NEC uPD78P078 - Manual (Page 495)

495
CHAPTER 21 REAL-TIME OUTPUT PORT
21.1 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 request 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.
21.2 Real-Time Output Port Configuration
The real-time output port consists of the following hardware.
Table 21-1. Real-time Output Port Configuration
Item Configuration
Register Real-time output buffer register (RTBL, RTBH)
Control register Port mode register 12 (PM12)
Real-time output port mode register (RTPM)
Real-time output port control register (RTPC)
Figure 21-1. Real-time Output Port Block Diagram
Internal Bus
Real-time Output
Port Control
Register
EXTR BYTE
Output Trigger
Control Circuit
Port Mode
Register 12
(PM12)
Real-time Output
Buffer Register
Higher 4 Bits
(RTBH) Real-time Output
Buffer Register
Lower 4 Bits
(RTBL)
Output Latch
P120 P127
Real-time Output port
Mode Register (RTPM)
INTP2
INTTM1
INTTM2