hello there, i wanna read very low currents between 0 and 20mA to be precise, all the sensors i found so far dont go under 100mA or arent precise in that level, I'm trying the INA 219 but i dont know if it'll do the job. what do u advise me to use ? not really advanced something simple will do
Hello lyes1921
Read the data sheet.
Have a nice day and enjoy coding in C++.
Дайте миру шанс!
I have read it but didnt find the precision, i know the range is -3A to +3A but i dont know how big the error is
This current is at a certain resistance of the shunt resistor. If you are not going to measure high currents, you can replace the shunt resistor with another one with a higher value suitable for your purposes.
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Please describe the circuit for which the current is to be measured. Better, post a schematic diagram of it.
The INA219 is a bi-directional high-side sensor with 12-bit A/D, so in theory 11-bit one direction.
That's 3200mA/2048 = 1.56mA per A/D step. So not ok for your 0-20mA load.
You could change the 0.1ohm sense resistor to 1ohm, for a 320mA range.
Or use the 16-bit INA226.
I assume you don't mean a 4-20mA sensor, because the INA is the wrong choice for that.
Leo..
What voltage source are you measuring the current of, is it DC or AC? Do you require galvanic isolation or not?
I use one for 20mA ok.
I tried using it to measure model railroad track power. It didn't even come close to the needed sensitivity. As mentioned, it resolves more than a milliamp per bit once it's been through the A/D.
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Then, as explained, you should not display two decimal places.
Unless you have changed the sense resistor to 10ohms (32mA FS).
Leo..
didnt know the range will change when u change the shunt Resistor, how do i calculate the proper value of the resistor i need ? will it affect precision ?
and yes it's for 4-20mA use, what sensor is more appropriate ? the INA is all i found online
how is the precision ? have you tested it with an Ampermeter ?
did u change the resistor ?
how do i calculate the proper value of the resistor suited for me ?
Which Arduino.
A simple 51 ohm sense resistor will do for an Uno/Mega/Nano (1.1volt Aref).
With maybe some pin-protection parts around it.
A better option (resolution) would be an ADS1115 with a 100 ohm sense resistor,
with the same optional pin-protection parts.
Used on boards like this one, with built-in sensor supply.
This topic comes up several times a month.
Google "Arduino 4-20mA" for examples/code.
Leo..
I'll print whatever I like thanks.
Sure. As long as you know you're printing nonsense.
Leo..
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Might have a niche in politics. 
I agree 100.0000000%.