HD404654 Datasheet, PDF (65/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404654 Series
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 23. 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 23 PWM Output Following Update of Timer Write Register
Mode
Free running
PWM Output
Timer Write Register is Updated during
High PWM Output
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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