control current with paralell resistor to 5v motor

system · August 9, 2011, 8:12am

// made by StoneSizzerPaper
// feel free to reply
/*
project: control motor speed (in free run);

for this project:
8 x 560R resistors
1 x breadboard/circuitboard
8 green LED
1 blue LED
5v motor,20mA free runn, this one was 13ohm (motor)
Arduino duemilanove
jump wires maybe.

the circuit:
GND =>-motor
motor+ => R1(560) => - LED1+ => digital in (2)
motor+ => R2(560) => - LED2+ => digital in (3)
motor+ => R3(560) => - LED3+ => digital in (4)
motor+ => R4(560) => - LED4+ => digital in (5)
motor+ => R5(560) => - LED5+ => digital in (6)
motor+ => R6(560) => - LED6+ => digital in (7)
motor+ => R7(560) => - LED7+ => digital in (8)
motor+ => R8(560) => - LED8+ => digital in (9)
motor+=-LEDblue+ => -motor

Program
Eenter number between 0 and 8 to control speed of motor.
*/

void setup(){
Serial.begin(9600);
pinMode(2,OUTPUT);
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(7,OUTPUT);
pinMode(8,OUTPUT);
pinMode(9,OUTPUT);
}
byte inByte;
void loop()
{
if (Serial.available() > 0) {
inByte = Serial.read();
if (inByte == '0'){
Serial.println("0 W");
digitalWrite(2,LOW); digitalWrite(3,LOW); digitalWrite(4,LOW); digitalWrite(5,LOW);
digitalWrite(6,LOW); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}

if (inByte == '1'){// 0.06v 0,00519
Serial.println("0,3114 mW");
digitalWrite(2,HIGH); digitalWrite(3,LOW); digitalWrite(4,LOW); digitalWrite(5,LOW);
digitalWrite(6,LOW); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '2'){//0.12v 0,00997A
Serial.println("1,1964 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,LOW); digitalWrite(5,LOW);
digitalWrite(6,LOW); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '3'){//0.18v 0,01128A
Serial.println("2,0304 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,LOW);
digitalWrite(6,LOW); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '4'){//0.23v 0,01242
Serial.println("2,8566 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,HIGH);
digitalWrite(6,LOW); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '5'){//1.31v 0,0135A
Serial.println("17,685 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,HIGH);
digitalWrite(6,HIGH); digitalWrite(7,LOW); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '6'){//1,75v 0,0135A
Serial.println("23,625 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,HIGH);
digitalWrite(6,HIGH); digitalWrite(7,HIGH); digitalWrite(8,LOW); digitalWrite(9,LOW);
}
if (inByte == '7'){//1,89 0,0146A
Serial.println("27,594 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,HIGH);
digitalWrite(6,HIGH); digitalWrite(7,HIGH); digitalWrite(8,HIGH); digitalWrite(9,LOW);
}
if (inByte == '8'){// 2,00v 0,015A
Serial.println("30,00 mW");
digitalWrite(2,HIGH); digitalWrite(3,HIGH); digitalWrite(4,HIGH); digitalWrite(5,HIGH);
digitalWrite(6,HIGH); digitalWrite(7,HIGH); digitalWrite(8,HIGH); digitalWrite(9,HIGH);
}
}
}

cr0sh · August 9, 2011, 6:32pm

StoneSizzerPaper:
// made by StoneSizzerPaper
// feel free to reply

Use the code button (#) on the editor.
This is a poor way to hook up a motor to the Arduino.
Try to turn on more than one motor at "full power", and you're likely to burn something out on the Arduino.

The proper way to control a motor is with a relay/transistor/MOSFET (single direction), or via an h-bridge of some sort (once again, composed of relays/transistors/MOSFETs); you also can't neglect the flyback diodes, either (as well as noise suppression capacitors on the motor itself).

If your example hasn't burned out your Arduino yet, it is surely on its way.

Read the following tutorials to gain a better understanding of what to do right (from Mike Cook's - aka Grumpy_Mike's - website):

http://www.thebox.myzen.co.uk/Workshop/Introduction.html

system · August 9, 2011, 8:32pm

I use the blue LED as the fly-back diode. I calculated the paralell circut to sum of 0,05A trugh the motor. On full trottle. Any fastere i would've burn out the arduino. The green diodes prevent analog port draw current on LOW pins from HIGH pins.

system · August 9, 2011, 10:27pm

Huh. LED's for flyback? Never thought of that for some reason.. though I suppose there's no reason it wouldn't work. I don't know if it would be a good idea on a large coil with a big spike, but I guess a diode is a diode is a diode whether it emits light or not..

Grumpy_Mike · August 9, 2011, 10:38pm

but I guess a diode is a diode is a diode whether it emits light or not.

