MB95630H Series
84
FUJITSU SEMICONDUCTOR LIMITED
MN702-00009-1v0-E
CHAPTER 6 I/O PORT
6.2 Configuration and Operations
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Operations of I/O Port
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Operation as an output port
•
A pin becomes an output port if the bit in the DDRx register corresponding to that pin is set
to "1".
•
For a pin shared with other peripheral functions, disable the output of such peripheral
functions.
•
When a pin is used as an output port, it outputs the value of the PDRx register to external
pins.
•
If data is written to the PDRx register, the value is stored in the output latch and is output to
the pin set as an output port as it is.
•
Reading the PDRx register returns the PDRx register value.
●
Operation as an input port
•
A pin becomes an input port if the bit in the DDRx register corresponding to that pin is set
to "0".
•
For a pin shared with other peripheral functions, disable the output of such peripheral
functions.
•
When using an analog input shared pin as an input port, set the corresponding bit in the A/D
input disable register (upper/lower) (AIDRH/AIDRL) to "1".
•
If data is written to the PDRx register, the value is stored in the output latch but is not
output to the pin set as an input port.
•
Reading the PDRx register returns the pin value. However, if the read-modify-write (RMW)
type of instruction is used to read the PDRx register, the PDRx register value is returned.
●
Operation as a peripheral function output pin
•
A pin becomes a peripheral function output pin if the peripheral output function is enabled
by setting the output enable bit of a peripheral function corresponding to that pin.
•
The pin value can be read from the PDRx 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 the PDRx register. However, if the read-modify-write (RMW) type of
instruction is used to read the PDRx register, the PDRx register value is returned.
●
Operation as a peripheral function input pin
•
To set a pin as an input port, set the bit in the DDRx register bit corresponding to the input
pin of a peripheral function to "0".
•
When using the analog input shared pin as another peripheral function input pin, configure
it as an input port, which is the same as the operation as an input port.
•
Reading the PDRx register returns the pin value, regardless of whether the peripheral
function uses that pin as its input pin. However, if the read-modify-write (RMW) type of
instruction is used to read the PDRx register, the PDRx register value is returned.