to the master. The SS pin of the master is not shown but is assumed to be
inactive. The SS pin of the master must be high or must be reconfigured as
general-purpose I/O not affecting the SPI. (See 15.6.2 Mode Fault Error.) When
CPHA = 0, the first SPSCK edge is the MSB capture strobe. Therefore, the slave
must begin driving its data before the first SPSCK edge, and a falling edge on the
SS pin is used to start the slave data transmission. The slave’s SS pin must be
toggled back to high and then low again between each byte transmitted as shown
in Figure 15-6.
SPSCK CYCLE #
FOR REFERENCE
1
2
3
4
5
6
7
8
MSB
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
LSB
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
LSB
SPSCK, CPOL = 0
SPSCK, CPOL = 1
MOSI
FROM MASTER
MISO
FROM SLAVE
MSB
SS, TO SLAVE
CAPTURE STROBE
Figure 15-5. Transmission Format (CPHA = 0)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
215
Serial Peripheral Interface Module (SPI)
MISO/MOSI
BYTE 1
BYTE 2
BYTE 3
MASTER SS
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 15-6. CPHA/SS Timing
When CPHA = 0 for a slave, the falling edge of SS indicates the beginning of the
transmission. This causes the SPI to leave its idle state and begin driving the MISO
pin with the MSB of its data. Once the transmission begins, no new data is allowed
into the shift register from the transmit data register. Therefore, the SPI data
register of the slave must be loaded with transmit data before the falling edge of
SS. Any data written after the falling edge is stored in the transmit data register and
transferred to the shift register after the current transmission.
15.5.3 Transmission Format When CPHA = 1
Figure 15-7 shows an SPI transmission in which CPHA is logic 1. The figure should
not be used as a replacement for data sheet parametric information. Two
waveforms are shown for SPSCK: one for CPOL = 0 and another for CPOL = 1.
The diagram may be interpreted as a master or slave timing diagram since the
serial clock (SPSCK), master in/slave out (MISO), and master out/slave in (MOSI)
pins are directly connected between the master and the slave. The MISO signal is
the output from the slave, and the MOSI signal is the output from the master. The
SS line is the slave select input to the slave. The slave SPI drives its MISO output
only when its slave select input (SS) is at logic 0, so that only the selected slave
drives to the master. The SS pin of the master is not shown but is assumed to be
inactive. The SS pin of the master must be high or must be reconfigured as
general-purpose I/O not affecting the SPI. See 15.6.2 Mode Fault Error. When
CPHA = 1, the master begins driving its MOSI pin on the first SPSCK edge.
Therefore, the slave uses the first SPSCK edge as a start transmission signal. The
SS pin can remain low between transmissions. This format may be preferable in
systems having only one master and only one slave driving the MISO data line.
When CPHA = 1 for a slave, the first edge of the SPSCK indicates the beginning
of the transmission. This causes the SPI to leave its idle state and begin driving the
MISO pin with the MSB of its data. Once the transmission begins, no new data is
allowed into the shift register from the transmit data register. Therefore, the SPI
data register of the slave must be loaded with transmit data before the first edge of
SPSCK. Any data written after the first edge is stored in the transmit data register
and transferred to the shift register after the current transmission.
Data Sheet
216
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Error Conditions
SPSCK CYCLE #
FOR REFERENCE
1
2
3
4
5
6
7
8
MOSI
FROM MASTER
MSB
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
LSB
MISO
FROM SLAVE
MSB
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
SPSCK, CPOL = 0
SPSCK, CPOL = 1
LSB
SS, TO SLAVE
CAPTURE STROBE
Figure 15-7. Transmission Format (CPHA = 1)
15.5.4 Transmission Initiation Latency
When the SPI is configured as a master (SPMSTR = 1), writing to the SPDR starts
a transmission. CPHA has no effect on the delay to the start of the transmission,
but it does affect the initial state of the SPSCK signal. When CPHA = 0, the SPSCK
signal remains inactive for the first half of the first SPSCK cycle. When CPHA = 1,
the first SPSCK cycle begins with an edge on the SPSCK line from its inactive to
its active level. The SPI clock rate (selected by SPR1:SPR0) affects the delay from
the write to SPDR and the start of the SPI transmission. See
Figure 15-8 The internal SPI clock in the master is a free-running derivative of the
internal MCU clock. To conserve power, it is enabled only when both the SPE and
SPMSTR bits are set. SPSCK edges occur halfway through the low time of the
internal MCU clock. Since the SPI clock is free-running, it is uncertain where the
write to the SPDR occurs relative to the slower SPSCK. This uncertainty causes
the variation in the initiation delay shown in Figure 15-8. This delay is no longer
than a single SPI bit time. That is, the maximum delay is two MCU bus cycles for
DIV2, eight MCU bus cycles for DIV8, 32 MCU bus cycles for DIV32, and 128 MCU
bus cycles for DIV128.
15.6 Error Conditions
These flags signal SPI error conditions:
•
Overflow (OVRF) — Failing to read the SPI data register before the next full
byte enters the shift register sets the OVRF bit. The new byte does not
transfer to the receive data register, and the unread byte still can be read.
OVRF is in the SPI status and control register.
•
Mode fault error (MODF) — The MODF bit indicates that the voltage on the
slave select pin (SS) is inconsistent with the mode of the SPI. MODF is in
the SPI status and control register.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
217
Serial Peripheral Interface Module (SPI)
WRITE
TO SPDR
INITIATION DELAY
BUS
CLOCK
MOSI
MSB
BIT 6
BIT 5
SPSCK
CPHA = 1
SPSCK
CPHA = 0
SPSCK CYCLE
NUMBER
1
2
3
INITIATION DELAY FROM WRITE SPDR TO TRANSFER BEGIN
WRITE
TO SPDR
BUS
CLOCK
EARLIEST LATEST
SPSCK = INTERNAL CLOCK ÷ 2;
2 POSSIBLE START POINTS
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
WRITE
TO SPDR
SPSCK = INTERNAL CLOCK ÷ 8;
8 POSSIBLE START POINTS
LATEST
SPSCK = INTERNAL CLOCK ÷ 32;
32 POSSIBLE START POINTS
LATEST
SPSCK = INTERNAL CLOCK ÷ 128;
128 POSSIBLE START POINTS
LATEST
BUS
CLOCK
EARLIEST
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
Figure 15-8. Transmission Start Delay (Master)
15.6.1 Overflow Error
The overflow flag (OVRF) becomes set if the receive data register still has unread
data from a previous transmission when the capture strobe of bit 1 of the next
transmission occurs. If an overflow occurs, all data received after the overflow and
before the OVRF bit is cleared does not transfer to the receive data register and
does not set the SPI receiver full bit (SPRF). The unread data that transferred to
the receive data register before the overflow occurred can still be read. Therefore,
Data Sheet
218
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Error Conditions
an overflow error always indicates the loss of data. Clear the overflow flag by
reading the SPI status and control register and then reading the SPI data register.
OVRF generates a receiver/error CPU interrupt request if the error interrupt enable
bit (ERRIE) is also set. MODF and OVRF can generate a receiver/error CPU
interrupt request. See Figure 15-11. It is not possible to enable MODF or OVRF
individually to generate a receiver/error CPU interrupt request. However, leaving
MODFEN low prevents MODF from being set.
If the CPU SPRF interrupt is enabled and the OVRF interrupt is not, watch for an
overflow condition. Figure 15-9 shows how it is possible to miss an overflow. The
first part of Figure 15-9 shows how it is possible to read the SPSCR and SPDR to
clear the SPRF without problems. However, as illustrated by the second
transmission example, the OVRF bit can be set in between the time that SPSCR
and SPDR
are read.
BYTE 1
BYTE 2
BYTE 3
BYTE 4
1
4
6
8
SPRF
OVRF
READ
SPSCR
2
READ
SPDR
5
3
1
BYTE 1 SETS SPRF BIT.
2
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
CPU READS BYTE 1 IN SPDR,
CLEARING SPRF BIT.
BYTE 2 SETS SPRF BIT.
3
4
7
5
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
6
BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST.
7
CPU READS BYTE 2 IN SPDR, CLEARING SPRF BIT,
BUT NOT OVRF BIT.
8
BYTE 4 FAILS TO SET SPRF BIT BECAUSE
OVRF BIT IS NOT CLEARED. BYTE 4 IS LOST.
Figure 15-9. Missed Read of Overflow Condition
In this case, an overflow can easily be missed. Since no more SPRF interrupts can
be generated until this OVRF is serviced, it is not obvious that bytes are being lost
as more transmissions are completed. To prevent this, either enable the OVRF
interrupt or do another read of the SPSCR following the read of the SPDR. This
ensures that the OVRF was not set before the SPRF was cleared and that future
transmissions can set the SPRF bit. Figure 15-10 illustrates this process.
Generally, to avoid this second SPSCR read, enable the OVRF interrupt to the
CPU by setting the ERRIE bit.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
219
Serial Peripheral Interface Module (SPI)
BYTE 1
SPI RECEIVE
COMPLETE
BYTE 2
5
1
BYTE 3
7
BYTE 4
11
SPRF
OVRF
READ
SPSCR
2
READ
SPDR
4
6
3
8
1
BYTE 1 SETS SPRF BIT.
2
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
CPU READS BYTE 1 IN SPDR,
CLEARING SPRF BIT.
3
9
12
10
14
13
8
CPU READS BYTE 2 IN SPDR,
CLEARING SPRF BIT.
9
CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
10 CPU READS BYTE 2 SPDR,
CLEARING OVRF BIT.
4
CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
11 BYTE 4 SETS SPRF BIT.
5
BYTE 2 SETS SPRF BIT.
12 CPU READS SPSCR.
6
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
13 CPU READS BYTE 4 IN SPDR,
CLEARING SPRF BIT.
7
BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST.
14 CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
Figure 15-10. Clearing SPRF When OVRF Interrupt Is Not Enabled
15.6.2 Mode Fault Error
Setting the SPMSTR bit selects master mode and configures the SPSCK and
MOSI pins as outputs and the MISO pin as an input. Clearing SPMSTR selects
slave mode and configures the SPSCK and MOSI pins as inputs and the MISO pin
as an output. The mode fault bit, MODF, becomes set any time the state of the
slave select pin, SS, is inconsistent with the mode selected by SPMSTR.
To prevent SPI pin contention and damage to the MCU, a mode fault error occurs if:
•
The SS pin of a slave SPI goes high during a transmission.
•
The SS pin of a master SPI goes low at any time.
For the MODF flag to be set, the mode fault error enable bit (MODFEN) must be
set. Clearing the MODFEN bit does not clear the MODF flag but does prevent
MODF from being set again after MODF is cleared.
MODF generates a receiver/error CPU interrupt request if the error interrupt enable
bit (ERRIE) is also set. The SPRF, MODF, and OVRF interrupts share the same
CPU interrupt vector. MODF and OVRF can generate a receiver/error CPU
interrupt request. See Figure 15-11. It is not possible to enable MODF or OVRF
individually to generate a receiver/error CPU interrupt request. However, leaving
MODFEN low prevents MODF from being set.
Data Sheet
220
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Error Conditions
In a master SPI with the mode fault enable bit (MODFEN) set, the mode fault flag
(MODF) is set if SS goes to logic 0. A mode fault in a master SPI causes these
events to occur:
NOTE:
•
If ERRIE = 1, the SPI generates an SPI receiver/error CPU interrupt request.
•
The SPE bit is cleared.
•
The SPTE bit is set.
•
The SPI state counter is cleared.
•
The data direction register of the shared I/O port regains control of port
drivers.
To prevent bus contention with another master SPI after a mode fault error, clear
all SPI bits of the data direction register of the shared I/O port before enabling the
SPI.
When configured as a slave (SPMSTR = 0), the MODF flag is set if SS goes high
during a transmission. When CPHA = 0, a transmission begins when SS goes low
and ends once the incoming SPSCK goes back to its idle level following the shift
of the eighth data bit. When CPHA = 1, the transmission begins when the SPSCK
leaves its idle level and SS is already low. The transmission continues until the
SPSCK returns to its idle level following the shift of the last data bit. See 15.5
Transmission Formats.
NOTE:
Setting the MODF flag does not clear the SPMSTR bit. Reading SPMSTR when
MODF = 1 will indicate a mode fault error occurred in either master mode or slave
mode.
When CPHA = 0, a MODF occurs if a slave is selected (SS is at logic 0) and later
unselected (SS is at logic 1) even if no SPSCK is sent to that slave. This happens
because SS at logic 0 indicates the start of the transmission (MISO driven out with
the value of MSB) for CPHA = 0. When CPHA = 1, a slave can be selected and
then later unselected with no transmission occurring. Therefore, MODF does not
occur since a transmission was never begun.
In a slave SPI (MSTR = 0), the MODF bit generates an SPI receiver/error CPU
interrupt request if the ERRIE bit is set. The MODF bit does not clear the SPE bit
or reset the SPI in any way. Software can abort the SPI transmission by clearing
the SPE bit of the slave.
NOTE:
A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a high
impedance state. Also, the slave SPI ignores all incoming SPSCK clocks, even if it
was already in the middle of a transmission.
To clear the MODF flag, read the SPSCR with the MODF bit set and then write to
the SPCR register. This entire clearing procedure must occur with no MODF
condition existing or else the flag is not cleared.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
221
Serial Peripheral Interface Module (SPI)
15.7 Interrupts
Four SPI status flags can be enabled to generate CPU interrupt requests as shown
in Table 15-2.
Table 15-2. SPI Interrupts
Flag
Request
SPTE transmitter empty
SPI transmitter CPU interrupt request (SPTIE = 1, SPE = 1)
SPRF receiver full
SPI receiver CPU interrupt request (SPRIE = 1)
OVRF overflow
SPI receiver/error interrupt request (ERRIE = 1)
MODF mode fault
SPI receiver/error interrupt request (ERRIE = 1)
The SPI transmitter interrupt enable bit (SPTIE) enables the SPTE flag to generate
transmitter CPU interrupt requests, provided that the SPI is enabled (SPE = 1).
The SPI receiver interrupt enable bit (SPRIE) enables the SPRF bit to generate
receiver CPU interrupt requests, provided that the SPI is enabled (SPE = 1). (See
Figure 15-11.)
SPTE
SPTIE
SPE
SPI TRANSMITTER
CPU INTERRUPT REQUEST
SPRIE
SPRF
SPI RECEIVER/ERROR
CPU INTERRUPT REQUEST
ERRIE
MODF
OVRF
Figure 15-11. SPI Interrupt Request Generation
The error interrupt enable bit (ERRIE) enables both the MODF and OVRF bits to
generate a receiver/error CPU interrupt request.
The mode fault enable bit (MODFEN) can prevent the MODF flag from being set
so that only the OVRF bit is enabled by the ERRIE bit to generate receiver/error
CPU interrupt requests.
Data Sheet
222
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
Resetting the SPI
These sources in the SPI status and control register can generate CPU interrupt
requests:
•
SPI receiver full bit (SPRF) — The SPRF bit becomes set every time a byte
transfers from the shift register to the receive data register. If the SPI
receiver interrupt enable bit, SPRIE, is also set, SPRF can generate either
an SPI receiver/error or CPU interrupt.
•
SPI transmitter empty (SPTE) — The SPTE bit becomes set every time a
byte transfers from the transmit data register to the shift register. If the SPI
transmit interrupt enable bit, SPTIE, is also set, SPTE can generate either
an SPTE or CPU interrupt request.
15.8 Resetting the SPI
Any system reset completely resets the SPI. Partial resets occur whenever the SPI
enable bit (SPE) is low. Whenever SPE is low:
•
The SPTE flag is set.
•
Any transmission currently in progress is aborted.
•
The shift register is cleared.
•
The SPI state counter is cleared, making it ready for a new complete
transmission.
•
All the SPI port logic is defaulted back to being general-purpose I/O.
