from machine import PWM, Pin
import time

# Creates pwm and dir signals to drive a DRI0044 motor driver
# Starting from 0, the motor speed is incremented to its max value, turning clockwise
# Then it decelerates to 0.
# It does the same counter-clockwise, then starts all over again

# create a PWM on GP0 with freq = 50 kHz and duty cycle = 0%
pwm = PWM(0, freq=50000, duty_u16=0)
# set GP1 as an general purpose output
dir = Pin(1, Pin.OUT)

# pwm duty cycle sets the motor speed, dir state sets the motor direction (0=CW or 1=CCW)
# This code is to use with a DRI0044 motor driver

def motor_set_speed(dc):
    """ set the motor duty cycle.
        paramater: dc is a float in [-1, 1] range.
        the motor turns clockwise for positive dc values
        and conuter-clockwise for negative dc values """
    if dc < 0:
        dir.on();
        dc = -dc
    else:
        dir.off()
    if dc > 1:
        dc = 1
    pwm.duty_u16(int(dc*65535)) # duty_16 needs and unsigned 16-bit integer

dc = 0      # initial duty cycle, in per unit
incr = 0.1  # duty cycle increment

while True:
    dc = dc + incr
    if (dc >= 1) or (dc <=-1):
        incr = -incr
    motor_set_speed(dc)
    time.sleep(0.01)