Blog #4: Getting it wrong. The Epiphany

RE: Blog #4: Getting it wrong. The Epiphany

scottiebabe — Mon, 18 Apr 2022 23:25:03 GMT

Provided the RPI and/or train's power supplies are floating you can measure the train's load current as follows:

RE: Blog #4: Getting it wrong. The Epiphany

jc2048 — Sat, 16 Apr 2022 11:20:20 GMT

I don't think that works. With the bridge, you'll have the OV of the click board a diode drop above whichever of the controller outputs is most negative. One way round, the sense resistor will be close to the controller output that is most negative, so it will be below the 0V and blow the chip.

RE: Blog #4: Getting it wrong. The Epiphany

dougw — Fri, 15 Apr 2022 22:53:49 GMT

I am not quite clear what your circuit looks like.

I don't know anything about the power system - if it is varying the voltage to adjust train speed or if it is using PWM, you may need to run the measurement system from the power supply instead of from the train power.

RE: Blog #4: Getting it wrong. The Epiphany

dougw — Fri, 15 Apr 2022 22:50:18 GMT

It looks like the Current 6 Click will measure current in either direction over a wide common mode range.

The bridge should work to power the circuit, assuming it is within the 3.3 or 5 V limit of the Click.. If it is a 12 V system you might also need a regulator.