These items are reset only by a system reset:
•
All control bits in the SPCR
•
All control bits in the SPSCR (MODFEN, ERRIE, SPR1, and SPR0)
•
The status flags SPRF, OVRF, and MODF
By not resetting the control bits when SPE is low, the user can clear SPE between
transmissions without having to set all control bits again when SPE is set back high
for the next transmission.
By not resetting the SPRF, OVRF, and MODF flags, the user can still service these
interrupts after the SPI has been disabled. The user can disable the SPI by writing
0 to the SPE bit. The SPI can also be disabled by a mode fault occurring in an SPI
that was configured as a master with the MODFEN bit set.
15.9 Queuing Transmission Data
The double-buffered transmit data register allows a data byte to be queued
and transmitted. For an SPI configured as a master, a queued data byte is
transmitted immediately after the previous transmission has completed. The SPI
transmitter empty flag (SPTE) indicates when the transmit data buffer is ready to
accept new data. Write to the transmit data register only when the SPTE bit is high.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
223
Serial Peripheral Interface Module (SPI)
Figure 15-12 shows the timing associated with doing back-to-back transmissions
with the SPI (SPSCK has CPHA:CPOL = 1:0).
WRITE TO SPDR
SPTE
1
3
8
5
2
10
SPSCK
CPHA:CPOL = 1:0
MOSI
MSBBIT BIT BIT BIT BIT BIT LSBMSBBIT BIT BIT BIT BIT BIT LSBMSBBIT BIT BIT
6 5 4
6 5 4 3 2 1
6 5 4 3 2 1
BYTE 1
BYTE 2
BYTE 3
9
4
SPRF
6
READ SPSCR
11
7
READ SPDR
12
1 CPU WRITES BYTE 1 TO SPDR, CLEARING SPTE BIT.
7 CPU READS SPDR, CLEARING SPRF BIT.
2 BYTE 1 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
8 CPU WRITES BYTE 3 TO SPDR, QUEUEING BYTE
3 AND CLEARING SPTE BIT.
9 SECOND INCOMING BYTE TRANSFERS FROM SHIFT
REGISTER TO RECEIVE DATA REGISTER, SETTING
SPRF BIT.
10 BYTE 3 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
11 CPU READS SPSCR WITH SPRF BIT SET.
3 CPU WRITES BYTE 2 TO SPDR, QUEUEING BYTE 2
AND CLEARING SPTE BIT.
FIRST INCOMING BYTE TRANSFERS FROM SHIFT
REGISTER TO RECEIVE DATA REGISTER, SETTING
SPRF BIT.
5 BYTE 2 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
6 CPU READS SPSCR WITH SPRF BIT SET.
4
12 CPU READS SPDR, CLEARING SPRF BIT.
Figure 15-12. SPRF/SPTE CPU Interrupt Timing
For a slave, the transmit data buffer allows back-to-back transmissions without the
slave precisely timing its writes between transmissions as in a system with a single
data buffer. Also, if no new data is written to the data buffer, the last value
contained in the shift register is the next data word to be transmitted.
For an idle master or idle slave that has no data loaded into its transmit buffer, the
SPTE is set again no more than two bus cycles after the transmit buffer empties
into the shift register. This allows the user to queue up a 16-bit value to send. For
an already active slave, the load of the shift register cannot occur until the
transmission is completed. This implies that a back-to-back write to the transmit
data register is not possible. The SPTE indicates when the next write can occur.
15.10 Low-Power Mode
The WAIT instruction puts the MCU in a low power-consumption standby mode.
The SPI module remains active after the execution of a WAIT instruction. In wait
mode the SPI module registers are not accessible by the CPU. Any enabled CPU
interrupt request from the SPI module can bring the MCU out of wait mode.
Data Sheet
224
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
I/O Signals
If SPI module functions are not required during wait mode, reduce power
consumption by disabling the SPI module before executing the WAIT instruction.
To exit wait mode when an overflow condition occurs, enable the OVRF bit to
generate CPU interrupt requests by setting the error interrupt enable bit (ERRIE).
See 15.7 Interrupts.
Since the SPTE bit cannot be cleared during a break with the BCFE bit cleared, a
write to the transmit data register in break mode does not initiate a transmission nor
is this data transferred into the shift register. Therefore, a write to the SPDR in
break mode with the BCFE bit cleared has no effect.
15.11 I/O Signals
The SPI module has five I/O pins and shares four of them with a parallel I/O port.
The pins are:
•
MISO — Data received
•
MOSI — Data transmitted
•
SPSCK — Serial clock
•
SS — Slave select
The SPI has limited inter-integrated circuit (I2C) capability (requiring software
support) as a master in a single-master environment. To communicate with I2C
peripherals, MOSI becomes an open-drain output when the SPWOM bit in the SPI
control register is set. In I2C communication, the MOSI and MISO pins are
connected to a bidirectional pin from the I2C peripheral and through a pullup
resistor to VDD.
15.11.1 MISO (Master In/Slave Out)
MISO is one of the two SPI module pins that transmits serial data. In full duplex
operation, the MISO pin of the master SPI module is connected to the MISO pin of
the slave SPI module. The master SPI simultaneously receives data on its MISO
pin and transmits data from its MOSI pin.
Slave output data on the MISO pin is enabled only when the SPI is configured as
a slave. The SPI is configured as a slave when its SPMSTR bit is logic 0 and its SS
pin is at logic 0. To support a multiple-slave system, a logic 1 on the SS pin puts
the MISO pin in a high-impedance state.
When enabled, the SPI controls data direction of the MISO pin regardless of the
state of the data direction register of the shared
I/O port.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
225
Serial Peripheral Interface Module (SPI)
15.11.2 MOSI (Master Out/Slave In)
MOSI is one of the two SPI module pins that transmits serial data. In full-duplex
operation, the MOSI pin of the master SPI module is connected to the MOSI pin of
the slave SPI module. The master SPI simultaneously transmits data from its MOSI
pin and receives data on its MISO pin.
When enabled, the SPI controls data direction of the MOSI pin regardless of the
state of the data direction register of the shared I/O port.
15.11.3 SPSCK (Serial Clock)
The serial clock synchronizes data transmission between master and slave
devices. In a master MCU, the SPSCK pin is the clock output. In a slave MCU, the
SPSCK pin is the clock input. In full-duplex operation, the master and slave MCUs
exchange a byte of data in eight serial clock cycles.
When enabled, the SPI controls data direction of the SPSCK pin regardless of the
state of the data direction register of the shared I/O port.
15.11.4 SS (Slave Select)
The SS pin has various functions depending on the current state of the SPI. For an
SPI configured as a slave, the SS is used to select a slave. For CPHA = 0, the SS
is used to define the start of a transmission. See 15.5 Transmission Formats.
Since it is used to indicate the start of a transmission, the SS must be toggled high
and low between each byte transmitted for the CPHA = 0 format. However, it can
remain low between transmissions for the CPHA = 1 format. See Figure 15-13.
MISO/MOSI
BYTE 1
BYTE 2
BYTE 3
MASTER SS
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 15-13. CPHA/SS Timing
When an SPI is configured as a slave, the SS pin is always configured as an input.
It cannot be used as a general-purpose I/O regardless of the state of the MODFEN
control bit. However, the MODFEN bit can still prevent the state of the SS from
creating a MODF error. See 15.12.2 SPI Status and Control Register.
NOTE:
A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a
high-impedance state. The slave SPI ignores all incoming SPSCK clocks, even if
it was already in the middle of a transmission.
When an SPI is configured as a master, the SS input can be used in conjunction
with the MODF flag to prevent multiple masters from driving MOSI and SPSCK.
Data Sheet
226
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
I/O Registers
(See 15.6.2 Mode Fault Error.) For the state of the SS pin to set the MODF flag,
the MODFEN bit in the SPSCK register must be set. If the MODFEN bit is low for
an SPI master, the SS pin can be used as a general-purpose I/O under the control
of the data direction register of the shared I/O port. With MODFEN high, it is an
input-only pin to the SPI regardless of the state of the data direction register of the
shared I/O port.
The CPU can always read the state of the SS pin by configuring the appropriate
pin as an input and reading the port data register. See Table 15-3.
Table 15-3. SPI Configuration
SPE
SPMSTR
MODFEN
SPI Configuration
State of SS Logic
0
X(1)
X
Not enabled
General-purpose I/O;
SS ignored by SPI
1
0
X
Slave
Input-only to SPI
1
1
0
Master
without MODF
General-purpose I/O;
SS ignored by SPI
1
1
1
Master with MODF
Input-only to SPI
1. X = don’t care
15.11.5 VSS (Clock Ground)
VSS is the ground return for the serial clock pin, SPSCK, and the ground for the port
output buffers. To reduce the ground return path loop and minimize radio frequency
(RF) emissions, connect the ground pin of the slave to the VSS pin of the master.
15.12 I/O Registers
Three registers control and monitor SPI operation:
•
SPI control register, SPCR
•
SPI status and control register, SPSCR
•
SPI data register, SPDR
15.12.1 SPI Control Register
The SPI control register (SPCR):
•
Enables SPI module interrupt requests
•
Selects CPU interrupt requests or DMA service requests
•
Configures the SPI module as master or slave
•
Selects serial clock polarity and phase
•
Configures the SPSCK, MOSI, and MISO pins as open-drain outputs
•
Enables the SPI module
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
227
Serial Peripheral Interface Module (SPI)
Address: $0044
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
SPRIE
R
SPMSTR
CPOL
CPHA
SPWOM
SPE
SPTIE
0
0
1
0
1
0
0
0
R
= Reserved
Figure 15-14. SPI Control Register (SPCR)
SPRIE — SPI Receiver Interrupt Enable Bit
This read/write bit enables CPU interrupt requests generated by the SPRF bit.
The SPRF bit is set when a byte transfers from the shift register to the receive
data register. Reset clears the SPRIE bit.
1 = SPRF CPU interrupt requests enabled
0 = SPRF CPU interrupt requests disabled
SPMSTR — SPI Master Bit
This read/write bit selects master mode operation or slave mode operation.
Reset sets the SPMSTR bit.
1 = Master mode
0 = Slave mode
CPOL — Clock Polarity Bit
This read/write bit determines the logic state of the SPSCK pin between
transmissions. See Figure 15-5 and Figure 15-7. To transmit data between SPI
modules, the SPI modules must have identical CPOL values. Reset clears the
CPOL bit.
CPHA — Clock Phase Bit
This read/write bit controls the timing relationship between the serial clock and
SPI data. See Figure 15-5 and Figure 15-7. To transmit data between SPI
modules, the SPI modules must have identical CPHA bits. When CPHA = 0, the
SS pin of the slave SPI module must be set to logic 1 between bytes. See
Figure 15-13. Reset sets the CPHA bit.
When CPHA = 0 for a slave, the falling edge of SS indicates the beginning of
the transmission. This causes the SPI to leave its idle state and begin driving
the MISO pin with the MSB of its data, once the transmission begins, no new
data is allowed into the shift register from the data register. Therefore, the slave
data register must be loaded with the desired transmit data before the falling
edge of SS. Any data written after the falling edge is stored in the data register
and transferred to the shift register at the current transmission.
When CPHA = 1 for a slave, the first edge of the SPSCK indicates the beginning
of the transmission. The same applies when SS is high for a slave. The MISO
pin is held in a high-impedance state, and the incoming SPSCK is ignored. In
certain cases, it may also cause the MODF flag to be set. See 15.6.2 Mode
Fault Error. A logic 1 on the SS pin does not in any way affect the state of the
SPI state machine.
Data Sheet
228
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
I/O Registers
SPWOM — SPI Wired-OR Mode Bit
This read/write bit disables the pullup devices on pins SPSCK, MOSI, and MISO
so that those pins become open-drain outputs.
1 = Wired-OR SPSCK, MOSI, and MISO pins
0 = Normal push-pull SPSCK, MOSI, and MISO pins
SPE — SPI Enable Bit
This read/write bit enables the SPI module. Clearing SPE causes a partial reset
of the SPI. See 15.8 Resetting the SPI. Reset clears the SPE bit.
1 = SPI module enabled
0 = SPI module disabled
SPTIE— SPI Transmit Interrupt Enable Bit
This read/write bit enables CPU interrupt requests generated by the SPTE bit.
SPTE is set when a byte transfers from the transmit data register to the shift
register. Reset clears the SPTIE bit.
1 = SPTE CPU interrupt requests enabled
0 = SPTE CPU interrupt requests disabled
15.12.2 SPI Status and Control Register
The SPI status and control register (SPSCR) contains flags to signal these
conditions:
•
Receive data register full
•
Failure to clear SPRF bit before next byte is received (overflow error)
•
Inconsistent logic level on SS pin (mode fault error)
•
Transmit data register empty
The SPI status and control register also contains bits that perform these functions:
•
Enable error interrupts
•
Enable mode fault error detection
•
Select master SPI baud rate
Address: $0045
Bit 7
Read:
SPRF
Write:
R
Reset:
6
ERRIE
0
0
R
= Reserved
5
4
3
OVRF
MODF
SPTE
R
R
R
0
0
1
2
1
Bit 0
MODFEN
SPR1
SPR0
0
0
0
Figure 15-15. SPI Status and Control Register (SPSCR)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
229
Serial Peripheral Interface Module (SPI)
SPRF — SPI Receiver Full Bit
This clearable, read-only flag is set each time a byte transfers from the shift
register to the receive data register. SPRF generates a CPU interrupt request if
the SPRIE bit in the SPI control register is set also.
During an SPRF CPU interrupt (DMAS = 0), the CPU clears SPRF by reading
the SPI status and control register with SPRF set and then reading the SPI data
register.
Reset clears the SPRF bit.
1 = Receive data register full
0 = Receive data register not full
ERRIE — Error interrupt Enable Bit
This read/write bit enables the MODF and OVRF bits to generate CPU interrupt
requests. Reset clears the ERRIE bit.
1 = MODF and OVRF can generate CPU interrupt requests.
0 = MODF and OVRF cannot generate CPU interrupt requests.
OVRF — Overflow Bit
This clearable, read-only flag is set if software does not read the byte in the
receive data register before the next full byte enters the shift register. In an
overflow condition, the byte already in the receive data register is unaffected,
and the byte that shifted in last is lost. Clear the OVRF bit by reading the SPI
status and control register with OVRF set and then reading the receive data
register. Reset clears the OVRF bit.
1 = Overflow
0 = No overflow
MODF — Mode Fault Bit
This clearable, read-only flag is set in a slave SPI if the SS pin goes high during
a transmission with the MODFEN bit set. In a master SPI, the MODF flag is set
if the SS pin goes low at any time with the MODFEN bit set. Clear the MODF bit
by reading the SPI status and control register (SPSCR) with MODF set and then
writing to the SPI control register (SPCR). Reset clears the MODF bit.
1 = SS pin at inappropriate logic level
0 = SS pin at appropriate logic level
SPTE — SPI Transmitter Empty Bit
This clearable, read-only flag is set each time the transmit data register
transfers a byte into the shift register. SPTE generates an SPTE CPU interrupt
request or an SPTE DMA service request if the SPTIE bit in the SPI control
register is set also.
NOTE:
Do not write to the SPI data register unless the SPTE bit is high.
For an idle master of idle slave that has no data loaded into its transmit buffer,
the SPTE will be set again within two bus cycles since the transmit buffer
empties into the shift register. This allows the user to queue up a 16-bit value to
send. For an already active slave, the load of the shift register cannot occur until
Data Sheet
230
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Serial Peripheral Interface Module (SPI)
I/O Registers
the transmission is completed. This implies that a back-to-back write to the
transmit data register is not possible. The SPTE indicates when the next write
can occur.
Reset sets the SPTE bit.
1 = Transmit data register empty
0 = Transmit data register not empty
MODFEN — Mode Fault Enable Bit
This read/write bit, when set to 1, allows the MODF flag to be set. If the MODF
flag is set, clearing the MODFEN does not clear the MODF flag. If the SPI is
enabled as a master and the MODFEN bit is low, then the SS pin is available as
a general-purpose I/O.
If the MODFEN bit is set, then this pin is not available as a general-purpose I/O.
