7"-CTS with Lime2 Rev B: capacitive touch not working (i2c issues)

[ventosus]

I'm running with the latest image [1] on a Lime2 Rev B with the 7" capacitive touch screen. The touch screen does not work, though. Seems I have some i2c issues:

    olimex@olinuxino:~$ dmesg | grep Goodix
    [   10.972668] Goodix-TS 2-0014: 2-0014 supply AVDD28 not found, using dummy         regulator
    [   10.972798] Goodix-TS 2-0014: 2-0014 supply VDDIO not found, using dummy regulator
    [   11.071680] Goodix-TS 2-0014: i2c test failed attempt 1: -6
    [   11.099942] Goodix-TS 2-0014: i2c test failed attempt 2: -6
    [   11.127433] Goodix-TS 2-0014: I2C communication failure: -6

Anyone having the same issues ?

[1] Armbian_5.92.4_Olinuxino-a20_Debian_buster_next_5.2.21.7z

[LubOlimex]

LIME2 hardware revision B? Some hardware fiddling would be required to connect a capacitive touch to the board. There are 4 pins that need to be changed. You would need to separate the four wires responsible for the touch and connect them to the GPIO/I2C2(TWI2) pins elsewhere (they are not available at the LCD connector). To be specific:

#37 INT/X1 should go to PH10
#38 RES/X2 should go to PH11
#39 SCL/Y1 should go to PB20/TWI2-SCK
#40 SDA/Y2 should go to PB21/TWI2-SDA

You can find the required signals at the GPIO-3 and GPIO-1 connectors (in all cases refer to the schematic for your revision)

In newer hardware revisions of LIME2 the boards are sold configured for resistive touch, to re-configure them for capacitive touch you need to change the position of a resistor matrix. But this won't work in older hardware revisions where no such option was available.

I attach excerpt of newer revision on how the connection SHOULD BE (screenshot from newest hardware revision but demonstrates which 4 connections have to be established):

[ventosus]

@LubOlimex thanks for the clarifications.

Would have been nice if this information would have been mentioned somewhere in [1], e.g.

*compatible starting from LIME2 rev XY*

[1] https://www.olimex.com/Products/OLinuXino/LCD/LCD-OLinuXino-7/open-source-hardware

[LubOlimex]

It is mentioned as "... compatible... with A10, A20 when digital interface is enabled"

What you suggested would probably still be misleading since even with latest revision to get the capacitive touch working with A20 boards you need to move a resistor matrix unless specifically the board was manufactured for CTS compatibility (unsolder from original position; solder on new position).