shaddow501 Posted June 12, 2019 Share Posted June 12, 2019 Hello Does anyone know how to toggle GPIO output at boot / power up as an overlay or similar? I have seen only examples that show GPIO in function and I didnt find much information how to toggle GPIO out function. Basically I would like to be able to turn LCD back light on when the board is booting and than to be able to control the brightness. (That I can do after the Linux is up and running) but before the Linux is up I still want to be able to control the LCD back light. Can anyone help with that matter? Link to comment Share on other sites More sharing options...
nradulovic Posted June 13, 2019 Share Posted June 13, 2019 Hello, Did you have a look at this? https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt There are some attributes that can set initial value during initialization. See for example: output-low and output-high properties. Is that what you need? Link to comment Share on other sites More sharing options...
shaddow501 Posted June 14, 2019 Author Share Posted June 14, 2019 On 6/13/2019 at 10:17 AM, nradulovic said: Hello, Did you have a look at this? https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt There are some attributes that can set initial value during initialization. See for example: output-low and output-high properties. Is that what you need? Actually I need to see a working example of the dts file... Because I do not know how to build it correctly. Link to comment Share on other sites More sharing options...
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