When the SPI is enabled as a slave, the SS pin is not available as a
general-purpose I/O regardless of the value of MODFEN. See 15.11.4 SS
(Slave Select).
If the MODFEN bit is low, the level of the SS pin does not affect the operation
of an enabled SPI configured as a master. For an enabled SPI configured as a
slave, having MODFEN low only prevents the MODF flag from being set. It does
not affect any other part of SPI operation. See 15.6.2 Mode Fault Error.
SPR1 and SPR0 — SPI Baud Rate Select Bits
In master mode, these read/write bits select one of four baud rates as shown in
Table 15-4. SPR1 and SPR0 have no effect in slave mode. Reset clears SPR1
and SPR0.
Table 15-4. SPI Master Baud Rate Selection
SPR1:SPR0
Baud Rate Divisor (BD)
00
2
01
8
10
32
11
128
Use this formula to calculate the SPI baud rate:
CGMOUT
Baud rate = -------------------------2 × BD
where:
CGMOUT = base clock output of the clock generator module (CGM)
BD = baud rate divisor
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
Data Sheet
231
Serial Peripheral Interface Module (SPI)
15.12.3 SPI Data Register
The SPI data register consists of the read-only receive data register and the
write-only transmit data register. Writing to the SPI data register writes data into the
transmit data register. Reading the SPI data register reads data from the receive
data register. The transmit data and receive data registers are separate registers
that can contain different values. See Figure 15-3.
Address: $0046
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:
Indeterminate after reset
Figure 15-16. SPI Data Register (SPDR)
R7:R0/T7:T0 — Receive/Transmit Data Bits
NOTE:
Data Sheet
232
Do not use read-modify-write instructions on the SPI data register since the register
read is not the same as the register written.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Serial Peripheral Interface Module (SPI)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 16. Timer Interface A (TIMA)
16.1 Introduction
This section describes the timer interface module A (TIMA). The TIMA is a
4-channel timer that provides:
•
Timing reference with input capture
•
Output compare
•
Pulse-width modulator functions
Figure 16-2 is a block diagram of the TIMA.
16.2 Features
Features of the TIMA include:
•
Four input capture/output compare channels:
– Rising-edge, falling-edge, or any-edge input capture trigger
– Set, clear, or toggle output compare action
•
Buffered and unbuffered pulse-width modulator (PWM) signal generation
•
Programmable TIMA clock input:
– 7-frequency internal bus clock prescaler selection
– External TIMA clock input (4-MHz maximum frequency)
•
Free-running or modulo up-count operation
•
Toggle any channel pin on overflow
•
TIMA counter stop and reset bits
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
233
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
MOTOROLA
CLOCK GENERATOR
MODULE
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
OSC1
OSC2
CGMXFC
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
USER FLASH VECTOR SPACE — 46 BYTES
TIMER INTERFACE
MODULE B
DDRF
MONITOR ROM — 240 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 16-1. Block Diagram Highlighting TIMA Block and Pins
Timer Interface A (TIMA)
Data Sheet
234
INTERNAL BUS
M68HC08 CPU
Timer Interface A (TIMA)
Features
TCLK
PTE3/TCLKA
PRESCALER SELECT
INTERNAL
BUS CLOCK
PRESCALER
TSTOP
PS2
TRST
PS1
PS0
16-BIT COUNTER
TOF
TOIE
INTERRUPT
LOGIC
16-BIT COMPARATOR
TMODH:TMODL
CHANNEL 0
ELS0B
ELS0A
TOV0
CH0MAX
16-BIT COMPARATOR
TCH0H:TCH0L
CH0F
16-BIT LATCH
MS0A
CHANNEL 1
ELS1B
MS0B
ELS1A
TOV1
CH1MAX
16-BIT COMPARATOR
TCH1H:TCH1L
CH0IE
CH1F
16-BIT LATCH
CH1IE
MS1A
CHANNEL 2
ELS2B
ELS2A
TOV2
CH2MAX
16-BIT COMPARATOR
TCH2H:TCH2L
CH2F
16-BIT LATCH
MS2A
CHANNEL 3
ELS3B
MS2B
ELS3A
TOV3
CH3MAX
16-BIT COMPARATOR
TCH3H:TCH3L
CH2IE
CH3F
16-BIT LATCH
MS3A
CH3IE
PTE4
LOGIC
PTE4/TCH0A
INTERRUPT
LOGIC
PTE5
LOGIC
PTE5/TCH1A
INTERRUPT
LOGIC
PTE6
LOGIC
PTE6/TCH2A
INTERRUPT
LOGIC
PTE7
LOGIC
PTE7/TCH3A
INTERRUPT
LOGIC
Figure 16-2. TIMA Block Diagram
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
235
Timer Interface A (TIMA)
Addr.
Register Name
$000E
$000F
$0010
Bit 7
$0016
PS2
PS1
PS0
0
0
0
TIMA Counter Register High Read:
(TACNTH) Write:
See page 247. Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
TIMA Counter Register Low Read:
(TACNTL) Write:
See page 247. Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
R
R
R
R
R
R
R
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
Read:
$0019
R
0
TIMA Channel 1 Status/Control Read:
Register (TASC1) Write:
See page 249. Reset:
TIMA Channel 1 Register High
(TACH1H) Write:
See page 252. Reset:
TIMA Channel 1 Register Low Read:
(TACH1L) Write:
See page 252. Reset:
$0018
TRST
Bit 0
0
TIMA Channel 0 Register Low Read:
(TACH0L) Write:
See page 252. Reset:
$0017
0
1
1
TIMA Channel 0 Register High Read:
(TACH0H) Write:
See page 252. Reset:
$0015
0
2
0
TIMA Channel 0 Status/Control
Register (TASC0) Write:
See page 249. Reset:
$0014
TSTOP
3
0
Read:
$0013
TOIE
4
TOF
TIMA Counter Modulo Read:
Register Low (TAMODL) Write:
See page 248. Reset:
$0012
5
TIMA Status/Control Register Read:
(TASC) Write:
See page 245. Reset:
TIMA Counter Modulo Read:
Register High (TAMODH) Write:
See page 248. Reset:
$0011
6
TIMA Channel 2 Status/Control Read:
Register (TASC2) Write:
See page 249. Reset:
0
CH0F
0
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
CH1F
0
CH1IE
0
R
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
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
CH2F
0
0
R
CH2IE
MS2B
MS2A
ELS2B
ELS2A
TOV2
CH2MAX
0
0
0
0
0
0
0
= Reserved
Figure 16-3. TIM I/O Register Summary
Data Sheet
236
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
Functional Description
Addr.
$001A
$001B
$001C
$001D
Register Name
TIMA Channel 2 Register High Read:
(TACH2H) Write:
See page 252. Reset:
TIMA Channel 2 Register Low Read:
(TACH2L) Write:
See page 252. Reset:
TIMA Channel 3 Status/Control Read:
Register (TASC3) Write:
See page 249. Reset:
TIMA Channel 3 Register High Read:
(TACH3H) Write:
See page 252. Reset:
Read:
$001E
TIMA Channel 3 Register Low
(TACH3L) Write:
See page 252. Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
2
1
Bit 0
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
CH3F
0
CH3IE
0
R
MS3A
ELS3B
ELS3A
TOV3
CH3MAX
0
0
0
0
0
0
0
0
Bit 15
14
13
12
11
10
9
Bit 8
2
1
Bit 0
Indeterminate after reset
Bit 7
6
5
4
3
Indeterminate after reset
= Reserved
R
Figure 16-3. TIM I/O Register Summary (Continued)
16.3 Functional Description
Figure 16-2 shows the TIMA structure. The central component of the TIMA is the
16-bit TIMA counter that can operate as a free-running counter or a modulo
up-counter. The TIMA counter provides the timing reference for the input capture
and output compare functions. The TIMA counter modulo registers,
TAMODH–TAMODL, control the modulo value of the TIMA counter. Software can
read the TIMA counter value at any time without affecting the counting sequence.
The four TIMA channels are programmable independently as input capture or
output compare channels.
16.3.1 TIMA Counter Prescaler
The TIMA clock source can be one of the seven prescaler outputs or the TIMA
clock pin, PTE3/TCLKA. The prescaler generates seven clock rates from the
internal bus clock. The prescaler select bits, PS[2:0], in the TIMA status and control
register select the TIMA clock source.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
237
Timer Interface A (TIMA)
16.3.2 Input Capture
An input capture function has three basic parts:
1. Edge select logic
2. Input capture latch
3. 16-bit counter
Two 8-bit registers, which make up the 16-bit input capture register, are used to
latch the value of the free-running counter after the corresponding input capture
edge detector senses a defined transition. The polarity of the active edge is
programmable. The level transition which triggers the counter transfer is defined by
the corresponding input edge bits (ELSxB and ELSxA in TASC0–TASC3 control
registers with x referring to the active channel number). When an active edge
occurs on the pin of an input capture channel, the TIMA latches the contents of the
TIMA counter into the TIMA channel registers, TACHxH–TACHxL. Input captures
can generate TIMA CPU interrupt requests. Software can determine that an input
capture event has occurred by enabling input capture interrupts or by polling the
status flag bit.
The free-running counter contents are transferred to the TIMA channel status and
control register (TACHxH–TACHxL, see 16.7.5 TIMA Channel Registers) on
each proper signal transition regardless of whether the TIMA channel flag
(CH0F–CH3F in TASC0–TASC3 registers) is set or clear. When the status flag is
set, a CPU interrupt is generated if enabled. The value of the count latched or
“captured” is the time of the event. Because this value is stored in the input capture
register two bus cycles after the actual event occurs, user software can respond to
this event at a later time and determine the actual time of the event. However, this
must be done prior to another input capture on the same pin; otherwise, the
previous time value will be lost.
By recording the times for successive edges on an incoming signal, software can
determine the period and/or pulse width of the signal. To measure a period, two
successive edges of the same polarity are captured. To measure a pulse width, two
alternate polarity edges are captured. Software should track the overflows at the
16-bit module counter to extend its range.
Another use for the input capture function is to establish a time reference. In this
case, an input capture function is used in conjunction with an output compare
function. For example, to activate an output signal a specified number of clock
cycles after detecting an input event (edge), use the input capture function to
record the time at which the edge occurred. A number corresponding to the desired
delay is added to this captured value and stored to an output compare register (see
16.7.5 TIMA Channel Registers). Because both input captures and output
compares are referenced to the same 16-bit modulo counter, the delay can be
controlled to the resolution of the counter independent of software latencies.
Reset does not affect the contents of the input capture channel registers.
Data Sheet
238
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
Functional Description
16.3.3 Output Compare
With the output compare function, the TIMA 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 TIMA can set, clear, or
toggle the channel pin. Output compares can generate TIMA CPU interrupt
requests.
16.3.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare pulses as
described in 16.3.3 Output Compare. The pulses are unbuffered because
changing the output compare value requires writing the new value over the old
value currently in the TIMA channel registers.
An unsynchronized write to the TIMA 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 TIMA overflow interrupt routine to write a
new, smaller output compare value may cause the compare to be missed. The
TIMA may pass the new value before it is written.
Use this method 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 TIMA overflow
interrupts and write the new value in the TIMA overflow interrupt routine. The
TIMA 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.
16.3.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare channel whose
output appears on the PTE4/TCH0A pin. The TIMA channel registers of the linked
pair alternately control the output.
Setting the MS0B bit in TIMA channel 0 status and control register (TASC0) links
channel 0 and channel 1. The output compare value in the TIMA channel 0
registers initially controls the output on the PTE4/TCH0A pin. Writing to the TIMA
channel 1 registers enables the TIMA channel 1 registers to synchronously control
the output after the TIMA overflows. At each subsequent overflow, the TIMA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
239
Timer Interface A (TIMA)
channel registers (0 or 1) that control the output are the ones written to last. TASC0
controls and monitors the buffered output compare function, and TIMA channel 1
status and control register (TASC1) is unused. While the MS0B bit is set, the
channel 1 pin, PTE5/TCH1A, is available as a general-purpose I/O pin.
Channels 2 and 3 can be linked to form a buffered output compare channel whose
output appears on the PTE6/TCH2A pin. The TIMA channel registers of the linked
pair alternately control the output.
Setting the MS2B bit in TIMA channel 2 status and control register (TASC2) links
channel 2 and channel 3. The output compare value in the TIMA channel 2
registers initially controls the output on the PTE6/TCH2A pin. Writing to the TIMA
channel 3 registers enables the TIMA channel 3 registers to synchronously control
the output after the TIMA overflows. At each subsequent overflow, the TIMA
channel registers (2 or 3) that control the output are the ones written to last. TASC2
controls and monitors the buffered output compare function, and TIMA channel 3
status and control register (TASC3) is unused. While the MS2B bit is set, the
channel 3 pin, PTE7/TCH3A, 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.
16.3.4 Pulse-Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel, the TIMA
can generate a PWM signal. The value in the TIMA counter modulo registers
determines the period of the PWM signal. The channel pin toggles when the
counter reaches the value in the TIMA counter modulo registers. The time between
overflows is the period of the PWM signal.
As Figure 16-4 shows, the output compare value in the TIMA channel registers
determines the pulse width of the PWM signal. The time between overflow and
output compare is the pulse width. Program the TIMA to clear the channel pin on
output compare if the polarity of the PWM pulse is 1 (ELSxA = 0). Program the
TIMA to set the pin if the polarity of the PWM pulse is 0 (ELSxA = 1).
The value in the TIMA 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 TIMA counter
modulo registers produces a PWM period of 256 times the internal bus clock period
if the prescaler select value is $000 (see 16.7.1 TIMA Status and Control
Register).
The value in the TIMA 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 TIMA channel registers produces a duty cycle of
128/256 or 50 percent.
Data Sheet
240
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
Functional Description
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
POLARITY = 1
(ELSxA = 0)
TCHx
PULSE
WIDTH
POLARITY = 0
(ELSxA = 1)
TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 16-4. PWM Period and Pulse Width
16.3.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as described
in 16.3.4 Pulse-Width Modulation (PWM). The pulses are unbuffered because
changing the pulse width requires writing the new pulse width value over the value
currently in the TIMA channel registers.
An unsynchronized write to the TIMA 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 TIMA overflow interrupt routine to write a new, smaller pulse width value may
cause the compare to be missed. The TIMA may pass the new value before it is
written to the TIMA channel registers.
Use this method 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 TIMA overflow interrupts and
write the new value in the TIMA overflow interrupt routine. The TIMA
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 percent duty cycle
generation and removes the ability of the channel to self-correct 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.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
241
Timer Interface A (TIMA)
16.3.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose output
appears on the PTE4/TCH0A pin. The TIMA channel registers of the linked pair
alternately control the pulse width of the output.
Setting the MS0B bit in TIMA channel 0 status and control register (TASC0) links
channel 0 and channel 1. The TIMA channel 0 registers initially control the pulse
width on the PTE4/TCH0A pin. Writing to the TIMA channel 1 registers enables the
TIMA channel 1 registers to synchronously control the pulse width at the beginning
of the next PWM period. At each subsequent overflow, the TIMA channel registers
(0 or 1) that control the pulse width are the ones written to last. TASC0 controls and
monitors the buffered PWM function, and TIMA channel 1 status and control
register (TASC1) is unused. While the MS0B bit is set, the channel 1 pin,
PTE5/TCH1A, is available as a general-purpose
I/O pin.
Channels 2 and 3 can be linked to form a buffered PWM channel whose output
appears on the PTE6/TCH2A pin. The TIMA channel registers of the linked pair
alternately control the pulse width of the output.
Setting the MS2B bit in TIMA channel 2 status and control register (TASC2) links
channel 2 and channel 3. The TIMA channel 2 registers initially control the pulse
width on the PTE6/TCH2A pin. Writing to the TIMA channel 3 registers enables the
TIMA channel 3 registers to synchronously control the pulse width at the beginning
of the next PWM period. At each subsequent overflow, the TIMA channel registers
(2 or 3) that control the pulse width are written to last. TASC2 controls and monitors
the buffered PWM function, and TIMA channel 3 status and control register
(TASC3) is unused. While the MS2B bit is set, the channel 3 pin, PTE7/TCH3A, is
available as a general-purpose
I/O pin.
