edit

serialstep/serialstep-DRV8428P/README.md

@@ -26,3 +26,14 @@ Microstepping up to 32 is achieved through PWM on the H-bridge inputs. A high fr
 TCC0 is then setup in normal PWM mode with a period of 2400, yielding 20kHz with a prescaler of 1. This is more than 11 bits of resolution for a nice, smooth sine signal on each of the PWM inputs:
 
 <img src="img/pwm_lookup.png" width="100%">
+
+## Measuring angle with 1/32 microstepping.
+
+Cut and populated this board Mar. 3, 2022.  Stepper used has measured 1.8 Ohm coil resistance, and is labelled "Shinano Kenshi STP-42D201-37".  This is not the standard stepper we have been using.  With this motor, the driver chip is not happy at high current.  Need to be lowered to 1.2V (0.4 A) for motor to run well.
+
+<img src="img/pwm_board.jpg" width="50%">
+
+Set up with pivot/mirror 3378mm distant from ruler.  Beam translation 212 mm corresponds to one 1.8 degree step. 
+
+<img src="img/steps.svg" width="50%">
+