arduino nano bike speedometer

arduino nano bike speedometer and odometer
arduino nano bike speedometer and odometer

I tricked out my dad bike with an arduino nano based speedometer, odometer, clock, and temperature sensor.

A DS3231 RTC keeps the time and temperature.  I implemented a attachInterrupt() function to keep track of tire rotation via a reed switch.

reed switch for a bike speedometer / odomoeter using an arduino nano
reed switch for a bike speedometer / odomoeter using an arduino nano

This way, I do not have to programmatically monitor  the reed switch;  a routine is executed (in this case that calculates the distance traveled) each time the state of the digital pin the switch is connected to changes.

 //bike speedometer
#include "RTClib.h"
RTC_DS3231 rtc;

char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 10;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

float start, finished;
float elapsed, time;
//float circMetric=2.164; // wheel circumference relative to sensor position (in meters)
float circMetric=1; // wheel circumference relative to sensor position (in meters)
float circImperial; // using 1 kilometer = 0.621371192 miles
float speedk, speedm;    // holds calculated speed vales in metric and imperial
float miles_traveled = 0;
float feet_traveled = 0;
char miles[100];

void setup () {
  attachInterrupt(0, speedCalc, CHANGE); //digital pin 2
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("BIKE SPEEDOMETER!");
  circImperial=circMetric*.62137; // convert metric to imperial for MPH calculations

  //rtc stuff
  int temp = 0;

  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }//end if

  if (rtc.lostPower()) {
    Serial.println("RTC lost power, lets set the time!");
    // following line sets the RTC to the date & time this sketch was compiled
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
  }//end if rtc lost power
}//end setup

void speedCalc()
  speedk=((3600*circMetric)/elapsed) * 0.12; // km/h
  speedm=((3600*circImperial)/elapsed) * 0.12; // Miles per hour
  feet_traveled += 1.1; 
  miles_traveled = feet_traveled / 5280; 
  //sprintf(miles, "%.2f", miles_traveled);

void loop()
  DateTime now =;  
  int temp = 0;

  //lcd.print(" km/h ");
  lcd.print(" MPH   ");
  lcd.print(" mi");;
  //lcd.print(" ms/rev      ");
  lcd.print(now.hour(), DEC);
  lcd.print(now.minute(), DEC);
  lcd.print(now.second(), DEC);
  lcd.print(' ');
  temp = rtc.getTemperature() * 9/5 + 32;
  delay(1000); // adjust for personal preference to minimise flicker


arduino bike speedometer
arduino bike speedometer

“When Morning Guilds the Skies” arranged by Mark Hayes

Bach said music’s purpose is, “for the glory of God, and the refreshment of the Human spirit”.  I am playing this arrangement of ‘When Morning Guilds the Skies’ for offertory at Cathedral Baptist Church on 10-27-2019.  I am thankful for every opportunity I have to do music in God’s house.

1   Rejoice in the LORD, O ye righteous: for praise is comely for the upright.
2 Praise the LORD with harp: sing unto him with the psaltery and an instrument of ten strings.
3 Sing unto him a new song; play skillfully with a loud noise.
Psalms 33:1-3

homemade bluetooth work speaker that kicks

home made 25W stereo bluetooth speaker project
home made 25W stereo bluetooth speaker project

I have a huge project going on at work right now, and loud music is absolutely essential.  I ordered some Boss CH3220 140W speakers and used a 25W bluetooth audio amplifier board and whipped up in one evening a killer work speaker that kicks hard.

It is working great as is, but I am totally not done.  I am going to add a raspberry pi to play my saved mp3’s and roll some of my own features.

25W bluetooth audio amplifier board
25W bluetooth audio amplifier board

I am very impressed with the quality of the sound and how easy it was to pair with this board.  I tested the speakers with ‘dont tread on me’ by metallica.  The frequency response of these 3.5″ speakers is surprisingly very good.