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.
16.3.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered PWM signals,
use this initialization procedure:
1. In the TIMA status and control register (TASC):
a. Stop the TIMA counter by setting the TIMA stop bit, TSTOP.
b. Reset the TIMA counter and prescaler by setting the TIMA reset bit,
TRST.
2. In the TIMA counter modulo registers (TAMODH–TAMODL), write the value
for the required PWM period.
Data Sheet
242
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
Functional Description
3. In the TIMA channel x registers (TACHxH–TACHxL), write the value for the
required pulse width.
4. In TIMA 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 16-2.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (polarity 1 — to clear output on compare) or 1:1 (polarity 0 —
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 16-2.)
NOTE:
In PWM signal generation, do not program the PWM channel to toggle on output
compare. Toggling on output compare prevents reliable 0 percent duty cycle
generation and removes the ability of the channel to self-correct 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 TIMA status control register (TASC), clear the TIMA stop bit, TSTOP.
Setting MS0B links channels 0 and 1 and configures them for buffered PWM
operation. The TIMA channel 0 registers (TACH0H–TACH0L) initially control the
buffered PWM output. TIMA status control register 0 (TASC0) controls and
monitors the PWM signal from the linked channels. MS0B takes priority over
MS0A.
Setting MS2B links channels 2 and 3 and configures them for buffered PWM
operation. The TIMA channel 2 registers (TACH2H–TACH2L) initially control the
buffered PWM output. TIMA status control register 2 (TASC2) controls and
monitors the PWM signal from the linked channels. MS2B takes priority over
MS2A.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIMA
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 percent duty cycle output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the TOVx bit
generates a 100 percent duty cycle output. (See 16.7.4 TIMA Channel Status and
Control Registers.)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
243
Timer Interface A (TIMA)
16.4 Interrupts
These TIMA sources can generate interrupt requests:
•
TIMA overflow flag (TOF) — The timer overflow flag (TOF) bit is set when
the TIMA counter reaches the modulo value programmed in the TIMA
counter modulo registers. The TIMA overflow interrupt enable bit, TOIE,
enables TIMA overflow interrupt requests. TOF and TOIE are in the TIMA
status and control registers.
•
TIMA channel flags (CH3F–CH0F) — The CHxF bit is set when an input
capture or output compare occurs on channel x. Channel x TIMA CPU
interrupt requests are controlled by the channel x interrupt enable bit,
CHxIE.
16.5 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
The TIMA remains active after the execution of a WAIT instruction. In wait mode,
the TIMA registers are not accessible by the CPU. Any enabled CPU interrupt
request from the TIMA can bring the MCU out of wait mode.
If TIMA functions are not required during wait mode, reduce power consumption by
stopping the TIMA before executing the WAIT instruction.
16.6 I/O Signals
Port E shares five of its pins with the TIMA:
•
PTE3/TCLKA is an external clock input to the TIMA prescaler.
•
The four TIMA channel I/O pins are PTE4/TCH0A, PTE5/TCH1A,
PTE6/TCH2A, and PTE7/TCH3A.
16.6.1 TIMA Clock Pin (PTE3/TCLKA)
PTE3/TCLKA is an external clock input that can be the clock source for the TIMA
counter instead of the prescaled internal bus clock. Select the PTE3/TCLKA input
by writing logic 1s to the three prescaler select bits, PS[2:0]. See 16.7.1 TIMA
Status and Control Register.
The maximum TCLK frequency is the least: 4 MHz or bus frequency ÷ 2.
PTE3/TCLKA is available as a general-purpose I/O pin when not used as the TIMA
clock input. When the PTE3/TCLKA pin is the TIMA clock input, it is an input
regardless of the state of the DDRE3 bit in data direction register E.
Data Sheet
244
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
I/O Registers
16.6.2 TIMA Channel I/O Pins (PTE4/TCH0A–PTE7/TCH3A)
Each channel I/O pin is programmable independently as an input capture pin or an
output compare pin. PTE2/TCH0 and PTE4/TCH2 can be configured as buffered
output compare or buffered PWM pins.
16.7 I/O Registers
These input/output (I/O) registers control and monitor TIMA operation:
•
TIMA status and control register (TASC)
•
TIMA control registers (TACNTH–TACNTL)
•
TIMA counter modulo registers (TAMODH–TAMODL)
•
TIMA channel status and control registers (TASC0, TASC1, TASC2, and
TASC3)
•
TIMA channel registers (TACH0H–TACH0L, TACH1H–TACH1L,
TACH2H–TACH2L, and TACH3H–TACH3L)
16.7.1 TIMA Status and Control Register
The TIMA status and control register:
•
Enables TIMA overflow interrupts
•
Flags TIMA overflows
•
Stops the TIMA counter
•
Resets the TIMA counter
•
Prescales the TIMA counter clock
Address: $000E
Bit 7
Read:
TOF
Write:
0
Reset:
6
5
TOIE
TSTOP
0
0
1
R
= Reserved
4
3
0
0
TRST
R
0
0
2
1
Bit 0
PS2
PS1
PS0
0
0
0
Figure 16-5. TIMA Status and Control Register (TASC)
TOF — TIMA Overflow Flag
This read/write flag is set when the TIMA counter reaches the modulo value
programmed in the TIMA counter modulo registers. Clear TOF by reading the
TIMA status and control register when TOF is set and then writing a logic 0 to
TOF. If another TIMA overflow occurs before the clearing sequence is complete,
then writing logic 0 to TOF has no effect. Therefore, a TOF interrupt request
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
245
Timer Interface A (TIMA)
cannot be lost due to inadvertent clearing of TOF. Reset clears the TOF bit.
Writing a logic 1 to TOF has no effect.
1 = TIMA counter has reached modulo value.
0 = TIMA counter has not reached modulo value.
TOIE — TIMA Overflow Interrupt Enable Bit
This read/write bit enables TIMA overflow interrupts when the TOF bit becomes
set. Reset clears the TOIE bit.
1 = TIMA overflow interrupts enabled
0 = TIMA overflow interrupts disabled
TSTOP — TIMA Stop Bit
This read/write bit stops the TIMA counter. Counting resumes when TSTOP is
cleared. Reset sets the TSTOP bit, stopping the TIMA counter until software
clears the TSTOP bit.
1 = TIMA counter stopped
0 = TIMA counter active
NOTE:
Do not set the TSTOP bit before entering wait mode if the TIMA is required to exit
wait mode. Also when the TSTOP bit is set and the timer is configured for input
capture operation, input captures are inhibited until the TSTOP bit is cleared.
TRST — TIMA Reset Bit
Setting this write-only bit resets the TIMA counter and the TIMA prescaler.
Setting TRST has no effect on any other registers. Counting resumes from
$0000. TRST is cleared automatically after the TIMA counter is reset and
always reads as logic 0. Reset clears the TRST bit.
1 = Prescaler and TIMA counter cleared
0 = No effect
NOTE:
Setting the TSTOP and TRST bits simultaneously stops the TIMA counter at a
value of $0000.
PS[2:0] — Prescaler Select Bits
These read/write bits select either the PTE3/TCLKA pin or one of the seven
prescaler outputs as the input to the TIMA counter as Table 16-1 shows. Reset
clears the PS[2:0] bits.
Table 16-1. Prescaler Selection
Data Sheet
246
PS[2:0]
TIMA Clock Source
000
Internal bus clock ÷1
001
Internal bus clock ÷ 2
010
Internal bus clock ÷ 4
011
Internal bus clock ÷ 8
100
Internal bus clock ÷ 16
101
Internal bus clock ÷ 32
110
Internal bus clock ÷ 64
111
PTE3/TCLKA
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
I/O Registers
16.7.2 TIMA Counter Registers
The two read-only TIMA counter registers contain the high and low bytes of the
value in the TIMA counter. Reading the high byte (TACNTH) latches the contents
of the low byte (TACNTL) into a buffer. Subsequent reads of TACNTH do not affect
the latched TACNTL value until TACNTL is read. Reset clears the TIMA counter
registers. Setting the TIMA reset bit (TRST) also clears the TIMA counter registers.
NOTE:
If TACNTH is read during a break interrupt, be sure to unlatch TACNTL by reading
TACNTL before exiting the break interrupt. Otherwise, TACNTL retains the value
latched during the break.
Register Name and Address:
TACNTH — $000F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Register Name and Address:
TACNTL — $0010
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 16-6. TIMA Counter Registers (TACNTH and TACNTL)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
247
Timer Interface A (TIMA)
16.7.3 TIMA Counter Modulo Registers
The read/write TIMA modulo registers contain the modulo value for the TIMA
counter. When the TIMA counter reaches the modulo value, the overflow flag
(TOF) becomes set, and the TIMA counter resumes counting from $0000 at the
next timer clock. Writing to the high byte (TAMODH) inhibits the TOF bit and
overflow interrupts until the low byte (TAMODL) is written. Reset sets the TIMA
counter modulo registers.
Register Name and Address:
Read:
Write:
Reset:
TAMODH — $0011
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
1
1
1
1
1
1
1
1
Register Name and Address:
Read:
Write:
Reset:
TAMODL — $0012
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Figure 16-7. TIMA Counter Modulo Registers
(TAMODH and TAMODL)
NOTE:
Reset the TIMA counter before writing to the TIMA counter modulo registers.
16.7.4 TIMA Channel Status and Control Registers
Each of the TIMA channel status and control registers:
Data Sheet
248
•
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 TIMA overflow
•
Selects 0 percent and 100 percent PWM duty cycle
•
Selects buffered or unbuffered output compare/PWM operation
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
I/O Registers
Register Name and Address:
Bit 7
Read:
CH0F
Write:
0
Reset:
0
TASC0 — $0013
6
5
4
3
2
1
Bit 0
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
4
3
2
1
Bit 0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
Register Name and Address:
Bit 7
Read:
CH1F
Write:
0
Reset:
0
TASC1 — $0016
6
CH1IE
0
Register Name and Address:
Bit 7
Read:
CH2F
Write:
0
Reset:
0
Read:
CH3F
Write:
0
Reset:
0
R
0
TASC2 — $0019
6
5
4
3
2
1
Bit 0
CH2IE
MS2B
MS2A
ELS2B
ELS2A
TOV2
CH2MAX
0
0
0
0
0
0
0
4
3
2
1
Bit 0
MS3A
ELS3B
ELS3A
TOV3
CH3MAX
0
0
0
0
0
Register Name and Address:
Bit 7
5
TASC3 — $001C
6
CH3IE
0
0
R
= Reserved
5
0
R
0
Figure 16-8. TIMA Channel Status
and Control Registers (TASC0–TASC3)
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 TIMA counter registers matches the
value in the TIMA channel x registers.
When CHxIE = 1, clear CHxF by reading TIMA channel x status and control
register with CHxF set, and then writing a 0 to CHxF. If another interrupt request
occurs before the clearing sequence is complete, then writing 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 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
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
249
Timer Interface A (TIMA)
CHxIE — Channel x Interrupt Enable Bit
This read/write bit enables TIMA CPU interrupts on channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
MSxB — Mode Select Bit B
This read/write bit selects buffered output compare/PWM operation. MSxB
exists only in the TIMA channel 0 and TIMA channel 2 status and control
registers.
Setting MS0B disables the channel 1 status and control register and reverts
TCH1A pin to general-purpose I/O.
Setting MS2B disables the channel 3 status and control register and reverts
TCH3A pin to general-purpose I/O.
Reset clears the MSxB bit.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MSxA — Mode Select Bit A
When ELSxB:A ≠ 00, this read/write bit selects either input capture operation or
unbuffered output compare/PWM operation. See Table 16-2.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
When ELSxB:A = 00, this read/write bit selects the initial output level of the
TCHxA pin once PWM, input capture, or output compare operation is enabled.
See Table 16-2. 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 TIMA status and control register (TASC).
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 port E,
and pin PTEx/TCHxA is available as a general-purpose I/O pin. However,
channel x is at a state determined by these bits and becomes transparent to the
respective pin when PWM, input capture, or output compare mode is enabled.
Table 16-2 shows how ELSxB and ELSxA work. Reset clears the ELSxB and
ELSxA bits.
NOTE:
Data Sheet
250
Before enabling a TIMA channel register for input capture operation, make sure
that the PTEx/TACHx pin is stable for at least two bus clocks.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
I/O Registers
Table 16-2. Mode, Edge, and Level Selection
MSxB:MSxA
ELSxB:ELSxA
X0
00
Mode
Configuration
Pin under port control; initialize timer output level high
Output preset
X1
00
Pin under port control; initialize timer output level low
00
01
Capture on rising edge only
00
10
00
11
Capture on rising or falling edge
01
00
Software compare only
01
01
01
10
01
11
1X
01
1X
10
1X
11
Input capture
Output
compare
or PWM
Capture on falling edge only
Toggle output on compare
Clear output on compare
Set output on compare
Buffered
output compare
or buffered PWM
Toggle output on compare
Clear output on compare
Set output on compare
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 TIMA 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 TIMA counter overflow.
0 = Channel x pin does not toggle on TIMA counter overflow.
NOTE:
When TOVx is set, a TIMA 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 is 1 and clear output on compare is selected, setting the
CHxMAX bit forces the duty cycle of buffered and unbuffered PWM signals to
100 percent. As Figure 16-9 shows, CHxMAX bit takes effect in the cycle after
it is set or cleared. The output stays at 100 percent duty cycle level until the
cycle after CHxMAX is cleared.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
251
Timer Interface A (TIMA)
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PTEx/TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
CHxMAX
TOVx
Figure 16-9. CHxMAX Latency
16.7.5 TIMA Channel Registers
These read/write registers contain the captured TIMA counter value of the input
capture function or the output compare value of the output compare function. The
state of the TIMA channel registers after reset is unknown.
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the TIMA
channel x registers (TACHxH) inhibits input captures until the low byte (TACHxL)
is read.
In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of the TIMA
channel x registers (TACHxH) inhibits output compares until the low byte
(TACHxL) is written.
Register Name and Address:
Read:
Write:
TACH0H — $0014
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
Reset:
TACH0L — $0015
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Indeterminate after reset
Figure 16-10. TIMA Channel Registers
(TACH0H/L–TACH3H/L)
Data Sheet
252
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Timer Interface A (TIMA)
I/O Registers
Register Name and Address: TACH1H — $0017
Read:
Write:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TACH1L — $0018
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TACH2H — $001A
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TACH2L — $001B
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TACH3H — $001D
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TACH3L — $001E
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset:
Indeterminate after reset
Figure 16-10. TIMA Channel Registers
(TACH0H/L–TACH3H/L) (Continued)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface A (TIMA)
Data Sheet
253
Timer Interface A (TIMA)
Data Sheet
254
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface A (TIMA)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 17. Timer Interface B (TIMB)
17.1 Introduction
This section describes the timer interface module B (TIMB). The TIMB is a
2-channel timer that provides:
•
Timing reference with input capture
•
Output compare
•
Pulse-width modulation functions
Figure 17-2 is a block diagram of the TIMB.
NOTE:
The TIMB module is not available in the 56-pin shrink dual in-line package (SDIP).
17.2 Features
Features of the TIMB include:
•
Two input capture/output compare channels:
– 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 TIMB clock input:
– 7-frequency internal bus clock prescaler selection
– External TIMB clock input (4-MHz maximum frequency)
•
Free-running or modulo up-count operation
•
Toggle any channel pin on overflow
•
TIMB counter stop and reset bits
17.3 Functional Description
Figure 17-2 shows the TIMB structure. The central component of the TIMB is the
16-bit TIMB counter that can operate as a free-running counter or a modulo
up-counter. The TIMB counter provides the timing reference for the input capture
and output compare functions. The TIMB counter modulo registers,
TBMODH–TBMODL, control the modulo value of the TIMB counter. Software can
read the TIMB counter value at any time without affecting the counting sequence.
The two TIMB channels are programmable independently as input capture or
output compare channels.
