upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 169

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

4.4 Port Function Operation
The port operation differs according to the I/O mode settings, as follows.
4.4.1 Write to I/O ports
(1)
(2)
Caution:
4.4.2 Read from I/O port
(1)
(2)
4.4.3 I/O port calculation
(1)
(2)
Caution:
Output mode
Values are written to output latches using transfer instructions. Moreover, the output latch contents
are output to the pin. Once data has been written to an output latch, it is held until data is newly
written to that output latch.
Input mode
Values are written to output latches using transfer instructions. However, since the output buffer is
off, the status of the pin does not change.
Once data has been written to an output latch, it is held until data is newly written to that output
latch.
Output mode
The contents of the output latch are read using a transfer instruction. The contents of the output
latch do not change.
Input mode
The pin status is read using a transfer instruction. The contents of the output latch do not change.
Output port
Calculation for the output latch contents is performed and the result is written to the output latch.
The output latch contents are output to the pin.
Once data has been written to an output latch, it is held until data is newly written to that output
latch.
Input mode
The output latch contents become undefined. However, since the output buffer is off, the pin status
does not change.
In the case of a 1-bit memory manipulation instruction, the manipulation target is 1
bit, but the port is accessed in 8-bit units. Therefore, for ports where input and output
are mixed, the contents of output latches of pins specified for input other than the
manipulation target bit become undefined.
In the case of a 1-bit memory manipulation instruction, the manipulation target is 1
bit, but the port is accessed in 8-bit units. Therefore, for ports where input and output
are mixed, the contents of output latches of pins specified for input other than the
manipulation target bit become undefined.
User’s Manual U16702EE3V2UD00
Chapter 4 Port Functions
169