Fujitsu Semiconductor Controller MB89950/950A Hardware Manual page 147

Note:
Do not change the count clock cycle (CNTR: P1, P0) during operation of the interval timer function
(CNTR: TPE = "1").
References:
• Setting the COMR register value to "00
the selected count clock.
• When the counter is stopped (CNTR: TPE = "0") while the interval timer function is selected, the PWM
pin outputs an "L" level.
" causes the PWM pin output to be inverted with the cycle of
H
CHAPTER 7 8-BIT PWM TIMER
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