PD17012_15 Datasheet, PDF (121/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
12.2.5 Errors of basic timer 0
Errors of basic timer 0 include an error due to the detection time of the BTM0CY flag, and an error that occurs
when the time interval at which the BTM0CY flag is to be set is changed.
The following paragraphs (1) and (2) describe each error.
(1) Error due to detection time of BTM0CY flag
The time to detect the BTM0CY flag must be shorter than the time at which the BTM0CY flag is set (refer
to 12.2.6 Notes on using basic timer 0).
Where the time interval at which the BTM0CY flag is detected is tCHECK and the time interval at which the
flag is set is tSET (250, 10, 5, or 1 ms), tCHECK and tSET must relate as follows.
tCHECK < tSET
At this time, the error of the timer when the BTM0CY flag is detected is as follows, as shown in Figure
12-5.
0 < Error < tSET
Figure 12-5. Error of Basic Timer 0 due to Detection Time of BTM0CY Flag
BTM0CY flag
H
setting pulse
L
1
BTM0CY flag
0
tSET
tCHECK1
tCHECK2
tCHECK3
SKT1
BTM0CY
<1>
SKT1
BTM0CY
<2>
SKT1
BTM0CY
<3>
SKT1
BTM0CY
<4>
As shown in Figure 12-5, the timer is updated because BTM0CY flag is 1 when it is detected in step <2>.
When the flag is detected next in step <3>, it is 0. Therefore, the timer is not updated until the flag is
detected again in <4>.
This means that the timer is extended by the time of tCHECK3.
Data Sheet U10101EJ4V0DS
119