CM0 – A new Raspberry Pi you can't buy | Hacker News Reader

CM0 – A new Raspberry Pi you can't buy

jeffgeerling.com

211 pointsspeckx64 comments

geerlingguy and simonw really amaze me at how well and consistently they cover their respective spaces of interest. Great content, easy to read, and thorough! I'm sure there are others doing deep reporting like this on their own subjects. I'd love to read them too.

Jean-Louis Gassée's Monday Notes about tech and Apple. He's been in the business since the 60's, worked at Apple in the 80's, founded BeOS: https://mondaynote.com/

Raymond Chen's The Old New Thing. He's an engineer at Microsoft that has been blogging about maintaining legacy systems, Windows and MS-DOS for over 2 decades. https://devblogs.microsoft.com/oldnewthing/

Hackaday is a good blog too, there's many authors so it can be hit or miss but it's full of curious folks. https://hackaday.com/

I miss Gassée's the Monday Note, it seems he hasn't published one since 2023.

Want me to show you on the doll where he hurt me?

Who is simonw?

https://simonwillison.net/about/

famous pelican enthusiast

A Pelican fond of Cycling.

Looks like you can buy one through the usual suspect - https://www.aliexpress.us/item/3256810106029551.html

God bless aliexpress

So it could be possible to make a small portable screen device with this, or maybe not because (I think) the RPI is not optimized to work on a battery.

I would prefer a touchscreen with it.

I am not talking about a smartphone, because smartphones are often more powerful, more expensive. I would just prefer a device to do simple computing, with full access to the OS.

Smartphones tend to have android and powerful hardware, and a 4G or 5G antenna. I would just be happy with wifi and enough power to run some C or python code.

I am just curious what is the cheapest screen device that is possible to make with this, as long as it has wifi, a touch screen and be completely open. So far RPI is nice, but it's not really what I want.

You buy any cheap Android phone and run Termux on it.

If you’re looking at something with a screen, the ESP32 ecosystem has tons of options. Look up Waveshare and Elegoo ESP32 modules.

You know the fun thing is, something like the Allwinner A133 - which is one of the most popular SOCs in lower-end tablets today - is like $5, or $3 in quantity.

It turns out it's actually not as hard as you'd expect to whip together your own board with one of those + LPDDR4 RAM + eMMC storage + fixings, and get yourself something like what you're talking about for... I dunno, sub $50? Maybe even sub $20 depending on how much RAM you put on it and what other capabilities you give it.

I'm in the middle of designing just such a board right now. Totally recommend taking a stab at it if you have any EE chops at all (or want to learn!)

Interesting. I'm currently having great fun learning systems programming on the Allwinner A64, and never considered the option of building a board with one, assuming they are still available. Are you documentating your project somewhere?

I'm not but I totally could!

Feel free to drop me a line - my email is firstname@website, where both can be found on my GitHub profile (same username as HN).

And yes, the A64 is still available! https://www.lcsc.com/product-detail/C3036453.html

Lets just go with $50 and $20. If you're looking at that on top of the cost of a raspberry pi, comparing that to a super low-end Android phone, used, for something like $80-$100, is that really the way to go? The OS is different but termux has enough features, especially after rooting, that you can probably run whatever you're shooting for. Of course as a hobby, the parts that you find fun don't have to be the parts that I, or anyone else finds fun, so don't take this as me pissing in your cereal, it's more like there's the milk part and the cornflake part and so different strokes for different folks.

Maybe you’ll find a “cheap yellow display” interesting https://github.com/witnessmenow/ESP32-Cheap-Yellow-Display

It has a display, WiFi, Bluetooth and you can write whatever software you want for it.

It’s based on an ESP32, which is a microcontroller not a full computer like a raspberry pi

The "Cheap Yellow Display" was one of my favorite discoveries this year, it's now just my default choice for any micro-controller based project with a small display most of the time.

