NEC uPD78P078 - Manual (Page 496)

496
CHAPTER 21 REAL-TIME OUTPUT PORT
(1) Real-time output buffer register (RTBL, RTBH)
Addresses of RTBL and RTBH are mapped individually in the special function register (SFR) area as shown
in Figure 21-2.
When specifying 4 bits x 2 channels as the operating mode, data are set individually in RTBL and RTBH.
When specifying 8 bits x 1 channel as the operating mode, data are set to both RTBL and RTBH by writing
8-bit data to either RTBL or RTBH.
Table 21-2 shows operations during manipulation of RTBL and RTBH.
Figure 21-2. Real-time Output Buffer Register Configuration
Table 21-2. Operation in Real-time Output Buffer Register Manipulation
In Read Note 1 In Write Note 2
Higher 4 Bits Lower 4 Bits Higher 4 Bits Lower 4 Bits
RTBL RTBH RTBL Invalid RTBL
RTBH RTBH RTBL RTBH Invalid
RTBL RTBH RTBL RTBH RTBL
RTBH RTBH RTBL RTBH RTBL
Notes 1. Only the bits set in the real-time output port mode can be read. When a read is performed to the bits
set in the port mode, 0 is read out.
2. After setting data in the real-time output port, output data should be set in RTBL and RTBH by the
time a real-time output trigger is generated.
Higher
4 Bits Lower
4 Bits
RTBL
RTBH
FF30H
FF31H
Operating Mode
Register to be
Manipulated
4 Bits x 2 Channels
8 Bits x 1 Channel