NEC PD754144 User Manual page 179

(7) Notes on application of carrier generator (restarting)
If forced reloading is performed by directly rewriting the contents of the no return zero flag (NRZ) and then
the timer is restarted (by setting bit 3 of TM2 to "1") when the carrier clock is high (TOUT F/F holds "1"), the
carrier may not be output to the PTO2 pin as shown below.
NRZ
TOUT F/F 0 1
Clock
PTO2
Likewise, if forced reloading is performed by directly rewriting the contents of NRZ and the timer is restarted
(by setting bit 3 of TM2 to "1") when the carrier clock is high (TOUT F/F holds "1"), the high-level period of
the carrier output to the PTO2 pin may be extended as shown below.
NRZ
TOUT F/F 0 1
Clock
PTO2
CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
SET1 NRZ
0
0 1
SET1 TM2.3
CLR1 NRZ
0
0 1
SET1 TM2.3
User's Manual U10676EJ3V0UM
1
1 0
Carrier is
not output
1
1 0
High-level period of
carrier is extended
1 0
1 0
179