Operations; Initialization - Epson S1C17M12 Technical Manual

6 I/O PORTS (PPORT)

6.4 Operations

6.4.1 Initialization

After a reset, the ports except for the debugging function are configured as shown below.
• Port input: Disabled
• Port output: Disabled
• Pull-up: Off
• Pull-down: Off
• Port pins: High impedance state
• Port function: Configured to GPIO
This status continues until the ports are configured via software. The debugging function ports are configured for
debug signal input/output.
Initial settings when using a port for a peripheral I/O function
When using the Pxy port for a peripheral I/O function, perform the following software initial settings:
1. Set the following PxIOEN register bits:
- Set the PxIOEN.PxIENy bit to 0.
- Set the PxIOEN.PxOENy bit to 0.
2. Set the PxMODSEL.PxSELy bit to 0.
3. Initialize the peripheral circuit that uses the pin.
4. Set the PxFNCSEL.PxyMUX[1:0] bits. (Select peripheral I/O function)
5. Set the PxMODSEL.PxSELy bit to 1.
For the list of the peripheral I/O functions that can be assigned to each port of this IC, refer to "Control Register
and Port Function Configuration of this IC." For the specific information on the peripheral I/O functions, refer
to the respective peripheral circuit chapter.
Initial settings when using a port as a general-purpose output port
(only for the ports with GPIO function)
When using the Pxy port pin as a general-purpose output pin, perform the following software initial settings:
1. Set the PxIOEN.PxOENy bit to 1.
2. Set the PxMODSEL.PxSELy bit to 0.
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 PxINTCTL.PxIEy bit. * (Disable interrupt)
2. When using the chattering filter, configure the PPORT operating clock (see "PPORT Operating Clock") and
set the PxCHATEN.PxCHATENy bit to 1. *
When the chattering filter is not used, set the PxCHATEN.PxCHATENy bit to 0 (supply of the PPORT op-
erating clock is not required).
3. Configure the following PxRCTL register bits when pulling up/down the port using the internal pull-up or
down resistor:
- PxRCTL.PxPDPUy bit
- Set the PxRCTL.PxRENy bit to 1.
Set the PxRCTL.PxRENy bit to 0 if the internal pull-up/down resistors are not used.
4. Set the PxMODSEL.PxSELy bit to 0. (Enable GPIO function)
6-4
(Disable input)
(Disable output)
(Disable peripheral I/O function)
(Enable peripheral I/O function)
(Enable output)
(Enable GPIO function)
(Select pull-up or pull-down resistor)
(Enable pull-up/down)
Seiko Epson Corporation
S1C17M12/M13 TECHNICAL MANUAL
(Rev. 1.2)