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Building New Boards Based on Adafruit Schematics
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Building New Boards Based on Adafruit Schematics

by kleeb on Sun Apr 30, 2017 4:29 pm

Hi all,

Not sure if this is the right forum for this question, so if not I apologize:

I've never posted here before, but have been a longtime fan of Adafruit's store and tutorials for most of my work : ) - especially the fact that all of their boards have open schematics and .brd files. It makes it especially easy to create new boards based on existing diagrams.

I am currently working on a board for a client that incorporates the nrf8001 Bluetooth circuit, and using the files provided I was able to layout everything almost identically to the Adafruit layout. However, lacking a parts list I had to make educated guesses on some of the parts, and when the circuit was produced, the bluetooth did not initialize (I had the SMT done by a local PCB manufacturer - pcb.ng - so I trust that the soldering was done professionally).

There's a good chance I messed something up unrelated to the parts, but I was wondering if there exists a BOM somewhere to go along with these circuits, in the event that someone would like to reproduce one of these boards. It would make the process much smoother. If anyone has any advice related to this particular circuit, I would also very much appreciate it.

Thanks!

-Mark

kleeb
 
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Re: Building New Boards Based on Adafruit Schematics

by adafruit_support_mike on Mon May 01, 2017 1:01 am

Our BOMs aren't written in a way that's useful to anyone outside the building.. we have feeder-loading tables for the pick-and-place machine written in terms of our inventory codes, and those trace back to supplier parts that we usually buy in lots of 10k or more. Something as simple as '10k 0805 5% resistor' would be hard for a hobbyist to obtain from the codes we use.

What parts did you have to guess at, and what guesses did you make?

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Re: Building New Boards Based on Adafruit Schematics

by kleeb on Mon May 01, 2017 10:07 pm

I think it's fairly easy to infer most of the parts - 0805 resistors and capacitors for instance - they're not going to alter the circuit significantly. Sometimes it's difficult to see from the schematic whether inductors or the ferrite bead are polarized or not (especially delicate when it comes to an antenna circuit like this). I also think the 32.768 kHz crystal changed from the schematic to the current product for sale on the site. I used Digikey #535-9166-1-ND and crossed my fingers!

Don't get me wrong, the fact that the schematics are free to view and download is a huge help! I couldn't possibly recreate something like this otherwise. It's just a little disheartening when you get the boards back and they don't work : (

Thanks for your help!

kleeb
 
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Joined: Fri Jan 27, 2012 1:24 pm

Re: Building New Boards Based on Adafruit Schematics

by adafruit_support_mike on Tue May 02, 2017 2:04 am

Inductors and ferrites don't have polarity, so you shouldn't have to worry about that.

The ferrite bead in the design is used for noise filtering between the digital and analog VDD rails, and on this schematic it looks like all the other inductor values are listed:

https://cdn-learn.adafruit.com/assets/a ... 1473958497

The make of crystal shouldn't matter much as long as it oscillates, and both the 32.768kHz and the 16MHz are configured as simple gate oscillators. Those tend to be pretty robust.

By way of troubleshooting, are both crystals oscillating, and what amount of noise (if measurable) do you see on the AVDD rail?

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