UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 269

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(3) Up to 1 count clock is required after an operation to start timer/counter 0 (CE0
(4) While an instruction that writes data to the compare register (CR0n: n = 0, 1) is executed, a match between CR0n, to which
(5) A match between timer register 0 (TM0) and compare register (CR0n: n = 0, 1) is detected only when TM0 is incremented.
(6) If the PPG cycle is extremely short as compared with the time required to acknowledge an interrupt, the value of the CR0n
0 actually starts (see Figure 8-52).
For example, when using timer/counter 0 as an interval timer, the first interval time is delayed by up to 1 clock. The second
and those that follow are at the specified interval.
the data is to be written, and timer register 0 (TM0) is not detected. For example, if the contents of CR0n do not change
before and after the writing, the interrupt request is not generated even if the value of TM0 matches the value of CR0n, nor
does the timer output (TOn: n = 0, 1) change.
Write data to CR0n when timer/counter 0 is executing counting operation, in the timing that the contents of TM0 do not
coincide with the value of CR0n before and after writing (e.g., immediately after an interrupt request has been generated
because TM0 and CR0n have matched).
Therefore, the interrupt request is not generated even if the same value as TM0 is written to CR0n, and the timer output
(TOn: n = 0, 1) does not change.
cannot be rewritten by interrupt processing that is performed when the values in the timer register 0 (TM0) and the compare
register (CR0n: n = 0, 1) match. Use another method (for example, to poll the interrupt request flags in software with all
the interrupts masked).
Count Clock
TM0
CE0
Figure 8-52 Operation When Counting Is Started
CHAPTER 8 TIMER/COUNTER 0
0
Count Start Command (CE0
in Software
Timing to Start Actual Counting
0
1
1) has been performed before timer/counter
1)
2
3
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