Current Sensor Callibration
The preferred method for R4 is to use V/2 using a resistor network with tolerance of &lt;0.05% for matched equal values. The absolute value accuracy is unimportant.



This would not work for you due to Hall sensor noise equiv of 100mApp with +/-30A range.

Instead use an R shunt.  1 Ohm
RT0805BRD071RL Digikey







simulate this circuit &ndash; Schematic created using CircuitLab

Rail-Rail type needed with Gnd input sensing.