Operations Of Port E - Fujitsu F2MC-8FX Hardware Manual

9.11.2

Operations of Port E

This section describes the operations of port E.
Operations of Port E
Operation as an output port
• Setting the corresponding DDR bit to "1" sets a pin as an output port.
• For a peripheral function sharing pins, disable its output.
• When a pin is set as an output port, it outputs the value of the PDR to pins.
• If data is written to the PDR, the value is stored in the output latch and output to the pin as it is.
• Reading the PDR returns the PDR value.
Operation as an input port
• Setting the corresponding DDR bit to "0" sets a pin as an input port.
• For a peripheral function sharing pins, disable its output.
• When using the LCD shared pin as an input port, select the common/segment pin in LCDC enable
registers (LCDCE1 to 6), and then set the port input control bit (PICTL) in LCDC enable register
(LCDCE1) to "1".
• If data is written to the PDR, the value is stored in the output latch but not output to the pin.
• Reading the PDR returns the pin value. However, the read-modify-write command returns the PDR
value.
Operation at reset
• Resetting the CPU initializes the DDR values to "0", and sets the port input enabled. Note that the pin
sharing for the LCD output is set its port input disabled since the port input control bit (PICTL) in
LCDC enable register (LCDCE1) is set to "0".
Operation in stop mode and watch mode
• If the pin state specification bit in the standby control register (STBC:SPL) is set to "1" when the device
switches to stop or watch mode, the pin is set forcibly to the high-impedance state regardless of the
DDR value. Note that the input is locked to "L" and blocked in order to prevent leaks due to freed input.
However, if the peripheral function input is enabled for the external interrupt, the input is enabled and
not blocked.
• If the pin state specification bit is "0", the state remains in port I/O or peripheral function I/O and the
output is maintained.
Operation of the external interrupt input pin
• Set the DDR register bit, which is corresponding to the external interrupt input pin, to "0".
• As with an input port, when using the LCD shared pin as an external interrupt input pin, configure it as
an input port.
• For other peripheral functions sharing pins, disable its output.
• Pin values are continuously input to the external interrupt circuit. When using the pin for a function
other than an interrupt, you must disable the corresponding external interrupt.
CHAPTER 9 I/O PORT
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