NOTE:
The TIMB module is not available in the 56-pin SDIP.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
255
PTA
PTA7–PTA0
PTB
PTB7/ATD7
PTB6/ATD6
PTB5/ATD5
PTB4/ATD4
PTB3/ATD3
PTB2/ATD2
PTB1/ATD1
PTB0/ATD0
PTC
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1/ATD9(1)
PTC0/ATD8
PTD
PTD6/IS3
PTD5/IS2
PTD4/IS1
PTD3/FAULT4
PTD2/FAULT3
PTD1/FAULT2
PTD0/FAULT1
PTE
CONTROL AND STATUS REGISTERS — 112 BYTES
DDRA
ARITHMETIC/LOGIC
UNIT
PTE7/TCH3A
PTE6/TCH2A
PTE5/TCH1A
PTE4/TCH0A
PTE3/TCLKA
PTE2/TCH1B(1)
PTE1/TCH0B(1)
PTE0/TCLKB(1)
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING PROPERLY
MODULE
DDRB
CPU
REGISTERS
USER FLASH — 32,256 BYTES
TIMER INTERFACE
MODULE A
USER RAM — 768 BYTES
MOTOROLA
CLOCK GENERATOR
MODULE
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ
MODULE
VDDA
VSSA(3)
VREFL(3)
VREFH
PWMGND
PWM6–PWM1
VSS
VDD
VDDAD
VSSAD
ANALOG-TO-DIGITAL CONVERTER
MODULE
PULSE-WIDTH MODULATOR
MODULE
DDRC
SERIAL PERIPHERAL INTERFACE
MODULE(2)
POWER-ON RESET
MODULE
SINGLE BREAK
MODULE
PTF5/TxD
PTF4/RxD
PTF3/MISO(1)
PTF2/MOSI(1)
PTF1/SS(1)
DDRE
OSC1
OSC2
CGMXFC
SERIAL COMMUNICATIONS INTERFACE
MODULE
PTF
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
USER FLASH VECTOR SPACE — 46 BYTES
TIMER INTERFACE
MODULE B
DDRF
MONITOR ROM — 240 BYTES
PTF0/SPSCK(1)
POWER
Notes:
1. These pins are not available in the 56-pin SDIP package.
2. This module is not available in the 56-pin SDIP package.
3. In the 56-pin SDIP package, these pins are bonded together.
Figure 17-1. Block Diagram Highlighting TIMB Block and Pins
Timer Interface B (TIMB)
Data Sheet
256
INTERNAL BUS
M68HC08 CPU
Timer Interface B (TIMB)
Functional Description
TCLK
PTE0/TCLKB
PRESCALER SELECT
INTERNAL
BUS CLOCK
PRESCALER
TSTOP
PS2
TRST
PS1
PS0
16-BIT COUNTER
TOF
TOIE
INTERRUPT
LOGIC
16-BIT COMPARATOR
TMODH:TMODL
ELS0B
CHANNEL 0
ELS0A
TOV0
CH0MAX
16-BIT COMPARATOR
TCH0H:TCH0L
CH0F
ELS1B
CHANNEL 1
CH0IE
MS0B
ELS1A
TOV1
CH1MAX
16-BIT COMPARATOR
TCH1H:TCH1L
CH1F
PTE2
LOGIC
PTE2/TCH1B
INTERRUPT
LOGIC
16-BIT LATCH
CH1IE
MS1A
PTE1/TCH0B
INTERRUPT
LOGIC
16-BIT LATCH
MS0A
PTE1
LOGIC
Figure 17-2. TIMB Block Diagram
Addr.
Register Name
Bit 7
Read:
$0051
TIMB Status/Control Register
(TBSC) Write:
See page 265. Reset:
TOF
$0052
$0053
$0054
6
5
4
3
0
0
TRST
R
2
1
Bit 0
PS2
PS1
PS0
TOIE
TSTOP
0
0
1
0
0
0
0
0
TIMB Counter Register High Read:
(TBCNTH) Write:
See page 267. Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
TIMB Counter Register Low Read:
(TBCNTL) Write:
See page 267. Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
1
1
1
1
1
1
1
1
R
= Reserved
TIMB Counter Modulo Register Read:
High (TBMODH) Write:
See page 268. Reset:
0
Figure 17-3. TIMB I/O Register Summary
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
257
Timer Interface B (TIMB)
Addr.
$0055
$0056
Register Name
TIMB Counter Modulo Register Read:
Low (TBMODL) Write:
See page 268. Reset:
TIMB Channel 0 Status/Control Read:
Register Write:
(TBSC0) See page 269. Reset:
TIMB Channel 0 Register High Read:
(TBCH0H) Write:
See page 272. Reset:
$0057
TIMB Channel 0 Register Low Read:
(TBCH0L) Write:
See page 272. Reset:
$0058
Read:
$0059
TIMB Channel 1 Status/Control
Register Write:
(TBSC1) See page 269. Reset:
$005A
$005B
TIMB Channel 1 Register High Read:
(TBCH1H) Write:
See page 272. Reset:
TIMB Channel 1 Register Low Read:
(TBCH1L) Write:
See page 272. Reset:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 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
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
CH0F
0
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
CH1F
0
CH1IE
0
R
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 2
Bit 1
Bit 0
Indeterminate after reset
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Indeterminate after reset
R
= Reserved
Figure 17-3. TIMB I/O Register Summary (Continued)
17.3.1 TIMB Counter Prescaler
The TIMB clock source can be one of the seven prescaler outputs or the TIMB
clock pin, PTE0/TCLKB. The prescaler generates seven clock rates from the internal
bus clock. The prescaler select bits, PS[2:0], in the TIMB status and control register
select the TIMB clock source.
17.3.2 Input Capture
An input capture function has three basic parts:
1. Edge select logic
2. Input capture latch
3. 16-bit counter
Two 8-bit registers, which make up the 16-bit input capture register, are used to
latch the value of the free-running counter after the corresponding input capture
edge detector senses a defined transition. The polarity of the active edge is
Data Sheet
258
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
Functional Description
programmable. The level transition which triggers the counter transfer is defined by
the corresponding input edge bits (ELSxB and ELSxA in TBSC0–TBSC1 control
registers with x referring to the active channel number). When an active edge
occurs on the pin of an input capture channel, the TIMB latches the contents of the
TIMB counter into the TIMB channel registers, TCHxH–TCHxL. Input captures can
generate TIMB CPU interrupt requests. Software can determine that an input
capture event has occurred by enabling input capture interrupts or by polling the
status flag bit.
The free-running counter contents are transferred to the TIMB channel status and
control register (TBCHxH–TBCHxL, see 17.7.5 TIMB Channel Registers) on
each proper signal transition regardless of whether the TIMB channel flag
(CH0F–CH1F in TBSC0–TBSC1 registers) is set or clear. When the status flag is
set, a CPU interrupt is generated if enabled. The value of the count latched or
“captured” is the time of the event. Because this value is stored in the input capture
register two bus cycles after the actual event occurs, user software can respond to
this event at a later time and determine the actual time of the event. However, this
must be done prior to another input capture on the same pin; otherwise, the
previous time value will be lost.
By recording the times for successive edges on an incoming signal, software can
determine the period and/or pulse width of the signal. To measure a period, two
successive edges of the same polarity are captured. To measure a pulse width, two
alternate polarity edges are captured. Software should track the overflows at the
16-bit module counter to extend its range.
Another use for the input capture function is to establish a time reference. In this
case, an input capture function is used in conjunction with an output compare
function. For example, to activate an output signal a specified number of clock
cycles after detecting an input event (edge), use the input capture function to
record the time at which the edge occurred. A number corresponding to the desired
delay is added to this captured value and stored to an output compare register (see
17.7.5 TIMB Channel Registers). Because both input captures and output
compares are referenced to the same 16-bit modulo counter, the delay can be
controlled to the resolution of the counter independent of software latencies.
Reset does not affect the contents of the input capture channel register
(TBCHxH–TBCHxL).
17.3.3 Output Compare
With the output compare function, the TIMB 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 TIMB can set, clear, or
toggle the channel pin. Output compares can generate TIMB CPU interrupt
requests.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
259
Timer Interface B (TIMB)
17.3.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare pulses as
described in 17.3.3 Output Compare. The pulses are unbuffered because
changing the output compare value requires writing the new value over the old
value currently in the TIMB channel registers.
An unsynchronized write to the TIMB 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 TIMB overflow interrupt routine to write a
new, smaller output compare value may cause the compare to be missed. The
TIMB may pass the new value before it is written.
Use this method 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 TIMB overflow
interrupts and write the new value in the TIMB overflow interrupt routine. The
TIMB 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.
17.3.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare channel whose
output appears on the PTE1/TCH0B pin. The TIMB channel registers of the linked
pair alternately control the output.
Setting the MS0B bit in TIMB channel 0 status and control register (TBSC0) links
channel 0 and channel 1. The output compare value in the TIMB channel 0
registers initially controls the output on the PTE1/TCH0B pin. Writing to the TIMB
channel 1 registers enables the TIMB channel 1 registers to synchronously control
the output after the TIMB overflows. At each subsequent overflow, the TIMB
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 TIMB channel 1
status and control register (TBSC1) is unused. While the MS0B bit is set, the
channel 1 pin, PTE2/TCH1B, is available as a general-purpose I/O pin.
NOTE:
Data Sheet
260
In buffered output compare operation, do not write new output compare values to
the currently active channel registers. User software should track the currently
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
Functional Description
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.
17.3.4 Pulse-Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel, the TIMB
can generate a PWM signal. The value in the TIMB counter modulo registers
determines the period of the PWM signal. The channel pin toggles when the
counter reaches the value in the TIMB counter modulo registers. The time between
overflows is the period of the PWM signal.
As Figure 17-4 shows, the output compare value in the TIMB channel registers
determines the pulse width of the PWM signal. The time between overflow and
output compare is the pulse width. Program the TIMB to clear the channel pin on
output compare if the polarity of the PWM pulse is 1 (ELSxA = 0). Program the
TIMB to set the pin if the polarity of the PWM pulse is 0 (ELSxA = 1).
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
POLARITY = 1
(ELSxA = 0)
TCHx
PULSE
WIDTH
POLARITY = 0
(ELSxA = 1)
TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 17-4. PWM Period and Pulse Width
The value in the TIMB 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 TIMB counter
modulo registers produces a PWM period of 256 times the internal bus clock period
if the prescaler select value is $000 (see 17.7.1 TIMB Status and Control
Register).
The value in the TIMB 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 TIMB channel registers produces a duty cycle of
128/256 or 50 percent.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
261
Timer Interface B (TIMB)
17.3.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as described
in 17.3.4 Pulse-Width Modulation (PWM). The pulses are unbuffered because
changing the pulse width requires writing the new pulse width value over the value
currently in the TIMB channel registers.
An unsynchronized write to the TIMB 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 TIMB overflow interrupt routine to write a new, smaller pulse width value may
cause the compare to be missed. The TIMB may pass the new value before it is
written to the TIMB channel registers.
Use this method 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 TIMB overflow interrupts and
write the new value in the TIMB overflow interrupt routine. The TIMB
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 percent duty cycle
generation and removes the ability of the channel to self-correct 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.
17.3.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose output
appears on the PTE1/TCH0B pin. The TIMB channel registers of the linked pair
alternately control the pulse width of the output.
Setting the MS0B bit in TIMB channel 0 status and control register (TBSC0) links
channel 0 and channel 1. The TIMB channel 0 registers initially control the pulse
width on the PTE1/TCH0B pin. Writing to the TIMB channel 1 registers enables the
TIMB channel 1 registers to synchronously control the pulse width at the beginning
of the next PWM period. At each subsequent overflow, the TIMB channel registers
(0 or 1) that control the pulse width are the ones written to last. TBSC0 controls and
monitors the buffered PWM function, and TIMB channel 1 status and control
Data Sheet
262
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
Functional Description
register (TBSC1) is unused. While the MS0B bit is set, the channel 1 pin,
PTE2/TCH1B, is available as a general-purpose I/O pin.
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.
17.3.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered PWM signals,
use this initialization procedure:
1. In the TIMB status and control register (TBSC):
a. Stop the TIMB counter by setting the TIMB stop bit, TSTOP.
b. Reset the TIMB counter and prescaler by setting the TIMB reset bit,
TRST.
2. In the TIMB counter modulo registers (TBMODH–TBMODL), write the value
for the required PWM period.
3. In the TIMB channel x registers (TBCHxH–TBCHxL), write the value for the
required pulse width.
4. In TIMB channel x status and control register (TBSCx):
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 17-2.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (polarity 1 — to clear output on compare) or 1:1 (polarity 0 —
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 17-2.)
NOTE:
In PWM signal generation, do not program the PWM channel to toggle on output
compare. Toggling on output compare prevents reliable 0 percent duty cycle
generation and removes the ability of the channel to self-correct 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 TIMB status control register (TBSC), clear the TIMB stop bit, TSTOP.
Setting MS0B links channels 0 and 1 and configures them for buffered PWM
operation. The TIMB channel 0 registers (TBCH0H–TBCH0L) initially control the
buffered PWM output. TIMB status control register 0 (TBSC0) controls and
monitors the PWM signal from the linked channels. MS0B takes priority over
MS0A.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
263
Timer Interface B (TIMB)
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIMB
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 percent duty cycle output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the TOVx bit
generates a 100 percent duty cycle output. (See 17.7.4 TIMB Channel Status and
Control Registers.)
17.4 Interrupts
These TIMB sources can generate interrupt requests:
•
TIMB overflow flag (TOF) — The timer overflow flag (TOF) bit is set when
the TIMB counter reaches the modulo value programmed in the TIMB
counter modulo registers. The TIMB overflow interrupt enable bit, TOIE,
enables TIMB overflow interrupt requests. TOF and TOIE are in the TIMB
status and control registers.
•
TIMB channel flags (CH1F–CH0F) — The CHxF bit is set when an input
capture or output compare occurs on channel x. Channel x TIMB CPU
interrupt requests are controlled by the channel x interrupt enable bit,
CHxIE.
17.5 Wait Mode
The WAIT instruction puts the MCU in low-power standby mode.
The TIMB remains active after the execution of a WAIT instruction. In wait mode,
the TIMB registers are not accessible by the CPU. Any enabled CPU interrupt
request from the TIMB can bring the MCU out of wait mode.
If TIMB functions are not required during wait mode, reduce power consumption by
stopping the TIMB before executing the WAIT instruction.
17.6 I/O Signals
Port E shares three of its pins with the TIMB:
•
PTE0/TCLKB is an external clock input to the TIMB prescaler.
•
The two TIMB channel I/O pins are PTE1/TCH0B and PTE2/TCH1B.
17.6.1 TIMB Clock Pin (PTE0/TCLKB)
PTE0/TCLKB is an external clock input that can be the clock source for the TIMB
counter instead of the prescaled internal bus clock. Select the PTE0/TCLKB input
by writing 1s to the three prescaler select bits, PS[2:0]. See 17.7.1 TIMB Status
and Control Register.
The maximum TCLK frequency is the least: 4 MHz or bus frequency ÷ 2.
Data Sheet
264
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
I/O Registers
PTE0/TCLKB is available as a general-purpose I/O pin or ADC channel when not
used as the TIMB clock input. When the PTE0/TCLKB pin is the TIMB clock input,
it is an input regardless of the state of the DDRE0 bit in data direction register E.
17.6.2 TIMB Channel I/O Pins (PTE1/TCH0B–PTE2/TCH1B)
Each channel I/O pin is programmable independently as an input capture pin or an
output compare pin. PTE1/TCH0B and PTE2/TCH1B can be configured as
buffered output compare or buffered PWM pins.
