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A project log for Metamer SAO

You’ve heard of RGB, now get ready for RRAYLLGTTBB+UV+WWCWBWDW

reid-sox-harrisReid Sox-Harris 10/13/2024 at 18:180 Comments

This SAO was originally designed to bring to the Open Hardware Summit 2024 in Montreal, Canada. They hinted at the possibility of a SAO connector on the badge pretty close to the summit date, so it was a bit of a scramble to get this designed and fabbed in time. I went with JLCPCB to fab it, which meant 3ish days in production + about a week to ship + a day or two to assemble... rather tight, but doable. Unfortunately this meant having to comprimise on build quality: I wanted a white soldermask and ENIG plating to really get that 1931 clean white vibe, but time constraints meant I had to go with good 'ol green soldermask and HASL. Ah well, a green SAO is better than no SAO. 

Soldering went alright, though without a stencil it did take a little while. Out of the three boards I assembled, one worked perfectly, one nearly worked with the exclusion of one of the LEDs, and one stubbornly refused to do anything at all. Not bad for a rushed soldering session, and I only needed one to work fully anyway. Some hastily thrown together Arduino code later, and we have light!

Not too bad, not too bad. Seeing all the fun colors was quite nice, though it was a pretty uneven spread of intensities. I wrote a little helper to normalize the intensities and that resulted in a pretty good looking SAO, I felt. It turned out that the OHS badge designer chose to not connect the I2C lines (sad) but did connect the GPIO pins (yay) which meant a little I2C bitbanging and the SAO was OHS-compatible. 

I had intended to write some effects to give a little motion and intregue, but ran out of time for OHS. Hopefully I can do something fancier for next time, though generally I was very pleased that it worked out given the super short timeline I was working with. 

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