This is a placeholder topic for “Raspberry Pi Compute Module 5” comments.
The newly released Raspberry Pi Compute Module 5 comes with 32 different configurations to choose from, giving you ultimate flexibility when choosing your CM board.
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This is a product I don’t fully understand.
I like the form factor and the price.
Very rarely do I need the full array of IO like you find on the pi4b or pi5.
This thing appeals to me because it looks I might be able to select my IO depending on my project. Is that right?
How would I get IO into this thing? I can’t see much detail on the back but it looks like it’s got PCI Express ports… for ram? Maybe I can use those as custom IO?
Can anyone shed some light as to what I am looking at and how it fits into maker style projects?
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Hi Pix,
The compute modules are wild boards, usually to access the pins you’d use an IO board like this one for the Compute Module 4. To get the most out of it you’d use one of these boards.
I wouldn’t say these are more friendly to work with than your standard Pi. There is plenty of documentation on how to use these so you can get exactly what you want out of but for most makers the standard Pi will be the better option.
The PCIE slots are for additional RAM so you can get these fast, I’ve seen that this may be the top contender for the Pi that can replace a desktop with this being listed as a big reason.
Jeff Geerling recently put out his video for the CM5 and an article, I recommend that you have a look at these because he’ll be much more over it than I am.
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Jeff is pretty cool but he seems more interested in specs than actually making something with it.
It seems like the correct way to interface with this is through printing custom PCBs?
Do I understand?
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There are a few different IO boards that were released by different companies for the CM4. I think you’ll get the most out of it with a custom board however. It’s a chance to dive a bit deeper into PCB design.
The amount of documentation available for the compute module will hopefully set you up to do what you are after properly. There’s a bit about on Raspberry Pi’s site.
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Hi Jonny!
The connectors on the back are called mezzanine connectors - all of the IO from the B models are exposed without any interface IC’s.
i.e. on the Pi 4 instead of a USB socket, you get one layer back - another PCIe lane.
For the Pi 5, you do get access to the RP1 pin controller so you get the same I2C, SPI… pins that come with a model B.
The datasheet is comprehensive on what pins are available: https://datasheets.raspberrypi.com/cm5/cm5-datasheet.pdf
But the short if it is - you get to create an SBC without having to do really fun routing like RAM., a staged power up sequence or a lot of the other low level functions that a chip like the Broadcom SoC require.
The compute module line, I would say is borderline for Makers, a majority might stumble across a carrier board that suits there needs or they are interested in trying something more industrial (which is the main use-case)
Yeah pretty much - if you are keen on the dive, this document: https://datasheets.raspberrypi.com/cm5/cm5-datasheet.pdf
Along with the IO board https://datasheets.raspberrypi.com/cm5/cm5io-datasheet.pdf
Are a good reference for what you can do
https://www.raspberrypi.com/documentation/computers/compute-module.html#specifications
Liam
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You asked the very question I was thinking. Thanks!
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I’ll do anything for a cute form factor. 
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