Operations Of Port 5 - Fujitsu F2MC-8FX Hardware Manual

9.5.2

Operations of Port 5

This section describes the operations of port 5.
Operations of Port 5
Operation as an output port
• Setting the corresponding DDR bit to "1" sets a pin as an output port.
• For a peripheral function sharing pins, disable its output.
• When a pin is set as an output port, it outputs the value of the PDR to pins.
• If data is written to the PDR, the value is stored in the output latch and output to the pin as it is.
• Reading the PDR returns the PDR value.
Operation as an input port
• Setting the corresponding DDR bit to "0" sets a pin as an input port.
• For a peripheral function sharing pins, disable its output.
• If data is written to the PDR, the value is stored in the output latch but not output to the pin.
• Reading the PDR returns the pin value. However, the read-modify-write command returns the PDR
value.
Operation as a peripheral function output
• Setting the output enable bit of a peripheral function sets the corresponding pin as a peripheral function
output.
• The pin value can be read from the PDR register even if the peripheral function output is enabled.
Therefore, the output value of a peripheral function can be read by the read operation on PDR register.
However, the read-modify-write command returns the PDR value.
Operation as a peripheral function input
• Set the DDR register bit, which is corresponding to the peripheral function input pin, to "0" to set a pin
as an input port.
• Reading the PDR register returns the pin value, regardless of whether the peripheral function uses an
input pin. However, the read-modify-write command returns the PDR value.
Operation at reset
• Resetting the CPU initializes the DDR values to "0", and sets the port input enabled.
CHAPTER 9 I/O PORT
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