Arduino Bike Speedometer

Monitor your road speed using the Arduino. This project uses a magnetic switch (also called a reed switch) to measure the speed of one of the bike's wheels.  The Arduino calculates the mph, and send this information out to the LCD screen on the handlebars as you ride.  It is compatible with any kind of bike/wheel, simply enter the radius of the wheel in the firmware to calibrate the device for your setup.

Parts List:

(1x) Arduino Uno REV 3 Radioshack 276-128
(1x) Switch-Magnetic Reed Radioshack 55050593
(1x) 10K Ohm 1/4-Watt Carbon Film Resistor Radioshack #271-1335
(1x) 9V Alkaline Battery Radioshack #23-866
(1x) Heavy-Duty 9V Snap Connectors Radioshack #270-324
(1x) PC Board with Copper Radioshack #276-147
(1x) Parallax 27977-RT Serial Backlit LCD Radioshack 276-120
(x2) SPST PC-Mountable Submini Toggle Switch Radioshack #275-645
(2x) Male Header Pins Jameco 103393
(1x) Female Pin Sockets Jameco 308567

Additional Materials:
22 Gauge Wire Radioshack #278-1224
Solder Radioshack #64-013
sand paper
plywood
wood glue
hot glue
screws
zip ties
sugru

Download Arduino IDE

Step 1: Schematic

The schematic for this project is shown above.

It consists of three switches:
-one to connect to a 9V power supply
-one to switch the backlight of the LCD on and off
-a magnetic switch (called a reed switch) which closes each time the wheel completes one full rotation.

The Parallex LCD is designed to connect to the arduino using only three pins (ignore the labels and the other pins int his schematic).  One to 5V, one to ground, and a third to serial out (TX)- on the arduino, serial out is digital pin 1.

10kOhm resistors are connected to the reed and backlight switches to prevent excess current between 5V and ground (you should never directly connect 5V and ground on the arduino!)

Comments

[delphino-999]

Hey, nice project, but isn't it a little big?! :)
I know it's not so easy to keep things small, but i would suggest using an Arduino Nano or similar, and a smaller 3D Printed box...
And regarding the electronics of it, maybe use a dynamo and a rechargeable battery?
The older dynamo were pretty annoying, but i think the newer ones are pretty awesome, since they're so silent and have a bearly noticeable resistance (mechanical resistance) since they're in the center of the wheel.
Anyhow, nice project, i like these kinds of projects, because they're relatively easy to build and you can always improve them with fairly small efforts (eg. add average speed, driven distance, automatic standby when the wheel didn't turn for a certain amount of time, etc.), there are thousands of possibilities! :)

[allenkevan24]

So far I have everything working the way it should, but i can't get my lcd display to display anything at all but the backlight works fine. Any advice?

[amandaghassaei]

it's the same lcd? you might try some of these sketches just to make sure it's working.
http://learn.parallax.com/KickStart/27977

[12niraj12]

what is the total power lost in the ARDUINO developed speedometer.

[col0n]

Would this be possible to make with an arduino micro?

[amandaghassaei]

Yes

[shad0w88]

Nice!...Would this work for a motorcycle? With more added functionality like temp, battery or Fuel?

How about RPM can that be calculated?

[amandaghassaei]

probably, I think the limiting factor would be the speed of the reed switch- there is a mechanical piece in the switch that moves back and forth to complete the circuit. At 60mph, ~1ft radius tires rotate at 25-30 rotations per second. As long as the reed switch can switch back and forth that quickly you would be able to measure speed/rpm on a motorcycle

If you want the lcd to output rpm:
add:
float rpm = 0.00; //variable rpm
and insert the line:
rpm = float(6000)/float(timer);//calculate rotations per minute
after:
mph = (56.8*float(circumference))/float(timer);
and:
rpm=0;
after:
mph=0;

and create the function:
void displayRPM(){
Serial.write(12);//clear
Serial.write("RPM=");
Serial.write(13);//start a new line
Serial.print(rpm);
Serial.write(" RPM ");
//Serial.write("0.00 RPM ");
}

and call this function in the main loop when you would like to display the RPM

and yes you could definitely expand to include temp, battery, etc, there are plenty of available pinson the arduino.

[amandaghassaei]

I realized that the line should say:
rpm = float(60000)/float(timer);//calculate rotations per minute

[soshimo]

Why not use a Hall Effect sensor? There are no moving parts and it works off the disruption of a magnetic field. They are used in many high speed applications because of this. Those POV devices you see for bike wheels use a hall effect sensor to know when to flash the LEDs for the POV illusion.

[amandaghassaei]

hall effect sensor would work too

[tesladude123]

would you be able to post the whole rpm code please, i just cant get it to work.

Thanks.

