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| 2024/02/02 | DESK-MX9-L-5.0.0 release | ||
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Contents
Peripheral GPIOsEdit
i.MX93 can handle external pins in many different ways and most of them can be configured as GPIOs. When a pin is set as a GPIO, it is possible to read its value, change its direction or change output value directly from the shell.
Accessing the peripheralEdit
Usage with libgpiodEdit
Information about GPIOs library libgpiod - C library and tools - can be found on git.kernel.org
It is possible to compile libgpiod in the target (if the related Yocto package is not available for installation). Once the autoconf-archive package has been installed
dnf install autoconf-archive
it is possible to clone the libgpiod git repository and compile the related sources:
git clone https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git cd libgpiod ./autogen.sh --enable-tools=yes --prefix=/usr/local make make install
Once installed, the gpio utilities are available in the target:
root@desk-mx93:~# gpio gpiodetect gpioget gpioinfo gpiomon gpionotify gpioset
gpiomon exampleEdit
If a push button, with proper pull-up, is connected to a GPIO line available - for example using the J33.28 pin available on SBC AXEL Lite WIDE connector - the related GPIO can be used as an interrupt:
- J33.28 is connected to J10.191 SO-DIMM pin
- J33 connector is the WIDE connector in the AURA Evaluation Kit
- J10 connector is the SO-DIMM connector in the AURA Evaluation Kit
- ALT-0 alternate function for this pin is
GPIO2_IO12
- the corresponding pin number is associated to
gpiochip0line12 gpiomonutility can be used for monitor the pin status and triggering, for example, the falling-edge event:
root@desk-mx93:~# gpiomon -e falling -c 0 12 503.836012614 falling gpiochip0 12 504.229875114 falling gpiochip0 12 504.229962281 falling gpiochip0 12 504.229970823 falling gpiochip0 12 ^Croot@desk-mx93:~#
gpioset exampleEdit
For changing a GPIO output status, the gpioset utility can be used:
- the following example set to High the pin
GPIO_IO00connected to J10.179 SO-DIMM pin
root@desk-mx93:~# gpioset -c 0 0=1