How to use GPIO for am335x

RSB-4220

GPIO Number	Linux OS(/sys/class/gpio/)	Default direction
IDI0	gpio498	in
IDI1	gpio499	in
IDI2	gpio500	in
IDI3	gpio501	in
IDO0	gpio502	out
IDO1	gpio503	out
IDO2	gpio504	out
IDO3	gpio505	out

RSB-4221

GPIO Number	Linux OS(/sys/class/gpio/)	Default direction
GPIO0	gpio490	in
GPIO1	gpio491	in
GPIO2	gpio492	in
GPIO3	gpio493	in
GPIO4	gpio494	in
GPIO5	gpio495	in
GPIO6	gpio496	in
GPIO7	gpio497	in
GPIO8	gpio498	in
GPIO9	gpio499	in
GPIO10	gpio500	in
GPIO11	gpio501	in
GPIO12	gpio502	in
GPIO13	gpio503	in

ROM-3310

GPIO Number	Linux OS(/sys/class/gpio/)	Default direction
GPIO0	gpio490	in
GPIO1	gpio491	in
GPIO2	gpio492	in
GPIO3	gpio493	in
GPIO4	gpio494	in
GPIO5	gpio495	in
GPIO6	gpio496	in
GPIO7	gpio497	in
GPIO8	gpio498	in
GPIO9	gpio499	in
GPIO10	gpio503	in
GPIO11	gpio504	in

Test

Export GPIO then you can use control GPIO from userr space through sysfs

Export GPIO0

# echo 490 > /sys/class/gpio/export

Set GPIO direction to in/out

# echo "out" > /sys/class/gpio/gpio490/direction

Set GPIO value 0/1 if GPIO pin define is output

#  echo 1 > /sys/class/gpio/gpio490/value

Unexport GPIO0

# echo 490 > /sys/class/gpio/unexport

GPIO 490 and GPIO 491 are taken as an example:

• Connect GPIO 490 and GPIO 491
• Export GPIO 490 and GPIO 491

# echo 490 > /sys/class/gpio/export
# echo 491 > /sys/class/gpio/export

• Set GPIO 490 to output

# echo "out" > /sys/class/gpio/gpio490/direction

• Set GPIO 491 to input

# echo "in" > /sys/class/gpio/gpio491/direction

• Change GPIO 490 to 1 and read GPIO 491 value

# echo 1 > /sys/class/gpio/gpio490/value
# cat /sys/class/gpio/gpio491/value
1

• Change GPIO 490 to 0 and read GPIO 491 value

# echo 0 > /sys/class/gpio/gpio490/value
# cat /sys/class/gpio/gpio491/value
0