UPD780957 Datasheet, PDF (123/326 Pages) NEC – 8-Bit Single-Chip Microcontrollers

CHAPTER 6 REAL-TIME OUTPUT FUNCTION
6.5 Real-Time Output Function Operating Cautions
(1) Before enabling a real-time output operation again after it was disabled (by changing RCE1 = 0 to RCE1 = 1),
it is necessary to preset the same value as the initial value of the RTO1 output latch to the lower 4 bits of
RTO10.
(2) Set bit 7 (RCE1) of RTO operation mode register 1 (RTM1) to 0 before writing to RTO data registers 10 and
11 (RTO10 and RTO11).
(3) Set bit 7 (RCE1) of RTM1 to 0 before accessing RTO reload interrupt compare register 1 (RTC1).
(4) Set the port mode of P64 to P67 to the output mode and set the output latches to 0 before enabling a real-
time output operation.
(5) Setting bit 7 (RCE1) of RTM1 to 0 initializes the RTO1 output latches of RTO10 and RTO11 to 00H.
User’s Manual U13655EJ2V1UD
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