Raspberry Pi 3 B+ for SMMB

Super Mega Microbot, that beloved and neglected creation, is due for a facelift. The biggest challenge we had at the last competition was the instability of the USB bus on the odroid-U2 when we had both a USB camera and USB 5GHz wifi adapter attached. Cue 2.5 years of waiting, and one aborted attempt, and it looks like the problem is solved!

The aborted attempt

The challenge in this problem is that almost no single board computers in the odroid-ish form factor have both:

  1. a non-USB camera option that works
  2. integrated 5GHz wifi, or any kind of high speed interface that would allow for a non-USB based 5GHz wifi

There are many contenders which have one or the other, or a nominal camera interface, but the board support package that is released to amateurs doesn’t support it.  Not only that, almost no boards have any high speed interfaces except USB, which means there aren’t even options for doing anything better.

For a moment though in 2017 I thought I had the problem solved with the introduction of the Intel Joule.  On paper it ticked all the boxes, dual camera ports, with software that worked, integrated 5GHz wifi, a supported GPU, and on paper enough of a community that support would be not an issue.  The only downside was that as a system on module, it required a fair amount of a carrier board to be able to actually use it in an end application.  That said, I did try, and built up a carrier board to be able to mount it in the turret of SMMB.

However, I wasn’t actually able to get the Joule to boot on this carrier board, despite it matching the reference board schematic in every way I could check.  To double down on the failure, Intel discontinued the Joule shortly after I had the prototype carrier board in hand which, unsurprisingly, reduced my incentive to try and get it working.

More promising

rpi3bp

Lo and behold, with sufficient time, comes the announcement of the Raspberry Pi 3 Model B+.  On paper it solves nearly every problem as well as the Joule, including needing much less support from a carrier board to be functional.

Pluses:

  1. Onboard 5Ghz wifi
  2. Camera port, with off the shelf camera modules and functional software
  3. Onboard ethernet (although through USB, sigh)
  4. Onboard serial which can run at high data rates (>= 1Mbps)
  5. Stock debian based linux
  6. A production guarantee until 2023!

Downsides:

  1. Not quite as fast as the Joule or Odroid
  2. The GPU doesn’t support any form of GPGPU very easily
  3. Only 1G of RAM

I ordered some and got to work, with results that are definitely more promising, although not without their share of stumbles and pitfalls, and it will definitely take more than one post to describe.  So… more for next time.

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