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sdra
Posts: 9
Joined: Wed Jan 27, 2016 9:42 pm
Location: Amsterdam, NL

Help with Buildroot and Adafruit TFT 2.8 CapTouch

Fri Jun 03, 2016 11:40 am

Hi,

I'm using https://github.com/gamaral/rpi-buildroot to build a minimal system that boots in 4 seconds.
I could have everything working (including the TFT display) except the touchscreen of the Adafruit 2.8" TFT cap:
https://www.adafruit.com/product/1983

As far as I know the driver to be used is the ft6236 which is now in the stock Raspberry Pi linux sources since
version 4.4.y which is the one I'm using with buildroot.

However just modprobe ft6236 does not work. The module is loaded, but the /dev/input/eventX
is not created, and nothing is printed in dmesg.

As another attempt I'm trying to get it working with the pitft28-capacitive-overlay.dtb Device Tree Blob Overlay.
Kernels 4.4 should have dtb loaded by default, the dtb is in the boot partition in overlays/ directory and I have
in my config.txt:

Code: Select all

# Enable SPI :
dtparam=spi=on

# Enable I2C :
dtparam=i2c1=on
dtparam=i2c_arm=on

dtoverlay=pitft28-capacitive,rotate=90,speed=32000000,fps=20
dtoverlay=pitft28-capacitive,touch-swapxy=true,touch-invx=true
Am I missing something? How can I get the touchscreen working?

DirkS
Posts: 7732
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Thu Jun 09, 2016 10:21 am

Using 2 lines to configure the screen is not going to work.
You need to put all the options on a single line.

Code: Select all

dtoverlay=pitft28-capacitive,rotate=90,speed=32000000,fps=20,touch-swapxy=true,touch-invx=true

User avatar
sdra
Posts: 9
Joined: Wed Jan 27, 2016 9:42 pm
Location: Amsterdam, NL

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Thu Jun 09, 2016 12:02 pm

Hi DirkS,

thanks for your answer! didn't work though :( btw, afaik config.txt has a line length limit of max 79 characters,
however I cannot find this in the docs anymore???

what do you mean: "If you're using the Adafruit screen yo don't need the 'stand-alone' ft6206 overlay"?

DirkS
Posts: 7732
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Thu Jun 09, 2016 1:48 pm

sdra wrote:what do you mean: "If you're using the Adafruit screen yo don't need the 'stand-alone' ft6206 overlay"?
pitft28-capacitive-overlay.dts contains all the infomation for configuring the screen + the touch panel.
Using the ft6206 overlay is pointless.
thanks for your answer! didn't work though :( btw, afaik config.txt has a line length limit of max 79 characters,
Can't remember ever seeing any reference to that. IIRC MS-DOS's config.sys had this limitation...
Even if that's the case then you cannot solve that by adding another line. If you do that then the logs will undoubtedly show up some error messages...

BTW: you can make the line shorter by leaving out the default values.
in your case it means that you don't need to add spi-max-frequency and rotation

User avatar
sdra
Posts: 9
Joined: Wed Jan 27, 2016 9:42 pm
Location: Amsterdam, NL

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Fri Sep 23, 2016 3:29 pm

BTW, I still could not manage to get the touchscreen working.
With the image build by adafruit, /dev/input/touchscreen exists
and the touchscreen works. Manual build with buildroot does not.

I also couldn't figure out if ft6206 and ft6236 are the same.
Anyone got it working with buildroot and not raspbian?

User avatar
sdra
Posts: 9
Joined: Wed Jan 27, 2016 9:42 pm
Location: Amsterdam, NL

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Fri Sep 23, 2016 4:48 pm

[SOLVED]

turns out I was missing the proper modprobe sequence :(
and probably the proper dtbo which is stored in:
output/images/rpi-firmware/overlays/pitft28-capacitive.dtbo

here are the modules needed:

Code: Select all

# Init adafruit 2.8 tft touchscreen
modprobe i2c_bcm2708
modprobe i2c-dev
modprobe ft6236
This creates /dev/input/mouse0.
Also ft6206 and ft6236 are compatible (same?) drivers. Apparently ft6236 will be removed in kernel 4.9 since it was already implemented in edt-ft5x06

msamiullah
Posts: 2
Joined: Sun Mar 12, 2017 5:54 pm

Re: Help with Buildroot and Adafruit TFT 2.8 CapTouch

Sun Mar 12, 2017 5:57 pm

I am looking for the same image the only diference is that I am running 2.2inch tft. Is it possible if you could share buildroot image or let me know what libraries you used. I only need access to mounting usb drives and tft screen,

thanks

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