How to use GPIO for RK3399 RSB4710

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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

RSB-4710

GPIO Number GPIO formed Numeric Representation
GPIO1
GPIO2_B0
72
GPIO2
GPIO1_C1
50
GPIO3
GPIO4_A3
131
GPIO4
GPIO3_D4
124
GPIO5
GPIO4_A4
132
GPIO6
GPIO0_B0
8

Note:

GPIO3 is used to mute speak in later version.

Test

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