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Does a pull-up resistor need to be connected externally to each unused pin?

Latest Updated:10/31/2008

Question:

Does a pull-up resistor need to be connected externally to each unused pin?

Answer:

No, a pull-up resistor does not need to be connected externally to each unused pin.
When an internal pull-up resistor is used, the initial value of the pull-up control register is set to 00h after a reset.
Note that this causes the pull-up resistor to be disabled and the direction register to be left open for input until the pull-up control register is set after a reset.
Suitable Products
R8C/18
R8C/19
R8C/1A
R8C/1B
R8C/20
R8C/21
R8C/22
R8C/23
R8C/24
R8C/25
R8C/26
R8C/27
R8C/28
R8C/29
R8C/2A
R8C/2B
R8C/2C
R8C/2D
R8C/2E
R8C/2F
R8C/2G
R8C/2H
R8C/2J
R8C/2K
R8C/2L
R8C/32C
R8C/33C
R8C/34C
R8C/35C
R8C/36C
R8C/38C
R8C/3GC
R8C/3JC
R8C/32D
R8C/33D
R8C/35D
R8C/3GD
R8C/33T
R8C/38A
R8C/34E, R8C/34F, R8C/34G, R8C/34H
R8C/36E, R8C/36F, R8C/36G, R8C/36H
R8C/38E, R8C/38F, R8C/38G, R8C/38H
R8C/L35C
R8C/L36C
R8C/L38C
R8C/L3AC