17.7 I/O Registers
These input/output (I/O) registers control and monitor TIMB operation:
•
TIMB status and control register (TBSC)
•
TIMB control registers (TBCNTH–TBCNTL)
•
TIMB counter modulo registers (TBMODH–TBMODL)
•
TIMB channel status and control registers (TBSC0 and TBSC1)
•
TIMB channel registers (TBCH0H–TBCH0L and TBCH1H–TBCH1L)
17.7.1 TIMB Status and Control Register
The TIMB status and control register:
•
Enables TIMB overflow interrupts
•
Flags TIMB overflows
•
Stops the TIMB counter
•
Resets the TIMB counter
•
Prescales the TIMB counter clock
Address:
$0051
Bit 7
6
5
TOIE
TSTOP
1
Read:
TOF
Write:
0
Reset:
0
0
R
= Reserved
4
3
0
0
TRST
R
0
0
2
1
Bit 0
PS2
PS1
PS0
0
0
0
Figure 17-5. TIMB Status and Control Register (TBSC)
TOF — TIMB Overflow Flag
This read/write flag is set when the TIMB counter reaches the modulo value
programmed in the TIMB counter modulo registers. Clear TOF by reading the
TIMB status and control register when TOF is set and then writing a logic 0 to
TOF. If another TIMB overflow occurs before the clearing sequence is complete,
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
265
Timer Interface B (TIMB)
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 = TIMB counter has reached modulo value.
0 = TIMB counter has not reached modulo value.
TOIE — TIMB Overflow Interrupt Enable Bit
This read/write bit enables TIMB overflow interrupts when the TOF bit becomes
set. Reset clears the TOIE bit.
1 = TIMB overflow interrupts enabled
0 = TIMB overflow interrupts disabled
TSTOP — TIMB Stop Bit
This read/write bit stops the TIMB counter. Counting resumes when TSTOP is
cleared. Reset sets the TSTOP bit, stopping the TIMB counter until software
clears the TSTOP bit.
1 = TIMB counter stopped
0 = TIMB counter active
NOTE:
Do not set the TSTOP bit before entering wait mode if the TIMB is required to exit
wait mode. Also, when the TSTOP bit is set and the timer is configured for input
capture operation, input captures are inhibited until TSTOP is cleared.
TRST — TIMB Reset Bit
Setting this write-only bit resets the TIMB counter and the TIMB prescaler.
Setting TRST has no effect on any other registers. Counting resumes from
$0000. TRST is cleared automatically after the TIMB counter is reset and
always reads as logic 0. Reset clears the TRST bit.
1 = Prescaler and TIMB counter cleared
0 = No effect
NOTE:
Setting the TSTOP and TRST bits simultaneously stops the TIMB counter at a
value of $0000.
PS[2:0] — Prescaler Select Bits
These read/write bits select either the PTE0/TCLKB pin or one of the seven
prescaler outputs as the input to the TIMB counter as Table 17-1 shows. Reset
clears the PS[2:0] bits.
Data Sheet
266
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
I/O Registers
Table 17-1. Prescaler Selection
PS[2:0]
TIMB Clock Source
000
Internal bus clock ÷1
001
Internal bus clock ÷ 2
010
Internal bus clock ÷ 4
011
Internal bus clock ÷ 8
100
Internal bus clock ÷ 16
101
Internal bus clock ÷ 32
110
Internal bus clock ÷ 64
111
PTE0/TCLKB
17.7.2 TIMB Counter Registers
The two read-only TIMB counter registers contain the high and low bytes of the
value in the TIMB counter. Reading the high byte (TBCNTH) latches the contents
of the low byte (TBCNTL) into a buffer. Subsequent reads of TBCNTH do not affect
the latched TBCNTL value until TBCNTL is read. Reset clears the TIMB counter
registers. Setting the TIMB reset bit (TRST) also clears the TIMB counter registers.
NOTE:
If TBCNTH is read during a break interrupt, be sure to unlatch TBCNTL by reading
TBCNTL before exiting the break interrupt. Otherwise, TBCNTL retains the value
latched during the break.
Register Name and Address:
TBCNTH — $0052
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Register Name and Address:
TBCNTL — $0053
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 17-6. TIMB Counter Registers (TBCNTH and TBCNTL)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
267
Timer Interface B (TIMB)
17.7.3 TIMB Counter Modulo Registers
The read/write TIMB modulo registers contain the modulo value for the TIMB
counter. When the TIMB counter reaches the modulo value, the overflow flag
(TOF) becomes set, and the TIMB counter resumes counting from $0000 at the
next timer clock. Writing to the high byte (TBMODH) inhibits the TOF bit and
overflow interrupts until the low byte (TBMODL) is written. Reset sets the TIMB
counter modulo registers.
Register Name and Address:
Read:
Write:
Reset:
TBMODH — $0054
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
1
1
1
1
1
1
1
1
Register Name and Address:
Read:
Write:
Reset:
TBMODL — $0055
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
1
1
1
1
1
1
Figure 17-7. TIMB Counter Modulo Registers
(TBMODH and TBMODL)
NOTE:
Reset the TIMB counter before writing to the TIMB counter modulo registers.
17.7.4 TIMB Channel Status and Control Registers
Each of the TIMB channel status and control registers:
Data Sheet
268
•
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 TIMB overflow
•
Selects 0 percent and 100 percent PWM duty cycle
•
Selects buffered or unbuffered output compare/PWM operation
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
I/O Registers
Register Name and Address:
Bit 7
Read:
CH0F
Write:
0
Reset:
0
TBSC0 — $0056
6
5
4
3
2
1
Bit 0
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
0
0
0
0
0
0
0
4
3
2
1
Bit 0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
0
0
0
0
0
Register Name and Address:
Bit 7
Read:
CH1F
Write:
0
Reset:
TBSC1 — $0059
6
CH1IE
0
0
R
= Reserved
5
0
R
0
Figure 17-8. TIMB Channel Status
and Control Registers (TBSC0–TBSC1)
CHxF — Channel x Flag
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 TIMB counter registers matches the
value in the TIMB channel x registers.
When CHxIE = 1, clear CHxF by reading TIMB channel x status and control
register with CHxF set, and then writing a 0 to CHxF. If another interrupt request
occurs before the clearing sequence is complete, then writing 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 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 TIMB CPU interrupts on channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
MSxB — Mode Select Bit B
This read/write bit selects buffered output compare/PWM operation. MSxB
exists only in the TIMB channel 0.
Setting MS0B disables the channel 1 status and control register and reverts
TCH1B to general-purpose I/O.
Reset clears the MSxB bit.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
269
Timer Interface B (TIMB)
MSxA — Mode Select Bit A
When ELSxB:A ≠ 00, this read/write bit selects either input capture operation or
unbuffered output compare/PWM operation. See Table 17-2.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
When ELSxB:A = 00, this read/write bit selects the initial output level of the
TCHx pin once PWM, input capture, or output compare operation is enabled. See
Table 17-2. 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 TIMB status and control register (TBSC).
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 port E,
and pin PTEx/TCHxB is available as a general-purpose I/O pin. However,
channel x is at a state determined by these bits and becomes transparent to the
respective pin when PWM, input capture, or output compare mode is enabled.
Table 17-2 shows how ELSxB and ELSxA work. Reset clears the ELSxB and
ELSxA bits.
NOTE:
Before enabling a TIMB channel register for input capture operation, make sure
that the PTEx/TBCHx 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 TIMB 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 TIMB counter overflow.
0 = Channel x pin does not toggle on TIMB counter overflow.
Data Sheet
270
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Timer Interface B (TIMB)
I/O Registers
Table 17-2. Mode, Edge, and Level Selection
MSxB:MSxA
ELSxB:ELSxA
X0
00
X1
00
00
01
00
10
00
11
Capture on rising or falling edge
01
00
Softare compare only
01
01
01
10
01
11
1X
01
1X
10
1X
11
NOTE:
Mode
Configuration
Pin under port control; initialize timer output level high
Output preset
Pin under port control; initialize timer output level low
Capture on rising edge only
Input capture
Capture on falling edge only
Toggle output on compare
Output compare
or PWM
Clear output on compare
Set output on compare
Buffered output
compare
or buffered
PWM
Toggle output on compare
Clear output on compare
Set output on compare
When TOVx is set, a TIMB 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 is 1 and clear output on compare is selected, setting the
CHxMAX bit forces the duty cycle of buffered and unbuffered PWM signals to
100 percent. As Figure 17-9 shows, CHxMAX bit takes effect in the cycle after
it is set or cleared. The output stays at 100 percent duty cycle level until the
cycle after CHxMAX is cleared.
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PTEx/TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
CHxMAX
TOVx
Figure 17-9. CHxMAX Latency
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Timer Interface B (TIMB)
Data Sheet
271
Timer Interface B (TIMB)
17.7.5 TIMB Channel Registers
These read/write registers contain the captured TIMB counter value of the input
capture function or the output compare value of the output compare function. The
state of the TIMB channel registers after reset is unknown.
In input capture mode (MSxB–MSxA = 0:0), reading the high byte of the TIMB
channel x registers (TBCHxH) inhibits input captures until the low byte (TBCHxL)
is read.
In output compare mode (MSxB–MSxA ≠ 0:0), writing to the high byte of the TIMB
channel x registers (TBCHxH) inhibits output compares until the low byte
(TBCHxL) is written.
Register Name and Address:
Read:
Write:
TBCH0H — $0057
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TBCH0L — $0058
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
TBCH1H — $005A
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset:
Indeterminate after reset
Register Name and Address:
Read:
Write:
Reset:
TBCH1L — $005B
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Indeterminate after reset
Figure 17-10. TIMB Channel Registers
(TBCH0H/L–TBCH1H/L)
Data Sheet
272
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Timer Interface B (TIMB)
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 18. Development Support
18.1 Introduction
This section describes the break module, the monitor read-only memory (MON),
and the monitor mode entry methods.
18.2 Break Module (BRK)
The break module (BRK) can generate a break interrupt that stops normal program
flow at a defined address to enter a background program. Features include:
•
Accessible input/output (I/O) registers during the break interrupt
•
Central processor unit (CPU) generated break interrupts
•
Software-generated break interrupts
•
Computer operating properly (COP) disabling during break interrupts
18.2.1 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).
These 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 microcontroller unit (MCU) to normal operation.
Figure 18-1 shows the structure of the break module.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
273
Development Support
IAB15–IAB8
BREAK ADDRESS REGISTER HIGH
8-BIT COMPARATOR
IAB15–IAB0
CONTROL
BREAK
8-BIT COMPARATOR
BREAK ADDRESS REGISTER LOW
IAB7–IAB0
Figure 18-1. Break Module Block Diagram
Addr.
$FE00
Register Name
Read:
SIM Break Status Register
(SBSR) Write:
See page 277.
Reset:
$FE03
Read:
SIM Break Flag Control
Register (SBFCR) Write:
See page 278.
Reset:
Read:
Break Address Register High
$FE0C
(BRKH) Write:
See page 276.
Reset:
Read:
Break Address Register Low
$FE0D
(BRKL) Write:
See page 276.
Reset:
$FE0E
Read:
Break Status and Control
Register (BRKSCR) Write:
See page 276.
Reset:
Note: Writing a 0 clears BW.
Bit 7
6
5
4
3
2
1
Bit 0
R
R
R
R
R
R
BW
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
0
0
0
0
0
0
BRKE
BRKA
0
0
0
0
0
0
0
0
R
= Reserved
0
= Unimplemented
Figure 18-2. I/O Register Summary
Data Sheet
274
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Break Module (BRK)
18.2.1.1 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.
18.2.1.2 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.
18.2.1.3 TIM1 and TIM2 During Break Interrupts
A break interrupt stops the timer counters.
18.2.1.4 COP During Break Interrupts
The COP is disabled during a break interrupt when VTST is present on the RST pin.
18.2.2 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power- consumption standby
modes.
18.2.2.1 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. Clear the BW
bit by writing logic 0 to it.
18.2.2.2 Stop Mode
The break module is inactive in stop mode. The STOP instruction does not affect
break module register states.
18.2.3 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)
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
275
Development Support
18.2.3.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module enable
and status bits.
Address:
Read:
Write:
$FE0E
Bit 7
6
BRKE
BRKA
0
0
Reset:
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 18-3. 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
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
18.2.3.2 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 18-4. 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 18-5. Break Address Register Low (BRKL)
Data Sheet
276
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Break Module (BRK)
18.2.3.3 Break Status Register
The 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.
Address:
Read:
Write:
$FE00
Bit 7
6
5
4
3
2
1
Bit 0
R
R
R
R
R
R
BW
R
0
Reset:
Figure 18-6. SIM Break Status Register (SBSR)
BW — Break Wait Bit
This read/write bit is set when a break interrupt causes an exit from wait mode.
Clear BW by writing a logic 0 to it. Reset clears BW.
1 = Break interrupt during wait mode
0 = No break interrupt during wait mode
BW can be read within the break interrupt routine. The user can modify the
return address on the stack by subtracting 1 from it. The following code is an
example.
This code works if the H register was stacked in the break interrupt routine. Execute
this code at the end of the break interrupt routine.
HIBYTE
EQU
5
LOBYTE
EQU
6
; If not BW, do RTI
BRCLR
BW,BSR, RETURN
; See if wait mode or stop mode
; was exited by break.
TST
LOBYTE,SP
; If RETURNLO is not 0,
BNE
DOLO
; then just decrement low byte.
DEC
HIBYTE,SP
; Else deal with high byte also.
DOLO
DEC
LOBYTE,SP
; Point to WAIT/STOP opcode.
RETURN
PULH
RTI
; Restore H register.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
277
Development Support
18.2.3.4 Break Flag Control Register
The 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 18-7. 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
18.3 Monitor ROM (MON)
The monitor ROM (MON) allows complete testing of the microcontroller unit (MCU)
through a single-wire interface with a host computer. Monitor mode entry can be
achieved without the use of VTST as long as vector addresses $FFFE and $FFFF
are blank, thus reducing the hardware requirements for in-circuit programming.
Features include:
•
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
•
4800 baud–28.8 Kbaud communication with host computer
•
Execution of code in random-access memory (RAM) or ROM
•
FLASH programming
18.3.1 Functional Description
The monitor ROM receives and executes commands from a host computer.
Figure 18-8 shows a sample circuit used to enter monitor mode and communicate
with a host computer via a standard RS-232 interface.
Data Sheet
278
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Monitor ROM (MON)
VDD
10 kΩ
MC68HC908MR16/
MC68HC908MR32
S1
RST
0.1 µF
VHI
10 kΩ
IRQ
VDDA
1
10 µF
MC145407
VDDA
20
+
+
3
18
4
17
0.1 µF
10 µF
VDDAD
VDDAD
0.1 µF
10 µF
+
2
19
+
10 µF
VREFH
VDD
VREFH
0.1 µF
CGMXFC
0.02 µF
DB-25
2
5
16
3
6
15
OSC1
X1
4.9152 MHz
20 pF
7
10 MΩ
OSC2
VDD
1
MC74HC125
VREFL
VSSAD
VSSA
PWMGND
VSS
20 pF
14
2
3
6
5
VDD
VDD
4
0.1 µF
VDD
7
VDD
10 kΩ
10 kΩ
A
B
PTA0
PTA7
PTC2
S3
VDD
S2 Position A — Bus clock = CGMXCLK ÷ 4 or CGMVCLK ÷ 4
S2 Position B — Bus clock = CGMXCLK ÷ 2
S3 Position A — Parallel communication
S3 Position B — Serial communication
VDD
10 kΩ
10 kΩ
A
S2
B
PTC3
PTC4
Figure 18-8. Monitor Mode Circuit
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
279
Development Support
Simple monitor commands can access any memory address. In monitor mode, the
MCU can execute host-computer code in RAM while all 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 pullup resistor.
18.3.1.1 Entering Monitor Mode
There are two methods for entering monitor:
NOTE:
•
The first is the traditional M68HC08 method where VDD + VHI is applied to
IRQ1 and the mode pins are configured appropriately.
•
A second method, intended for in-circuit programming applications, will
force entry into monitor mode without requiring high voltage on the IRQ1 pin
when the reset vector locations of the FLASH are erased ($FF).
