How to use GPIO

Configuration

The RK3399 bank/bit notation for GPIOs must be formed as "GPIO<GPIO_bank>_<gpio_bit>" 

The numeric value of GPIO is calculated as follows:

32 x (gpio_bank) + gpio_bit

gpio_bit : A0～A7 0-7 B0～B7 8-15 C0～C7 16-23 D0～D7 24-31

E.g. GPIO2_B0 becomes 72

ROM-5780

GPIO Number	GPIO formed	Numeric Representation
GPIO0	GPIO1_A2	34
GPIO1	GPIO1_A3	35
GPIO2	GPIO1_B1	41
GPIO3	GPIO1_B2	42
GPIO4	GPIO1_B5	45
GPIO5	GPIO1_C2	50
GPIO6	GPIO1_C4	52
GPIO7	GPIO1_C6	54
GPIO8	GPIO1_C7	55
GPIO9	GPIO2_A2	66
GPIO10	GPIO2_A3	67
GPIO11	GPIO4_C5	149

Test

Here we take GPIO1 of 4710 as an example.3710 and 5780 are similar to set up.

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

Export GPIO1

# echo 72 > /sys/class/gpio/export

Set GPIO direction to in/out

# echo "out" > /sys/class/gpio/gpio72/direction

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

#  echo 1 > /sys/class/gpio/gpio72/value

Used as IRQ signal

Note:You have to configure GPIO to input

#  echo "rising" > /sys/class/gpio/gpio72/edge

• rising: Trigger on rising edge
• falling: Trigger on falling edge
• both: Trigger on both edges
• none: Disable interrupt on both edges

Unexport GPIO1

# echo 72 > /sys/class/gpio/unexport

Test

GPIO1 and GPIO2 are taken as an example:

• Connect GPIO1 and GPIO2
• Export GPIO1 and GPIO2

# echo 72 > /sys/class/gpio/export
# echo 50 > /sys/class/gpio/export

• Set GPIO 1 to output

# echo "out" > /sys/class/gpio/gpio72/direction

• Set GPIO 2 to input

# echo "in" > /sys/class/gpio/gpio50/direction

• Change GPIO1 to 1 and read GPIO2value

# echo 1 > /sys/class/gpio/gpio72/value
# cat /sys/class/gpio/gpio50/value 
1

• Change GPIO1 to 0 and read GPIO2 value

# echo 0 > /sys/class/gpio/gpio72/value
# cat /sys/class/gpio/gpio50/value 
0