Fujitsu MB90480 Series Hardware Manual page 204

CHAPTER 8 I/O PORT
Notes:
• If this register is accessed with a command of the read-modify-write type (such as the bit-set
command), the contents of the output registers corresponding to the other bits specified for input
are replaced with the input value of the pin at the time of access even if the bit specified by the
command is set to the required value. Therefore, when a pin for input is switched to a pin for
output, be sure to define DDR after writing the desired value to PDR, and then switch it to a pin
for output.
• P77 and P76 of MB90485 series do not have DDR function. Data is always valid as a port. So
set the PDR value to "1" when P77 and P76 are used as I
2
stop I C).
Also this port has the open drain output format (without P-ch), therefore it is necessary to set the
PDR value to "1" in order to turn off the output transistor and to add a pull-up resistor to external
output when this port is used as an input port.
182
2
C pins (When using as P77 and P76,