Funny enough, seeing all types of different suggestions under the sun here in the sibling posts; it's also unsurprising, since I myself can't tell where the gap is between what the Pi offers vs. what you're hoping for, as that would have been the first thing I suggested.

In addition to all the other suggestions, you might look at PINE64's offerings. Maybe one of their tablets, their PinePhone, or one of their SBCs or SOCs.

Some of the gaming handhelds that have mainline Linux support might be the ticket.

Ah, and the Vivid Unit: https://www.vividunit.com/Main_Page

Unfortunate name, as "CM0" is a common abbreviation for the ARM Cortex-M0 core.

Browsing the web on here is almost completely out of the question, since it only has 512 Megs of RAM

How far we have fallen... a quadcore 1GHz CPU and 512MB of RAM seems like ample computing power for those who have been very productive on PCs with far less.

I didn't know that castellated holes on a PCB were to facilitate SMT.

Sure makes it look like a stamp though… ;-)

Castellations also enable use in a "burning fixture" like the below. The fixture has bent pins that hold the PCB physically and connect electrically to the PCB's leads.

https://www.amazon.com/DIYmall-ESP32-WROOM-32-Programming-Fi...

Would love to see someone design a PLCC or IC Socket that would let you slide one of these in (like those old sockets they had in Macs for optional FPU chips).

I just looked that up and it seems like a nice system (although physically complex/costly to manufacture) [0]. The only FPU-optional Mac I had was a IIsi which had an optional FPU that used the Nubus slot.

0. https://www.worthpoint.com/worthopedia/macintosh-color-class...

"But unlike all the other Compute Modules, the CM0 has castellated edges like a Pico. That way, a company integrating this into their product can just pick and place it and solder it onto their main PCB, instead of working with more delicate board-to-board connectors."

But wasn't the board-to-board slide-in connection the whole point with other CM models?

Not sure why you're being downvoted. This is a reasonable question.

From my discussions with Raspberry Pi, and with a few companies who integrated CM4/5 into their products, the board to board connectors were a massive pain to automate in a production line (not necessarily soldering the connectors, but in inserting Compute Modules.

It's surprising how good human fingers can be at getting the alignment, the push, and the slight 'pop' and the feedback required to know when it's seated properly.

That, mixed with requiring extra standoffs and screws to secure the CM to boards for any kind of vibration/mobile use cases probably informed the decision to go to castellated / solder-on.

It's not as friendly for quick swaps or upgrades, but it also reduces the total board height when it's all put together.

I wonder how robust the solder joints are for castellated boards. I’d still imagine that to be a weak point vibration-wise. Definitely easier to automate, but would it be that much more robust?

Thinking about those CM sockets and I think the answer is yes - a castellated solder joint (is that the right term?) would be stronger. But other sockets might be more robust than the CM0.

at a previous job we went with the previous generation SODIMM CMs for this reason. they didn't honor their stocking pledges though. typical broadcom things

I it would be great if some company put these into a small 7in tablet. Thats a very underserved form factor in the maker space.

For the modern web it isn’t fast enough. Thank the JavaScript slingers for that.

For sure, I hear you

I just want affordable, linux-powered displays in a slim tablet form factor. Performance and battery life are not a priority for my use case

Unfortunately I feel anything sold as a tablet comes with the assumption that it needs to compete with an iPad and be used for content consumption and gaming.

Ive seen raspberry pi kits sold that do just about everything else but this.

These use a very old and SoC and only 512MB of LPDDR2.

Using this for a tablet would be a very disappointing and slow experience. There are many better SoCs to use. If someone was set on using a Raspberry Pi, the full size compute modules would be a much better choice.

These are for embedding in very simple devices. You wouldn’t want to use it for anything like web browsing or trying to run a modern GUI app.

Thanks, yeah I understand their poor performance and energy efficiency for use in a tablet for content consumption or gaming.

