Project

General

Profile

Can't read state of output GPIO pins » gpio_read_output_test.sh

bash script demonstrating the issue - Tim Troester, 03/16/2026 05:43 PM

 
1
export GPIO_PIN_NUMBER=638 # corresponds to /dev/gpiochip2, line index 10
2

    
3
echo $GPIO_PIN_NUMBER > /sys/class/gpio/export
4

    
5
trap "echo $GPIO_PIN_NUMBER > /sys/class/gpio/unexport" EXIT 
6

    
7
echo "EXPORTED PIN ${GPIO_PIN_NUMBER}: "
8
ls /sys/class/gpio
9

    
10
echo "SETTING MODE TO OUTPUT"
11
echo 'out' > /sys/class/gpio/gpio${GPIO_PIN_NUMBER}/direction
12

    
13
while true; do
14
    echo "SETTING VALUE TO 1"
15
    echo 1 > /sys/class/gpio/gpio${GPIO_PIN_NUMBER}/value
16
    echo "VALUE IS: " $(cat /sys/class/gpio/gpio${GPIO_PIN_NUMBER}/value)
17
    sleep 5
18

    
19
    echo "SETTING VALUE TO 0"
20
    echo 0 > /sys/class/gpio/gpio${GPIO_PIN_NUMBER}/value
21
    echo "VALUE IS: " $(cat /sys/class/gpio/gpio${GPIO_PIN_NUMBER}/value)
22
    sleep 5
23
done
24
 
(2-2/2) Go to top
Add picture from clipboard (Maximum size: 1 GB)