How to install an OS on Raspberry Pi CM4 eMMC

For use with Home Assistant Yellow – The Hard Way – macOS/Linux Edition

Video Guide:

https://youtu.be/gyn2xUCV9tw

Table of Contents

• Preface
• Pre-Requisites
• Preparing the I/O Board
• Installing Software Dependencies
• Downloading the Raspberry Pi Foundation’s usbboot tool
• Building the usbboot tool
• mounting the eMMC Storage
• Flashing an OS onto the eMMC
• Summary

Preface

When you buy a Raspberry Pi Compute Module 4, with eMMC storage there’s no Operating System on the board at all, and being that the eMMC is soldered to the board, it’s not like we can easily take it out and flash an image to it like we can with the micro-SD cards from a Regular Raspberry Pi.

There’s a number of steps and pre-requisites to prepare a CM4 for booting. This process works for installing ANY image on the CM4, not just for Home Assistant.

Preparing the I/O Board

There’s a few steps to prepare the I/O Board before we can flash an OS onto the eMMC storage.

Installing some Software dependencies

We need to install some Software dependencies before we can mount the eMMC storage. We’ll be using the Raspberry Pi Foundation’s usbboot tool

To do this, on macOS you’ll need to have homebrew and git command line tools installed per the Software Pre-Requisites above

libusb

libusb is essentially a USB “driver” that will allow us to mount the eMMC storage.

To install libusb, provided you’ve got Homebrew installed on your Mac, simply run:

brew install libusb

if you’re on Linux, use your regular package manager, like apt.
Example:

sudo apt install git libusb-1.0-0-dev pkg-config

pkg-config

Another dependency for the usb-boot tool from the Raspberry Pi Foundation is pkg-config

Like with libusb, it’s fairly simple to install”

brew install pkg-config

again for Linux, use your regular package manager

Downloading the Raspberry Pi foundation usbboot tool.

In order to mount the eMMC storage, we’ll need to download and build the Raspberry Pi Foundation’s usbboot tool.

from your command line, change into a working directory, and then run

git clone --depth=1 https://github.com/raspberrypi/usbboot

Once that’s completed cloning cd into the usbboot directory:

cd usbboot

Building the usbboot tool

Now we need to build the usbboot tool

The Raspberry Pi Foundation have made this really simple with a Makefile
Simply run:

make

After about a minute, the build will be completed, and you’ll notice some new files in the folder.

Mounting the eMMC Storage

To mount the eMMC Storage, we need to plug in the microSD cable to the I/O board, power up the I/O board, and then we need to run the usbboot tool

./rpiboot

and after a moment, the eMMC Storage will be mounted, and available for flashing.

Flashing the OS onto the Storage

The rest of the flashing process is the same as a regular SD card.

Using Raspberry Pi Imager, or your favourite card flashing utility, simply select the “RPi-MSD-001” storage option and then write the image to the storage.

Summary

As you can see, there’s a few steps to preparing a CM4 for imaging. If you’re not comfortable using the Command Line, then this is probably not the process for you.

There’s a MUCH easier way to get Home Assistant installed onto a CM4 to use with Home Assistant Yellow.

That said, this process works with ANY Raspberry Pi Image, not just Home Assistant, so it has the added advantage of being more universally functional.