And I am guessing that a part of the reason for a lack of any such RaspPi tablets is that marketing such a tablet would come with the need to negatively differentiate it from any similarly priced android tablet.

However I can think of many use cases, mainly for folks in the maker space, that are not content consumption or gaming or long battery life. I am thinking of dashboards or smart home control panels.

Right now I have a few raspi4s mounted on the back of an official touchscreen encased in an adjustable plastic stand. Been working great for years, but the size is clunky and processing power is more than what I need it for, which is just displaying a web page with some information and buttons.

Would love a thin display to mount on a wall near a door or have others lying flat on a table next to a beside or couch. Basically always plugged in but with an included battery for the odd moment when I need to carry it somewhere.

So many other uses i could think of.

Ive looked at Amazon Fire tablets, but the locked-down android and really android of any kind is just not something I am interested in.

Ive seen raspberry pis used for just about everything else but not this

> which is just displaying a web page with some information and buttons.

If all the device needs to be is a dumb terminal locked to displaying a web page, it's really hard to beat the value proposition of modding a dirt cheap Amazon/Android tablet. Most Pi home-built solutions with an addon touchscreen, battery etc will be less elegant solutions that cost more a lot of the time.

Locking a cheap android tablet to a single page is super common in home-brew home automation builds etc, even in builds where Pis are used. You can trivially turn a great many Amazon tablets into home automation dash/remotes/web kiosks.

> but the locked-down android and really android of any kind is just not something I am interested in.

When all you want is the browser, Android is as good a place to start as virtually any other on a device like this.

Thanks, that’s good advice

I have a fire tablet that I’ve tried that with, but for various reasons I prefer to have Linux on all the things. As a long time Android phone user Android still gives me an irrational ick, non-standard android even more so.

Ideally all my home devices would controlled and managed by the same underlying OS and tooling

I have to stop being such a prude, it just frustrates me that after so many years I can’t buy a cheap Linux tablet

> I can’t buy a cheap Linux tablet

much better, you can make one yourself! and considering touch displays out there (Waveshare have nice ones) already have supports to hook up your pi without much CAD tinkering, it's all about making a case and developing your system for a battery (which also are quite popular and have already made solutions). if we stop being prudes all we get is Jeff and Jobs locked devices! take a look at the cyber-deck scene on Reddit

There’s a plethora of old phones and tablets you can purchase on the cheap ($50-$100) and install Linux. They are all faster then rpi0

I have ordered RP2040 chips on custom boards before from JLCPCB. Could you do the same for the compute mods?

Those boards have a lot more on the board than just the cpu. At a minimum they have power conditioning and ram, usually also storage. A lot of what you pay for with an sbc is that routing and layout. If it’s got WiFi as well, you could be paying for the testing that goes into rf micro strips and potentially certifications on em emissions.

It is, of course possible to do all that yourself, but the system on module exists, because this integration has value that people are willing to pay for.

Got it. I was more responding to the idea that you can’t get the modules outside of China when you can simply have them made via JLCPCB.

Ah I see. I guess if the design files are available that might be possible. Not sure about component availability though. I don’t remember for sure, but I thought there was something custom about the Broadcom Soc they were using, although that might have been for a different model.

Where was this when when I was integrating an rPi0-2W into what was once an Avegant Glyph? [project inspired by https://youtu.be/RQeOm3CuUFY]

- gerlingguy says no HDMI chip (sigh), ah well... where's my Subpac?

Does anyone understand why RPi decided to make this China only?

Possibly for the same reasons there is no equivalent to JLCPCB outside China.

OSH Park, Aisler, Eurocircuits, DKRed?

It seems to be more that they are simultaneously launching and killing the product.

Sounds like they entered into a contact to develop and sell the CM0 to several large manufacturers who happen to all be in China, hence the launch. But then discovered the supply of ram chips that it uses is extremely low (they apparently stopped manufacturing them years ago) and they want to direct as many of them as possible towards the Pi Zero 2.

