How to use GPIO

Configuration/Test

Configuration

The RK3288 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 - 8

Group GPIO0 only 24 gpios,So each GPIO Num subtracts 8.

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

E.g. GPIO2_A4 becomes 60

RSB-4680

GPIO Number	GPIO formed	Numeric Representation
GPIO0	GPIO7_A3	219
GPIO1	GPIO7_A4	220
GPIO2	GPIO7_A5	221
GPIO3	GPIO7_C5	237
GPIO4	GPIO8_A2	250
GPIO5	GPIO8_A3	251
GPIO6	GPIO8_A0	248
GPIO7	GPIO8_A1	249

Test

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

Export GPIO0

# echo 219 > /sys/class/gpio/export

Set GPIO direction to in/out

# echo "out" > /sys/class/gpio/gpio219/direction

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

#  echo 1 > /sys/class/gpio/gpio219/value

Used as IRQ signal

Note:You have to configure GPIO to input

#  echo "rising" > /sys/class/gpio/gpio219/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 219 > /sys/class/gpio/unexport

Test

GPIO 219 and GPIO 220 are taken as an example:

• Connect GPIO 219 and GPIO 220
• Export GPIO 219 and GPIO 220

# echo 219 > /sys/class/gpio/export
# echo 220 > /sys/class/gpio/export

• Set GPIO 219 to output

# echo "out" > /sys/class/gpio/gpio219/direction

• Set GPIO 220 to input

# echo "in" > /sys/class/gpio/gpio220/direction

• Change GPIO 219 to 1 and read GPIO 220 value

# echo 1 > /sys/class/gpio/gpio219/value
# cat /sys/class/gpio/gpio220/value
1

• Change GPIO 219 to 0 and read GPIO 220 value

# echo 0 > /sys/class/gpio/gpio219/value
# cat /sys/class/gpio/gpio220/value
0