PCB Footprints

[Folknology]

On the L2-124QFN data sheet, section 2.5 only shows 8 VDDIO pins for the Xcore power and ground table. Section 3.5 package pinout however, shows an extra VDDIO pin on B4. I am assuming the package pinout section 3.5 is correct.

Like wise B5 is also missing from the VDD table in section 2.4 but is present in 3.5 package pinout.

@leon did you catch this also, when designing your footprints?

Please can someone from Xmos confirm which is right and also amend the datasheet accordingly please.

regards
Al

[leon_heller]

I've only done the footprint, I haven't created the part itself.

Leon

[TonyD]

For those PCB designers who use Easy-PC schematic capture and PCB layout software there's now a Xmos ic library at www.xcore.com/projects/easy-pc-pcb-library.

Theres not many parts in at the moment but we'll add more soon.

[Folknology]

xmos-2v0-draft.lbr.zip

Hi Guys

I created the L2-QFN124 as an Eagle library part. I used @sjalloq xmos.lbr file and added my part in there. the library file is attached containing @sjalloq part also.

This is a draft, please do not use this yet as I still have some issues with it, it is purely for test purposes until issues are ironed out.

Issues:
1) Like Leon I have used similar dimensions for the B row vias at the momemnt they are very close even with their small dimensions. This could be an issue with PCB manufacturers only a couplel I am familiar with will handle these small features.
2) I may have found a weird Eagle bug, when I add the part to my PCB, the vias grow to a much larger size. @sjalloq can you try using the new library version and placing the L2 part to se if you get the same issue please. This could be caused by the fact I had to manually enter the drill sizes as they were smaller than Eagle offered via the menus.
3) I still have some pin out issues where different parts of the datasheet do not agree, I am awaiting feedback on this thread to iron out those.

Please see attached file

let me know your thoughts..

regards
Al

[Folknology]

I am getting closer to solving the via resizing issue but still have ways to go. Its partly due to my lack of experience with Eagle and high density packages, but it is also partly down to the wacky way in which the Eagle package manager/editor operates, watch this space..

On another point on this thread I spoke about setting up a github project to house the Xmos library files for Eagle. I still thinks this is a good idea but we still have a versioning problem due to the nature of its binary files. However I think I may be able to find a solution to this.

In Eagle one can export the libraries as a script, I have had to do this before to fix something (can't remember what it was). This script can then be re-imported back into Eagle and works with different versions I believe.

So why is that relevant?

Well when you export it as a script it exports into an editable text file. We could use this as the equivalent to a library source file. In others words if we use the script files in the git repository it will probably be possible to merge in changes from different forks. Patches can be created and new versions/forks produced, this is what Git is good at.

So what do you think, I got no response on the git suggestion before, therefore, unless anyone objects, I would like to create a git repository for it.

Thoughts?

[leon_heller]

That footprint of mine isn't suitable for any of the ordinary PCB suppliers as the vias are 0.45 mm with a 0.25 mm drill and the tracks are 0.15 mm wide. One PCB prototype company that could manage them is Eurocircuits, but they will probably be quite expensive. I've tried using 0.6 mm vias with a 0.3 mm drill which can be managed by PCB Pool, for instance, but they simply won't fit.

Leon

[Folknology]

@leon I went through the same exercise because PCBPool are cheaper for one/two off prototypes. Eurocircuits get cheaper for multiples.

[russf]

Folknology:

On another point on this thread I spoke about setting up a github project to house the Xmos library files for Eagle.

I would say 'please go ahead'.

I'm also using Eagle and I use Git and SVN for Source Control. I will be following along shortly with some board designs of my own.

I think you are touching on a bigger subject that can be summarized as: reducing friction losses in collaboration. I'll write a post on this topic sometime this week.

Best wishes,

--r

[Folknology]

I will set this up either later in the week or over the weekend depending on work load (hight at the moment!). I have several repositories to setup and will do them all together to save time. If anyone has feedback/features they would like or files/dirs/structures included let me know. I will set it up in a generic way with sub folders for different cad package variations, then others can be added as required.

regards
Al

[TonyD]

I've updated the EasyPC library now at v0.20 with XS1 L1 128-pin TQFP component and footprint. Thanks goes to Shareef for his EagleCAD library which I reused the footprint from.