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  • Author Author: spannerspencer
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Raspberry Pi Zero - Technical Details

Now that the Raspberry Pi Zero is out there in the wild and ready for all you fruit-loving hackers and makers to put it to inspired and sensational use, more detailed tech specs are also starting to appear. And for the sake of ease, I thought I'd compile everything I've found that really drills down into this latest, smallest Linux-driven beauty.

 

If there's something else under the Raspberry Pi Zero's hood that you think the electronics community would benefit from knowing about, please feel free to add it in the comments.

 

Pi Zero Mechanical Drawing

A few people have already stareted working on CAD drawings for Pi Zero cases, ready for 3D printing, so here are more precise technical drawings so you can ensure a safe and snug fit. And if you're creating a case or an accessory, share it here as we're excited to see what makers can add to the Pi Zero's repertoire.

 

A vector image of the technical drawing is also attached to this document for you to download.

 

image

 

Broadcom BCM2835 Datasheet

Attached to this document is a full datasheet for the brains of the Pi Zero, the Broadcom BCM2835 SoC, in case anyone really wants to get inside its silicon and wring every last function from Pi Zero.

 

Technical Specifications

These can be found elsewhere on element14 already, but it seems like they ought to be here too, for the sake of completion.

    • CPU: Broadcom BCM2835, which can run at up to 1GHz.
    • RAM: 512MB
    • Power: 5V, supplied via micro USB connector, drawing 160mA (even when connected to an HD display).
    • Dimensions: 65mm x 30mm x 5mm
    • Video & Audio: 1080P HD video output. Audio output via mini-HDMI connector.
    • Storage: MicroSD card.
    • Operating System: Linux, installed via NOOBS.

 

image

Attachments:
https://community.element14.com/cfs-file/__key/communityserver-wikis-components-files/00-00-00-01-69/Raspberry-Pi-Zero-_2D00_-Mechanical-Drawing.ai
imageBCM2835 Datasheet.pdf
  • in reply to rew

    Roger Wolff wrote:

     

    That said.... I have the impression that the "runs at 1GHz" whereas the original 'pi had "runs at 700MHz, but might be overclockable" means that something in the board design of the original pi was a bit flaky. Decoupling maybe....

    I think the RasPi Zero does a better job with the low voltage regulator.  The BCM2835 has its own low-voltage switching regulator which requires an external inductor (L3 probably) plus external capacitors.  These are all on the top layer on RasPi Zero whereas they're all over on the earlier RasPis.  Keeping the control loop tight on a switching regulator is very important.

     

    However, maybe it's just that you can get faster DRAM for the same price nowadays.  I'll leave checking the DRAM specs as an exercise for the interested student image

     

    I'm actually quite impressed by how few pull-up/down resistors the BCM2835 needs.  Most SoCs need a bunch of pull-up/down resistors for boot configuration -- take a look at Minnowboard.

  • in reply to johnbeetem

    Note that although this is a lots-of-pins BGA package, this "scaled down" version of the 'pi only uses a small amount of the possible IO of the CPU. Things like DSI and CSI are not routed anywhere. Empty balls. Possibly this frees up enough board space on the top layer to circumvent all the vias. OK. Strike that. You can see on the picture that each capacitor has a via and not a line going under the CPU.

     

    That said.... I have the impression that the "runs at 1GHz" whereas the original 'pi had "runs at 700MHz, but might be overclockable" means that something in the board design of the original pi was a bit flaky. Decoupling maybe....

  • I'm a little leery of all those bypass capacitors on the top surface of the board.  Normally, you put bypass on the opposite side of the board, but there are no populated components on the back side of the Zero (as you can see at Adafruit).  This saves a lot of manufacturing cost.

     

    The problem is that each via through the PC board is electrically an inductor.  If you have to go through two vias to get to a bypass cap, that's two inductors adding in series.  If the other end of the cap needs to connect to a power or ground plane through a via, that's three in series.

     

    It's best electrically to have no vias between IC power pins and bypass caps, but that's usually not possible for BGAs since they usually have power balls in the middle.  Next best is to have bypass caps right below the BGA so at least you only have one via and a short trace (traces also add inductance).

     

    Ah well, engineering is always a bunch of trade-offs image

  • Attached to this document is a full datasheet for the brains of the Pi Zero, the Broadcom BCM2835 SoC,

     

    I was hoping the "full datasheet" would indeed be the full datasheet. However this is just the "arm peripherals" datasheet that has been available since 2012....