PD17012_15 Datasheet, PDF (124/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
12.2.6 Cautions on using basic timer 0
(1) BTM0CY flag detection time interval
Keep the time to detect the BTM0CY flag shorter than the time at which the BTM0CY flag is set.
This is because if the time of processing B is longer than the time interval at which the BTM0CY flag is
set as shown in Figure 12-8, setting of the BTM0CY flag is overlooked.
Figure 12-8. BTM0CY Flag Detection and BTM0CY Flag
H
BTM0CY flag
setting pulse _L
1
BTM0CY flag
0
tSET
<1>
<2>
<3>
<4>
<5>
SKT1 BTM0CY SKT1 BTM0CY
Processing A
Processing B
SKT1 BTM0CY
Because execution time of processing B takes too long
after detection of BTM0CY flag that has been set to 1 in
<2>, the BTM0CY flag that is set to 1 in <3> cannot be
detected.
(2) Timer updating processing time and BTM0CY flag detection time interval
As described in (1) above, time interval tSET at which the BTM0CY flag is detected must be shorter than
the time for which to set the BTM0CY flag.
At this time, even if the time interval at which the BTM0CY flag is detected is short, if the updating
processing time of the timer is long the processing of the timer may not be executed normally at CE reset.
Therefore, the following condition must be satisfied.
tCHECK + tTIMER < tSET
tCHECK: Time to detect BTM0CY flag
tTIMER: Timer updating processing time
tSET: Time to set BTM0CY flag
An example is given below.
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Data Sheet U10101EJ4V0DS