The arduino can't seem to output correctly

Question

i am a beginner at python and I am average at Arduino and I had the idea of using both of them together for a project. I have been trying to make a Arduino + Python car which I can control with my computer. I have used Pyfirmata and the code seems perfect to me. When I run the code from CMD i have a weird bug/issue. I have uploaded Standard Firmata to the arduino UNO. I get no errors while uploading or running its just that its output is messed up.

Here's the Python Code:

from pyfirmata import Arduino, util
import time
board = Arduino("COM3")
MotorLeft = board.get_pin('d:10:o') # Assigning output to PIN
MotorRight = board.get_pin('d:11:o') # Assisging output to PIN 
play = True
while play:
 control = input(
 print("Enter W, A or D to move forwards, left or right. Enter 0 to exit"))
 if control != 0:
 if control == "W" or "w":
 MotorRight.write(1)
 MotorLeft.write(1)
 time.sleep(1)
 MotorRight.write(0)
 MotorLeft.write(0)
 if control == "A" or "a":
 MotorLeft.write(1)
 time.sleep(1)
 MotorLeft.write(0)
 if control == "D" or "d":
 MotorRight.write(1)
 time.sleep(1)
 MotorRight.write(0)
 else:
 print("Invalid Commmand")
 else:
 print("Exited Succesfully")
 play = True

Currently I have not built the car, I am using a pair of LEDs to do what the motors function and to test out the code.

Heres the CMD response:

Here is the link for the output video. I entered "W" which should ideally turn on both of the LEDs however, both of them turn on then off and then turn on off one by one.

https://youtu.be/DjUkkpzF0so

• smajli: Is it possible to see what is your Arduino code?
• Juraj: @smajli, Arduino code is PyFirmata

Answer 1

I cannot check it, but I guess you have to change the or commands like:

if control == "W" or "w":

Change to

if ((control == 'W') or (control == 'w'))

And similar for the other if statements.

Also, you can do not need to check for control == 0, since it will not be a character otherwise.

Besides that, the elif (else if) construct is normally used in Python, so instead of:

if control != 0:
 if control == "W" or "w":
 MotorRight.write(1)
 MotorLeft.write(1)
 time.sleep(1)
 MotorRight.write(0)
 MotorLeft.write(0)
 if control == "A" or "a":
 MotorLeft.write(1)
 time.sleep(1)
 MotorLeft.write(0)
 if control == "D" or "d":
 MotorRight.write(1)
 time.sleep(1)
 MotorRight.write(0)
 else:
 print("Invalid Commmand")

You can write:

if ((control == 'W') or (control == 'w')):
 MotorRight.write(1)
 MotorLeft.write(1)
 time.sleep(1)
 MotorRight.write(0)
 MotorLeft.write(0)
elif ((control == 'A') or (control == 'a')):
 MotorLeft.write(1)
 time.sleep(1)
 MotorLeft.write(0)
elif ((control == 'D') or (control == 'd')):
 MotorRight.write(1)
 time.sleep(1)
 MotorRight.write(0)
else:
 print("Invalid Commmand")

Also, you can combine the or in a list (but I cannot check it, no python compiler at hand), e.g.

if (control in ['W', 'w']):

• SKAI: Thank You. I will try to make these changes
• SKAI: Thank You! This project works now! Do you know what causes this problem? so I can avoid this problem in the future.
• Michel Keijzers: Great to hear, you can accept my answer than, to let others notify the problem has been solved.
• Chad G: if control=='W' or 'w' since 'w' is not equal to 0, this will always be true, its the same as writing if control=='W' or True