The third one works

A project log for Low power mesh networking for small sensor grids

Tiny MQTT-interoperable broadcast mesh networking with simple radios

DanielDaniel 04/17/2017 at 00:590 Comments

The pictured board is my third attempt to assemble a working unit. After the first one didn't work, I got discouraged for quite some time. The second board was coming along nicely, but an overzealous application of a heat gun formed a bubble in the solder mask, lifting the parts off in a wave. It probably doesn't work. Then the third one was gently assembled with a more relaxed 325 degree iron temperature, first with the MCU rotated 90 degrees, second with it placed correctly, and now it is working great.

Lessons learned include putting the largest orientation marker you can afford on the soldermask layer of your footprints. Also, it took a long time to get the programmer working correctly. It's still possible that board #1 actually works, just the programmer wasn't able to connect.