Yes but check the data sheet an LED has a poor reverse breakdown and poor reverse current ratings. That is they are quite easy to blow up.

system · August 9, 2011, 11:17pm

I was going to use a real fly-back diode on my breadboard, but the leads on that diode are thicker than the holes in my breadboard.

Grumpy_Mike · August 10, 2011, 5:42am

So that's alright then, laws of physics will change because of that.

system · August 10, 2011, 3:28pm

Yeah that's what I was thinking. They can't have anywhere near the tolerances that a "standard" diode has.. but for something tiny, it would work, at least for a while. For that matter, I guess it would be fine to use a transistor connected as a diode.. better than nothing but surely going to fail long before using the proper device for the job.

I'm a huge fan of doing things the wrong way just to see if it will work.. I think we file this in the "Works but Not Recommended" column of EE Design. Come to think of it, I had to check twice that it wasn't me in the first place, being so cruel to those little 'lectrons

system · August 10, 2011, 4:53pm

some recommendations:
use switch case instead of if if if
use transistors and diodes
control the current in a binary way wit R1 = 50 ohm; r2 = 100 ohm; r3 = 200 ohm etc.
or better, use PWM.
Use a H-bridge to control the motor in both directions

system · August 11, 2011, 2:01am

hmm yes this was nicer...

/*
project: control motor speed (in free run);

for this project:
8 x 560R resistors
1 x breadboard/circuitboard
8 green LED
1 blue LED
5v motor,20mA free runn, this one was 13ohm (motor) 
Arduino duemilanove
jump wires maybe.

the circuit:
GND =>-motor
motor+ => R1(560) => - LED1+ => digital in (2)
motor+ => R2(560) => - LED2+ => digital in (3)
motor+ => R3(560) => - LED3+ => digital in (4)
motor+ => R4(560) => - LED4+ => digital in (5)
motor+ => R5(560) => - LED5+ => digital in (6)
motor+ => R6(560) => - LED6+ => digital in (7)
motor+ => R7(560) => - LED7+ => digital in (8)
motor+ => R8(560) => - LED8+ => digital in (9)
motor+=-LEDblue+ => -motor (If you can use a real flyback diode)
(LED1 - LED8 can also be a real flyback diode, but use higher resistor for R1 - R8);

Program
Enter number between 0 and 8 to control speed of motor.
*/

byte ledPins[] = {0,2,3,4,5,6,7,8,9};


void setup()
{// setup 
  Serial.begin(9600);
  for(byte cnt=1;cnt<9;cnt++)//if cnt is les than 9 then add 1 and execute serial and set pin mode
  {Serial.println(cnt,DEC); pinMode(ledPins[cnt],OUTPUT);}
  pinMode(13,OUTPUT);//program run indicator
}// end of setup
byte inByte;

void loop()
{// Start of looping program
if (Serial.available() > 0) {
    inByte = Serial.read();

    switch (inByte) 
    {//switch cases starts here
     case '0':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}break;
     case '1':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<2;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '2':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<3;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '3':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<4;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '4':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<5;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '5':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<6;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '6':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<7;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '7':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<8;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
     case '8':for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],LOW);}for(byte cnt=1;cnt<9;cnt++){digitalWrite(ledPins[cnt],HIGH);}break;
 }//switch cases ends here
} else 
{//if no serial trafic, blink
digitalWrite(13,HIGH);
delay(100);
digitalWrite(13,LOW);
delay(100);
}// end of else

}//end of loop routine code

Grumpy_Mike · August 11, 2011, 8:16pm

See a pattern in those case statements?
You can get rid of them altogether and just have two for() loops.

Hint

the first loop happens in every case so just do it
use the inByte variable as the limit counter in the second loop.

system · August 12, 2011, 7:13am

the first loop happens in every case so just do it

use the inByte variable as the limit counter in the second loop.

- that will cause all pinout to LOW, what ever input is
- '0' is a string not a number.

Grumpy_Mike · August 12, 2011, 8:34am

No because that is what you do now followed by setting the outputs
Convert it to a number. It is a single char so an OR with 0xf is all that is needed

system · August 12, 2011, 9:53am

I stick to KISS.

Grumpy_Mike · August 12, 2011, 8:41pm

Your choice but it makes you look like a rank beginner.

system · August 12, 2011, 10:10pm

Your choice but it makes you look like a rank beginner.

Yep. But look can desive....

Grumpy_Mike · August 13, 2011, 7:54pm

I think you mean looks can deceive.

Inability to use a spell checker can't (I am dyslexic)

system · August 13, 2011, 8:44pm

some recommendations:
use switch case instead of if if if
use transistors and diodes
control the current in a binary way wit R1 = 50 ohm; r2 = 100 ohm; r3 = 200 ohm etc.
or better, use PWM.
Use a H-bridge to control the motor in both directions

Now I am ready to try this out.

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control current with paralell resistor to 5v motor

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