NEC uPD78P078 - Manual (Page 497)

497
CHAPTER 21 REAL-TIME OUTPUT PORT
21.3 Real-Time Output Port Control Registers
The following three registers control the real-time output port.
• Port mode register 12 (PM12)
• Real-time output port mode register (RTPM)
• Real-time output port control register (RTPC)
(1) Port mode register 12 (PM12)
This register sets the input or output mode of port 12 pins (P120 to P127) which also function as real-time
output pins (RTP0 to RTP7). To use port 12 as a real-time output port, the port pin that performs real-time
output must be set in the output mode (PM12n = 0: n = 0 to 7).
PM12 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to FFH.
Figure 21-3. Port Mode Register 12 Format
(2) Real-time output port mode register (RTPM)
This register selects the real-time output port mode/port mode bit-wise.
RTPM is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 00H.
Figure 21-4. Real-time Output Port Mode Register Format
Cautions 1. When using these bits as a real-time output port, set the ports to which real-time output
is performed to the output mode (set the bits of the port mode register 12 (PM12) to 0).
2. In the port specified as a real-time output port, data cannot be set to the output latch.
Therefore, when setting an initial value, data should be set to the output latch before
setting the real-time output mode.
7
RTPM7
6
RTPM6
5
RTPM5
4
RTPM4
3
RTPM3
2
RTPM2
1
RTPM1
0
RTPM0
Symbol
RTPM
Address
FF34H 00H
After
Reset
R/W
R/W
RTPMn
0
1
Port mode
Real-time output port mode
Real-time Output Port Selection (n = 0 to 7)
7
PM127
6
PM126
5
PM125
4
PM124
3
PM123
2
PM122
1
PM121
0
PM120
Symbol
PM12
Address
FF2CH FFH
After
Reset
R/W
R/W
PM12n
0
1
Output mode (output buffer ON)
Input mode (output buffer OFF)
Selects I/O Mode of P12n Pin (n = 0 to 7)