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

Export GPIO then you can use control GPIO from user space through sysfs.

Export GPIO0

# echo 34 > /sys/class/gpio/export

Set GPIO direction to in/out

# echo "out" > /sys/class/gpio/gpio34/direction

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

#  echo 1 > /sys/class/gpio/gpio34/value

Used as IRQ signal

Note:You have to configure GPIO to input

#  echo "rising" > /sys/class/gpio/gpio34/edge

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

Unexport GPIO0

# echo 34 > /sys/class/gpio/unexport

Test

GPIO0 and GPIO1 are taken as an example:

• Connect GPIO0 and GPIO1
• Export GPIO0 and GPIO1

# echo 34 > /sys/class/gpio/export
# echo 35 > /sys/class/gpio/export

• Set GPIO 1 to output

# echo "out" > /sys/class/gpio/gpio34/direction

• Set GPIO 2 to input

# echo "in" > /sys/class/gpio/gpio35/direction

• Change GPIO 0 to 1 and read GPIO 2 value

# echo 1 > /sys/class/gpio/gpio34/value
# cat /sys/class/gpio/gpio35/value 
1

• Change GPIO 0 to 0 and read GPIO 2 value

# echo 0 > /sys/class/gpio/gpio34/value
# cat /sys/class/gpio/gpio35/value 
0