The CANOPi contains a VIA VL805 4 Port USB controller, just like a "normal" Raspbbery Pi 4. This USB controller needs some firmware loaded up during system initialization, before Linux boots.
As a vanilla CM4 does not contain this USB controller, it will not do that. Therefore we need to update the EEPROM on board the CM4. Normally you only need to do this once for any new CM4, the changes will survice reinstalling or changing the operating system, as long as you do not update the EEPROM again.
The procedure desrcribed here involves a second Raspberry Pi (any will do) with a second SD-card.
Prepare two SD-cards with the most recent version of Raspberry Pi OS (at least the release of Oct 5th 2021). One card is designated to be used for the CM4 in the CANOPi OBD dongle. Insert the first card into a Raspberry Pi (any Pi will do - there, you have support for keyboard and mouse) and type
sudo nano /boot/config.txt
And add the following lines
enable_uart=1
dtoverlay=dwc2,dr_mode=host
Press Ctrl-X to leave the editor and choose to save your changes.
Then type
sudo nano /etc/default/rpi-eeprom-update
And change it to include these lines
FIRMWARE_RELEASE_STATUS="stable"
CM4_ENABLE_RPI_EEPROM_UPDATE=1
Again, press Ctrl-X and choose to save cahnges.
Now, insert this SD card into the CANOPi dongle. That is, the first SD card now moved from the Pi to the CANOPi. Put the CANOPi to the side. We will need it later.
Proceed to the second SD card and insert it into the Raspberry Pi and boot it.
Make sure the Pi has Internet access and type
sudo apt install git libusb-1.0-0-dev build-essential
Next install usbboot
git clone --depth=1 https://github.com/raspberrypi/usbboot
cd usbboot
make
Remove the pieeprom.original and replace with the one to flash. Navigate to and remove the original file by typing
cd ~/usbboot/recovery
rm -f pieeprom.original.bin
Download a recent stable eeprom from https://github.com/raspberrypi/rpi-eeprom/raw/master/firmware/stable/, for example
curl -L -o pieeprom.original.bin https://github.com/raspberrypi/rpi-eeprom/raw/master/firmware/stable/pieeprom-2022-04-26.bin
Edit the boot.conf file to support the VL805 USB controller and configure proper poweroff behavior for CANOPi. Therefore, type
sudo nano ~/usbboot/recovery/boot.conf
And modify it to include the following lines
WAKE_ON_GPIO=0
POWER_OFF_ON_HALT=1
VL805=1
Press Ctrl-X and save.
Now update pieeprom.bin with the configuration in boot.conf by typing (still in ~/usbboot/recovery/)
sudo ./update-pieeprom.sh
Now prepare to flash the target by typing
cd ~/usbboot
sudo ./rpiboot -d recovery
Live the Pi. Now turn you attention back to the CANOPi.
Fit a jumper on nRPIREBO and GND. You can find the pin header on the top board. see the following picture for reference
Fit a CM4. If you have followed this fine manual, the first SD card is still inserted.
Now, connect one USB port from the Raspberry Pi to the microUSB port of the CANOPi dongle. Power on the CANOPi dongle and the flash process should initiate. A regular blinking pattern of the green LED or, in case a screen is connected, an entirely green screen indicates a finished and successful flash procedure.
Now, power off CANOPi dongle, remove the jumper and power the board back on. The CANOPi dongle should boot normally and, once the CM4 is started, USB devices should be fully supported by the dongle.