6 I/O PORTS (PPORT)
6-4
Seiko Epson Corporation
S1C17M20/M21/M22/M23/M24/M25
TECHNICAL MANUAL (Rev. 1.0)
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.
xxxx
SLPC bit for the CLK_PPORT clock
source.
If the CLGOSC.
xxxx
SLPC 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 P
x
CHATEN.P
x
CHATEN
y
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 P
xy
port for a peripheral I/O function, perform the following software initial settings:
1. Set the following P
x
IOEN register bits:
- Set the P
x
IOEN.P
x
IEN
y
bit to 0.
(Disable input)
- Set the P
x
IOEN.P
x
OEN
y
bit to 0.
(Disable output)
2. Set the P
x
MODSEL.P
x
SEL
y
bit to 0. (Disable peripheral I/O function)
3. Initialize the peripheral circuit that uses the pin.
4. Set the P
x
FNCSEL.P
xy
MUX[1:0] bits. (Select peripheral I/O function)
5. Set the P
x
MODSEL.P
x
SEL
y
bit to 1. (Enable peripheral I/O function)
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 P
xy
port pin as a general-purpose output pin, perform the following software initial settings:
1. Set the P
x
IOEN.P
x
OEN
y
bit to 1.
(Enable output)
2. Set the P
x
MODSEL.P
x
SEL
y
bit to 0. (Enable GPIO function)