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5.5 Port 5
Port 5 is the input/output port and is also used for the external bus function.
■ Functions of Port 5
The port has three registers per bit, namely DDR, PDR, and PFS, and the port input/output setup and
function selection can be executed independently per bit. The external bus function is selected for pins
whose PFS is "1", whereas the port function is selected for those whose PFS is "0". Pins whose DDR is "1"
are set to Output, whereas pins whose DDR is "0" are set to Input.
The PFS is initialized by a reset and the port function is selected. Also, the PDR is undefined and the DDR
is cleared to "0" and the port is specified to Input.
In terms of the DDR specification per bit, for output setup, the value written to the PDR is output to the pin,
and the PDR contents are read as the read value of the PDR in this case.
At the time of the input setup, the pin will have high impedance status. At this time, the pin level is read
from the read value of the PDR.
■ Block Diagram of Port 5
Figure 5.5-1 Block Diagram of Port 5
Pin
P57 to P50
PDR
PFS
DDR
Data register read
Peripheral output
Bus control