[amandaghassaei]

//bike speedometer
//by Amanda Ghassaei 2012
//http://www.instructables.com/id/Arduino-Bike-Speedometer/

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

//outputs speed of bicycle to LCD

//calculations
//tire radius ~ 13.5 inches
//circumference = pi*2*r =~85 inches
//max speed of 35mph =~ 616inches/second
//max rps =~7.25

#define reed A0//pin connected to read switch

//storage variables
float radius = 13.5;// tire radius (in inches)- CHANGE THIS FOR YOUR OWN BIKE


int reedVal;
long timer = 0;// time between one full rotation (in ms)
float mph = 0.00;
float rpm = 0.00; //variable rpm 
float circumference;
boolean backlight;

int maxReedCounter = 100;//min time (in ms) of one rotation (for debouncing)
int reedCounter;


void setup(){
  
  reedCounter = maxReedCounter;
  circumference = 2*3.14*radius;
  pinMode(1,OUTPUT);//tx
  pinMode(2,OUTPUT);//backlight switch
  pinMode(reed, INPUT);
  
  checkBacklight();
  
  Serial.write(12);//clear
  
  // TIMER SETUP- the timer interrupt allows preceise timed measurements of the reed switch
  //for mor info about configuration of arduino timers see http://arduino.cc/playground/Code/Timer1
  cli();//stop interrupts

  //set timer1 interrupt at 1kHz
  TCCR1A = 0;// set entire TCCR1A register to 0
  TCCR1B = 0;// same for TCCR1B
  TCNT1  = 0;
  // set timer count for 1khz increments
  OCR1A = 1999;// = (1/1000) / ((1/(16*10^6))*8) - 1
  // turn on CTC mode
  TCCR1B |= (1 << WGM12);
  // Set CS11 bit for 8 prescaler
  TCCR1B |= (1 << CS11);   
  // enable timer compare interrupt
  TIMSK1 |= (1 << OCIE1A);
  
  sei();//allow interrupts
  //END TIMER SETUP
  
  Serial.begin(9600);
}

void displayRPM(){
Serial.write(12);//clear
Serial.write("RPM=");
Serial.write(13);//start a new line
Serial.print(rpm);
Serial.write(" RPM ");
//Serial.write("0.00 RPM "); 

void checkBacklight(){
  backlight = digitalRead(2);
  if (backlight){
    Serial.write(17);//turn backlight on
  }
  else{
    Serial.write(18);//turn backlight off
  }
}

ISR(TIMER1_COMPA_vect) {//Interrupt at freq of 1kHz to measure reed switch
  reedVal = digitalRead(reed);//get val of A0
  if (reedVal){//if reed switch is closed
    if (reedCounter == 0){//min time between pulses has passed
      mph = (56.8*float(circumference))/float(timer);//calculate miles per hour
      rpm = float(6000)/float(timer);//calculate rotations per minute 
      timer = 0;//reset timer
      reedCounter = maxReedCounter;//reset reedCounter
    }
    else{
      if (reedCounter > 0){//don't let reedCounter go negative
        reedCounter -= 1;//decrement reedCounter
      }
    }
  }
  else{//if reed switch is open
    if (reedCounter > 0){//don't let reedCounter go negative
      reedCounter -= 1;//decrement reedCounter
    }
  }
  if (timer > 2000){
    mph = 0;//if no new pulses from reed switch- tire is still, set mph to 0
    rpm=0; 
  }
  else{
    timer += 1;//increment timer
  } 
}

void displayMPH(){
  Serial.write(12);//clear
  Serial.write("Speed =");
  Serial.write(13);//start a new line
  Serial.print(mph);
  Serial.write(" MPH ");
  //Serial.write("0.00 MPH ");
}

void loop(){
  //print mph once a second
  //displayMPH();
  displayRPM();
  delay(1000);
  checkBacklight();
}

[tesladude123]

Thankyou. It works perfectly.

[motto20]

I am trying to understand your code (which works great by the way) and am wondering about your RPM and MPH calculations. Where do the values 56.8 and 6000 come from in each calculation? Thank you.

[amandaghassaei]

to convert inches/ms to miles/hr you must multiply by:
1miles/63360inches * 1000ms/sec * 60sec/min * 60min/hr = 56.8
and yes, I think I made a mistake, it should be 60,000 to calculate rpm from rev/ms:
1000ms/sec*60sec/min = 60000
thanks for catching that.

[s0700419]

Hi, I have tried the code which tests the reed sensor. When the sensor and magnet are in contact the Serial Monitor outputs 1023, as expected. When they are not in contact the serial monitor outputs a range of values from 0 to 1023. Can any advise on where I have gone wrong?

[David97]

Maby your 10k resistor is not connected between ground and A0 properley.

[amandaghassaei]

sounds right

[bobbydeep]

What changes in the schematic should I do mam in order to use this for a car?

[amandaghassaei]

well you'll have to use the hall sensor instead of the reed switch, how many pins does your hall sensor have, do you have a schematic?

