It should be straightforward to drive a bridge made from two BTS7970s from an Arduino. Connect the IN pin of each BTS7970 to an Arduino output pin with PWM capability (two separate pins) and a 10K resistor to ground. Connect the two INH pins to Vcc if you want the bridge to be active all the time; alternatively, connect it to a digital output pin (one pin can drive both INH inputs) and a 10K resistor to ground.
To drive the motor in one direction, digitalWrite LOW to the first IN pin, analogWrite to the second IN pin, and set the INH pin high. To brake the motor, digitalWrite LOW to both pins. To run the motor in the other direction, write LOW to the second IN pin and PWM the first. To let the motor coast, write LOW to the INH pins.
Optionally, connect a current sense resistor between each IS pin and ground, and feed it to an Arduino analog input via an R-C filter.