GPIO Number to use in sysfs

Davi Evangelista

Hello,

I'm trying to use the sysfs to change the value of some GPIO pins in my board using the interfaces /sys/class/gpio/export and /sys/class/gpio/gpioXX/value but I don't know which value I should pass to the echo command that is used to create the pseudo-files under /sys/class/gpio/gpioXX...

Say I want to configure AM335x's GPIO1.25, what would be the value of X below?

$ echo X > /sys/class/gpio/export

Thanks!

DAVI

over 13 years ago

0 Miroslav Kiradzhiyski XID over 13 years ago

TI__Mastermind 25235 points

Hi,

This should help: http://processors.wiki.ti.com/index.php/GPIO_Driver_Guide#User_Space_-_Sysfs_control

Best regards,
Miroslav

0 Davi Evangelista over 13 years ago in reply to Miroslav Kiradzhiyski XID

Expert 1090 points

Not quite...

I know how to use the sysfs to handle a GPIO, I just don't know the number I should use to indicate which GPIO is which...

The pins I need to work with are the leftovers none of the drivers I use map. In fact, in the board configuration file, I map all the pins I use, including the ones in GPIO mode, using the struct pinmux_config. The file arch/arm/mach-omap2/mux33xx.c lists all the pins available and their function, but I don't know how to find these values to use in user space.

DAVI

0 Miroslav Kiradzhiyski XID over 13 years ago in reply to Davi Evangelista

TI__Mastermind 25235 points

Hi,

To convert GPIO signal to GPIO pin number do the following: (32 * (bank) + (gpio))

meaning that for GPIO1.25 you should do:

$ echo 57 > /sys/class/gpio/export

Best regards,
Miroslav

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GPIO Number to use in sysfs