I haven’t been able to use my miniature nodes the Funky v1 or Funky v2 with my energy harvesting board yet, in the means of plug-and-forget type of solution. Basically the issue is that we have a slowly rising voltage from the energy harvesting board, but the RFM12B will consume 0.68mA until fully initialized and put to sleep. During start-up the circuit will draw more current than the trickle may provide (low light level or low temperature difference, if using Peltier element) and the energy harvesting board output capacitor won’t ever reach its full charge level so the initialization of the RFM12B can happen. The Atmega32U4 is kept in RESET until the BOD level is reached, so it doesn’t consume almost anything. JCW from Jeelabs.org has dozen of articles on this matter, plus an elegant solution: add a MOSFET to control the RFM12B power state. I have adopted his solution for the Funky v2, following a discussion here. That means that the Funky can decide when to power up the RFM12B using a digital pin:
I have received the rev 1 boards today and quickly soldered one:
I have a small test sketch to flip back and forth the A5 pin HIGH and LOW, and the RFM12B’s power flips too. Looks good 🙂
I will toy a bit more and put the Funky v2 rev 1 for sale tomorrow.
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