Raspberry Pi with SPI tochscreen

asked Dec 25, 2019 in System Integration by bramvr

I'm taking the first steps in the Embedded Wizzard environment. I have a Raspberry Pi 3 with a 10.1" touchscreen witch is working correctly on the normal system. The display itself is connected by the HDMI port of the RPi and the touch sensor is connected by using the SPI bus. In normal environments, this setup works very well, but when I start an example of the Embedded Wizzard, the system doesn't respond on any touch on the touch sensor. The GUI via the HDMI isn't a problem only the touch input isn't correct. I tried to connect a normal (optical) mouse to the RPi but also no reaction. I think this is the problem because the touchscreen works as a mouse input in the normal environment. Is there a solution to solve this problem?


3 Answers

0 votes
answered Dec 25, 2019 by Manfred Schweyer

Hi Bram,

the Build Environment for Raspberry Pi 3 is prepared to work with the offical 7" Raspberry Pi touch display. In case you are using a different display / touch device there might be some adaptationes necessary. If the display is already working - that's great.

In order to access the touch device, it might be necessary to change the input device in /TargetSpecific/ew_bsp_touch.c. By default /dev/input/event0 is used. In most cases it is sufficent to change this setting.

You can also change this device setting within the command line when you start the executable:

EW_TOUCHDEVICE=/dev/input/event1 ./EmbeddedWizard-RasPi-3B


EW_TOUCHDEVICE=/dev/input/event2 ./EmbeddedWizard-RasPi-3B

Does it work?

Best regards,


0 votes
answered Dec 25, 2019 by bramvr
Hi Manfred,

Thanks for you're replay.

I do some tests with the EW_TOUCHDEVICE command but without success. But I notice now that the problem is different than expected. The test application reacts on a touch when I touch the screen in the lower bottom (found by random presses) but at that place, there are no functions thats triggers a touch event. It looks likes the coordinates that are coming from the touchscreen are different than the coordinates that the application uses. If I'm correct the official 7" Raspberry Pi touch display is a capacitive touch display, I'm currently using a resistive touchscreen maybe this is the problem. How can I solve this issue? By the way, the coordinates for the OS are correct and the reaction without the EW_TOUCHDEVICE is the same.


Best regards,
commented Dec 25, 2019 by bramvr
Same as above, I press accidentally the wrong button but I can't remove this (I'm new here :D )
commented Mar 20 by bramvr
Anybody thy had a solution for this problem, if more information is needed, just tell me ;)
0 votes
answered Mar 20 by bramvr
Anybody thy had a solution for this problem, if more information is needed, just tell me ;)

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