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7.4.2. Port Input/Output Control
Peripheral I/O function control
The port for which a peripheral I/O function is selected is controlled by the peripheral circuit. For
more information, refer to the respective peripheral circuit chapter.
Setting output data to a GPIO port
Write data (1 = high output, 0 = low output) to be output from the Pxy pin to the
PPORTPxDAT.PxOUTy bit.
Reading input data from a GPIO port
The data (1 = high input, 0 = low input) input from the Pxy pin can be read out from the
PPORTPxDAT.PxINy bit.
Chattering filter function
Some ports have a chattering filter function and it can be controlled in each port. This function is
enabled by setting the PPORTPxCHATEN.PxCHATENy bit to 1. The input sampling time to remove
chattering is deter- mined by the CLK_PPORT frequency configured using the PPORTCLK register in
common to all ports. The chattering filter removes pulses with a shorter width than the input
sampling time.
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Make sure the Pxy port interrupt is disabled before altering the PPORTCLK register and
PPORTPxCHATEN. PxCHATENy bit settings. A Pxy port interrupt may erroneously occur if these
settings are altered in an interrupt enabled status. Furthermore, enable the interrupt after a lapse
of four or more CLK_PPORT cycles from enabling the chattering filter function.
If the clock generator is configured so that it will supply CLK_PPORT to PPORT in SLEEP mode, the
chattering filter of the port will function even in SLEEP mode. If CLK_PPORT is configured to stop in
SLEEP mode, PPORT inactivates the chattering filter during SLEEP mode to input pin status transitions
directly to itself.
Key-entry reset function
This function issues a reset request when low-level pulses are input to all the specified ports
simultaneously. Make the following settings when using this function:
1.
Configure the ports to be used for key-entry reset as general-purpose input ports (refer to
"Initial settings when using a port as a general-purpose input port (only for the ports with GPIO
function)").
2.
Configure the input pin combination for key-entry reset using the PPORTCLK.KRSTCFG[1:0] bits.
Note:
When enabling the key-entry reset function, be sure to configure the port pins to be used for it as
general-purpose input pins before setting the PPORTCLK.KRSTCFG[1:0] bits.
PPORT issues a reset request immediately after all the input pins specified by the
PPORTCLK.KRSTCFG[1:0] are set to a low level if the chattering filter function is disabled (initial
status). To issue a reset request only when low-level signals longer than the time configured are
input, enable the chattering filter function for all the ports used for key-entry reset.
The pins configured for key-entry reset can also be used as general-purpose input pins.
7-6
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S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
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