ADS7846 driver

Question

I am having an issue with the touchscreen ADS7846, the touchscreen is recognized, and set to event0 but I am unable to get the touch input to work.

When I prees on the display in some points - it always pressed on the farthest point (top left).

This is some of what I got after running evtest

 

root@visionsom:~# evtest

No device specified, trying to scan all of /dev/input/event*

Available devices:

/dev/input/event0:      ADS7846 Touchscreen

Select the device event number [0-0]: 0

Input driver version is 1.0.1

Input device ID: bus 0x0 vendor 0x0 product 0x0 version 0x0

Input device name: "ADS7846 Touchscreen"

Supported events:

  Event type 0 (EV_SYN)

  Event type 1 (EV_KEY)

    Event code 330 (BTN_TOUCH)

  Event type 3 (EV_ABS)

    Event code 0 (ABS_X)

      Value      0

      Min        0

      Max      239

    Event code 1 (ABS_Y)

      Value      0

      Min        0

      Max      319

    Event code 24 (ABS_PRESSURE)

      Value      0

      Min        0

      Max        0

Properties:

Testing ... (interrupt to exit)

 

Event: time 1601816198.312857, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1

Event: time 1601816198.312857, type 3 (EV_ABS), code 0 (ABS_X), value -2984

Event: time 1601816198.312857, type 3 (EV_ABS), code 1 (ABS_Y), value -2588

Event: time 1601816198.312857, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 65493

Event: time 1601816198.312857, -------------- SYN_REPORT ------------

Event: time 1601816198.331193, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 0

Event: time 1601816198.331193, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 0

Event: time 1601816198.331193, -------------- SYN_REPORT ------------

Answer 1

Hello Nikita,

in general Embedded Wizard is a middleware solution which build on top of some APIs like the touch driver, graphic accelerator, etc.

The touch driver itself or developing of touch driver basically is not our main business. Thus, can I kindly forward you to the touch drivers module manufacturer, in your case Texas Instruments?

Often chip manufacturers do have driver examples which you could modify to your special needs for the use with Embedded Wizard.

Best regards,

Tim

Comments

Just a further remark: The X and Y values reported by evtest indicates that either the HW or the driver is misconfigured as they are negative and too far away from the given min and max values ( [0|239] and [0|319]) that the kernel driver reports. As my colleague already mentioned, best would be to get in contact with the system vendor in order to solve the issue as this is not related to nor can be fixed within Embedded Wizard.

Hope this helps,
Manuel