What Is a Raspberry Pi Compute Module? Simply Explained

Occasionally, you might hear a news story about the Raspberry Pi Compute Module (CM) and wonder: What is the Pi Compute Module? Can I use it for my own projects? In this post, I’ll be answering these questions and more to satisfy your curiosity.

The Raspberry Pi Compute Module is a Raspberry Pi with a more compact form factor. The Pi CM is a fully customizable System-on-Module (SoM) for embedded applications.

There’s more to this little powerhouse than its size—read on, and I’ll explain why companies have been ordering thousands of these compute modules at a time.

If you’re feeling lost in all the Raspberry Pi jargon, I’ve got something to help you out. I’ve created a free glossary that explains all the essential terms and abbreviations in a way that’s easy to understand. It’s a great resource to have by your side. Get your free copy here.

Raspberry Pi Compute Module vs. Standard Models

What’s the difference between a regular Raspberry Pi and a Raspberry Pi Compute Module? An oversimplified explanation is that the Raspberry Pi CM looks like a smaller Pi with all of its ports and connectors removed.

It’s easier to understand when compared to a standard Pi model. That’s because Compute Modules numbered similarly to the standard Pis both use the same base hardware. Let’s compare a Raspberry Pi CM 4 with a regular Pi 4B:

	Raspberry Pi 4B	Raspberry Pi Compute Module 4
Dimensions	88mm x 56mm x 19.5mm	55mm x 40mm x 4.7mm
CPU	Cortex-A72 64-bit @ 1.5 GHz (quad-core)	Cortex-A72 64-bit @ 1.5 GHz (quad-core)
Memory	2GB / 4GB / 8GB	1GB / 2GB / 4GB / 8GB
Storage	Your choice of capacity: SD card / SSD / USB flash	On-board eMMC Flash: 0GB / 8GB / 16GB / 32GB
Graphics	H.265 (4kp60) H264 (1080p60) OpenGL ES 3.1, Vulkan 1.0	H.265 (4kp60) H264 (1080p60) OpenGL ES 3.1, Vulkan 1.0
Wi-Fi / Bluetooth	Wi-Fi b/g/n/ac: included Bluetooth 5.0: included	Wi-Fi b/g/n/ac: optional Bluetooth 5.0: optional
Retail Price	Starting at $30	Starting at $35

On the surface, their core specs seem almost identical. The biggest differences are actually found on the Compute Module’s board interface:

• Standalone: The Pi Compute Module cannot function without a carrier board.
• Ports: None, so no USB, HDMI, Ethernet, etc.
• Storage: None (or on-board via eMMC Flash).
• Power: 5V expansion header instead of a USB power supply.
• PCIe Support: PCIe Gen2 x 1-lane. There’s no PCIe connector, however, so you’ll need a carrier board to access it. (A PCIe connector didn’t appear on standard Pi models until the Pi 5.)

The key difference is the first point. Unlike a standard Raspberry Pi which works as a stand-alone computer, the Raspberry Pi Compute Module needs a carrier board to function.

That’s because the entire purpose of the Raspberry Pi Compute Module is to be able to supply your own carrier board—AKA, a printed circuit board (PCB). You can design a custom PCB to perform specialized tasks while harnessing the Pi’s incredible versatility and famed robustness.

What Can Be Built With a Raspberry Pi Compute Module?

Now that you understand the purpose of a Raspberry Pi Compute Module and its hardware, what can a Pi CM be used to make?

Industrial Applications

The Raspberry Pi CM shines for industrial applications. It has many surprising uses across wildly different scenarios. For example, the Pi Compute Module may be used to create:

• Embedded systems
• IoT devices
• Thin clients
• Digital signs
• Industrial controllers
• Home automation hubs

https://www.youtube.com/watch?v=OQi0gQfNQ1A

Why might a company prefer using a Pi Compute Module for its product designs over a regular Raspberry Pi?

• Custom application: You can make your carrier board perform anything you need your product to do.
• Special I/O needs: Since you’re providing a custom PCB, you can add any connectors you need. For example, you can add dual gigabit Ethernet or a special interface that connects to your factory crushing machine.
• Smaller form factor: The Pi Compute Module is smaller and flatter than a regular Pi, which is always an advantage when developing embedded systems or IoT devices.
  (Related: Getting Started with Apertis on Raspberry Pi)
• Lower cost at scale: The Pi Compute Module costs only a little less than an equivalent Raspberry Pi model with the same specs. But when you factor in not having to buy separate micro SD cards and volume discounts across thousands of units, the savings add up.

Consumer Applications

Okay, so the Raspberry Pi Compute Module is a champ for industrial applications. But what about consumer usage? The truth is the Pi Compute Module is not meant for personal use—mainstream users don’t normally have access to custom-printed PCBs. I know I don’t.

Maybe some of you savvy readers out there know how to get your hands on custom PCBs. If so, here are some personal projects you could try with a Raspberry Pi Compute Module:

• Assemble a cool cyberdeck or other handheld device.
• Build your own robot.
• Create a rack-mountable server blade.
• Design a super router or NAS from the ground up.
• Experiment with hardware design and embedded systems.
• Learn to program for special applications, since the Compute Module uses the same processor and OS as a regular Raspberry Pi.

If you have an idea for a new invention, the Pi Compute Module could be great for prototyping your design before you begin mass production. Who knows, maybe your products might even become popular consumer accessories.

Getting Started With a Raspberry Pi Compute Module

As mentioned, the Raspberry Pi Compute Module cannot run as a stand-alone device. If you’re prototyping with a Pi CM, you have to provide the rest of the hardware solution.

At a minimum, you’ll need these:

• Carrier board: The PCB holds the Pi Compute Module and provides connectivity options for your specific application.
• Power supply: You’ll want to supply at least 5V and 1A, but the power requirements can be much higher and will depend entirely on your PCB and application.
• Software: You could use Raspberry Pi OS Lite, but you can also choose from the many operating systems that run on Pi hardware.
• Enclosure: You don’t want your Pi Compute Module exposed to the elements, so you’ll need to design an enclosure of some sort to hold all the internals.

The rest is up to your imagination. For example, your design might include extras such as:

• LED displays
• Robotic arms
• Laser detectors

If you’re in the prototyping phase, the Raspberry Pi Foundation sells reference boards you can use to test your designs. The CM 4 IO Board works with a Pi CM 4 and provides many connectivity options. The Raspberry Pi Development Kit for Compute Module 5 comes fully loaded with everything you might need: CM 5, IO Board, enclosure, an antenna kit, and more.

https://youtu.be/myAAn-XiG-0

As you can see, the Raspberry Pi Compute Module is best for industrial applications and not for home use. But if you’ve got an idea for a product that takes advantage of the Pi CM, I look forward to seeing your invention on store shelves in the future!

Whenever you’re ready, here are other ways I can help you:

Test Your Raspberry Pi Level (Free): Not sure why everything takes so long on your Raspberry Pi? Take this free 3-minute assessment and see what’s causing the problems.

The RaspberryTips Community: Need help or want to discuss your Raspberry Pi projects with others who actually get it? Join the RaspberryTips Community and get access to private forums, exclusive lessons, and direct help (try it for just $1).

Master your Raspberry Pi in 30 days: If you are looking for the best tips to become an expert on Raspberry Pi, this book is for you. Learn useful Linux skills and practice multiple projects with step-by-step guides.

Master Python on Raspberry Pi: Create, understand, and improve any Python script for your Raspberry Pi. Learn the essentials step-by-step without losing time understanding useless concepts.

You can also find all my recommendations for tools and hardware on this page.