NEC PD78P214 Manuale Utente

Chapter 6 Real-Time Output Function

6.2 REAL-TIME OUTPUT CONTROL REGISTER (RTPC)

The real-time output control register (RTPC) is an 8-bit register to specify the functions of port 0. An 8-bit
manipulation instruction and a bit manipulation instruction can be used to read data from and write data to the
RTPC register. Fig. 6-2 shows the format of this register.

When the RESET signal is input, the RTPC is reset to 00H.

Fig. 6-2 Real-Time Output Port Control Register (RTPC) Format

Caution When the P0ML or P0MH is set to 1, the output buffer for the corresponding output port is turned on to output the contents of the

port 0 output latch, regardless of the contents of the port 0 mode register (PM0). Therefore, initialize the contents of the output
latch before specifying the real-time output port.

6.3 ACCESS TO THE REAL-TIME OUTPUT PORT

The buffer registers (P0H and P0L) are mapped to independent addresses in the SFR area, as shown in Fig. 6-3.
When the 4-bit

× 2-channel real-time output function is specified, data can be set in each buffer register (P0H or

P0L) independently.

When the 8-bit

× 1-channel real-time output function is specified, 8-bit data can be set in the buffer registers by

writing to either one (P0H or P0L).

Table 6-1 lists the operating modes of port 0 and the operations needed for the port 0 buffer registers.

Fig. 6-3 Configuration of the Buffer Registers (P0H and P0L)

P0H

P0L

Low-order
4 bits

High-order
4 bits

0FF0AH

0FF0BH

BYTE

P0MH

EXTR

P0ML

RTPC

P0ML

Real-time output port mode

Port mode

Function specification of P00 to P03 pins

EXTR

Enabled.

Disabled

Data transfer by INTP0 from buffer register to
output latch

P0MH

Real-time output port mode

Port mode

Function specification of P04 to P07 pins

BYTE

8-bit real-time output port

4-bit separate real-time output port

Operation mode for real-time output mode

BYTE = 0: Only P0L data is transferred
BYTE = 1: Both P0L and P0H data are
transferred