
57
μ
PD70433
9.3
REAL-TIME OUTPUT PORT FUNCTION
Port 7 of the V55PI incorporates a real-time output port function, and can output the contents of the port 7 buffer (P7H,
P7L) at programmable intervals from timer 0 bit-wise.
9.3.1
Real-Time Output Port Configuration
The real-time output port configuration is shown in Figure 9-2. It comprises the following buffer registers, output and
control registers.
(1)
Port 7 buffer (P7H, P7L)
The buffer registers hold the data to be output next when port 7 is set to the real-time output port mode.
The port 7 buffer contents are not affected by reset input.
(2)
Real-time output port (RTP)
Real-time output port output data is held in this port after being taken from the port 7 buffer, and output from the
pins.
RTP can be read or written to by an 8-bit or single-bit manipulation instruction (unlike the port 7 output port).
(3)
Real-time output port delay specification regiser (RTPD) and delay counter
This register is set and used when using the mode in which a delay time is inserted in the timing for output from
the real-time output port (RTP) to the output pins.
If the P7L bit is set to "0", "0" is output to the corresponding output pin bit after the elapse of the delay time equivalent
to the count clock cycle time set in the real-time output port delay specification register after the time at which the transfer
trigger is generated. The delay time in this case is counted by the delay counter.
(4)
Real-time output port control register (RTPC)
RTPC specifies the operating mode of the real-time output port. It is possible to specify whether or not a delay is
to be inserted when data is output, the timing for transferring data to the port 7 buffer, the transfer timing trigger, and
so on.