Problem with Arduino and INA226 power meter module

Question

I am new to the use of Arduino in general, and to the INA226 Module for power metering.

I first got everything set up WITHOUT anything plugged to the INA226 module metering pins (V+, ISens+, Isens-, V- not connected to any power source) and running a sample code that gets data being read by the INA226, of course, all values return 0, but at least I know the program runs and the arduino can connect to the INA226. Now, the problem comes when I try to get some reading such as 5V or even 3.3V from the Arduino pins.

I connected the circuit as follows:

^{simulate this circuit – Schematic created using CircuitLab}

(I noticed that I wrote A6 instead of A4, sorry about that)

But when I do this, there is no reading at all from the serial console. I tried connecting the V+ and Isens+ directly to the 5V pin leaving everything else as shown in the diagram, but the Arduino board doesn't even turn on.

I tried referencing other sources, but their tests use external power supplies or other equipment I don't have.

I would be really thankful if someone could lend me a hand here or help me understand why am I having this problem and how can I make it read something basic such as 5V or 3.3V directly from the Arduino board.

Thanks!

Answer 1

There is a discrepancy in pin terminology between your schematic & what TI uses in their datasheets. I don't see anything in their datasheets using I+ or I-. I only see V+ & V-. These 2 pins perform all your voltage & current measurements depending on the "mode" you tell the IC to use.

As near as I can tell based on your schematic, you should be seeing the voltage reading based on what is applied between V+ & V- (In your case, 3.3vdc) if you've told the chip to read the bus voltage channel.

You should also be getting a current reading between the V+ & V- pins if you've told the chip to read the shunt voltage channel. Since the part is designed for a full scale voltage differential of 36v between the V+ & V- pins, I suspect a reading of about 10% of max (based on a 3.3v differential).

I confess to not knowing the board or its operation but having looked it up on the TI website, it does appear to have a few jumper settings & a calibration routine to follow. There's a user guide on TI's website as well as the usual technical data pages. Perhaps those will assist in setting the jumpers correctly. ina226 data sheet & eval board user guide bc

Answer 2

If this is the usual Arduino-style module with a shunt resistor already in it, then with your schematic, you have [nearly] shorted your supply rail. Your schematic should have the load wired in series to the Isense+ and Isense- terminals, and the V+ and V- terminals should be connected in parallel across the voltage powering the load.

The current must "pass through" the Isense terminals, and the module has to measure the voltage across the load in order to be able to get both I and V to compute power consumption.