
S1C62N82 TECHNICAL HARDWARE
EPSON
I-41
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (I/O Ports)
I/O Ports (P00–P03)
The S1C62N82 Series have a 4-bit general-purpose I/O port.
Figure 4.5.1 shows the configuration of the I/O port. The
four bits of the I/O port P00–P03 can be set to either input
mode or output mode. The mode can be set by writing data
to the I/O control register (IOC).
4.5
Configuration of I/O
port
Fig. 4.5.1
Configuration of I/O port
Input or output mode can be set for the four bits of I/O port
P00–P03 by writing data into I/O control register IOC.
To set the input mode, 0 is written to the I/O control regis-
ter. When an I/O port is set to input mode, its impedance
becomes high and it works as an input port. However, the
input line is pulled down when input data is read.
The output mode is set when 1 is written to the I/O control
register (IOC). When an I/O port set to output mode works
as an output port, it outputs a high signal (VDD) when the
port output data is 1, and a low signal (VSS) when the port
output data is 0.
After an initial reset, the I/O control register is set to 0, and
the I/O port enters the input mode.
I/O control register
and I/O mode
Address
Register
Input
control
I/O control
register
(IOC)
Data
bus
Pxx
VSS
Address