¶ GPIO Programming
This chapter takes YY3588's GPIO1_PA4 as an example to explain the use of the GPIO user interface
¶ 1 Schematic location
¶ 2 Interface usage
Set GPIO 36 to user mode operation
echo 36 > /sys/class/gpio/export
Set GPIO 101 to output
echo out > /sys/class/gpio/gpio36/direction
When GPIO 36 is output, set the level
High level
echo 1 > /sys/class/gpio/gpio36/value
Low level
echo 0 > /sys/class/gpio/gpio36/value
Set GPIO 36 is set as input
echo in > /sys/class/gpio/gpio36/direction
When GPIO 36 is input, read its level, 1 is high, 0 is low
cat sys/class/gpio/gpio36/value
Cancel GPIO 36 user mode operation
echo 36 > /sys/class/gpio/unexport
¶ 3 Modification of device tree
¶ 4 GPIO output PWM square wave DEMO
- Readers can control the square wave period by adjusting the parameter time
cat GPOI_PWM.sh
#!/bin/bash
#GPIO1_PA4 --- gpio36
echo 36 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio36/direction
echo 1 > /sys/class/gpio/gpio36/value
while true; do
echo 1 > /sys/class/gpio/gpio36/value
sleep $1 && echo "delay $1"
echo 0 > /sys/class/gpio/gpio36/value
sleep $1 && echo "delay $1"
done
root@linaro-alip:/# ./GPIO_PWM.sh 0.01
delay 0.01
delay 0.01
delay 0.01
...
- The phenomenon is as shown in the figure
