The next image show how we can wire up the raspberry pi to the motor driver to control the two motors of the rc car.
I did my best, but I know it's a messy drawing.
Change the server.py to control the car
You can find the project at github here
In the server script, we will use a Car class to wrap all the needed functionalities to control the car.
For example: car.runForward(), car.setSpeed(), car.turnLeft() ...
The final server script look like this:
from bottle import post, route, static_file, run
from car import Motor, Car
car = Car(Motor(23, 24), Motor(18, 15, 14))
@route("/")
def index():
return static_file("index.html", root="./")
@post("/right")
def right():
car.turnRight()
@post("/left")
def left():
car.turnLeft()
@post("/center")
def center():
car.resetDir()
@post("/forward/<amount>")
def forwardWithSpeed(amount):
car.setSpeed(int(amount))
car.runForward()
@post("/backward/<amount>")
def backwardWithSpeed(amount):
car.setSpeed(int(amount))
car.runBackward()
@post("/speed/<amount>")
def speed(amount):
car.setSpeed(int(amount))
@post("/stop")
def stop():
car.stop()
@post("/siren")
def siren():
car.siren()
run(host="0.0.0.0", port=8080, debug=True)
The car needs tow Motors instances passed as parameters.
The Motor class receive 2 or 3 numbers. These numbers are raspberry pi pins out used to control the motor. For more information about the pins, you can see here
I think if I try to explain how the GPIOs are set and used to control the motor and change the speed, the article will be too long. But I think also that by just reading the code and little search, you can understand how it works.
The Car and The Motor classes are defined like this:
import RPi.GPIO as GPIO
import pygame
GPIO.setmode(GPIO.BCM)
class Motor:
def __init__(self, io1: int, io2: int, io3=-1) -> None:
self.io1 = io1
self.io2 = io2
GPIO.setup(io1, GPIO.OUT)
GPIO.setup(io2, GPIO.OUT)
if io3 > 0:
GPIO.setup(io3, GPIO.OUT)
self.io3 = GPIO.PWM(io3, 1000)
self.io3.start(60)
def forward(self):
GPIO.output(self.io1, GPIO.HIGH)
GPIO.output(self.io2, GPIO.LOW)
def backward(self):
GPIO.output(self.io1, GPIO.LOW)
GPIO.output(self.io2, GPIO.HIGH)
def stop(self):
GPIO.output(self.io1, GPIO.LOW)
GPIO.output(self.io2, GPIO.LOW)
def setSpedd(self, speed: int):
self.io3.ChangeDutyCycle(speed)
class Car:
def __init__(self, frontMotor: Motor, backMotor: Motor) -> None:
self.frontMotor = frontMotor
self.backMotor = backMotor
pygame.mixer.init()
pygame.mixer.music.load("siren.mp3")
pygame.mixer.music.set_volume(1.0)
def turnRight(self):
self.frontMotor.forward()
def turnLeft(self):
self.frontMotor.backward()
def resetDir(self):
self.frontMotor.stop()
def runForward(self):
self.backMotor.forward()
def runBackward(self):
self.backMotor.backward()
def stop(self):
self.backMotor.stop()
def setSpeed(self, speed: int):
self.backMotor.setSpedd(speed)
def siren(self):
if(pygame.mixer.music.get_busy()==0):
pygame.mixer.music.play()
else:
pygame.mixer.music.stop()
#to do : call this method on server stop
def cleanup():
GPIO.cleanup()
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