Gimbal Motor Current Sensing with SimpleFOCShield

I would like to use the SimpleFOCShield with in-line current sensing.

I want to sense the current from an iPower GBM4108H-120T Gimbal Motor, and it seems that I need to get the shunt resistor value and the amplification gain (current-sense op-amp gain) to do this.

How can I get these values, please?

Also, how should I decide to use a range of 3.3V or 5V? I’d like to measure small current changes as accurately as possible.

Thank you very much.

So the shunt resistor value is written on the shunt itself. If the shield exactly the same as the one in my designs it will have 0.01Ohm(10milliOhm) resitor. And this is indicated as R010. If it has 6milliOhm resitor it will have indication R006 etc.

For the amplification gain, the ones I’ve used is INA240A2 which has the amplification gain of 50. If you have INA240A1 the gain is 20, and A3 has the gain of 100 and A4 had the gain of 200. They have the same layout but just diffet gain.

The amplifier is a component next to the shunt resistor.

Regarding the 3.3 or 5v logic, if you wanna be safe and if you change your microcontroller often, then I’d choose the 3.3v.
However the best approach is if you’re using the microcontroller with 5v logic to use the 5v range, and to be use 3.3v range for 3.3v based logic boards.

Another reason why to use 5v logic is because it supports higher range of current measurements. However if the microcontroller does not support 5v analog input it will not be capable of exploiting this range. :slight_smile:

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Thank you very much @Antun_Skuric