HD404318 Datasheet, PDF (40/66 Pages) Hitachi Semiconductor – 4-bit HMCS400-series microcomputer

HD404318 Series
$FF + 1
Timer C
count value
$00
Overflow
Time
CPU
operation
Normal Timer C Normal Timer C
operation clear operation clear
Program
runaway
Reset
Normal
operation
Figure 31 Watchdog Timer Operation Flowchart
Notes on Use
When using the timer output as PWM output, note the following point. From the update of the timer write
register until the occurrence of the overflow interrupt, the PWM output differs from the period and duty
settings, as shown in table 8. The PWM output should therefore not be used until after the overflow
interrupt following the update of the timer write register. After the overflow, the PWM output will have the
set period and duty cycle.
Table 8 PWM Output Following Update of Timer Write Register
PWM Output
Mode
Timer Write Register is Updated during
High PWM Output
Free running
Timer write
register
updated to
value N
Interrupt
request
Timer Write Register is Updated during
Low PWM Output
Timer write
register
updated to
value N
Interrupt
request
Reload
T × (255 – N) T × (N + 1)
Timer write
register
updated to
value N
Interrupt
request
T × (N' + 1)
T × (255 – N) T × (N + 1)
Timer write
register
updated to
value N
Interrupt
request
T
T × (255 – N)
T
T
T × (255 – N)
T
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