CM3-Panel-7-basic technical documentation Buy
Prepare a microSD card image for CM3-panel-7-basic
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 October 20th 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
RaspiOS bullseye 2021-10-30 notes
Inside the file config.txt, change this line:
dtoverlay=vc4-kms-v3d
in:
dtoverlay=vc4-fkms-v3d
and:
max_framebuffers=2
in
#max_framebuffers=2
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
In case the touch screen or raspicam freeze after a system upgrade (sudo apt upgrade) take care to these lines inside the /boot/config.txt file:
# 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
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
Systems designer, webmaster of www.acmesystems.it and founder of Acme Systems srl
Personal email: tanzilli@acmesystems.it
Web pages: https://www.acmesystems.it --- https://www.acmestudio.it
Github repositories: https://github.com/tanzilli --- https://github.com/acmesystems
Telegram group dedicated to the Acme Systems boards: https://t.me/acmesystemssrl
