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NEC PD754144 User Manual

Page 167

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CHAPTER 6 PERIPHERAL HARDWARE FUNCTION

167

User’s Manual U10676EJ3V0UM

Remark If a timer (channel 1) interrupt is generated when the PTO2 pin is low and the carrier

clock is high (NRZ = 0, carrier clock = high level), the carrier is output to the PTO2 pin

from the pulse after the carrier clock.

If a timer (channel 1) interrupt is generated when the PTO2 pin is high and the carrier

clock is high (NRZ = 1, carrier clock = high level), the PTO2 pin does not become low

until the end of the carrier clock being output.

This processing is performed to keep the width of the high-level pulse output from the

PTO2 pin constant regardless of the NRZ switching timing (see figure below).

Carrier clock

No return zero flag (NRZ)

PTO2 pin

PTO2 does not go high even if NRZ is
set to "1" until the next carrier clock
goes high.

PTO2 does not go low even if NRZ is
reset to "0" until the next carrier clock
goes high.

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