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S1C88650 TECHNICAL MANUAL EPSON 59
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (I/O Ports)
■ DC output control
P00D–P07D: 00FF62H
P10D–P17D: 00FF63H
How I/O port terminal Pxx data readout and
output data settings are performed.
When writing data:
When "1" is written: HIGH level
When "0" is written: LOW level
When the I/O port is set to output mode, the data
written is output as is to the I/O port terminal. In
terms of port data, when "1" is written, the port
terminal goes to HIGH (V
DD) level and when "0" is
written to a LOW (VSS) level.
Even when the port is in input mode, data can still
be written in.
When reading out data:
When "1" is read: HIGH level ("1")
When "0" is read: LOW level ("0")
When an I/O port is in input mode, the voltage
level being input to the port terminal is read out.
When terminal voltage is HIGH (V
DD), it is read as
a "1", and when it is LOW (VSS), it is read as a "0".
Furthermore, in output mode, the contents of the
data register are read out.
At initial reset, this register is set to "1" (HIGH
level).
Note: The data registers of the ports that are
configured to the data bus, serial interface
outputs and special outputs can be used as
general purpose registers that do not affect
the terminal inputs/outputs.
IOC00–IOC07: 00FF60H
IOC10–IOC17: 00FF61H
Sets the I/O ports to input or output mode.
When "1" is written: Output mode
When "0" is written: Input mode
Reading: Valid
IOCxx is the I/O control register which correspond
to each I/O port in a bit unit.
Writing "1" to the IOCxx register will switch the
corresponding I/O port Pxx to output mode, and
writing "0" will switch it to input mode.
When the special output is used, "1" must always be
set for the I/O control registers (IOC14–IOC17) of
I/O ports which will become output terminals.
At initial reset, this register is set to "0" (input
mode).
Note: The I/O control registers of the ports that are
configured to the data bus, serial interface
inputs/outputs and special outputs can be
used as general purpose registers that do
not affect the terminal inputs/outputs.
PULP00–PULP07: 00FF64H
PULP10–PULP17: 00FF65H
The pull-up during the input mode are set with
these registers.
When "1" is written: Pull-up ON
When "0" is written: Pull-up OFF
Reading: Valid
PULPxx is the pull-up control register
corresponding to each I/O port (in bit units).
When "Gate direct" is selected by mask option, the
corresponding pull-up control register is
disconnected from the input line, so it can be used
as a general-purpose register.
By writing "1" to the PULPxx register, the
corresponding I/O ports are pulled up (during
input mode), while writing "0" turns the pull-up
function OFF.
At initial reset, these registers are all set to "1", so
the pull-up function is set to ON.
Note: The pull-up control registers of the ports that
are configured to the serial interface outputs
or special outputs can be used as general
purpose registers that do not affect the pull-
up control. The pull-up control registers of
the port that are configured to the serial
interface inputs function the same as the I/O
port.
■ Special output control
PTOUT0: 00FF30H•D3
PTOUT1: 00FF31H•D3
PTOUT2: 00FF38H•D3
PTOUT3: 00FF39H•D3
Controls the TOUT (programmable timer output
clock) signal output.
When "1" is written: TOUT signal output
When "0" is written: DC output
Reading: Valid
PTOUT0–PTOUT3 are the output control registers
for the TOUT0–TOUT3 signals. When PTOUT0 (or
PTOUT1) is set to "1", the TOUT0 (or TOUT1) signal
is output from the P14 port terminal. When
PTOUT2 (or PTOUT3) is set to "1", the TOUT2 (or
TOUT3) signal is output from the P15 port terminal.
When "0" is set, P14/P15 is set for DC output.
At this time, settings of the I/O control register
IOC14/IOC15 and data register P14D/P15D
become invalid.
At initial reset, PTOUT is set to "0" (DC output).
Note: If PTOUT0 and PTOUT1 are set to "1" at the
same time, PTOUT1 is effective. Similarly, if
PTOUT2 and PTOUT3 are set to "1",
PTOUT3 is effective. Furthermore, if the
programmable timer is set in 16-bit mode, the
TOUT0 and TOUT2 signals cannot be output.