INA219 to measure total load of multiple sensors

Hello All,
I have an INA219 (Adafruit knock-off) and was able to wire it to measure the current, voltage and power consumption of a simple LED, but now I’d like to use it to measure the total load for a circuit comprised of a GSM module and a GPS module (and Arduino of course). Is there a way to do this? For the simple LED example all I had to do was connect the INA219 between the Arduino and the LED, but there was only one input from the Arduino so it was easy to do. In this case, I have 2 inputs (TX and RX) for both the GSM and GPS modules.

Thank you in advance!!

The Adafruit INA219 high side current sensor is used to measure the current draw by any module, up to about 3 Amperes. Connect it between the module power source positive terminal and the module power input(s).

Consult the Adafruit current sensor tutorial for examples..

Don't forget to connect all the grounds together.

Thank you for your reply. The thing that has me most confused in their tutorial is the part where it says "Connect V- to the positive terminal or lead of the load. This puts the sense resistor in-line with the circuit."

If I have TX and RX pins for two sensors each, where would the lead of the load be? I am using Pins 2 and 3 for the GSM module and pins 8 and 9 for the GPS module.

Forget about TX/RX pins.

An INA219 module has four connections on one side for 5volt, ground, SDA (A4), SCL (A5).
Those pins power the module, and send the (I2C) current and voltage data to the processor.

The other side, with the scew terminal, is for the actual current sensing.
All the current (+wire) from the supply to your project (+wire) has to run over those two connections.

So connect supply(+) to one, and project(+) to the other screw.
All grounds of all modules should be shared.
Post a diagram and/or picture(s) if you're not sure.

I see, that makes sense. Doing so would put the INA219 in series with the circuit and allow it to measure. It seems simple enough if I have an external power supply, but what if I’m powering it with the same USB connection that powers the Arduino? I currently have the 5V, GND, SDA, and SCL pins of the INA219 connected to their appropriate locations (did a quick test and confirmed), and the GSM is also wired correctly. All I’m having trouble with is the Vin- and Vin+ connections.

I figured I’d simplify things and test the GSM module on its own before also attaching the GPS module. So far, I ran the 5V pin from the Arduino into the Vin+ on the INA219, then ran the Vin- pin to the + rail on the breadboard, which then powers the GSM module as well as the VCC pin on the INA219. Is this correct? The code I have gives me a current value which appropriately spikes when an SMS is sent, but the value seems a bit off (about 200mA when I expect something closer to 2A). It’s also giving me a load voltage of 0V which doesn’t make sense. I’ve attached a drawing.

Thank you for your help!

It does not matter to the current sensor where the power comes from.

However, neither USB nor the Arduino can safely power a GSM module, which will typically consume 2 Amperes while transmitting. You will damage your circuitry if you try.

Thank you all for your help! Just as an update, I was able to measure the voltage and current, but I wired a separate circuit for the INA219 - this helped me put things together as all I have to then do is wire the INA219 "in line" with my circuit and share a common ground.