upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 207

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

7.4.6 Cautions
(1) Error when timer starts
(2) Operation after compare register is changed while timer is counting
(3) TMn read out during timer operation
Remarks 1. N > X > M
Caution Except when the TIn input is selected, always set TCEn = 0 before setting the stop state.
An error of up to 1 clock occurs in the time until the match signal is generated after the timer starts. The reason is
that 8-bit counter n (TMn) starts asynchronously to the count pulse.
If the value after 8-bit compare register n (CRn0) changes is less than the value of the 8-bit timer register (TMn),
counting continues, overflows, and starts again from 0. Consequently, when the value after CRn0 changes (M) is
less than the value before the change (N) and less than the count value of the TMn register, the timer must restart
after CRn0 changes (n = 2 to 5).
Since reading out TMn during operation occurs while the selected clock is temporarily stopped, select a high- or
low-level waveform that is longer than the selected clock (n = 2 to 5).
TMn count value
2. n = 2 to 5
Figure 7-37. Timing After Compare Register Changes During Timer Count Operation
Count pulse
Remark
CRn0
TMn count value
Count pulse
n = 2 to 5
X
N
CHAPTER 7
–
Figure 7-36. Start Timing of Timer n
1
Timer starts
00H
↑
User’s Manual U12768EJ4V1UD
X
TIMER/COUNTER FUNCTION
01H
02H
M
FFH
03H
00H
04H
01H
02H
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