Direct GPIO access

[JulianR 0]

Hi there,

I am trying to port software from RPI4 to the tinkerboard. We used to access the GPIOs not with WiringPI but manually using "nmap" with a file descriptor ("/dev/mem"). To find the peripheral offset address we were reading this file: "/proc/device-tree/soc/ranges". But I can not find this path or a similar one on the tinkerboard. Can someone help me to get on the right track?

Thanks in advance!

Julian R.

[tooz 52]

hello @JulianR, 

here's the GPIO config table for your reference: User Guide · TinkerBoard/TinkerBoard Wiki · GitHub

[JulianR 0]

Thank you for your response.

The paths there do not exist on my board (Tinkerboard2). For example physical pin 3 states: "/sys/class/gpio/gpio73".

If I do an ls on that path, none of them listed there:

$ sudo ls /sys/class/gpio/

export gpio16 gpio25 gpiochip0 gpiochip128 gpiochip32 gpiochip64 gpiochip96 unexport

 

[yi-hsin_hung 3]

Hi @JulianR:

     This is the linux common functions. Need to echo the pin number to export and then show the gpio$number in the path.

Please reference the following website link and reference sample. Thank a lot!

--->  Website link for GPIO Programming: Using the sysfs Interface

https://www.ics.com/blog/gpio-programming-using-sysfs-interface

---> Examples

1. GPIO input control example

 

0, 8

GPIO: /sys/class/gpio/gpio8

TEST_CLKOUT2

GPIO0_B0

7

* Console command:

- Export the GPIO pin

echo 8 > /sys/class/gpio/export

- Set the GPIO pin to input mode

echo in > /sys/class/gpio/gpio8/direction

- Read input value:

cat /sys/class/gpio/gpio8/value

 

2. GPIO output control example

 

0, 8

GPIO: /sys/class/gpio/gpio8

TEST_CLKOUT2

GPIO0_B0

7

* Console command:

- Export the GPIO pin

echo 8 > /sys/class/gpio/export

- Set the GPIO pin to output mode

echo out > /sys/class/gpio/gpio8/direction

- Set value to GPIO pin:

echo 1 >  /sys/class/gpio/gpio8/value

- Read the GPIO value

cat /sys/class/gpio/gpio8/value

[JulianR 0]

Thanks a lot!