Overview Of The I/O Port - Fujitsu FR60 Hardware Manual

CHAPTER 5 I/O PORT
5.1

Overview of the I/O Port

This section provides an overview of the I/O port.
■ Basic Block Diagram of the I/O Port
The pins of the MB91350A device can be used as I/O ports. To do so, set so that the corresponding pins are
not used for I/O with the external bus interface or peripherals.
Figure 5.1-1 shows the basic configuration of the port.
Port Bus
Peripheral
output
■ I/O Ports With Pull-up Resistors
The I/O ports with pull-up resistors are configured as follows:
• PDR: Port data register
• DDR: Data direction register
• PFR: Port function register
• PCR: Pull-up resistor control register
●
Port input mode (PFR=0 & DDR=0)
PDR read: Reads the level of the corresponding external pin.
PDR write: Writes a setting value to the PDR.
●
Port output mode (PFR= 0 & DDR=1)
PDR read: Reads the value of the PDR.
PDR write: Outputs the value of the PDR to the corresponding external pin.
●
Peripheral output mode (PFR=1 & DDR=×)
PDR read: Reads the value of the corresponding peripheral output.
PDR write: Writes a setting value to the PDR.
232
Figure 5.1-1 Basic Block Diagram of the Port
Peripheral input
PDR read
1
PDR
0
PFR
DDR
PCR
PCR = 0: Without a pull-up resistor
PCR = 1: With a pull-up resistor
Pull-up resistor
0
(about 50 kΩ)
1
Pin
DDR: Data Direction Register
PDR: Port Data Register
PFR: Port Function Register
PCR: Pull-up resistor control register