200
CHAPTER 13 WATCH PRESCALER
13.5
Explanation of Watch Prescaler Operations and Setup
Procedure Example
The watch prescaler operates as an interval timer.
■
Operations of Interval Timer Function (Watch Prescaler)
The counter of the watch prescaler continues to count down using the subclock divided by two as its count
clock as long as the subclock oscillates.
When cleared (WPCR:WCLR = 1), the counter starts to count down from "7FFF
H
". Once "0000
H
" is
reached, the counter returns to "7FFF
H
" to continue the count. When the time set by the interrupt interval
time select bits is reached during down-counting, the watch interrupt request flag bit (WPCR:WTIF) is set
to "1" in any mode other than the main stop mode. In other words, a watch interrupt request is generated at
each selected interval time, based on the time when the counter was last cleared.
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Clearing Watch Prescaler
If the watch prescaler is cleared when the output of the watch prescaler is used in other peripheral
functions, this will affect the operation by changing the count time or in other manners.
When clearing the counter by using the watch prescaler initialization bit (WTCR:WCLR), perform setup so
that this does not have unexpected effects on other peripheral functions.
When the output of the watch prescaler is selected as the count clock, clearing the watch prescaler also
clears the watchdog timer.
The watch prescaler is cleared not only by the watch prescaler initialization bit (WTCR:WCLR) but also
when the subclock is stopped and a count is required for the oscillation stabilization wait time.
•
When moving from the subclock mode or sub PLL clock mode to the stop mode
•
When the subclock oscillation stop bit in the system clock control register (SYCC:SUBS) is set to "1" in
the main clock mode or main PLL clock mode
In addition, the counter of the watch prescaler is cleared and stops operation when a reset is generated.
■
Operating Examples of Watch Prescaler
Figure 13.5-1 shows operating examples under the following conditions:
1) When a power-on reset is generated
2) When entering the sleep mode during the operation of the interval timer function in the subclock mode
or sub PLL clock mode
3) When entering the stop mode during the operation of the interval timer function in the subclock mode or
sub PLL clock mode
4) When a request is issued to clear the counter
The same operation is performed when changing to the watch mode as for when changing to the sleep
mode.
Содержание F2 MC-8FX Family
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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 ...
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Страница 532: ...518 CHAPTER 27 REAL TIME CLOCK ...
Страница 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
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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 ...
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Страница 599: ...585 Pin Function Index V2 LCD power supply driving pin 2 439 V3 LCD power supply driving pin 3 439 ...
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