PD64A_15 Datasheet, PDF (18/66 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS FOR INFRARED REMOTE CONTROL TRANSMISSION

µPD64A, 65
3.2 KI Port/Special Port (P1)
3.2.1 KI port (P11: bits 4 to 7 of P1)
The KI port is a 4-bit input port for key entry.
The pin state can be read.
Use of a pull-down resistor for the KI port can be specified in 4-bit units by software using bit 5 of the P4 register.
After reset, a pull-down resistor is connected.
Table 3-3. KI/Special Port Register (P1)
Bit
Name
b7
b6
b5
b4
b3
b2
b1
b0
KI3
KI2
KI1
KI0
S1/LED S0
S2
Fixed to “1”
b1:
The state of the S2 pin is read (read only).
b2:
In input mode, the state of the S0 pin is read (read only).
In OFF mode, this bit is fixed to 1.
b3:
The state of the S1/LED pin is read regardless of input/output mode (read only).
b4 to b7: The state of the KI pin is read (read only).
Caution In order to prevent malfunction, do not input a high level to all the KI0 to KI3 pins when POC is
released due to supply voltage startup (these pins can be left open. When leaving open, keep
pull-down resistors connected).
3.2.2 S0 port (bit 2 of P1)
The S0 port is an input/OFF mode port.
The pin state can be read by setting this port to input mode with bit 0 of the P4 register.
In input mode, use of a pull-down resistor for the S0 and S1/LED ports can be specified in 2-bit units by software
using bit 4 of the P4 register.
If input mode is released (thus set to OFF mode), the pin becomes high impedance but through current does
not flow internally. In OFF mode, “1” can be read regardless of the pin state.
After reset, this port is set to OFF mode, thus becoming high impedance.
3.2.3 S1/LED port (bit 3 of P1)
The S1/LED port is an I/O port.
Bit 2 of the P4 register can be used to set input or output mode. The pin state can be read in both input mode
and output mode.
In input mode, use of a pull-down resistor for the S0 and S1/LED ports can be specified in 2-bit units by software
using bit 4 of the P4 register.
In output mode, the pull-down resistor is automatically disconnected, and this pin becomes the remote control
transmission display pin (refer to 4. TIMER).
After reset, this port enters output mode, and a high level is output.
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Data Sheet U14380EJ3V0DS00