Microstepping

To perform smaller steps you want to change the sequence to produce small changes per step instead of full ones.

If we start with the pbrStepper.py example provided we can build a microstepping sequence using sine and cosine.

Firstly we need to add the math library to the imports:

# Import library functions we need
import PicoBorgRev
import time
import math

# Tell the system how to drive the stepper

Next we remove the old stepping sequence (line 10):

# Tell the system how to drive the stepper
sequence = [[1.0, 1.0], [1.0, -1.0], [-1.0, -1.0], [-1.0, 1.0]] # Order for stepping 
stepDelay = 0.002                                               # Delay between steps

We should add the voltages for driving the stepper in its place, and a microstep count.
The voltages need to be the voltage actually connected to the PicoBorg Reverse, and the voltage the stepper is meant to work at:

# Tell the system how to drive the stepper
voltageIn = 12.0    # Battery voltage input to the PicoBorgReverse
voltageOut = 5.0    # Stepper motor voltage (see the stepper datasheet)
microsteps = 10     # Number of microsteps per full step
stepDelay = 0.002   # Delay between microsteps

Next we calculate the maximum power output using the voltages:

stepDelay = 0.002   # Delay between microsteps

# Calculate the microstepping sequence
if voltageOut < voltageIn:
    powerMax = voltageOut / voltageIn
else:
    powerMax = 1.0

# Name the global variables

Now we work out how the sine and cosine values for each position:

else:
    powerMax = 1.0
sequence = []
steps = 4 * microsteps
for i in range(steps):
    sinOut = math.sin((2.0 * math.pi * i) / steps)
    cosOut = math.cos((2.0 * math.pi * i) / steps)

# Name the global variables

Finally we work out the final power and add the step to the sequence:

for i in range(steps):
    sinOut = math.sin((2.0 * math.pi * i) / steps)
    cosOut = math.cos((2.0 * math.pi * i) / steps)
    drive1 = sinOut * powerMax
    drive2 = cosOut * powerMax
    sequence.append([drive1, drive2])

# Name the global variables

The rest of the code should then work normally.