Actions
Forum Thread Details
  • State Verified Answer
  • Replies 22 replies
  • Subscribers 402 subscribers
  • Views 2465 views
  • Users 0 members are here
Related

Python to Arduino to Motors...

wallarug

I have two reversable 12volt motors that I would like to control through PWM.  I want the speed to be constantly updated by the python code that will be sent through a TCP client-server.  I have the python piece of code working very well. I need some help with the Arduino Sketch please.  I have all the other pieces of code working except the Arduino Sketch.

 

I know everything about the hardware required (H-bridge, etc) but I need help with the sketch.

 

 

This is the Joystick Control and TCP client:

 

 

[code]import pygame

import socket

import sys

import os

pygame.init()

j = pygame.joystick.Joystick(0)

j.init()

 

print 'Initialized Joystick : %s' % j.get_name()

username = os.name

if username == "nt":

    username = "Windows"

print "Welcome commander, you are using " + username

 

 

 

 

a = 0

b = 0

aa = a

bb = b

 

 

 

 

 

 

 

 

i = raw_input("What do you want to detect?")

while i == "button":

    pygame.event.pump()

    #print j.get_axis(1)

    if j.get_button(1):

        print "Left"

    if j.get_button(0):

        print "Kill"

    if j.get_button(2):

        print "Right"

while i == "pos":

    pygame.event.pump()

    y = j.get_axis(1)   ######################################

    y = round(y,2)      # Increase to (x, 12) when using PWM!#

    x = j.get_axis(0)   #  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@   #

    x = round(x,2)      # Increase to (y, 12) when using PWM!#

    z = j.get_axis(2)   ######################################

    z = round(z,1)

    #print(x,y,z)

  

    if y < 0:          ############################

        y = abs(y)     #New Y-axes inversion code!#

    elif y > 0:        ############################

        y = y*-1

 

 

#############################################

# Formulas for working out the speed of the #

# motor in certain areas of the Joystick!   #

#############################################

 

 

    f = 1

    sy = f*(y)

    sx = f*(x)

   

 

 

#############################################

## Whenever the ROBOT is moving and the     #

##  Co-ordinates are not (0,0)              #

#############################################

 

 

                               

    if x != 0 and y != 0:      

        sy = abs(sy)                    #######

        if y > abs(x) and y > 0:        # Top!#

                                        ############

            if -1 < x < 0:              # Top Left!#

                                        ############################################

                c = abs(x)              # Convert to percentage and positive value!#

                a = (sy) - (c)          ############################################

                b = (sy)

                                        #############

            elif 0 < x < 1:             # Top Right!#

                                        ############################################

                d = abs(x)              # Convert to percentage and positive value!#

                b = (sy) - (d)          ############################################

                a = (sy)

            else:

                a = abs(x)

                b = abs(x)

 

 

                                        ##########

        elif y < -abs(x) and y < 0:     # Bottom!#

                                        ###############

            if -1 < x < 0:              # Bottom Left!#

                                        ############################################

                c = abs(x)              # Convert to percentage and positive value!#

                a = (sy) - (c)          ############################################

                b = (sy)

                                        ################

            elif 0 < x < 1:             # Bottom Right!#

                                        ############################################

                d = abs(x)              # Convert to percentage and positive value!#

                b = (sy) - (d)          ############################################

                a = (sy)

            else:                       ############################################

                a = abs(sy)             # So that values "a" and "b" are regonised #

                b = abs(sy)             #  by python reader (I had problems)!      #

                                        ############################################

 

 

 

 

                                           

#################################

# Special formula for when you  #

#   leave the "allowed" area    #

#################################

 

 

        elif y < abs(x) and y > -abs(x): 

            if x < 0:

                b = abs(x)

                a = 0

            elif x > 0:

                a = abs(x)

                b = 0

            else:

                a = 0

                b = 0

 

 

 

 

 

 

##################################

# Special Formula for all values #

#  on the x-axis for immediate   #

#    turning.                    #

##################################

 

 

    elif y == 0:

        if x < 0:

            a = 0

            b = abs(sx)

        elif x > 0:

            a = abs(sx)

            b = 0

        else:

            a = 0

            b = 0

 

 

 

 

 

 

#######################################

#  Anything else that is not defined  #

#   (Only when x and y = 0)           #

#######################################

 

 

    elif x == 0:

        a = abs(sy)

        b = abs(sy)

 

 

    else:

        a = 0

        b = 0

       

              

 

 

######################################

### PWM convetion for AnalogueWrite()#

######################################

 

 

    PWM = 255

    a = PWM*a

    a = round(a,0)

    a = int(a)

    b = PWM*b

    b = round(b,0)

    b = int(b)

 

 

 

 

 

 

 

 

####################################

# Printing Output - Only used in   #

# development of Joystick Control. #

####################################

 

 

    #print (a,b)

 

 

########################

# TCP client is below. #

########################

 

 

    data = (a,b)

    HOST, PORT = "192.168.12.12", 9999

    #HOST2, PORT2 = "10.88.112.174", 9998 # Change to server when necessary

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    sock.connect((HOST, PORT))              ## CIAN HAS CHANGED!!##

    ##sock.sendall(str(data) + "\n")

    ##print "Sent:     {}".format(data)

 

 

    if a != aa or b != bb:

        sock.sendall(str(data) + "\n")

        print "Sent:     {}".format(data)

##    elif a == aa and :

##        print (int(a),int(b))

 

 

    aa = a

    bb = b

 

 

 

 

#####################################################

##@@@@@@@@@@@@@@@@@@@@@@ END @@@@@@@@@@@@@@@@@@@@@ ##

#####################################################[/code]

 

 

This seems to work ok, I am working on getting the TCP Client quicker - so that is a bit of a mess right here.

