Raspberry Pi Compute Module 4S

Table of contents

Happy Birthday

I didn’t want to write a blog about the first 12 months of my website, but RASPICED celebrated its first birthday.
Thanks to all my readers, maybe there are one or two out there!

Raspberry Pi Compute Module 4S

Early this month the manufacturers of the Revolution Pi1 dropped an information about an upcoming new product RevPi S/SE series2, which contains a new Raspberry Pi Compute Module, called 4S.

If you see this, the image is broken :(

Since Revolution Pi produces industrial grade SPS, they use Compute Modules instead of the normal RPi boards, so their systems always have a SO-DIMM connector. The normal CM4 doesn’t have a SO-DIMM connector any more, they now have the two Hirose connectors on the buttom.
In order to get the better hardware into older CM-based systems, you had to use adapter boards like Gumstix’s Raspberry Pi CM4 Uprev.3

With the Compute Module 4S, Raspberry Pi none of these adapters are necessary any more. You get native compatibility, which is great.
So the CM4S will be a drop-in replacement for the industry, which embedded boards are widely spread and not easily changeable, only because the form factor of the CM changed.

Even in my daily job, I hope to see some of them. Some extra power is always appreciated.


The first glimpses of the CM4S were seen in December 2021 on the official GitHub repositories.4

I opened a thread on the official Raspberry Pi forums, in order to get some information about this new Compute Module, I never heard of before.5
It quickly became apparent that, that the CM4S could be a CM4 with SO-DIMM connector. They were right.

After revealing the CM4S Jeff Geerling wrote a blog about the new module and asked an important question: Will the new CM4S available to all, or is it an exclusive production for the Revolution Pi company?6
Until now, nobody gave an answer to this question, I guess we have to wait and hope this product will be available to all of us, regardless we are users of a RevPi or not.

Buying the CM4S

Beside the reveal this April, there is no CM4S available to buy, yet.
I asked BerryBase7, my preferred German Raspberry Pi reseller, but they couldn’t provide me a date, when they will be sold.

Since the CM4S isn’t officially announced, I guess we have to wait.

HWBOT Prime Benchmark Script - Version 3.2

I used the revealing of the CM4S for some updates of my HWBOT Prime Benchmark Script.

Change from Gist to Repository

As you know I used GitHub’s Gist for my script.8
In order to get a better release management, I opened a repository and migrated the different versions.9

From now on you can always get the latest version with: wget https://raw.githubusercontent.com/cr-chsn1/raspiced/main/hwbot_prime_benchmark/script/rpi_hwbot.sh

I will also change all the existing links to my Gist, in order you always get the latest version, even if you are reading an older blog.

Check for latest version

Beside the migration to a normal repository, I added a small check, if you are using the latest version of the script.
From version 3.2 onwards the scripts checks, if there is a newer version available. You can download it or continue with the current version.

If you see this, the image is broken :(

In order to get new (or corrected) functions or added support for newer RPi models, always use the latest version of my script.
You can take a look at the commits, what has changed from version to version.10

Added support for CM4S

Since there is no official documentation I assumed that the CM4S will get the next free number for the revision after the CM4, so the code should look like this: a03150
Take it with some caveat. If I can get my hands on a CM4S, I’ll check if my assumptions were correct.


If you see this, the image is broken :(

Update: 27.04.2022 / Version 3.3

Well, I wasn’t happy with the checksum function. So I made it a bit nicer.

If you see this, the image is broken :(

Overclocking (forecast)

Let’s make some predictions about the overclockabilty of the CM4S.
Since it will be based on the BCM2711C0, clocks above 2,000 MHz should be easy to reach. Even 2.5 GHz, with a little bit of extra voltage, will be possible. Nothing fancy, nothing special.

Mounting a cooler could be a little bit tricky, since the SO-DIMM connector is not that sturdy as the Hirose connector from the Compute Module 4.

Something I’ll find out, when I get my hands on one of the CM4S.
As always, I keep you updated.

  1. Revolution Pi ↩︎

  2. Revolution Pi RevPi S/SE series ↩︎

  3. Gumstix Raspberry Pi CM4 Uprev ↩︎

  4. Create bcm2711-rpi-cm4s.dts ↩︎

  5. Raspberry Pi Forum ↩︎

  6. Jeff Geerling: New Raspberry Pi: Compute Module 4S ↩︎

  7. BerryBase ↩︎

  8. HWBOT Prime Benchmark Script @ GitHub’s Gist ↩︎

  9. RASPICED repository on GitHub ↩︎

  10. HWBOT Prime Benchmark Script commits ↩︎