156
CHAPTER 6 PORT FUNCTIONS
6.4 Port Function Operations
Port operations differ depending on whether the input or output mode is set, as shown below.
6.4.1 Writing to input/output port
(1) Output mode
A value is written to the output latch by a transfer instruction, and the output latch contents are output from
the pin.
Once data is written to the output latch, it is retained until data is written to the output latch again.
(2) Input mode
A value is written to the output latch by a transfer instruction, but since the output buffer is OFF, the pin status
does not change.
Once data is written to the output latch, it is retained until data is written to the output latch again.
Caution In the case of 1-bit memory manipulation instruction, although a single bit is manipulated
the port is accessed as an 8-bit unit. Therefore, on a port with a mixture of input and output
pins, the output latch contents for pins specified as input are undefined except for the
manipulated bit.
6.4.2 Reading from input/output port
(1) Output mode
The output latch contents are read by a transfer instruction. The output latch contents do not change.
(2) Input mode
The pin status is read by a transfer instruction. The output latch contents do not change.
Summary of Contents for PD78052
Page 2: ...2 MEMO ...
Page 8: ...8 MEMO ...
Page 16: ...16 MEMO ...
Page 36: ...36 MEMO ...
Page 158: ...158 MEMO ...
Page 174: ...174 MEMO ...
Page 240: ...240 MEMO ...
Page 260: ...260 MEMO ...
Page 340: ...340 MEMO ...
Page 392: ...392 MEMO ...
Page 438: ...438 MEMO ...
Page 482: ...482 CHAPTER 20 REAL TIME OUTPUT PORT MEMO ...
Page 510: ...510 MEMO ...
Page 524: ...524 MEMO ...
Page 560: ...560 MEMO ...
Page 576: ...576 MEMO ...
Page 598: ...598 MEMO ...
Page 602: ...602 MEMO ...