 

 

This is how far I have gotten with the Arduino Sketch:

 

 

[code]/*

* Robot Motor Controller script with PWM speed control

*/

//---------------------- Motors

int motorL[] = {6, 7};

int motorR[] = {8, 9};

int ledPin = 13;

int motor_a = 0;

int motor_b = 0;

int dir_y = 5;

 

 

 

 

void setup() {

Serial.begin(9600);

int i;

for(i = 0; i < 2; i++){

pinMode(motorL[i], OUTPUT);

pinMode(motorR[i], OUTPUT);

pinMode(ledPin, OUTPUT);

}

 

 

}

 

 

void loop() {

drive_forward(); {

digitalWrite(motorL[0], HIGH);

digitalWrite(motorL[1], LOW);

digitalWrite(motorR[0], HIGH);

digitalWrite(motorR[1], LOW);

analogWrite(9, motor_a);

analogWrite(6, motor_b);

}

drive_backwards(); {

digitalWrite(motorL[0], LOW);

digitalWrite(motorL[1], HIGH);

digitalWrite(motorR[0], LOW);

digitalWrite(motorR[1], HIGH);

analogWrite(9, motor_a);

analogWrite(6, motor_b);

}

}

 

 

void if(y < 0) drive_foreward()

 

 

void if(y > 0) drive_backwards()[/code]

 

 

No surprise that it doesn't work.  I want it to read three values from the Python script which are the speed of the left motor (defined as "a"), speed of the right motor (defined as "b"), direction of motor (which is defined as "y" - when it is <0 it goes backwards or >0 goes forward).

 

 

For the [b]varying speed controls[/b], I will be using PWM (values between 0 -> 255) which uses the "analogWrite(Pin, value)" Syntax.  These values will be changing via the "a" and "b" values from the python script.

 

 

Is there anyway that you can help me with this.  I am really struggling.

 

 

Thanks in advance to anyone who can help.

Parents
  • 0

    ValueError: chr() arg not in range(256)

    How can I fix this?  The numbers that I am producing ARE in the range of 0-255.  (does that mean including 0? and 255?)

     

    This is a problem in the TCP client which is sending the data.

  • 0 in reply to wallarug

    Look at the tutorial again and instead of set up put it in the loop void

  • 0 in reply to evan.stoddard

    I should have mentioned that the above error was produce by python.  The PWM frequency problem has been solved.  I Accually just needed to ad some 470R Resistors into the circuit and then everything worked fine.

    The chr() command is in the python script and seems to be the only command that the Ardunio will interpret and then 'push' to the PWM channels.  I tried using int() and str() but they where not interpereted by the Ardunio once sent via the TCP.  I am going to try and divid by 16 in python and then Multiply by 16 in Ardunio.  This should fix the issue.  Would I put the 196 inside or outside of these brackets?

     

    if(Serial.available()==3)

    {

      Byte1 = Serial.read(); // Incoming data from Serial connection

      motor_a = int(Byte1);

      Byte2 = Serial.read(); // Incoming data from Serial connection

      motor_b = int(Byte2);

      Byte3 = Serial.read(); // Incoming data from Serial connection

      dir_y = int(Byte3);

  • 0 in reply to wallarug

    inside the brackets and i have no idea about the python script.  I dont know python that well

  • 0 in reply to evan.stoddard

    Don't worry, I found the problem ( I think).  There was a double-up in the rules and this casued the values to multiple by 2.  This caused the values to fall outside of the range of 0 -256.  I solved the prblem by re-writing ALL of the rules so that each specific case was solved and there was NO double ups.  This didn't take to long but it was was well worth the fix.

     

    No issues with python or Ardunio any more.  I will see if I can upload something here later to show you how far it has come.

     

    LED issue was solved (I think I said this before) and now has 2k2 transistors in place of 470R, which means that You can see more different when PWMing.

     

    I'll get back here if/when I have more problems, but for now I think everything is working correctly.

     

    Thanks for all your help with the Arduino.

Reply
  • 0 in reply to evan.stoddard

    Don't worry, I found the problem ( I think).  There was a double-up in the rules and this casued the values to multiple by 2.  This caused the values to fall outside of the range of 0 -256.  I solved the prblem by re-writing ALL of the rules so that each specific case was solved and there was NO double ups.  This didn't take to long but it was was well worth the fix.

     

    No issues with python or Ardunio any more.  I will see if I can upload something here later to show you how far it has come.

     

    LED issue was solved (I think I said this before) and now has 2k2 transistors in place of 470R, which means that You can see more different when PWMing.

     

    I'll get back here if/when I have more problems, but for now I think everything is working correctly.

     

    Thanks for all your help with the Arduino.

Children