IV - 3
Chapter 4 I/O Ports
Overview
4-1-2
I/O Port Status at Reset
Table 4-1-1
I/O Port Status at Reset (Single chip mode)
4
Port Name
I/O mode
Pull-up / Pull-down resistor
I/O port, special functions
Port 0
Input mode
No pull-up / pull-down resistor
I/O port
Port 1
Input mode
No pull-up / pull-down resistor
I/O port
Port 2
Input mode
P27,P23 : Pull-up resistor
Others : No pull-up resistor
I/O port
Port 3
Input mode
No pull-up resistor
I/O port
Port 4
Input mode
No pull-up resistor
I/O port
Port 5
Input mode
P50 : Pull-up resistor
Others : No pull-up resistor
I/O port
Port 6
Input mode
No pull-up resistor
I/O port
Port 7
Input mode
No pull-up resistor
I/O port
Port 8
Input mode
No pull-up resistor
I/O port
Port A
Input mode
No pull-up / pull-down resistor
I/O port
The values of pull-up/pull-down resistors should be caluculated in following ways
based on the electrical characteristics in LSI User's Manual of each model.
How to determine pull-up resistor value
ex) When pins maintain the low level guaranteed performance (not 0 V) as specified
in the electrical characteristics,
and at VDD = 5 V, VIN = 1.5 V,
input current is min. = - 30
A, typ = - 100 A, max. = - 300 A.
( - means current passing from microcontroller.)
When convert above values to resistor value, typ = 35 k
.
Note that this value varies wildely depending on the temperature.
In temperature variation from - 40 °C to 85 °C, the resistor value varies from
min. = 11.7 k
to max. = 117 k.
How to determine pull-down resistor value
ex) When pins maintain the high level guaranteed performance (not VDD) as speci-
fied in the electrical characteristics,
and at VDD = 5 V, VIN = 3.5 V,
input current is min. = - 30
A, typ = - 100 A, max. = - 300 A.
When convert these values to resistance value, typ = 35 k
.
Note that this value varies wildely depending on the temperature.
In temperature variation from - 40 °C to 85 °C, the resistor value varies from
min. = 11.7 k
to max. = 117 k.