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CHAPTER 27 REAL TIME CLOCK
27.5
Operation of the Real Time Clock
The operation of the real time clock is described in this section.
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Setting time and date
All registers and counters can be written even when they are updating. However, when counter(s) is/are
written, the counter value(s) is/are still updating. Therefore, written data may be altered right after it is
written. In order to set the time and date information properly. User is advised to set the pause bit
(RTCCRL:PAU) to "1" before setting. It can halt the one-second tick. After setting, RTCCRL:PAU can be
set "0" so as to resume the one-second tick.
For setting after power-on, user is strongly recommended to follow the following sequence:
1) Writing "0" to RTCCRH:PS
2) Writing "1" to RTCCRL:PAU
3) Writing data to SECR/MINR/HOUR/DOWR/DAYR/MONR/YEAR/FTTR
4) Writing "0" to RTCCRL:PAU
When the real time clock is in power save mode (writing "1" to RTCCRL:PS), all the counters and registers
cannot be written.
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Reading current time and date
When the counter latch bit (RTCCRL:CL) is changed from "0" to "1", all counters’s values at that moment
will be latched to coreesponding counter registers. When this bit is "1", the latched counter values are kept
and can be read.
When "0" is written to RTCCRL:CL, the content of the latches will be no longer secured. instead, when
this bit is "0", the latched counter values will being altered in line with the counters’s values
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Steps for transition to and from subclock/timebase timer/watch mode (RTCCRL:PS=1)
Since resource clock must be at least faster than subclock 4 times and this condition cannot be satisfied in
this mode. So we need to set "1" to RTCCRL:PS to meet this condition. The following are the steps for the
user to get into and out of watch/sub-clock run mode.
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Transition to subclock/timebase timer/watch mode (RTCCRL:PS=1)
1) Write "1" to RTCCRL:PS
2) Set Standby Control Register (STBC)/System Clock Register (SYCC).
3) Subclock/timebase timer/watch mode can be accessed.
●
After transition from watch/sub-clock mode
User can write RTCCRL:PS to "0" or "1" which based on user’s decision. But the read value of all counter
registers are indeterminate when setting RTCCRL:PS to "1".
Summary of Contents for F2 MC-8FX Family
Page 2: ......
Page 4: ......
Page 34: ...20 CHAPTER 1 DESCRIPTION ...
Page 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Page 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Page 56: ...42 CHAPTER 5 CPU ...
Page 73: ...59 CHAPTER 6 CLOCK CONTROLLER ...
Page 96: ...82 CHAPTER 6 CLOCK CONTROLLER ...
Page 104: ...90 CHAPTER 7 RESET ...
Page 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
Page 174: ...160 CHAPTER 10 TIMEBASE TIMER ...
Page 184: ...170 CHAPTER 10 TIMEBASE TIMER ...
Page 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Page 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 261: ...247 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 288: ...274 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 301: ...287 CHAPTER 17 16 BIT PPG TIMER ...
Page 316: ...302 CHAPTER 17 16 BIT PPG TIMER ...
Page 382: ...368 CHAPTER 21 UART SIO DEDICATED BAUD RATE GENERATOR ...
Page 390: ...376 CHAPTER 22 I2C ...
Page 395: ...381 CHAPTER 22 I2C ...
Page 399: ...385 CHAPTER 22 I2C ...
Page 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
Page 476: ...462 CHAPTER 24 LCD CONTROLLER ...
Page 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
Page 494: ...480 CHAPTER 26 CLOCK SUPERVISOR ...
Page 507: ...493 CHAPTER 27 REAL TIME CLOCK ...
Page 523: ...509 CHAPTER 27 REAL TIME CLOCK ...
Page 532: ...518 CHAPTER 27 REAL TIME CLOCK ...
Page 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 554: ...540 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
Page 595: ...581 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 596: ...582 INDEX Index ...
Page 597: ...583 INDEX ...
Page 600: ...586 Pin Function Index ...
Page 602: ......