24 I/O PORTS (GPIO)
24-4
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Pull-up Control
24.4
The I/O port contains a pull-up resistor that can be enabled or disabled individually for each bit using PUP
xy
/
GPIO_P
x
_PUP register. Setting PUP
xy
to 1 enables the pull-up resistor and pulls up the port pin in input mode. It
will not be pulled up if set to 0. The PUP
xy
setting is ignored and not pulled up in output mode.
Unused I/O ports should be set with pull-up enabled.
This pull-up setting is also enabled for ports for which the peripheral module function has been selected.
Port Input Interrupt and DMA
24.5
The GPIO module has four interrupt systems (port input interrupts 0 to 3) and the ports can be selected for generat-
ing each cause of interrupt.
The interrupt trigger conditions can also be selected from between input signal edge (rising edge or falling edge)
and input signal level (high level or low level).
Figure 24.5.1 shows the configuration of the port interrupt circuit.
SIET0
SEPT0
SFGP0
P30
P10
P50
P00
SPPT0
SCTP0[2:0]
SPT0[1:0]
Chattering
filter
Trigger
mode/polarity
control
Port input
interrupt 0
request
(to ITC)
Port input
interrupt 0
FPT0
SIET1
SEPT1
SFGP1
P31
P11
P51
P01
SPPT1
SCTP1[2:0]
SPT1[1:0]
Chattering
filter
Trigger
mode/polarity
control
FPT1
SIET2
SEPT2
SFGP2
P32
P12
P52
P02
SPPT2
SCTP2[2:0]
SPT2[1:0]
Chattering
filter
Trigger
mode/polarity
control
FPT2
SIET3
SEPT3
SFGP3
P33
P13
P53
P03
SPPT3
SCTP3[2:0]
SPT3[1:0]
Chattering
filter
Trigger
mode/polarity
control
FPT3
ANFEN
Noise
filter
ANFEN
Noise
filter
ANFEN
Noise
filter
ANFEN
Noise
filter