
S1C62740 TECHNICAL HARDWARE
EPSON
I-41
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (I/O Ports)
Control of I/O ports
Table 4.6.1 lists the I/O ports' control bits and their addresses.
Table 4.6.1 Control bits of I/O ports
I/O port data can be read and output data can be set through
these ports.
When writing data
When "1" is written: High level
When "0" is written: Low level
When an I/O port is set to the output mode, the written data is
output unchanged from the I/O port terminal. When "1" is written
as the port data, the port terminal goes high (VDD), and when "0" is
written, the level goes low (VSS).
Port data can be written also in the input mode.
When reading data out
When "1" is read: High level
When "0" is read: Low level
The terminal voltage level of the I/O port is read out. When the I/O
port is in the input mode the voltage level being input to the port
terminal can be read out; in the output mode the register value can
be read. When the terminal voltage is high (VDD) the port data that
can be read is "1", and when the terminal voltage is low (VSS) the
data is "0".
P00–P03, P10–P13, P20–P23:
I/O port data
(D8H, D9H, DAH)
*1 Initial value at the time of initial reset
*5 Constantly "0" when being read
*2 Not set in the circuit
*6 Refer to main manual
*3 Undefined
*7 Page switching in I/O memory is not necessary
*4 Reset (0) immediately after being read
Address
Comment
Register
D3
D2
D1
D0
Name
Init
1
0
*1
D6H
IOC0
R
0
IOC2
IOC1
IOC0
–
0
Output
Input
IOC1
IOC2
0
*2
*6
D7H
PUP0
R/W
0
PUP2
PUP1
PUP0
–
0
Unused
Pull up control register 2 (P20–P23)
Pull up control register 1 (P10–P13)
Pull up control register 0 (P00–P03)
On
Off
PUP1
PUP2
0
*2
*6
D8H
P00
P03
P02
P01
P00
–
High
Low
P01
P02
P03
*2
D9H
P10
P13
P12
P11
P10
–
High
Low
P11
P12
P13
*2
DAH
P20
P23
P22
P21
P20
–
High
Low
P21
P22
P23
*2
R/W
*7
R/W
Unused
I/O control register 2 (P20–P23)
I/O control register 1 (P10–P13)
I/O control register 0 (P00–P03)
R/W
R
I/O port (P00–P03)
I/O port (P10–P13)
I/O port (P20–P23)
When P20–P23 is selected as SIO port, P20–
P23 registers will function as register only
*5