A nifty li'l Onion Omega2

My First part: Onion Omega2

Onion_068a504224788ea7079e205198c32249_5.fzp (18.9 KB)

Unfortunatly not, this is only the fpz file for your part not the part (which would also include the svg files). In Fritzing you need to right click on your part in the mine parts bin and select export part which will write an fzpz file (the fpz and its associated svgs all zipped) and uploard that.


@Jaremi: I am very intersting in an onion omega2 part for fritzing. Could you imagine to try again an export of the part as @vanepp described?

Sure, I am busy going through the Fritzing standards guide to make sure it is done correctly, I’ll upload it in the next day or so.

I do not like to ask, but, are there already news?

Hi Netsrak,

I am finding it difficult to link the connections computer keeps telling me “No”
maybe someone can have a look.
I drew all the svg files hope they are uploaded correctly.
ONION omega 2 .fzpz (83.3 KB)

First (so as to not start off too negative :slight_smile: ) nice job on breadboard. The big red square on breadboard in fritzing isn’t a surprise, that is caused by the lack of any connectors in the breadboard svg. That is easy enough to correct, you (or perhaps I) just need to copy a suitable 40 pin connector in to breadboard so it has connections (actually you need to replace the 40 with a 32 pin version so it has the correct number of pins!). Same thing with schematic, it needs connector pins and terminals defined (that’s probably more a job for me as its a little trickier if you aren’t experienced at creating parts). PCB needs a fair bit of work, it looks like the current one is the Omega 2 card itself, when it needs to be the outline of the complete unit with connections for the 32 pin header and likely no connections for the Omega 2 itself (they should appear on the 32 pin connector I expect). If you like I’ll have a bash at fixing this up for you as thats likely to be easiest (and there looks to be good documentation to work from). With a fixed up example you can then see what changes are needed to your original. Assuming you have an expansion dock, it would be good to create an outline of the board in the PCB svg, I can easily enough create the pads for the 32 pin io connector but without a board (or a mechanical drawing which may be available on their site) it is hard to get the outline correct.


OK there were a number of problems. It looks like you were confusing the onion module and the doc (which is what you are trying to make). The module has 32 pins and the doc only has 30 (also there is a documentation error on the Onion site at

at “The Hardware”

it shows a 32 pin connector (with only 30 lines labeled). where the doc really only has a 30 pin connector (seeing that I started with a 32 pin connector :slight_smile: ). In any case lets start with what I did to fix breadboard:

Scaled the omega to 26.40 * 42.70mm (according to mechanical drawing) as is it was too large. Copied in from another svg 2 15 pin single headers (because duals are currently broken) via a cut and paste in Inkscape. Added and positioned (according to the mecahnical document on the Onion web site) the dual 30 pin connector (2 single 15s grouped) after deleting the 40 pin connector that didn’t have any connections attached. Then changed the connector pin designations to match what they should be for a dual (i.e.

pin 1 3 5 … 29
pin 0 2 4 … 28

(note: need to do this in schematic and pcb as well). Grouped then scaled and corrected the lettering on the labels and moved them to match the connector holes (using the connector documentation from the onion web site). Select all group set group id to breadboard Select all resize page to drawing and breadboard is done.


Rather than add connectors to yours, I created a part in Fritzing from a generic ic with pins set to 30, saved it as a new part, exported the part, unzipped the fzpz and swiped the schematic svg to copy in to yours. That gave me the correct number and configuration of terminals. Then I renumbered them to match breadboard and made the rectangle larger and added the pin labels from the data on the onion site. First I used xml editor to set the stroke and height of all the terminals from 0 0 to 10 10 (making a 10 thou by 10 thou rectangle as the terminal) with 0s Inkscape will not select or move the terminals. With a 10 thou rectangle it wll. At the end of it all again edit->select all and group setting the id to schematic this time. Then select all and resize document to page and schematic is done.


As noted your copy of PCB had the onion module which isn’t what is needed here. So in Fritzing selected a connector, changed it to 30 pin double row (which doesn’t work in breadboard view but does in pcb), edited saved and exported the part and then swiped the pcb svg to use for the onion. To start with it only has the dual row connector, so yet again renumber the pins to match breadboard then from the io doc mechanical drawings add the necessary lines in the correct places in silkscreen layer to produce an outline of the edges of the board. Save it and pcb is done.

fpz file:

Fixed up the metadata to remove references to the pi zero (which I assume you cloned this from) and add a description and more tags. Then moving on to the connectors, changed the names and descriptions to match those in the documentation on the onion site. I also deleted a number of extra connections possibly left over from the pi zero (which has 40 pins). Fixed up the bus pins to have the appropriate and appropriate number of members. Rezipped the resulting files in to an fzpz and loaded it to fritzing to test. The result is here:

(edit: I have updated this to change the name to Expansion Dock (which is what it is) and to correct a mistake of not post processing the schematic svg to remove font-size px which will cause problems. If you have downloaded the original please redownload this new one.

Expansion dock and Onion omega2.fzz (135.0 KB)

which is a sketch with the new part available to be exported by right clicking on it in temp and selecting export part. As you see all the pins make correct and correctly placed connections to the two 15 pin connectors used for testing. As well the pcb has paths on both sides of the copper and I exported the gerbers and checked that the drill sizes are correct and the silkscreen looks correct when exported. You should check all the pin labels go where you think they should in case the problem is that you have a different version than that described on the onion web site, but I think the problem was confusion between the module pinouts and those of the io doc. If you have questions feel free to ask.

Edit #2:

Since we were this far, it was relatively easy (with a detour down a poor pcb layout for 2mm headers) to also make a part for just the Onion omega2 module (without the dock) so I did that too. As above the part is available for export from the test .fzz file:

Onion_omega2.fzz (102.5 KB)

Since I don’t have one of these (at least yet :slight_smile: ), it would be good if one of you that does prints out a 1 to 1 copy of the pcb layout and check that what is in fritzing actually agrees with the part in real life.


Wow this is awesome! I’m Lazar, the CTO at Onion!
We’ve been wanting to make a Fritzing model of the Omega2 and the Docks for quite some time but just haven’t found the cycles! And yes, our illustrations do have 32 pins instead of 30 pins on the Expansion Header…

Would it be ok if we made a GitHub repo that includes the parts you’ve created so that all of the members of the Omega2 community can benefit from it?
The repo will be public and you will of course be mentioned as the contributor.

Please let me know!

Sure, that’s what they are for is to be shared.


Great! Here they are: https://github.com/OnionIoT/Fritzing-Models

We’ll be letting the whole Omega2 community know!