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Initial settings when using a port as a general-purpose input port
(only for the ports with GPIO function)
When using the Pxy port pin as a general-purpose input pin, perform the following software initial
settings:
1. Write 0 to the PPORTPxINTCTL.PxIEy bit. *
2. When using the chattering filter, configure the PPORT operating clock (see "PPORT Operating
Clock") and set the PPORTPxCHATEN.PxCHATENy bit to 1. *
When the chattering filter is not used, set the PPORTPxCHATEN.PxCHATENy bit to 0 (supply of
the PPORT operating clock is not required).
3. Configure the following PPORTPxRCTL register bits when pulling up/down the port using the
internal pull-up or down resistor:
PPORTPxRCTL.PxPDPUy bit
-
Set the PPORTPxRCTL.PxRENy bit to 1.
-
Set the PPORTPxRCTL.PxRENy bit to 0 if the internal pull-up/down resistors are not used.
4. Set the PPORTPxMODSEL.PxSELy bit to 0.
5. Configure the following bits when using the port input interrupt: *
Write 1 to the PPORTPxINTF.PxIFy bit.
-
PPORTPxINTCTL.PxEDGEy bit
-
Set the PPORTPxINTCTL.PxIEy bit to 1.
-
6. Set the following PPORTPxIOEN register bits:
Set the PPORTPxIOEN.PxOENy bit to 0.
-
Set the PPORTPxIOEN.PxIENy bit to 1.
-
* Steps 1 and 5 are required for the ports with an interrupt function. Step 2 is required for the ports
with a chattering filter function.
Table 7.4.1.1 lists the port status according to the combination of data input/output control and
pull-up/down control.
PPORTPxIOEN.
PPORTPxIOEN.
PxIENy bit
PxOENy bit
0
0
0
0
0
0
1
0
1
0
1
0
0
1
0
1
0
1
1
1
1
1
*1: Initial status. Current does not flow if the pin is placed into floating status.
*2: Use of the pull-up or pull-down function is recommended, as undesired current will flow if the port input is set to floating status.
Note:
If the PPORTPxMODSEL.PxSELy bit for the port without a GPIO function is set to 0, the port goes
into initial status (refer to "Initial Settings"). The GPIO control bits are configured to a read- only bit
always read out as 0.
S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
Table 7.4.1.1 GPIO Port Control List
PPORTPxRCTL.
PPORTPxRCTL.
PxRENy bit
PxPDPUy bit
0
×
1
0
1
1
0
×
1
0
1
1
0
×
1
0
1
1
1
0
1
1
Seiko Epson Corporation
(Disable interrupt)
(Select pull-up or pull-down resistor)
(Enable pull-up/down)
(Enable GPIO function)
(Clear interrupt flag)
(Select interrupt edge
(input rising edge/falling edge))
(Enable interrupt)
(Disable output)
(Enable input)
Input
Output
Disabled
Disabled
Disabled
Enabled
Disabled
Enabled
Disabled
Enabled
Disabled
Disabled
Enabled
Disabled
Enabled
Disabled
Enabled
Enabled
Enabled
Enabled
Enabled
Pull-up/pull-down
condition
Off (Hi-Z) *1
Pulled down
Pulled up
Off (Hi-Z) *2
Pulled down
Pulled up
Off
Off
Off
Off
Off
7-5
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