Building Glasgow

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Project Building Glasgow
Glasgow-render.jpg
debugging PCB assembly so we can build a PCB to debug our PCBs
Status Initializing
Contact noopwafel, Shiz
Last Update 2020-02-20

Wha?

We're going to try assembling some Glasgow [1] PCBs. The FPGA is BGA, and there are >100 jellybean parts to place, so this will probably involve the Reflow Oven. Failure is fun!

If we make this work, then we can probably put a bunch of them together for <100eur each (looks like total BOM+VAT is about 75eur), but for now this is just an experiment.

Glasgow is described as an `open source multitool for digital electronics'; it's basically an FPGA with configurable level shifting for 16 ESD-protected I/O pins, so you can connect it to a whole bunch of random interfaces:

Glasgow-block-diagram-1.png

Status

As of 18th Feb 2020, the first board works, but pin A7 is flaky. Replaced the level shifter on Feb 20: now everything seems to work!

noopwafel tried making one in the reflow oven (14th Feb 2020). Next time need to check reflow temp profile, placement in oven, placement of components, how to apply solder paste, need better tweezers, and there are other lessons along those lines. Having said that, it looks OK:

Glasgow-reflow-attempt1.jpg

We ordered 50 revC1 PCBs and a stencil from JLCPCB.

  • They asked for confirmation that the solder mask layer was meant to be missing the DNP parts, replied.

noopwafel bought about 10 board's worth of components.

  • We managed to import a BOM into Mouser, and to break Digikey's BOM manager.
  • Future thoughts: the HX4K is 1eur cheaper. Also, jellybean parts could be cheaper.
  • noopwafel has a BOM spreadsheet for managing this now; order split between mouser, digikey and TME.
  • In theory, we now have all of the parts we need! (Later note: turns out we missed 18pF 0402 caps, but there were some in the space's inventory.)