upd64a Renesas Electronics Corporation., upd64a Datasheet - Page 15

• Manufacturer Part Number: upd64a
• Description: 4-bit Single-chip Microcontroller For Infrared Remote Control Transmission
• Manufacturer: Renesas Electronics Corporation.

3.1 K
be read in output mode.
The K
Input/output mode is set by bit 1 of the P4 register.
If a read instruction is executed, the pin state can be read in input mode, whereas the output latch contents can
If a write instruction is executed, data can be written to the output latch regardless of input or output mode.
After reset, the port enters output mode, and the value of the output latch (P0) becomes 1111 1111B.
The K
Caution Because during double pressing of a key, a high-level output and a low-level output may conflict
b
0
to b
I/O
I/O
I/O
7
Port (P0)
: When reading: In input mode, state of the K
port is an 8-bit I/O port for key scan output.
port includes a pull-down resistor, which functions in input mode only.
When writing:
with each other at the K
be careful when using the K
The K
voltage range (V
Bit
Name
I/O
port is designed so that, even when connected directly to V
In output mode, the K
Data is written to the K
b
K
DD
7
I/O7
= 2.0 to 3.6 V), no problem may occur.
I/O
b
K
port, the low-level output current of the K
6
I/O6
I/O
Table 3-2. K
Data Sheet U14380EJ3V0DS00
port for purposes other than key scan output.
b
K
5
I/O5
I/O
I/O
pin’s output latch contents are read.
pin’s output latch regardless of input or output mode.
b
K
I/O
4
I/O4
I/O
Port (P0)
pin is read.
b
K
3
I/O3
b
K
2
I/O2
I/O
b
K
1
I/O1
DD
port is held low. Therefore,
within the normal supply
b
K
0
I/O0
PD64A, 65
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