Overview

The SWD-Over-USB-C adapter is a very convenient and compact debugging tool for serious Bristlemouth firmware developers.

As described in Hardware Required, it allows flashing firmware over SWD, debugging over SWD, and establishing a USB serial connection all over the same physical USB-C port on the Mote.

So why wouldn’t you use one of these? Well, they’re not commercially available off-the-shelf (yet…), so ordering one is a little more involved than usual.

There’s a hidden layer of icing here though – if you’ve never spun a custom circuit board fabrication, now you can! And, it will be way easier and cheaper than you’re imagining.

Ordering SWD-Over-USB-C Adapters from JLCPCB

JLCPCB is an affordable quick-turn PCBA (Printed Circuit Board Assembly) vendor that is popular for early prototyping, students and researchers, and low volume manufacturing. You could of course order these adapters from any PCB/PCBA vendor, but the maintainer of this project provides all the files needed for JLCPCB’s online quote and ordering system so that it’s almost as easy as ordering something off of Amazon.

1. Download and unzip the jlcpcb.zip package from the latest release of the SWD-Over-USB-C open source GitHub project [here].

   

2. Log into JLCPCB and upload the GERBER-swd_over_c.zip in the “Add gerber file” box for an Instant Quote.

   

3. The default options should all fill in correctly from the design (double-check the example below to be sure).

   • You can pick whatever PCB color suits your fancy.
   • We like to pay a little extra for ENIG for Surface Finish to minimize the use of lead and other harmful chemicals.
   • You can select whatever order quantity you want and you can adjust this later, but 5 is the minimum PCB quantity. You can get as few 2 of those PCBs assembled later, but there’s very little price difference for this design – roughly $40 for (5), and $35 for (2). So why not order 5 and make some friends on the Bristlemouth community forum?

   

4. Towards the bottom of the page, toggle on “PCB Assembly”.

   

5. All the automatically generated assembly options should be fine.

   

6. Hit “Confirm” at the bottom of the page, and it will take you to a project viewer.

7. Click on “Bill of Materials”.

   

8. Click “Add BOM File” and upload BOM-swd_over_c.csv from the release package**.**

9. Click “Add CPL File” and upload POS-swd_over_c.csv.

10. Click “Process BOM & CPL”. IF you get an error like:

    

    Just hit “Continue”.

11. It will show you an overview of the 4 different components on the PCB. Click “NEXT”.