[carmolim]

did you take a look in my code?

https://github.com/carmolim/cycloduino

[amandaghassaei]

does it work? do you have a specific question about it?

[carmolim]

hello.. is working... today I made the first on bike, and I found a max speed limitation... what can I do to remove this limitation?

[amandaghassaei]

what is the max speed you are seeing? btw this project looks awesome, will you post it as an instructable?

[carmolim]

I changed the maxReedCounter to 80, now I´m getting the maximum speed of 93 kph, I think...

well... I still have a long way ahead, butI´ll probably post the complete project here... I'm glad you liked the project I'm developing in my spare time and I'm having so much fun...

thank you for your help!

[bobbydeep]

I would like to know if this would work for a car?
That is can the reed switch be used for speeds upto 50kmph and car tyre radius of about 16 inches?

[amandaghassaei]

theoretically yes, I think your idea of using a hall effect sensor instead of a reed switch for this high frequency application is a good one.

[bobbydeep]

Also, mam can hall effect sensors be used ? will they work with this code and will they give pulses?

[amandaghassaei]

I think hall effect sensors would work with the code, though the schematic would change a bit.

[Adarsh_tronix]

Great Instructable.Appreciate it!

[myth21]

thanks i figured it out finally..

[myth21]

can you help me about the codes?? im not good at programming..code that can turn the led on depending on what is the measurement distance of the sensor?

[myth21]

http://www.youtube.com/watch?v=fZfSbN2ZwLw just like this one please?? thanks

[amandaghassaei]

start by try this code and seeing if you can output the distance with the serial monitor:
http://www.instructables.com/id/Easy-ultrasonic-4-pin-sensor-monitoring-hc-sr04/

[amandaghassaei]

here's another good link:
http://www.arduino.cc/en/Tutorial/Ping

[myth21]

actually i found some codes but it output the results to a piezo buzzer. and when i compile it says
"In file included from UltrasonicDemo.pde:8:
D:\arduino-1.0.2\libraries\Ultrasonic/Ultrasonic.h:11:22: error: WProgram.h: No such file or directory"

heres the code i found
//Vcc to 5 volt +
//Trig to pin 12
//Echo to pin 13
//Grd to Grd
//Piezo to pin 9
//GRD to GRD

#include "Ultrasonic.h"
Ultrasonic ultrasonic(12,13); //12,13 are pin assignements
intbuzzPin = 9; // positive connection of the piezo
int delay1 = 25;
void setup() {
Serial.begin(9600);

}

void loop()
{
Serial.print("cm :");
Serial.print(ultrasonic.Ranging(CM));
Serial.println("");
//delay(100);



if(ultrasonic.Ranging(CM) > 0 &&ultrasonic.Ranging(CM) <= 5)
{ tone(buzzPin, 100 ,100); delay(100);}
if(ultrasonic.Ranging(CM) > 5 &&ultrasonic.Ranging(CM) <= 10)
{tone(buzzPin, 100 ,100); delay(100);}
if(ultrasonic.Ranging(CM) > 10 &&ultrasonic.Ranging(CM) <= 20)
{tone(buzzPin, 15 ,100); delay(50);}
if(ultrasonic.Ranging(CM) > 20 &&ultrasonic.Ranging(CM) <= 30)
{tone(buzzPin, 14 ,100); delay(50);}
if(ultrasonic.Ranging(CM) > 30 &&ultrasonic.Ranging(CM) <= 40)
{tone(buzzPin, 13 ,100); delay(50);}

if(ultrasonic.Ranging(CM) > 40 &&ultrasonic.Ranging(CM) <= 60)
{tone(buzzPin, 12 ,100); delay(50);}
if(ultrasonic.Ranging(CM) > 60 &&ultrasonic.Ranging(CM) <= 90)
{tone(buzzPin, 11 ,100); delay(050);}
if(ultrasonic.Ranging(CM) > 90 &&ultrasonic.Ranging(CM) <= 120)
{tone(buzzPin, 10 ,100); delay(50);}
if(ultrasonic.Ranging(CM) > 120 &&ultrasonic.Ranging(CM) <= 200)
{tone(buzzPin, 9 ,100); delay(50);}
if(ultrasonic.Ranging(CM) > 120 &&ultrasonic.Ranging(CM) <= 200)
{tone(buzzPin, 8 ,150); delay(50);}
if(ultrasonic.Ranging(CM) > 200 &&ultrasonic.Ranging(CM) <= 300)
{tone(buzzPin, 9000 ,150); delay(50);}

}
i already put the files in the arduino library..but theres still error..can you help me.. thank you ..:)

[amandaghassaei]

you need to download a library called ultrasonic.h and add it to your libraries folder inside arduino

[myth21]

thanks.. ill try this..

[carmolim]

Hello again,

Just wanted to say that my project is hosted here: https://github.com/carmolim/cycloduino

I would like you to take a look to see if I am following in a good way and if possible give some suggestion.

Thank you.