from machine import Pin, PWM
import time

in1 = Pin(18, Pin.OUT)
in2 = Pin(5, Pin.OUT)
in3 = Pin(16, Pin.OUT)
in4 = Pin(4, Pin.OUT)
enA = PWM(Pin(21))
enB = PWM(Pin(2))
enA.freq(1000)
enB.freq(1000)

while True:
  
  # motor 1 forward direction
  in1.on()
  in2.off()
  enA.duty(1023)
  time.sleep(1)
  
  # motor 1 reverse direction
  in1.off()
  in2.on()
  enA.duty(50)
  time.sleep(1)

  # motor 2 forward direction
  in3.on()
  in4.off()
  enB.duty(1023)
  time.sleep(1)

  # motor 2 reverse direction
  in3.off()
  in4.on()
  enB.duty(50)
  time.sleep(1)