I’m using your Nema 11 stepper motors with 3.8V and 0.67 A/phase. If I input these values in your current setting formula
current limit = VREF * 5 * A/V
0.67A = VREF * 5 * 0.67A / 3.8V
VREF = 0,67A / 5 * 0.176A/V = 0,76V
That seems too high, as on the DRV8825 it is lower with only 0,335V (0,67A / 2). Where is my error?