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Refer to "Pin Descriptions" in the "Overview" chapter for the cell type, either the over voltage tolerant fail-safe
type I/O cell or the standard I/O cell, included in each port.
6.2.1 Schmitt Input
The input functions are all configured with the Schmitt interface level. When a port is set to input disable status
(PxIOEN.PxIENy bit = 0), unnecessary current is not consumed if the Pxy pin is placed into floating status.
6.2.2 Over Voltage Tolerant Fail-Safe Type I/O Cell
The over voltage tolerant fail-safe type I/O cell allows interfacing without passing unnecessary current even if a
voltage exceeding V
is applied to the port. Also unnecessary current is not consumed when the port is externally
DD
biased without supplying V
mum operating power supply voltage to the port.
6.2.3 Pull-Up/Pull-Down
The GPIO port has a pull-up/pull-down function. Either pull-up or pull-down may be selected for each port indi-
vidually. This function may also be disabled for the port that does not require pulling up/down.
When the port level is switched from low to high through the pull-up resistor included in the I/O cell or from high
to low through the pull-down resistor, a delay will occur in the waveform rising/falling edge depending on the time
constant by the pull-up/pull-down resistance and the pin load capacitance.
The rising/falling time is commonly determined by the following equation:
t
= -R
× (C
+ C
PR
INU
IN
t
= -R
× (C
+ C
PF
IND
IN
Where
t
:
Rising time (port level = low → high) [second]
PR
t
:
Falling time (port level = high → low) [second]
PF
V
:
High level Schmitt input threshold voltage [V]
T+
V
:
Low level Schmitt input threshold voltage [V]
T-
R
/R
: Pull-up/pull-down resistance [W]
INU
IND
C
:
Pin capacitance [F]
IN
C
:
Parasitic capacitance on the board [F]
BOARD
6.2.4 CMOS Output and High Impedance State
The I/O cells except for analog output can output signals in the V
put into high-impedance (Hi-Z) state.
6.2.5 LED Drive Pin
The I/O cell for the LED drive pin is formed as an Nch open drain type structure that allows directly driving of an
LED. This pin supports an output function only, so it does not allow software to perform input control and pull-up/
down control.
S1C17W12/W13 TECHNICAL MANUAL
(Rev. 1.2)
. However, be sure to avoid applying a voltage exceeding the recommended maxi-
DD
) × ln(1 - V
/V
)
BOARD
T+
DD
) × ln(1 - V
/V
)
BOARD
T-
DD
Seiko Epson Corporation
6 I/O PORTS (PPORT)
(Eq. 6.1)
and V
levels. Also the GPIO ports may be
DD
SS
6-3
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