UPD78F9222MC(T)-5A4-A NEC, UPD78F9222MC(T)-5A4-A Datasheet - Page 122

• Manufacturer Part Number: UPD78F9222MC(T)-5A4-A
• Description: 8BIT MCU, 4K FLASH, 256B RAM, 78F9222
• Manufacturer: NEC

Specifications of UPD78F9222MC(T)-5A4-A

• Controller Family/series: UPD78
• No. Of I/o's: 17
• Ram Memory Size: 256Byte
• Cpu Speed: 10MHz
• No. Of Timers: 4
• No. Of: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 4KB
• Oscillator Type: External, Internal

122
(17) Changing compare register during timer operation
<1> With the 16-bit timer capture/compare register 0n0 (CR0n0) used as a compare register, when changing
<2> If CR010 is changed during timer counting without performing processing <1> above, the value in
CR0n0 around the timing of a match between 16-bit timer counter 00 (TM00) and 16-bit timer
capture/compare register 0n0 (CR0n0) during timer counting, the change timing may conflict with the
timing of the match, so the operation is not guaranteed in such cases. To change CR0n0 during timer
counting, INTTM000 interrupt servicing performs the following operation.
<Changing cycle (CR000)>
1. Disable the timer output inversion operation at the match between TM00 and CR000 (TOC001 = 0).
2. Disable the INTTM000 interrupt (TMMK000 = 1).
3. Rewrite CR000.
4. Wait for 1 cycle of the TM00 count clock.
5. Enable the timer output inversion operation at the match between TM00 and CR000 (TOC001 = 1).
6. Clear the interrupt request flag of INTTM000 (TMIF000 = 0).
7. Enable the INTTM000 interrupt (TMMK000 = 0).
<Changing duty (CR010)>
1. Disable the timer output inversion operation at the match between TM00 and CR010 (TOC004 = 0).
2. Disable the INTTM000 interrupt (TMMK000 = 1).
3. Rewrite CR010.
4. Wait for 1 cycle of the TM00 count clock.
5. Enable the timer output inversion operation at the match between TM00 and CR010 (TOC004 = 1).
6. Clear the interrupt request flag of INTTM000 (TMIF000 = 0).
7. Enable the INTTM000 interrupt (TMMK000 = 0).
While interrupts and timer output inversion are disabled (1 to 4 above), timer counting is continued. If
the value to be set in CR0n0 is small, the value of TM00 may exceed CR0n0. Therefore, set the value,
considering the time lapse of the timer clock and CPU clock after an INTTM000 interrupt has been
generated.
Remark n = 0, 1
CR010 may be rewritten twice or more, causing an inversion of the output level of the TO00 pin at each
rewrite.
CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00
User’s Manual U16898EJ5V0UD