Create a Raspbian Stretch microSD for the CM3-Panel board

This article explains how to create a standard Raspbian Linux on MicroSD to use with the CM3-Panel.

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

This articles has been verified with Raspbian Strech Desktop and Lite version April and June 2018

Step-by-step guide

Create a standard microSD following the official instruction on:

Mount the MicroSD just created on your PC. The first partition boot is formatted as FAT32 and so is visible on Windown, Mac and Linux PC.

These are the files to changes:

  • config.txt
  • cmdline.txt

and these are the files to create:

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

STEP-1 - Edit config.txt

While booting up, the Raspberry Pi reads some configuration parameters from the first partition of MicroSD card.

These parameters are stored in a file called config.txt inside the first microSD partition.

You can edit this configuration from any PC because the first partition is formatted as FAT so it can be read with Mac, Windown or Linux. Use an ASCII editor like Nodepad or similar (please don't use Word :-) and add these lines at the end of this file:

#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
dtoverlay=i2c1-bcm2708,sda1_pin=44,scl1_pin=45,pin_func=6
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-2 : Edit cmdline.txt

The file cmdline.txt contains some parameters passed to the Linux Kernel during the boot. To enable the serial debug port changes:

console=serial0,115200

in:

console=serial1,115200

STEP-3 - Create overlays/goodix-7-acme.dtbo dts overlay blog file

This file is used to enable the capacitive touch.

You can just save this binary file in the overlays directory:

or compile it from this source:

To compile it save the source on the microSD and use the dtc (Device Tree Compiler) on the Raspberry Pi after the boot with this command:

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

STEP-4 - Create overlays/dt-blob.bin dts blog file

This file defines the Raspberry camera I2C lines used on the CM3-Panel.

You can just save this binary in the microSD:

or compile it from the sourse:

To command to use is:

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

To use the camera enable is using the utility:

sudo raspi-config

STEP-5 - Enable the SSH server

By default the SSH server is disabled on the Raspbian microsd images. 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

How to test the camera

sudo apt-get update
sudo apt-get install python-picamera

Save this python example in grab.py

from picamera import PiCamera
from time import sleep

camera = PiCamera()

camera.start_preview()
sleep(10)
camera.stop_preview()   

and run it by typing:

python grab.py

Sergio Tanzilli
System designer, software developer and company co-founder
tanzilli@acmesystems.it
Webpages: https://www.acmesystems.it and http://www.tanzolab.it
Github repository: https://github.com/tanzilli and https://github.com/acmesystems

EUR 20.00


R-LITE-8G-E - MicroSD with Raspbian Stretch Lite - April 2018

Ready to use microSD with preinstalled Raspbian Stretch Lite - April 2018 already configured to work with the CM3-Panel

  • SanDisk 8GB Industrial grade microSD
  • Class 10 HC
  • Temperature range: -25° to +85°

Please note that this card contains Open Source code under GPL license and you are buying just the memory card not the software on it. Any rights to this software or support are not included.

EUR 20.00


R-DESK-8G-E - MicroSD with Raspbian Stretch Desktop - April 2018

Ready to use microSD with preinstalled Raspbian Stretch Desktop - April 2018 already configured to work with the CM3-Panel

  • SanDisk 8GB Industrial grade microSD
  • Class 10 HC
  • Temperature range: -25° to +85°

Please note that this card contains Open Source code under GPL license and you are buying just the memory card not the software on it. Any rights to this software or support are not included.

| CM3-Panel |