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CM3-Panel-7-basic technical documentation

Make a Raspberry Pi OS microSD for CM3-PANEL

This article explains how to make a standard Raspbian Pi OS MicroSD to use with the CM3-PANEL normal and POE

The CM3-Panel is fully compatible with the Raspberry Pi 3 but maps some the peripherals on different pins. For this reason some files have to be added an some others have to be modified as explained on this guide.

Step-by-step guide

STEP-1 - Download the microSD image

Download and generate a standard Raspberry Pi OS microSD following the official instruction on:

This articles has been verified with Raspberry Pi OS Desktop and Lite version March 4th 2021

Mount the microSD just created on your PC (Linux or Windows) or your Mac. The first microSD partition labeled "boot" is formatted as FAT32 and visible on any system.

These files are to edit using an ASCII editor:

  • config.txt
  • cmdline.txt

and these are files to add:

  • dt-blob.bin
  • overlays/goodix-7-acme.dtbo

STEP-2 - Edit config.txt

Open with a ASCII editor the file config.txt and add these lines at the end of this file.

Do use editors like Nodepad, Nodepad++, Geany, Wrangler or similar, please don't use Word, Libre Office or Pages.

#Ignore the HDMI cable hotplug (to avoid the delay at startup)
hdmi_ignore_hotplug=1

# Set the debug port on GPIO32, GPIO33 pins
force_turbo=1
dtoverlay=uart1,txd1_pin=32,rxd1_pin=33

# Is not requested to insert this line
#enable_uart=1

# Activates the I2C 1 port on GPIO44 and 45 to talk with the
# touch screen controller end camera crypto-chip

# This line is deprecated
# dtoverlay=i2c1-bcm2708,sda1_pin=44,scl1_pin=45,pin_func=6

# Use this instead
dtoverlay=i2c1,pins_44_45

dtoverlay=goodix-7-acme

## Enable the DPI port to talk with the TFT display
dtoverlay=dpi18
overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
framebuffer_width=800
framebuffer_height=480
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x6f005
hdmi_timings=800 0 40 48 88 480 0 13 3 32 0 0 0 60 0 32000000 6

Comment this line to disable the audio section not used on this board

# Enable audio (loads snd_bcm2835)
# dtparam=audio=on

STEP-3 : Edit cmdline.txt

Open cmdline.txt and edit this line to enable the serial debug port:

console=serial0,115200

in:

console=serial1,115200

STEP-4 - Add goodix-7-acme.dtbo overlay blog file

goodix-7-acme.dtbo is used to enable the capacitive touch.

Download and save it in the overlays directory:

If your prefere you can compile it from this source:

To compile it you need a Linux PC or a Raspberry Pi and a Device Tree Compiler:

sudo dtc -@ -I dts -O dtb -o /boot/overlays/goodix-7-acme.dtbo /boot/overlays/goodix-7-acme.dts 

STEP-5 - Add dt-blob.bin blog file

dt-blob.bin defines the Raspberry camera I2C lines used on the CM3-Panel.

Download and save it in the boot directory:

of your prefere you can compile it from this source:

To compile it you need a Linux PC or a Raspberry Pi and a Device Tree Compiler:

sudo dtc -I dts -O dtb -o /boot/dt-blob.bin /boot/dt-blob.dts

STEP-6 - Enable the SSH server

By default the SSH server is disabled on the Rasperry pi OS standard microSD image. To enable it create an empty file called SSH with no extention on the first microSD partition. The ssh server will be enabled at first startup and you can reach the Linux command prompt via lan.

ssh pi@raspberrypi.local
Password: raspberry

STEP-7 - Configure the WiFi access

If you are using a CM3-PANEL model W you can configure the access to your WiFi network by adding in the root directory the file wpa_supplicant.conf with this content

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=IT

network={
    ssid="your access point name"
    psk="your access point password"
}

Change the line country=IT with yout country ISO code

STEP-8 - Boot

Umount the microSD from your PC and boot it on your CM3-Panel

Troubleshootings

Test the Raspberry Pi cam

Enable the camera interface by running the utility:

sudo raspi-config

Select:

3 Interface Options
    P1 Camera
        Would you like the camera interface to be enabled? -> Yes

Reboot and launch this command to see the image captured by the camera on the display

raspivid -o /dev/null -hf -t 0

Type ctlr-c to exit

Sergio Tanzilli
System designer, webmaster and Acme Systems co-founder

Personal email: tanzilli@acmesystems.it
Webpage: https://www.acmesystems.it
Github repositories: https://github.com/tanzilli and https://github.com/acmesystems
Telegram group dedicated to the Acme Systems boards: https://t.me/acmesystemssrl

CM3-Panel-7-basic technical documentation