Hitachi H8/3062 Hardware Manual page 280

Figure 8.28 shows examples of the output of PWM waveforms with duty cycles of 0% and 100%.
If the counter is cleared by compare match with GRB, and GRA is set to a higher value than GRB,
the duty cycle is 0%. If the counter is cleared by compare match with GRA, and GRB is set to a
higher value than GRA, the duty cycle is 100%.
16TCNT value
GRB
GRA
H'0000
TIOCA
16TCNT value
GRA
GRB
H'0000
TIOCA
260
Counter cleared by compare match B
Write to GRA
a. 0% duty cycle (TOA=0)
Counter cleared by compare match A
Write to GRB
b. 100% duty cycle (TOA=1)
Figure 8.28 PWM Mode (Example 2)
Write to GRA
Write to GRB
Time
Time