Difference between revisions of "How to use GPIO for RK3399 RSB4710"

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Revision as of 07:14, 14 February 2020

Introduction

GPIO, 全称 General-Purpose Input/Output(通用输入输出),是一种软件运行期间能够动态配置和控制的通用引脚。

RK3399有5组GPIO bank:GPIO0~GPIO4,每组又以 A0~A7, B0~B7, C0~C7, D0~D7 作为编号区分(不是所有 bank 都有全部编号,例如 GPIO4 就只有 C0~C7, D0~D2)。

所有的GPIO在上电后的初始状态都是输入模式,可以通过软件设为上拉或下拉,也可以设置为中断脚,驱动强度都是可编程的。

每个 GPIO 口除了通用输入输出功能外,还可能有其它复用功能,

例如 GPIO2_A2,可以利用成以下功能:

GPIO2_A2

CIF_D2

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_A4 becomes 68

RSB-4710

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