Clock Supply In Sleep Mode; Clock Supply In Debug Mode; Operations; Initialization - Epson S1C17M20 Technical Manual

6 I/O PORTS (PPORT)

6.3.2 Clock Supply in SLEEP Mode

When using the chattering filter function during SLEEP mode, the PPORT operating clock CLK_PPORT must be
configured so that it will keep suppling by writing 0 to the CLGOSC.xxxxSLPC bit for the CLK_PPORT clock
source.
If the CLGOSC.xxxxSLPC bit for the CLK_PPORT clock source is 1, the CLK_PPORT clock source is deacti-
vated during SLEEP mode and it disables the chattering filter function regardless of the PxCHATEN.PxCHATENy
bit setting (chattering filter enabled/disabled).

6.3.3 Clock Supply in DEBUG Mode

The CLK_PPORT supply during DEBUG mode should be controlled using the PCLK.DBRUN bit.
The CLK_PPORT supply to PPORT is suspended when the CPU enters DEBUG mode if the PCLK.DBRUN bit
= 0. After the CPU returns to normal mode, the CLK_PPORT supply resumes. The PPORT chattering filter stops
operating when the CLK_PPORT supply is suspended. If the chattering filter is enabled in PPORT, the input port
function is also deactivated. However, the control registers can be altered. If the PCLK.DBRUN bit = 1, the CLK_
PPORT supply is not suspended and the chattering filter will keep operating in DEBUG mode.

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.
6-4
(Disable input)
(Disable output)
(Disable peripheral I/O function)
(Enable peripheral I/O function)
(Enable output)
(Enable GPIO function)
Seiko Epson Corporation
S1C17M20/M21/M22/M23/M24/M25
TECHNICAL MANUAL (Rev. 1.0)