Jun 242014
Compute Module thumbnail

The Raspberry Pi Compute Module was launched yesterday and I felt I owed it to you, dear readers, to get one. ;) OK. So, maybe it’s not fair to blame you guys for it. I’d have bought one anyway, but you helped me to not dither over the decision.

I also have ideas for something I might do with it. But that’s top secret, so don’t tell anyone!

So What is the Compute Module?

It’s a small module in the same SODIMM form factor as a laptop memory module. You can see it in the middle of this photo…

Raspberry Pi compute module

Raspberry Pi compute module

…the big board it’s connected to is the development board, which breaks out all manner of ports which aren’t accessible on the standard model A/B Pis. It’s for embedded systems developers, who want to incorporate the Compute Module into their own products.

How Much?

The dev board kit is ~£152. I bought mine from Farnell yesterday and the UPS man just delivered it.

The instructions are clear and concise. I used an Ubuntu laptop to configure and flash the latest Raspbian (June 2014) to the module. It took about 20 minutes to write the image. I was getting a bit nervous that something had gone wrong (kid with a new toy) but it was fine.

I swapped the jumper around, plugged in my PiHub, keyboard dongle, wifi dongle and memory stick and it booted up perfectly first time. Happy days.

You’ll Need a Hub

There’s no ethernet on board, so if you want internet and keyboard/mouse, you’ll need a hub. Otherwise you get the chicken/egg situation of…

“how do I configure my wifi dongle with only one USB port?”

…since you can’t swap SD cards, having configured the card on another machine.

I suppose one way round this would be to dump a Raspbian image to disk with your wifi credentials already on it, then flash that to the compute module. But who’s got time for that when there’s a Pihub available?

I’m powering mine with the PiHub too, so using all the ports, but only one PSU. The dev kit comes with a PSU and two USB leads, along with camera and DSI display adaptors.

I’ve just made a quick ‘walkround video’. I’ll be back with more, when I’ve done something with it…

  27 Responses to “Raspberry Pi Compute Module”

  1. Isn’t the 1st partition a FAT partition, so you can edit your wifi settings from the computer you use to flash the module?

    • If you knew how to do it manually, yes, you could. I used to do it back in the days of MrEngman’s script for the Edimax dongle, but since the GUI wifi config came in, I’ve long-since forgotten how to do that. :)

      Actually, once you’ve flashed the device (you have to use dd from Linux), you can access both partitions, so I guess you could change anything you wanted if you knew how to. :)

      • The ups man has just been to my house too :-) I don’t have a linux laptop so I’m going to flash it from a pi. I’m just downloading a fresh img to a 16gb sd card now.

  2. Looks like it’s just begging to be mounted to the back of the HMDIPi case… ;-)

    I wonder if RPi.GPIO supports all the extra GPIO pins yet?
    Looks like the answer is yes, as long as you’re using the BCM numbering scheme :)

    • Re the HDMIPi thing, yes that thought had crossed my mind, but would need a custom board since the dev board is too big and too expensive for that use case.

      Gordon said that wiringpi works on the BCM numbers. Will try RPi.GPIO tomorrow evening.

      • Or you could build an HDMIPi driver board with an SODIMM socket…? ;-) (just kidding!)

        • Well obviously that was something we’ve thought about, but let’s get the KS rewards out of the way before we start another project ;p

          By the way, I just tested ports 28-45 using RPi.GPIO and they worked fine (as outputs). Must stop now.

  3. Brilliant intro video, Alex. Great to see the bits & pieces of the dev kit explained in such a down to earth fashion. And we appreciate your justification for its purpose :)

    All the best


  4. […] Alex Eames has done a great “Day 1″ video of his newly-arrived Compute Module. If you’d like to see one in the flesh, or just want to see what all the fuss is about, head on over to RasPi.tv and watch the video. […]

  5. Hi Alex,

    I’m curious whether this module corrupts its memory during power-failure (like the SD cards on the model A/B). If you have time please can you get it doing something and try pulling the power-cord … and see if it still boots? I suspect it will suffer the same.

