208
CHAPTER 6 Watchdog timer
6.1
Overview of Watchdog Timer
The watchdog timer is a 2-bit counter that uses the timebase timer or watch timer as a
count clock.If the counter is not cleared within a set interval time, the CPU is reset.
■
Functions of Watchdog Timer
•
The watchdog timer is a timer counter that is used to prevent program malfunction.When the watchdog
timer is started, the watchdog timer counter must continue to be cleared within a set interval time.If the
set time interval is reached without clearing the watchdog timer counter, the CPU is reset. This is called
watchdog timer
•
The interval time of the watchdog timer depends on the clock cycle input as a count clock and a
watchdog reset occurs between the minimum and maximum times.
•
The clock source output destination is set by the watchdog clock select bit in the watch timer control
register (WTC: WDCS).
•
The interval time of the watchdog timer is set by the timebase timer output select bit/watch timer output
select bit in the watchdog timer control register (WDTC: WT1, WT0).
Table 6.1-1 lists the interval times of the watchdog timer.
Table 6.1-1 Interval Time of Watchdog Timer
Min.
Max.
Clock Cycle
Min.
Max.
Clock Cycle
Approx. 3.58
ms
Approx. 4.61
ms
2
14
±
2
11
/HCLK
Approx.
0.457 s
Approx.
0.576 s
2
12
±
2
9
/SCLK
Approx.
14.33 ms
Approx. 18.3
ms
2
16
±
2
13
/HCLK
Approx.
3.584 s
Approx.
4.608 s
2
15
±
2
12
/SCLK
Approx.
57.23 ms
Approx.
73.73 ms
2
18
±
2
15
/HCLK
Approx.
7.168 s
Approx.
9.216 s
2
16
±
2
13
/SCLK
Approx.
458.75 ms
Approx.
589.82 ms
2
21
±
2
18
/HCLK
Approx.
14.336 s
Approx.
18.432 s
2
17
±
2
14
/SCLK
HCLK: Oscillation clock (4 MHz), SLCK: Sub clock (8.192 kHz)
Notes:
•
When the timebase timer output (carry signal) is used as a count clock to the watchdog
timer, clearing the timebase timer may extend the time for a watchdog reset to occur.
•
When the subclock is used as the machine cock, be sure to set the watchdog timer clock
source select bit (WDCS) in the watch timer control register (WTC) to "0" to select the
watch timer output.
Summary of Contents for F2MC-16LX Series
Page 2: ......
Page 3: ...FUJITSU LIMITED F2MC 16LX 16 bit Microcontroller MB90895 series Hardware Manual ...
Page 4: ......
Page 8: ...iv ...
Page 10: ...vi ...
Page 36: ...18 CHAPTER 2 HANDLING DEVICES ...
Page 176: ...158 CHAPTER 3 CPU ...
Page 224: ...206 CHAPTER 5 Timebase timer ...
Page 294: ...276 CHAPTER 8 16 bit reload timer ...
Page 366: ...348 CHAPTER 12 DTP external interrupt ...
Page 398: ...380 CHAPTER 13 8 10 bit A D converter ...
Page 446: ...428 CHAPTER 14 UART0 ...
Page 588: ...570 CHAPTER 17 Address Match Detecting Function ...
Page 626: ...608 CHAPTER 19 512 KBIT FLASH MEMORY ...
Page 676: ...658 APPENDIX Table A 9 3 Bit Operation Instruction Map first byte 6CH ...
Page 678: ...660 APPENDIX Table A 9 5 2 byte Instruction Map first byte 6FH MUL MULW DIVU A A A ...
Page 680: ...662 APPENDIX Table A 9 7 ea Instruction 2 first byte 71H ...
Page 681: ...663 APPENDIX A Instructions Table A 9 8 ea Instruction 3 first byte 72H ...
Page 682: ...664 APPENDIX Table A 9 9 ea Instruction 4 first byte 73H ...
Page 683: ...665 APPENDIX A Instructions Table A 9 10 ea Instruction 5 first byte 74H ...
Page 684: ...666 APPENDIX Table A 9 11 ea Instruction 6 first byte 75H ...
Page 685: ...667 APPENDIX A Instructions Table A 9 12 ea Instruction 7 first byte 76H ...
Page 686: ...668 APPENDIX Table A 9 13 ea Instruction 8 first byte 77H ...
Page 687: ...669 APPENDIX A Instructions Table A 9 14 ea Instruction 9 first byte 78H ...
Page 688: ...670 APPENDIX Table A 9 15 MOVEA RWi ea Instruction first byte 79H ...
Page 689: ...671 APPENDIX A Instructions Table A 9 16 MOV Ri ea Instruction first byte 7AH ...
Page 690: ...672 APPENDIX Table A 9 17 MOVW RWi ea Instruction first byte 7BH ...
Page 691: ...673 APPENDIX A Instructions Table A 9 18 MOV ea Ri Instruction first byte 7CH ...
Page 692: ...674 APPENDIX Table A 9 19 MOVW ea Rwi Instruction first byte 7DH ...
Page 693: ...675 APPENDIX A Instructions Table A 9 20 XCH Ri ea Instruction first byte 7EH ...
Page 694: ...676 APPENDIX Table A 9 21 XCHW RWi ea Instruction first byte 7FH ...
Page 710: ......