So we will probably see a follow up to both later, and the CM0-B (or whatever they call it) will be more widely available.

But they obviously knew the RAM was EoL since they already use it in the zero 2. It would be monumentally incompetent for either party to not know this so there must be a plan.

Perhaps these RAM chips are more readily available in China through some means. There are companies that will extend the lifetime of a product if you can get them the design, we've used it for niche (expensive) RAMs. Surprised that would be worth it for something at the low end. Maybe they just have a huge pile of them in China.

The 512Mb RAM die actually embedded into the same RP3A0 package as the CPU (it's the exact same CPU die used in the Raspberry Pi 3). So the stock is exactly the same world wide and linked. and I'm pretty sure the RP3A0 chips are packaged outside of China and would need to be shipped in for this.

Besides, China's RAM manufacturing is reasonably new, and only makes DDR4 and LPDDR4, not the older LPDDR2 which the RP3A0 uses.

But yes, they would have known LPDDR2 was EOL. It was EOLed 6 years ago, before they even launched the zero 2 (which they only introduced because the BCM2835 chip used by the original Zero was EOL), so it's not exactly clear why they are launching the CM0 now.

What makes the most sense to me is that they are currently developing a new chip, that will be a more-or-less drop in replacement for the RP3A0. If it's drop-in, then the design work on the CM0 won't be wasted.

Which would give us some clues on what the RP4x chip is, and it's current status (close enough that they know it will arrive before they run out of RP3A0 chips for the Pi Zero 2, but far enough away to bother launching the CM0 now, as long as the supply is limited).

This RP4x chip presumably needs to have low enough power/costs to fit the Pi Zero 3 budget (so quad Cortex-A725 cores?), while also using modern memory, LPDDR4 if not LPDDR5 to push the EOL out as far as possible. Since the Raspberry Pi 3 depends on the same EOL LPDDR2 memory, this theoretical RP4x chip will probably be used for a product refresh there too (and lowering their costs, as a bonus).

A new chip makes the most sense, good point. But pretty sure LPDDR4 is also pretty much EOL, it's going to get as expensive as LPDDR5 at this rate.

Problem is that I don't think LPDDR5 comes in any sizes smaller than 1GB, so if they want to stick to the current 512MB spec (and price point), LPDDR4 might be the way to go.

It might be nearer to EOL, but it's not actually EOL and should be fine for 5+ years after any EOL is announced.

Micron have announced EOL, yes they'll supply industry for a while but I don't think that's the place raspberry pi want to be.

Others seem to have delayed their announcements after realising they can still make a load of money off ddr4. Also not a great situation for a raspberry pi chip. https://www.trendforce.com/news/2025/09/02/news-samsung-sk-h...

I'm not sure that reporting is correct.

Micron have EOLed a bunch of ddr4/lpddr4 parts, but that happens all the time, even to current nodes. There are still plenty of LPDDR4 parts in Micron's catalog [1] that are not EOL. TBH, I'm not exactly sure what the pattern is, maybe it's just parts on older nodes?

Reporters might be overreacting to product change notifications?

Also, it doesn't really matter when the first fabs start EOLing parts, it only matters when the last fab closes. And LPDDR4 might be a long-lived part, simply because China have opened a DDR4/LPDDR4 fab. Which might actually cause non-Chinese fabs to shut down DDR4/LPDDR4 early to focus on nodes with less competition.

[1] https://www.micron.com/products/memory/dram-components/lpddr...

In short, it's a Raspberry Pi Zero 2 designed to be embedded into a finished device.

Jeff - can you please stop with the clickbait titles and the dramatic, bug-eye YouTube video thumbnails? You’re better than that. We will read your stuff and subscribe anyway don’t worry.

You can buy this - as well as the actual CM0 (Cortex-M0) from AliExpress although keep in mind it’s probably a knockoff chip and you likely won’t be able to debug it without a Segger or something.

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