For both methods, holding the PTC2 pin low when entering monitor mode causes
a bypass of a divide-by-two stage at the oscillator. The CGMOUT frequency is
equal to the CGMXCLK frequency, and the OSC1 input directly generates internal
bus clocks. In this case, the OSC1 signal must have a 50 percent duty cycle at
maximum bus frequency.
Table 18-1 is a summary of the differences between user mode and monitor mode.
Table 18-1. Mode Differences
Functions
COP
Rest
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
Modes
1. If the high voltage (VDD + VHI) is removed from the IRQ1 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.
18.3.1.2 Normal Monitor Mode
Table 18-2 shows the pin conditions for entering monitor mode.
Data Sheet
280
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
MC68HC908MR32 • MC68HC908MR16
MOTOROLA
Table 18-2. Monitor Mode Signal Requirements and Options
PTC2
(S2)
External
Clock(1)
CGMOUT
X
X
X
0
0
0
Development Support
RESET
(S1)
$FFFE
/$FFFF
X
GND
X
X
X
VTST
VDD
or
VTST
X
OFF
1
VTST
VDD
or
VTST
X
VDD
VDD
$FFFF
Blank
OFF
VDD
or
GND
VTST
$FFFF
Blank
OFF
X
X
X
X
VDD
or
GND
VDD
or
VTST
Non-$FF
OFF
Programmed
X
X
X
X
IRQ
PLL PTC3 PTC4
OFF
1
X
0
X
1
X
For Serial
Communication(2)
Bus
Frequency
COP
0
Disabled
2.4576
MHz
Disabled
2.4576
MHz
Disabled
2.4576
MHz
Disabled
—
—
—
—
4.9152 MHz 4.9152 MHz
9.8304 MHz 4.9152 MHz
9.8304 MHz 4.9152 MHz
Comment
Baud
PTA7
PTA0
(S3) Rate(3) (4)
X
X
0
1
0
9600
X
1
DNA
1
0
9600
X
1
DNA
1
0
9600
X
1
DNA
Enabled
X
X
—
Enters user mode — will encounter an
illegal address reset
Enabled
X
X
—
Enters user mode
PTC3 and PTC2 voltages only required if
IRQ = VTST; PTC2 determines frequency
divider
PTC3 and PTC2 voltages only required if
IRQ = VTST; PTC2 determines frequency
divider
External frequency always divided by 4
Development Support
Monitor ROM (MON)
281
Data Sheet — Rev. 6.0
1. External clock is derived by a 32.768 kHz crystal or a 4.9152/9.8304 MHz off-chip oscillator.
2. DNA = does not apply, X = don’t care
3. PAT0 = 1 if serial communication; PTA0 = X if parallel communication
4. PTA7 = 0 → serial, PTA7 = 1 → parallel communication for security code entry
No operation until reset goes high
Development Support
Enter monitor mode by either:
•
Executing a software interrupt instruction (SWI) or
•
Applying a logic 0 and then a logic 1 to the RST pin
Once out of reset, the MCU waits for the host to send eight security bytes. After
receiving the security bytes, the MCU sends a break signal (10 consecutive logic
0s) to the host computer, 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.
Monitor mode uses alternate vectors for reset and SWI. The alternate vectors are
in the $FE page instead of the $FF page and allow code execution from the internal
monitor firmware instead of user code. The computer operating properly (COP)
module is disabled in monitor mode as long as VHI is applied to either the IRQ pin
or the RST pin. (See Section 14. System Integration Module (SIM) for more
information on modes of operation.)
18.3.1.3 Forced Monitor Mode
If the voltage applied to the IRQ1 is less than VDD + VHI the MCU will come out of
reset in user mode. The MENRST module is monitoring the reset vector fetches
and will assert an internal reset if it detects that the reset vectors are erased ($FF).
When the MCU comes out of reset, it is forced into monitor mode without requiring
high voltage on the IRQ1 pin.
The COP module is disabled in forced monitor mode. Any reset other than a POR
reset will automatically force the MCU to come back to the forced monitor mode.
18.3.1.4 Data Format
Communication with the monitor ROM is in standard non-return-to-zero (NRZ)
mark/space data format. (See Figure 18-9 and Figure 18-10.)
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
STOP
BIT
NEXT
START
BIT
Figure 18-9. Monitor Data Format
$A5
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BREAK
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
STOP
BIT
STOP
BIT
NEXT
START
BIT
NEXT
START
BIT
Figure 18-10. Sample Monitor Waveforms
The data transmit and receive rate can be anywhere from 4800 baud to
28.8 Kbaud. Transmit and receive baud rates must be identical.
Data Sheet
282
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Monitor ROM (MON)
18.3.1.5 Echoing
As shown in Figure 18-11, the monitor ROM immediately echoes each received
byte back to the PTA0 pin for error checking.
SENT TO
MONITOR
READ
READ
ADDR. HIGH ADDR. HIGH
ADDR. LOW
ADDR. LOW
ECHO
DATA
RESULT
Figure 18-11. Read Transaction
Any result of a command appears after the echo of the last byte of the command.
18.3.1.6 Break Signal
A start bit followed by nine low bits is a break signal. See Figure 18-12. When the
monitor receives a break signal, it drives the PTA0 pin high for the duration of two
bits before echoing the break signal.
MISSING STOP BIT
2--STOP-BIT DELAY BEFORE ZERO ECHO
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Figure 18-12. Break Transaction
18.3.1.7 Commands
The monitor ROM uses these commands (see Table 18-3–Table 18-8):
•
READ, read memory
•
WRITE, write memory
•
IREAD, indexed read
•
IWRITE, indexed write
•
READSP, read stack pointer
•
RUN, run user program
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
283
Development Support
Table 18-3. READ (Read Memory) Command
Description
Read byte from memory
Operand
2-byte address in high-byte:low-byte order
Data Returned
Returns contents of specified address
Opcode
$4A
Command Sequence
SENT TO MONITOR
READ
ADDRESS
HIGH
READ
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
ECHO
RETURN
Table 18-4. WRITE (Write Memory) Command
Description
Operand
Data Returned
Opcode
Write byte to memory
2-byte address in high-byte:low-byte order; low byte followed by data byte
None
$49
Command Sequence
FROM HOST
WRITE
ADDRESS
HIGH
WRITE
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
ECHO
Table 18-5. IREAD (Indexed Read) Command
Description
Operand
Data Returned
Opcode
Read next 2 bytes in memory from last address accessed
2-byte address in high byte:low byte order
Returns contents of next two addresses
$1A
Command Sequence
FROM HOST
IREAD
IREAD
ECHO
Data Sheet
284
DATA
DATA
RETURN
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Monitor ROM (MON)
Table 18-6. IWRITE (Indexed Write) Command
Description
Operand
Data Returned
Opcode
Write to last address accessed + 1
Single data byte
None
$19
Command Sequence
FROM HOST
IWRITE
IWRITE
DATA
DATA
ECHO
A sequence of IREAD or IWRITE commands can access a block of memory
sequentially over the full 64-Kbyte memory map.
Table 18-7. READSP (Read Stack Pointer) Command
Description
Operand
Data Returned
Opcode
Reads stack pointer
None
Returns incremented stack pointer value (SP + 1) in high-byte:low-byte order
$0C
Command Sequence
FROM HOST
READSP
SP
HIGH
READSP
ECHO
SP
LOW
RETURN
Table 18-8. RUN (Run User Program) Command
Description
Executes PULH and RTI instructions
Operand
None
Data Returned
None
Opcode
$28
Command Sequence
FROM HOST
RUN
RUN
ECHO
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
285
Development Support
18.3.1.8 Baud Rate
With a 4.9152-MHz crystal and the PTC2 pin at logic 1 during reset, data is
transferred between the monitor and host at 4800 baud. If the PTC2 pin is at logic
0 during reset, the monitor baud rate is 9600. See Table 18-9.
Table 18-9. Monitor Baud Rate Selection
VCO Frequency Multiplier (N)
Monitor baud rate
1
2
3
4
5
6
4800
9600
14,400
19,200
24,000
28,800
18.3.2 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 user-defined data.
NOTE:
Do not leave locations $FFF6–$FFFD blank. For security reasons, program
locations $FFF6–$FFFD even if they are not used for vectors.
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 reset occurs. If the reset was not a power-on reset, security remains
bypassed and security code entry is not required. (See Figure 18-13.)
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 $60 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 can be reset (via power-pin reset only) and
brought up in monitor mode to attempt another entry. After failing the security
sequence, the FLASH mode can also be bulk erased by executing an erase routine
that was downloaded into internal RAM. The bulk erase operation clears the
security code locations so that all eight security bytes become $FF.
Data Sheet
286
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Development Support
Monitor ROM (MON)
VDD
4096 + 32 CGMXCLK CYCLES
RST
24 BUS CYCLES
PA7
COMMAND
BYTE 8
BYTE 2
BYTE 1
256 BUS CYCLES (MINIMUM)
FROM HOST
PA0
3
1
1
1
3
2
1
COMMAND ECHO
NOTES:
1 = Echo delay, 2 bit times
2 = Data return delay, 2 bit times
3 = Wait 1 bit time before sending next byte.
BREAK
BYTE 8 ECHO
BYTE 2 ECHO
BYTE 1 ECHO
FROM MCU
Figure 18-13. Monitor Mode Entry Timing
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
Development Support
287
Development Support
Data Sheet
288
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Development Support
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 19. Electrical Specifications
19.1 Introduction
This section contains electrical and timing specifications.
19.2 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. For
guaranteed operating conditions, refer to 19.5 DC Electrical Characteristics.
Characteristic(1)
Symbol
Value
Unit
Supply voltage
VDD
–0.3 to +6.0
V
Input voltage
VIn
VSS –0.3 to
VDD +0.3
V
Input high voltage
VHI
VDD + 4 maximum
V
I
±25
mA
Storage temperature
TSTG
–55 to +150
°C
Maximum current out of VSS
IMVSS
100
mA
Maximum current into VDD
IMVDD
100
mA
Maximum current per pin
excluding VDD and VSS
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).
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Data Sheet
289
Electrical Specifications
19.3 Functional Operating Range
Characteristic
Symbol
Value
Unit
TA
–40 to 85
–40 to 105
°C
VDD
5.0 ± 10%
V
Operating temperature range(1)
MC68HC908MR24CFU
MC68HC908MR24VFU
Operating voltage range
1. See Motorola representative for temperature availability.
C = Extended temperature range (–40°C to +85°C)
V = Automotive temperature range (–40°C to +105°C)
19.4 Thermal Characteristics
Characteristic
Symbol
Value
Unit
Thermal resistance,
64-pin QFP
θJA
76
°C/W
I/O pin power dissipation
PI/O
User determined
W
Power dissipation(1)
PD
PD = (IDD x VDD) + PI/O =
K/(TJ + 273°C)
W
Constant(2)
K
Average junction temperature
Maximum junction temperature
PD x (TA + 273°C)
+ PD2 x θJA
W/°C
TJ
TA + (PD x θJA)
°C
TJM
125
°C
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 measured PD.
With this value of K, PD and TJ can be determined for any value of TA.
Data Sheet
290
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Electrical Specifications
DC Electrical Characteristics
19.5 DC Electrical Characteristics
Characteristic(1)
Symbol
Min
Typ(2)
Max
Unit
Output high voltage
(ILoad = –2.0 mA) all I/O pins
VOH
VDD –0.8
—
—
V
Output low voltage
(ILoad = 1.6 mA) all I/O pins
VOL
—
—
0.4
V
PWM pin output source current
(VOH = VDD –0.8 V)
IOH
–7
—
—
mA
PWM pin output sink current (VOL = 0.8 V)
IOL
20
—
—
mA
Input high voltage, all ports, IRQs, RESET, OSC1
VIH
0.7 x VDD
—
VDD
V
Input low voltage, all ports, IRQs, RESET, OSC1
VIL
VSS
—
0.3 x VDD
V
—
—
—
—
—
—
30
12
700
mA
mA
µA
IIL
—
—
±10
µA
VDD supply current
Run(3)
Wait(4)
Stop(5)
IDD
I/O ports high-impedance leakage current
IIn
—
—
±1
µA
Capacitance
Ports (as input or output)
COut
CIn
—
—
—
—
12
8
pF
Low-voltage inhibit reset(6)
VLVR1
4.0
4.35
4.65
V
Low-voltage reset/recover hysteresis
VLVH1
40
90
150
mV
Low-voltage inhibit reset recovery
(VREC1 = VLVR1 + VLVH1)
VREC1
4.04
4.5
4.75
V
Low-voltage inhibit reset
VLVR2
3.85
4.15
4.45
V
Low-voltage reset/recover hysteresis
VLVH2
150
210
250
mV
Low-voltage inhibit reset recovery
(VREC2 = VLVR2 + VLVH2)
VREC2
4.0
4.4
4.6
V
POR re-arm voltage(7)
VPOR
0
—
100
mV
RPOR
0.035
—
—
V/ms
VPORRST
0
700
800
V
VHi
VDD + 2.5
—
8.0
V
Input current (input only pins)
POR rise time ramp
rate(8)
POR reset voltage(9)
Monitor mode entry voltage (on IRQ)
1. VDD = 5.0 Vdc ± 10%, 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 (fOSC = 8.2 MHz). 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 (fOSC = 8.2 MHz); 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 wait IDD;
measured with PLL and LVI enabled.
5. Stop IDD measured with PLL and LVI disengaged, OCS1 grounded, no port pins sourcing current. It is measured through
combination of VDD, VDDAD, and VDDA.
6. The low-voltage inhibit reset is software selectable. Refer to Section 9. Low-Voltage Inhibit (LVI).
7. Maximum is highest voltage that POR is guaranteed.
8. If minimum VDD is not reached before the internal POR is released, RST must be driven low externally until minimum VDD
is reached.
9. Maximum is highest voltage that POR is possible.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Data Sheet
291
Electrical Specifications
19.6 FLASH Memory Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
VRDR
1.3
—
—
V
—
1
—
—
MHz
fRead(1)
0
—
8M
Hz
FLASH page erase time
<1 K cycles
>1 K cycles
tErase
0.9
3.6
1
4
1.1
5.5
ms
FLASH mass erase time
tMErase
4
—
—
ms
FLASH PGM/ERASE to HVEN setup time
tNVS
10
—
—
µs
FLASH high-voltage hold time
tNVH
5
—
—
µs
FLASH high-voltage hold time (mass erase)
tNVHL
100
—
—
µs
FLASH program hold time
tPGS
5
—
—
µs
FLASH program time
tPROG
30
—
40
µs
FLASH return to read time
tRCV(2)
1
—
—
µs
FLASH cumulative program HV period
tHV(3)
—
—
4
ms
FLASH endurance(4)
—
10 k
100 k
—
Cycles
FLASH data retention time(5)
—
15
100
—
Years
RAM data retention voltage
FLASH program bus clock frequency
FLASH read bus clock frequency
1. fRead is defined as the frequency range for which the FLASH memory can be read.
2. 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 0.
3. tHV is defined as the cumulative high voltage programming time to the same row before next erase.
tHV must satisfy this condition: tNVS + tNVH + tPGS + (tPROG x 32) ≤ tHV maximum.
4. Typical endurance was evaluated for this product family. For additional information on how Motorola defines Typical
Endurance, please refer to Engineering Bulletin EB619.
5. Typical data retention values are based on intrinsic capability of the technology measured at high temperature and de-rated
to 25°C using the Arrhenius equation. For additional information on how Motorola defines Typical Data Retention, please refer
to Engineering Bulletin EB618.
