74CHAPTER 3 PIN FUNCTION (μPD78078 SUBSERIES)3.2.8 P70 to P72 (Port 7)This is a 3-bit input/output port. In addition to its use as an input/output port, it also has serial interface data input/output and clock input/output functions.The following operating modes can be specified bit-wise.(1) Port modePort 7 functions as a 3-bit input/output port. Bit-wise specification as an input port or output port is possibleby means of port mode register 7 (PM7). When used as input ports, on-chip pull-up resistors can beconnected by defining the pull-up resistor option register L (PUOL).(2) Control modePort 7 functions as serial interface data input/output and clock input/output.(a) SI2, SO2Serial interface serial data input/output pins(b) SCK2Serial interface serial clock input/output pin.(c) RxD, TxDAsynchronous serial interface serial data input/output pins.(d) ASCKAsynchronous serial interface serial clock input/output pin.Caution When this port is used as a serial interface, the I/O and output latches must be set accordingto the function the user requires.For the setting, refer to the operation mode setting list in Table 20-2. Serial InterfaceChannel 2.3.2.9 P80 to P87 (Port 8)These are 8-bit input/output ports. Besides serving as input/output ports, they function as an address bus.The following operating modes can be specified bit-wise.(1) Port modeThese ports function as 8-bit input/output ports. They can be specified bit-wise as input or output ports withport mode register 8 (PM8). When they are used as input ports, on-chip pull-up resistors can be connectedby defining the pull-up resistor option register H (PUOH).(2) Control modeThese ports function as lower address bus pins (A0 to A7) in external memory expansion mode. When apin is used as an address bus, the on-chip pull-up resistor is automatically not used.
