I had a chance to play with the frame buffer today after remembering this conversation.

I am finding the issue with the small text/garbidge written to the screen that you shared and looking into it.

Thanks for the point out.

@prima I tried your suggestion but I can't really get it to work.

With the method I outlined the terminal works fine, but the keyboard input (USB keyboard) is not so reliable. It stop registering keystrokes after a short period. Not sure if the keyboard input get redirected to another terminal in the background or something.

FRAMEBUFFER=/dev/fb1 <some command>

Anyway, here are my notes

Showing a terminal on the LCD TFT display

Very briefly:

• The CoreMP135 contains a ILITEK ILI9342C LCD TFT display with touch
• The Debian OS recognizes as the display as a framebuffer and makes it accesible at /dev/fb1
• Low level interaction directly with fb1 is below, see examples below. In all the included examples, I was signed in as root via the USB-C interface (ttyGS0)

# signed in as root
cat /dev/zero > /dev/fb1 # clear display
cat /dev/urandom > /dev/fb1 # show random 'static' on display
echo "HELLO WORLD" > /dev/fb1 # will show some extremely small in the top left corner - not discernible

• The M5Stack CoreMP135 Debian image includes fbv - a program for rendering .jpg on the framebuffer (TFT LCD). Example:

# signed in as root
. /usr/local/m5stack/bashrc # prepare environment for using fbv
/usr/local/m5stack/bin/fbv /root/mycoolpic.jpg # display .jpg on framebuffer, might only show part depending on jpg resolution

• It is also possible to show a (somewhat) fully functional terminal on the TFT LCD display using the fbterm program:

# signed in as root
apt install fbterm # install FbTerm
export FRAMEBUFFER=/dev/fb1 # Tell FbTerm to use fb1 as framebuffer
fbterm -s 12 < /dev/tty1 & # Tell fbterm to diplay tty1 terminal on fb1 with size 12. 

• Connect a BT keyboard or similar and enjoy a somewhat functional terminal
• One final note: I added root to the video group, although this should not be required.
  

Yesterday, I tried a to use the fbterm because it is included in the Debian repo (easy to install with apt), but I unfortutaly I could not get it work.

I have been looking for fbcon in the buildroot configuration menu but I have not been able to find it so far. But I have noticed that buildroot under kernel extensions include an optoin to compile FB TFT drivers. I will try and recompile with the FB TFT drivers tonight.

I will post updates here.

The CoreMP135 is a cool little device, but it is not as easy to use as the other M5 controllers.

Have you tried installing FBCon yet?

I think it should be possible to get a terminal on the LCD using the tools provided by the linux distribution. What i gathered from searching on google, is that fbcon can be used to display terminals on framebuffers (such as the ILI9342C). Unfortunately, fbcon is not included in the CoreMP135 Debian image. I am now playing around with the CoreMP135_buildroot repo to see if I can compile it there. I will keep digging.