Data Sheet
292
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Electrical Specifications
Control Timing
19.7 Control Timing
Characteristic(1)
Symbol
Min
Max
Unit
Frequency of operation(2)
Crystal option
External clock option(3)
fOSC
1
dc(4)
8
32.8
MHz
Internal operating frequency
fOP
—
8.2
MHz
RESET input pulse width low(5)
tIRL
50
—
ns
1. VDD = 5.0 Vdc ± 10%, VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD, unless otherwise noted
2. See 19.8 Serial Peripheral Interface Characteristics for more information.
3. No more than 10% duty cycle deviation from 50%.
4. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
5. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Data Sheet
293
Electrical Specifications
19.8 Serial Peripheral Interface Characteristics
Diagram
Number(1)
Characteristic(2)
Symbol
Min
Max
Unit
Operating frequency
Master
Slave
fOP(M)
fOP(S)
fOP/128
fOP/2
MHz
dc
fOP
1
Cycle time
Master
Slave
tCYC(M)
tCYC(S)
2
1
128
—
tCYC
2
Enable lead time
tLead(S)
15
—
ns
3
Enable lag time
tLag(S)
15
—
ns
4
Clock (SPCK) high time
Master
Slave
tSCKH(M)
tSCKH(S)
100
50
—
—
ns
5
Clock (SPCK) low time
Master
Slave
tSCKL(M)
tSCKL(S)
100
50
—
—
ns
6
Data setup time (inputs)
Master
Slave
tSU(M)
tSU(S)
45
5
—
—
ns
7
Data hold time (inputs)
Master
Slave
tH(M)
tH(S)
0
15
—
—
ns
8
Access time, slave(3)
CPHA = 0
CHPA = 1
tA(CP0)
tA(CP1)
0
0
40
20
ns
9
Disable time, slave(4)
tDIS(S)
—
25
ns
10
Data valid time after enable edge
Master
Slave(5)
tV(M)
tV(S)
—
—
10
40
ns
1. VDD = 5.0 Vdc ± 10%, all timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted; assumes 100 pF
load on all SPI pins
2. Numbers refer to dimensions in Figure 19-1 and Figure 19-2.
3. Time to data active from high-impedance state
4. Hold time to high-impedance state
5. With 100 pF on all SPI pins
Data Sheet
294
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Electrical Specifications
Serial Peripheral Interface Characteristics
SS
INPUT
SS PIN OF MASTER HELD HIGH
1
SPCK, CPOL = 0
OUTPUT
NOTE
SPCK, CPOL = 1
OUTPUT
NOTE
5
4
5
4
6
MISO
INPUT
MSB IN
BITS 6–1
10
11
MOSI
OUTPUT
MASTER MSB OUT
7
LSB IN
10
11
BITS 6–1
MASTER LSB OUT
Note: This first clock edge is generated internally, but is not seen at the SCK pin.
a) SPI Master Timing (CPHA = 0)
SS
INPUT
SS PIN OF MASTER HELD HIGH
1
SPCK, CPOL = 0
OUTPUT
SPCK, CPOL = 1
OUTPUT
5
NOTE
4
5
NOTE
4
6
MISO
INPUT
10
MOSI
OUTPUT
MSB IN
BITS 6–1
11
MASTER MSB OUT
7
LSB IN
10
BITS 6–1
11
MASTER LSB OUT
Note: This last clock edge is generated internally, but is not seen at the SCK pin.
b) SPI Master Timing (CPHA = 1)
Figure 19-1. SPI Master Timing
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Data Sheet
295
Electrical Specifications
SS
INPUT
3
1
SPCK, CPOL = 0
INPUT
11
5
4
2
SPCK, CPOL = 1
INPUT
5
4
9
8
MISO
INPUT
SLAVE
MSB OUT
6
MOSI
OUTPUT
BITS 6–1
7
NOTE
11
11
10
MSB IN
SLAVE LSB OUT
BITS 6–1
LSB IN
Note: Not defined, but normally MSB of character just received
a) SPI Slave Timing (CPHA = 0)
SS
INPUT
1
SPCK, CPOL = 0
INPUT
5
4
2
3
SPCK, CPOL = 1
INPUT
8
MISO
INPUT
MOSI
OUTPUT
5
4
10
NOTE
9
SLAVE
MSB OUT
6
7
BITS 6–1
SLAVE LSB OUT
11
10
BITS 6–1
MSB IN
LSB IN
Note: Not defined, but normally LSB of character previously transmitted
b) SPI Slave Timing (CPHA = 1)
Figure 19-2. SPI Slave Timing
Data Sheet
296
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Electrical Specifications
TImer Interface Module Characteristics
19.9 TImer Interface Module Characteristics
Characteristic
Input capture pulse width
Input clock pulse width
Symbol
Min
Max
Unit
tTIH, tTIL
125
—
ns
tTCH, tTCL
(1/fOP) + 5
—
ns
19.10 Clock Generation Module Component Specifications
Characteristic
Symbol
Min
Typ
Max
Notes
Crystal load capacitance
CL
—
—
—
Consult crystal
manufacturing data
Crystal fixed capacitance
C1
—
2 * CL
—
Consult crystal
manufacturing data
Crystal tuning capacitance
C2
—
2 * CL
—
Consult crystal
manufacturing data
Feedback bias resistor
RB
—
22 MΩ
—
Series resistor
RS
0
330 kΩ
1 MΩ
Filter capacitor
CF
—
CFACT*
(VDDA/fXCLK)
—
CBYP
Bypass capacitor
0.1 µF
—
Not required
CBYP must provide low ac
impedance from
f = fXCLK/100 to 100*fVCLK, so
series resistance must be
considered
—
19.11 CGM Operating Conditions
Characteristic
Symbol
Min
Typ
Max
Unit
Crystal reference frequency
fXCLK
1
—
8
MHz
Range nominal multiplier
fNOM
—
4.9152
—
MHz
VCO center-of-range frequency
fVRS
4.9152
—
32.8
MHz
VCO frequency multiplier
N
1
—
15
—
VCO center of range multiplier
L
1
—
15
—
fVCLK
fVRSMIN
—
fVRSMAX
—
VCO operating frequency
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Data Sheet
297
Electrical Specifications
19.12 CGM Acquisition/Lock Time Specifications
Description
Symbol
Min
Typ
Max
Notes
Filter capacitor multiply factor
CFACT
—
0.0154
—
F/sV
Acquisition mode time factor
KACQ
—
0.1135
—
V
Tracking mode time factor
KTRK
—
0.0174
—
V
Manual mode time to stable
tACQ
—
(8*VDDA)/
(fXCLK*KACQ)
—
If CF chosen
correctly
tAL
—
(4*VDDA)/
(fXCLK*KTRK)
—
If CF chosen
correctly
Manual acquisition time
tLock
—
tACQ+tAL
—
Tracking mode entry frequency
tolerance
∆TRK
0
—
± 3.6%
Acquisition mode entry frequency
tolerance
∆ACQ
±6.3%
—
± 7.2%
Lock entry frequency tolerance
∆Lock
0
—
± 0.9%
Lock exit frequency tolerance
∆UNL
±0.9%
—
± 1.8%
Reference cycles per acquisition mode
measurement
nACQ
—
32
—
Reference cycles per tracking mode
measurement
nTRK
—
128
—
Automatic mode time to stable
tACQ
nACQ/fXCLK
(8*VDDA)/
(fXCLK*KACQ)
—
If CF chosen
correctly
tAL
nTRK/fXCLK
(4*VDDA)/
(fXCLK*KTRK)
—
If CF chosen
correctly
tLock
—
tACQ+tAL
—
fJ
0
—
± (fXCLK)
*(0.025%)
*(N/4)
Manual stable to lock time
Automatic stable to lock time
Automatic lock time
PLL jitter (deviation of average bus
frequency over 2 ms)
Data Sheet
298
N = VCO
freq. mult.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Electrical Specifications
Analog-to-Digital Converter (ADC) Characteristics
19.13 Analog-to-Digital Converter (ADC) Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
Notes
Supply voltage
VDDAD
4.5
—
5.5
V
VDDAD should be tied to
the same potential as
VDD via separate traces
Input voltages
VADIN
0
—
VDDAD
V
VADIN <= VDDAD
Resolution
BAD
10
—
10
Bits
Absolute accuracy
AAD
—
—
±4
LSB
Includes quantization
ADC internal clock
fADIC
500 k
—
1.048 M
Hz
tAIC = 1/fADIC
Conversion range
RAD
VSSAD
—
VDDAD
V
Power-up time
tADPU
16
—
—
tAIC cycles
Conversion time
tADC
16
—
17
tAIC cycles
Sample time
tADS
5
—
—
tAIC cycles
Monotonicity
MAD
Zero input reading
ZADI
000
—
003
Hex
VADIN = VSSAD
Full-scale reading
FADI
3FC
—
3FF
Hex
VADIN = VDDAD
Input capacitance
CADI
—
—
30
pF
Not tested
VREFH/VREFL current
IVREF
—
1.6
—
mA
Absolute accuracy
(8-bit truncation mode)
AAD
—
—
±1
LSB
Quantization error
(8-bit truncation mode)
—
—
—
+ 7/8
– 1/8
LSB
Guaranteed
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Electrical Specifications
Includes quantization
Data Sheet
299
Electrical Specifications
Data Sheet
300
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Electrical Specifications
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Section 20. Ordering Information and Mechanical Specifications
20.1 Introduction
This section provides ordering information for the MC68HC908MR16 and
MC68HC908MR32 along with the dimensions for:
•
64-lead plastic quad flat pack (QFP)
•
56-pin shrink dual in-line package (SDIP)
The following figures show the latest package drawings at the time of this
publication. To make sure that you have the latest package specifications, contact
your local Motorola Sales Office.
20.2 Order Numbers
Table 20-1. Order Numbers
Operating
Temperature Range
MC Order Number(1)
68HC908MR16CFU
68HC908MR16VFU
–40°C to +85°C
–40°C to +105°C
68HC908MR16CB
68HC908MR16VB
–40°C to +85°C
–40°C to +105°C
68HC908MR32CFU
68HC908MR32VFU
–40°C to +85°C
–40°C to +105°C
68HC908MR32CB
68HC908MR32VB
–40°C to +85°C
–40°C to +105°C
1. FU = quad flat pack
B = shrink dual in-line package
MC68HC908MR32XXX
PACKAGE DESIGNATOR
FAMILY
TEMPERATURE RANGE
Figure 20-1. Device Numbering System
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Ordering Information and Mechanical Specifications
Data Sheet
301
Ordering Information and Mechanical Specifications
20.3 64-Pin Plastic Quad Flat Pack (QFP)
L
33
48
49
DETAIL A
S
D
S
H A-B
D
V
P
B
M
B
B
0.20 (0.008)
L
0.20 (0.008) M C A-B
0.05 (0.002) A-B
-B-
-A-
S
S
32
-A-, -B-, DDETAIL A
17
64
1
F
16
-DA
0.20 (0.008) M C A-B
0.05 (0.002) A-B
0.20 (0.008)
M
S
H A-B
S
S
D
S
D
S
J
N
BASE METAL
M
E
DETAIL C
D
0.20 (0.008)
C
-H-
-CH
SEATING
PLANE
M
G
U
T
R
DATUM
PLANE
-HQ
K
W
X
DETAIL C
Data Sheet
302
DATUM
PLANE
M
C A-B
S
D
S
SECTION B-B
0.01 (0.004)
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE ĆHĆ 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 A-B AND ĆDĆ TO BE DETERMINED AT
DATUM PLANE ĆHĆ.
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE ĆCĆ.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
(0.010) PER SIDE. DIMENSIONS A AND B DO
INCLUDE MOLD MISMATCH AND ARE DETERMINED
AT DATUM PLANE ĆHĆ.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
DAMBAR CANNOT BE LOCATED ON THE LOWER
RADIUS OR THE FOOT.
DIM
A
B
C
D
E
F
G
H
J
K
L
M
N
P
Q
R
S
T
U
V
W
X
MILLIMETERS
MIN
MAX
13.90 14.10
13.90 14.10
2.45
2.15
0.45
0.30
2.40
2.00
0.40
0.30
0.80 BSC
0.25
Ċ
0.23
0.13
0.95
0.65
12.00 REF
10°
5°
0.17
0.13
0.40 BSC
7°
0°
0.30
0.13
16.95 17.45
Ċ
0.13
Ċ
0°
16.95 17.45
0.45
0.35
1.6 REF
INCHES
MIN
MAX
0.547 0.555
0.547 0.555
0.085 0.096
0.012 0.018
0.079 0.094
0.012 0.016
0.031 BSC
Ċ
0.010
0.005 0.009
0.026 0.037
0.472 REF
5°
10°
0.005 0.007
0.016 BSC
0°
7°
0.005 0.012
0.667 0.687
0.005
Ċ
0°
Ċ
0.667 0.687
0.014 0.018
0.063 REF
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Ordering Information and Mechanical Specifications
MOTOROLA
Ordering Information and Mechanical Specifications
56-Pin Shrink Dual In-Line Package (SDIP)
20.4 56-Pin Shrink Dual In-Line Package (SDIP)
–A–
56
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIMENSIONS A AND B DO NOT INCLUDE MOLD
FLASH. MAXIMUM MOLD FLASH 0.25 (0.010)
29
–B–
1
28
L
H
C
–T–
K
SEATING
PLANE
G
F
D 56 PL
0.25 (0.010)
E
M
T A
S
N
J
M
56 PL
0.25 (0.010)
M
T B
INCHES
MIN
MAX
2.035
2.065
0.540
0.560
0.155
0.200
0.014
0.022
0.035 BSC
0.032
0.046
0.070 BSC
0.300 BSC
0.008
0.015
0.115
0.135
0.600 BSC
0_
15 _
0.020
0.040
MILLIMETERS
MIN
MAX
51.69
52.45
13.72
14.22
3.94
5.08
0.36
0.56
0.89 BSC
0.81
1.17
1.778 BSC
7.62 BSC
0.20
0.38
2.92
3.43
15.24 BSC
0_
15 _
0.51
1.02
S
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
DIM
A
B
C
D
E
F
G
H
J
K
L
M
N
Ordering Information and Mechanical Specifications
Data Sheet
303
Ordering Information and Mechanical Specifications
Data Sheet
304
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
Ordering Information and Mechanical Specifications
MOTOROLA
Data Sheet — MC68HC908MR32 • MC68HC908MR16
Appendix A. MC68HC908MR16
The information contained in this document pertains to the MC68HC908MR16 with
the exception of that shown in Figure A-1.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA
Data Sheet
MC68HC908MR16
305
MC68HC908MR16
$0000
↓
$005F
I/O REGISTERS — 96 BYTES
$0060
↓
$035F
RAM — 768 BYTES
$0360
↓
$7FFF
UNIMPLEMENTED — 31,904 BYTES
$8000
↓
$BEFF
FLASH — 16,128 BYTES
$BF00
↓
$FDFF
UNIMPLEMENTED — 16,128 BYTES
$FE00
SIM BREAK STATUS REGISTER (SBSR)
$FE01
SIM RESET STATUS REGISTER (SRSR)
$FE02
RESERVED
$FE03
SIM BREAK FLAG CONTROL REGISTER (SBFCR)
$FE04
RESERVED
$FE05
RESERVED
$FE06
RESERVED
$FE07
RESERVED
$FE08
FLASH CONTROL REGISTER (FLCR)
$FE09
UNIMPLEMENTED
$FE0A
UNIMPLEMENTED
$FE0B
UNIMPLEMENTED
$FE0C
SIM BREAK ADDRESS REGISTER HIGH (BRKH)
$FE0D
SIM BREAK ADDRESS REGISTER LOW (BRKL)
$FE0E
SIM BREAK FLAG CONTROL REGISTER (SBFCR)
$FE0F
LVI STATUS AND CONTROL REGISTER (LVISCR)
$FE10
↓
$FEFF
MONITOR ROM — 240 BYTES
$FF00
↓
$FF7D
UNIMPLEMENTED — 126 BYTES
$FF7E
FLASH BLOCK PROTECT REGISTER (FLBPR)
$FF7F
↓
$FFD1
UNIMPLEMENTED — 83 BYTES
$FFD2
↓
$FFFF
VECTORS — 46 BYTES
Figure A-1. MC68HC908MR16 Memory Map
Data Sheet
306
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MC68HC908MR16
MOTOROLA
blank
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2 Dai King Street
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852-26668334
HOME PAGE:
http://motorola.com/semiconductors
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© Motorola Inc. 2003
MC68HC908MR32/D
Rev. 6.0
11/2003