
215
CHAPTER 14 WATCH COUNTER
14.5
Explanation of Watch Counter Operations and Setup
Procedure Example
The watch counter counts down for the number of times specified in the count value by
RCTR5 to RCTR0 bits, using the count clock selected by CS1 and CS0 bits, when the
ISEL bit is set to "1". Once the counter underflows, WCFLG bit of the WCSR register is
set to "1", generating an interrupt.
■
Setup Procedure of Watch Counter
The setup procedure of the watch counter is described below.
(1) Select the count clock (CS1 and CS0 bits) and set the counter reload value (RCTR5 to RCTR0 bits).
(2) Set the ISEL bit of the WCSR register to "1" to start a down count and enable interrupts. Also disable
interrupts of the watch prescaler.
The watch counter performs counting by using a divided clock (asynchronous) from the watch
prescaler. An error of up to one count clock may occur at the beginning of a count cycle, depending on
the timing for setting the ISEL bit to "1".
(3) When the counter underflows, the WCFLG bit of the WCSR register is set to "1", generating an
interrupt.
(4) Write "0" to the WCFLG bit to clear it.
(5) If RCTR5 to RCTR0 bits are modified during counting, the reload value will be updated during a
reload after the counter is set to "1".
(6) When writing "0" to the ISEL bit, the counter becomes "0" and stops operation.
Figure 14.5-1 Descriptive Diagram of Watch Counter Operation
RCTR5 to 0
WCFLG
ISEL
7
9
CS1,0
"1,1"
(1)
(2)
(3)
(4)
(6)
CTR5 to 0
7
0
6
5
4
3
2 1
9 8
7
6
5 4
0
(5)
Count clock
Содержание F2 MC-8FX Family
Страница 2: ......
Страница 4: ......
Страница 30: ...16 CHAPTER 1 DESCRIPTION 1 FPT 64P M23 FPT 64P M24 2 For the I O circuit type refer to 1 8 I O Circuit Type ...
Страница 34: ...20 CHAPTER 1 DESCRIPTION ...
Страница 35: ...21 CHAPTER 2 HANDLING DEVICES This chapter gives notes on using 2 1 Device Handling Precautions ...
Страница 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Страница 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Страница 43: ...29 CHAPTER 4 MEMORY ACCESS MODE This chapter describes the memory access mode 4 1 Memory Access Mode ...
Страница 56: ...42 CHAPTER 5 CPU ...
Страница 73: ...59 CHAPTER 6 CLOCK CONTROLLER ...
Страница 96: ...82 CHAPTER 6 CLOCK CONTROLLER ...
Страница 104: ...90 CHAPTER 7 RESET ...
Страница 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
Страница 174: ...160 CHAPTER 10 TIMEBASE TIMER ...
Страница 184: ...170 CHAPTER 10 TIMEBASE TIMER ...
Страница 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Страница 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Страница 261: ...247 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Страница 288: ...274 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Страница 301: ...287 CHAPTER 17 16 BIT PPG TIMER ...
Страница 316: ...302 CHAPTER 17 16 BIT PPG TIMER ...
Страница 382: ...368 CHAPTER 21 UART SIO DEDICATED BAUD RATE GENERATOR ...
Страница 390: ...376 CHAPTER 22 I2C ...
Страница 395: ...381 CHAPTER 22 I2C ...
Страница 399: ...385 CHAPTER 22 I2C ...
Страница 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
Страница 476: ...462 CHAPTER 24 LCD CONTROLLER ...
Страница 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
Страница 494: ...480 CHAPTER 26 CLOCK SUPERVISOR ...
Страница 507: ...493 CHAPTER 27 REAL TIME CLOCK ...
Страница 523: ...509 CHAPTER 27 REAL TIME CLOCK ...
Страница 532: ...518 CHAPTER 27 REAL TIME CLOCK ...
Страница 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
Страница 554: ...540 CHAPTER 28 256 KBIT FLASH MEMORY ...
Страница 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
Страница 595: ...581 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Страница 596: ...582 INDEX Index ...
Страница 597: ...583 INDEX ...
Страница 599: ...585 Pin Function Index V2 LCD power supply driving pin 2 439 V3 LCD power supply driving pin 3 439 ...
Страница 600: ...586 Pin Function Index ...
Страница 602: ......