This time is the PCB of the Opentherm Interface (v1.0) for Alex and his JeeNode and my Jam Jar Firefly simulator.
The round ones are the JamJarFirely and the rectangular is the JeeNode interface. We've sent them to be produced by Lean, there were some delays but eventually we got them.
Alex mentioned that the Opentherm interface mentions having a loop powered Master and Alex wanted to try and do it with JeeNode. I thought about a version two.
I think that I have the hardware ready but surely a lot has to be done in the jeenode side in terms of software, there are only about 25mW available permanently (about 5V@5mA).
This is my first attempt, I've still just tested it on the breadboard but I think it will work. Here is my initial schematic, the LED on the input is a receive indicator and correct polarity indicator (lights dimly when correctly connected and blinks when receiving).
The rest of the circuit is a programmable shunt regulator with two voltages (the transmitter 7V and 16V since the loop is a current source) and a current to voltage converter (receiver).
1 month ago