@ajb2k3 OK, I figured it out using FbTerm, see my notes below. Just a note to temper expectations: The device is not very powerful (surprise). In my case, I am running Debian, connected to two tty terminals (ttyGS0 over USB-C and tty1 being shown in display), connected over WiFi dongle, and added a BT dongle for keyboard/mouse, and as a result the CoreMP135 very easily becomes sluggish and quite warm.

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.
  

@ajb2k3 no problem my friend

@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.

@ajb2k3 OK, I figured it out using FbTerm, see my notes below. Just a note to temper expectations: The device is not very powerful (surprise). In my case, I am running Debian, connected to two tty terminals (ttyGS0 over USB-C and tty1 being shown in display), connected over WiFi dongle, and added a BT dongle for keyboard/mouse, and as a result the CoreMP135 very easily becomes sluggish and quite warm.

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.
  

Hi @ajb2k3 , ok that makes sense, no problem.

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.

@ajb2k3 thanks for confirming. It not so clear from the provided schematic.

Do you know which pin on the AXP is providing boosted 5V? If I had to guess, I would say it is 'IPSOUT' but it is not so clear to me from the Schematic nor the AXP datasheet.

Do you know the part number of the IC noted 'DCDC' in screenshot below?

Thanks

Hi @Kabron
You can find the M5StickC documentation here https://docs.m5stack.com/en/core/m5stickc
I agree that the provided schematics leaves a lot of room for improvement.

Just to comment on your question. As far as I know and can see, the stickC does not include a boost functionality. It uses a uses the AXP192 as PMU. You can find the AXP datasheet here https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/docs/datasheet/core/AXP192_datasheet_en.pdf . The AXP has 3 channels for step down voltage regulation. But as far as I can see the stickC is only using 1 of them to supply 3.3V (VESP_3V3).

What voltage are seeing on the groove 5V pin when running on battery?

Hi @ajb2k3 can you elaborate?

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.

Hi,

I am running a CoreMP135 with the M5 debian image (kernel 5.15). I am interacting with the device over USB-C / serial tty. How can I show the tty terminal on the buildin display? If connect an external monitor via hdmi it will directly show a tty terminal on the external monitor, can i get the same output on the ILI9342C LCD?

Thanks