NEC uPD78056Y - Manual (Page 477)

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CHAPTER 20 REAL-TIME OUTPUT PORT
20.1 Real-Time Output Port Functions
Data set previously in the real-time output buffer register can be transferred to the output latch by hardware
concurrently with timer interrupt requests or external interrupt request generation, then output externally. This is called
the real-time output function. The pins that output data externally are called real-time output ports.
By using a real-time output, a signal which has no jitter can be output. This port is therefore suitable for control
of stepping motors, etc.
Port mode/real-time output port mode can be specified bit-wise.