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TCNT4
OVF
Buffer transfer
signal (BR to GR)
GR
In channel 3, IMFA is set to 1 only during up-counting. In channel 4, OVF is set to 1 only when
an underflow occurs. When buffering is selected, buffer register contents are transferred to the
general register at compare match A3 during up-counting, and when TCNT4 underflows.
General Register Settings in Complementary PWM Mode: When setting up general registers
for complementary PWM mode or changing their settings during operation, note the following
points.
• Initial settings
Do not set values from H'0000 to T – 1 (where T is the initial value of TCNT3). After the
counters start and the first compare match A3 event has occurred, however, settings in this
range also become possible.
• Changing settings
Use the buffer registers. Correct waveform output may not be obtained if a general register is
written to directly.
• Cautions on changes of general register settings
Figure 8-39 shows six correct examples and one incorrect example.
H'0001
H'0000
Set to 1
Buffer transfer
Figure 8-38 Undershoot Timing
Underflow
Overflow
H'FFFF
H'0000
Flag not set
No buffer transfer
247
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