FreeBSD, BBB, and 4DCAPE-43T: touchscreen

October 16, 2015 — 4 Comments

And yet another demo of 4DCAPE-43T, this time it’s touchscreen. On AM335x SoC touchscreen controller is coupled with analog-to-digital converter, for which there is a driver in FreeBSD HEAD: ti_adc. I had to implement touchscreen part and add driver <-> userland communication protocol. For proof of concept I used significantly dumbed-down version of Linux input event protocol. tslib serves as a userland part of the demo. I believe it’s de-facto standard for touchscreen devices interface in Linux world. Only two things were changed comparing to stock one: I added bsd-raw input plugin to communicate with kernel and rewrote framebuffer-related routines.

Code is in 4dcape-43t branch in my work-in-progress GitHub repo and in freebsd branch of tslib fork.



4 responses to FreeBSD, BBB, and 4DCAPE-43T: touchscreen

  1. Gonzo thanks for this. I am looking at the 4D- 4.3″ LCD and this helps a bunch…

    Keep up all the great hacking.

    Loving the HDMI support you added to the Beaglebone..

  2. Btw have you been following the developments of the graphics and input stack? Relevant article: … It seems like EvDev will be ported to FreeBSD, followed by LibInput, to get xf86-input-evdev to handle all input in

    Does any Linux for RPi (like Raspian) use EvDev, LibInput and xf86-input-evdev to enable external touch screen support in Would this be the future software stack to enable external touch screen support in with FreeBSD on RPi compatible devices, or are there other alternatives?

    • I wasn’t aware of this effort. Thanks for pointing me to it. Having evdev would mean a lot of software can work on FreeBSD without major modification. Like Qt.

      I think raspbian uses official 7″ touchscreen as a mouse through evdev (at least that’s how I read code). I already have driver for it for FreeBSD, only missing piece is userland integration in HEAD (my hack does not count). evdev would be this missing link.

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