UPD784020 Datasheet, PDF (31/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
8.3 REAL-TIME OUTPUT PORT
The real-time output port outputs data stored in the buffer, synchronized with a timer/counter 1 match interrupt
or external interrupt. Thus, pulse output that is free of jitter can be obtained.
Therefore, the real-time output port is best suited to applications (such as open-loop control over stepping motors)
where an arbitrary pattern is output at arbitrary intervals.
As shown in Fig. 8-4, the real-time output port is built around port 0 and the port 0 buffer register (P0H, P0L).
Fig. 8-4 Block Diagram of Real-Time Output Port
Internal bus
8
4
4
Real-time output port
Buffer register
control register
8
(RTPC)
P0H
P0L
INTP0 (externally)
INTC10 (from timer/counter 1)
INTC11 (from timer/counter 1)
Output trigger
control circuit
4
4
Output latch (P0)
P07
P00
31