    Many thanks.

    • LOL. Wouldn’t it be easier to ask Gordon Hollingworth, rather than try to get me to screw up my new toy? ;)

      I’m pretty sure, since this is for industrial apps, that it is more rugged than the model A/B Pis. I’ll ask the question.

      Here’s the answer

      • I believe corruption generally happens at the filesystem layer, and the filesystem layer sits “on top” of the SD card or eMMC module block layer; so I see no reason why the ext4 filesystem on the eMMC would be any “less corruptible” than the same ext4 filesystem on an SD card if you happen to pull power during the middle of a big write. But I’m no expert in these matters, so Gordon may have more info :-)

        If you want a filesystem that’s “less corruptible” you need to look at something like LogFS https://en.wikipedia.org/wiki/LogFS

  6. There is already project based on this module called ‘Modberry 500’

  7. Hey Alex, something we have long thought about but would have no idea where to start was to use the Pi from a specific video application that would actually require two (or more) sound processors – and hence multiple audio outputs (and probably at least one . Of course, we could use multiple USB sound cards, but ideally it would be nice to develop our own board – and I guess this is exactly where something like this might fit in. However, we have no clue how we would achieve this.

    It would be interesting to see how you take the Compute Module on and potentially develop a specific embed application and board, along with the cost that such a development might be.

    • I think using multiple USB sound cards will probably be your best/easiest/cheapest option (as long as the bandwidth requirement from multiple cards doesn’t overload the Pi’s USB bus http://www.raspberrypi.org/documentation/hardware/raspberrypi/usb.md ).
      AFAIK there are three ways of getting audio out of a Rev 2 ModelB Pi – analog audio out (uses 2 PWMs), digital audio out (over HDMI) and digital audio out (over I2S on the P5 header). I dunno if each of those audio outputs can be set to a different input source, but I do know that omxplayer for example can simultaneously output over both analog audio and HDMI audio.

      Although the Compute Module exposes a lot more GPIO pins, it doesn’t give you any additional audio capabilities – you still have two PWM channels, a single I2S interface, a single HDMI interface and a single USB interface (the two external USB ports are provided by the internal USB hub on the LAN9512 chip), exactly the same as you have on the Model B.

      Perhaps you’d just be better off using a cheap PC with multiple PCI sound cards? Depends what your exact requirements are, of course. (I’m a Pi expert, but not an audio expert)

  8. […] 2, column 3 is the Compute Module, sitting atop the Compute Module development board. This was launched 23 June 2014 as a way to […]

  9. […] 2, column 3 is the Compute Module, sitting atop the Compute Module development board. This was launched 23 June 2014 as a way to […]

  10. Hey!I have been trying to make my rpi compute module work and yet i couldnt do it.Initially i tried doing it using windows host.I followed all the steps mentioned in the rpi website.


    Finally i used win32 diskimager to burn the image file and when it finished i disconnected the usbslave port and also removed the jumper that enabled J4.I then switched it off and then connected it to a DELL monitor via the HDMI port and turned on the compute module.Guess what?It gave me nothing.Not even “no signal”. All the drivers were pre installed on my system.My system is also able to detect the compute module as soon as i plug it into the USB port . I could not open it.When i checked the disk space it was completely filled .I repeated this process 3 to 4 times and i failed miserably.Help me out please.

    I gave up hope on windows host and turned towards linux host.

    On the linux host i followed the element 14 website


    , i downloaded tools via github.Everything went fine till “sudo make”. But, when i do “sudo ./rpiboot” it gives me an error saying
    sudo: unable to execute ./rpiboot:no such file or directory
    Infact, i checked if the rpiboot.exe file existed or not in the directory using ‘ls’.It does exist.What am i doing wrong?I have been stuck here for the past few days.Someone please help me out.

    • It’s a very long time since I did anything with the CM, but I wonder if you are using the right image file? Raspbian has grown a lot over the last couple of years and I think there is limited space on the CM’s storage (is it 2 Gigs? I’ve forgotten). So you’ll need to use one of the smaller Raspbian images.

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