How to use GPIO for am335x

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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
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