UPD17717 Datasheet, PDF (112/408 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

µPD17717, 17718, 17719
11.3.2 Using input port
The input data is read by executing a read instruction (such as SKT) to the port register corresponding to
the port pin.
“1” is read from the port register when a high level is input to the corresponding port pin; when a low level
is input to the port pin, “0” is read from the register.
Nothing is affected even if a write instruction (such as MOV) is executed to the port register.
P0D has a pull-down resistor that can be connected or disconnected by software in 1-bit units. The pull-down
resistor is connected when “0” is written to the corresponding bit of the port 0D pull-down resistor selection
register. When “1” is written to the corresponding bit of this register, the pull-down resistor is disconnected.
11.3.3 Port 0D pull-down resistor selection register
The port 0D pull-down resistor selection register specifies whether a pull-down resistor is connected to P0D3
through P0D0 pins. The configuration and function of this register are illustrated below.
• Port 0D pull-down resistor selection register
Name
Port 0D pull-down resistor
selection
Flag symbol Address
b3 b2 b1 b0
PP PP
00 00
DD DD
PP PP
LL LL
DD DD
32 10
(BANK15)
66H
Read/Write
R/W
Power-ON reset
WDT&SP reset
CE reset
Clock stop
112
Selects pull-down resistor of P0D0 pin
0 Connects pull-down resistor to P0D0 pin
1 Disconnects pull-down resistor from P0D0 pin
Selects pull-down resistor of P0D1 pin
0
Connects pull-down resistor to P0D1 pin
1
Disconnects pull-down resistor from P0D1 pin
0
1
0
1
Selects pull-down resistor of P0D2 pin
Connects pull-down resistor to P0D2 pin
Disconnects pull-down resistor from P0D2 pin
Selects pull-down resistor of P0D3 pin
Connects pull-down resistor to P0D3 pin
Disconnects pull-down resistor from P0D3 pin
0000
0000
Retained
Retained