Hi Thawney,
The LEM current sensors are pretty robust - forgive the basic questions, but I'll start with the basics and work my way through.
First, measure between GND and 5v on the current sensor breakout board with everything plugged in (Careful not to short anything with the multimeter!) and verify that it is receiving +5V. (If it isn't check that the connector at the eChook has 5V and the connections between are good)
Next, check that the Ref and Out pins are each showing around 2.5v relative to ground. (If you have 5V, but either of those voltages are out, it's likely the current sensor is damaged)
Next at the eChook connector for the current sensor, verify that you have the same ~2.5v relative to ground on each of the middle pins of the connector - measure on the screw heads.
If everything has checked out so far the current sensor is probably working. Now let's look into the eChook board. For reference as we go through it, the current input circuit is in the documentation here:
docs.echook.uk/circuit-schematics/current-inputFirst check is that the op-amp (labelled as U3 on the PCB) is in the correct orientation, the dimple in the chip should be closest to the connector as shown below:
The pinĀ numbering on the chip is:
1-|*U |-8
2-| |-7
3-| |-6
4-|___|-5
Check that there is 5V between pins 4 (GND) and 8 (+5v).
Now de-power the board and check resistances there should be approximately
- 10Kohm, between pins 1 and 2
- 10Kohm between 3 and 4
- 47kohm between pin 1, and pin A2
on the Arduino.If all the above has passed and you have a way of testing under load (probably just spinning up the motor), watch the sense and ref voltages with the multimeter - easiest on the eChook connector:
The sense voltage should increase with current and ref should stay the same. If the opposite happens you've either got your wires swapped or the current sensor the wrong way around. Swap the sense and ref wires to fix it.
If the sense voltage moves as expected, now measure the the voltage between ground and the Current test point (CurrentTP), that should start at ~0v and increase with current. If it doesn't move, but the sense voltage does, it points to a fault in the Op-amp circuit, either a faulty op-amp or a bad connection somewhere. If it does move and the eChook app still shows no current there's either an issue with the Arduino, or your calibration file (if the Current Multiplier is set to 0 it will always read 0)
Hopefully that gives you plenty to get started with! Let me know how it goes.