Bike Auto-Turn Signal

This project is a turn signal for my E-bike that I take to and from school every day. There is a spring-loaded rocker switch with a left and a right arrow, which trigger the corresponding signals to start blinking. After a turn is made, it automatically shuts off the turn signal.

In this video, I demonstrate the operation of the turn signals from hitting the desired directional arrow on the rocker switch to the signal shutting off automatically after the turn is made.

Process

Discussion

During the in-class crit, I received two comments in particular that stuck with me and inspired me to go back and overhaul my original design that I brought to the crit that day. First, Garth made a very, very good point: more. heat. shrink. There was a short happening somewhere in my circuit, and it was inevitable because I had two connections touching that shouldn't have been touching in the first place. It was just too messy! Adding heat shrink over all of my exposed soldered connections helped make my project what it is now: functional. Before, it was just too messy to be sure it would work-- I could do something as simple as hit a small pot hole, and it could cause two of my connections to touch. Now, this isn't a worry! Plus, I also have to worry less about wire-to-wire connections coming undone because of the heat shrink's added durability to the connections. The second comment came from Zach himself. This was also integral to the future of my device: creating "j" shaped connections between every single wire, then soldering them together. Similar to the issue of the lack of heat shrink, I was having a lot of my wire-to-wire or wire-to-pin connections keep coming off! I have never had this happen to me before with my soldering, but this was also my first time making a lot of connections with solid wire to solid wire. Using the technique of creating a "j" hook between the two wires and then adding the solder made all of my connections stronger, and at least until this point, unbreakable! Again, adding in the heat shrink only helped!

As of right now, although I am proud of how far this project has come, I am still a tad unsatisfied, and therefore, it's a work in progress. Even though it can be powered with a battery pack, and this is my preferred method, I am confused as to why a 9V battery only works 70% of the time. The other 30% of the time, it will have the side of LEDs that were triggered get stuck on solid red and not shut off. I learned about a voltage regulator from Zach and implemented one, but it still has issues!  To be fair to myself, though, I am very proud of this system I've created. When running on a battery pack, it's very robust. As demonstrated in the video, it works very well and exactly as intended. I am especially proud of the auto-turn-off's robustness. I really got the sensitivity to the perfect amount (which happened to be + or - 20 degrees), so even if I'm not making a full 90-degree turn, it senses that I've made a change in direction. Although in the beginning I was hoping to make the auto-turn-off be purely mechanical for longevity's sake (i.e., turning my handles would hit a switch), I think that the digital compass ended up being a better solution to my problem and ultimately will be better in the long run because of how easily it can be adjusted if needed. I also really impressed myself with the cable that I made. It was really cool to take the knowledge I gained from working on the Plush Neuron over the summer, and the 200+ hours of soldering and fabrication that I put into it, and transfer that to my own application. Without having that prior experience, I wouldn't have known how to make my own custom cable/connections in the way that I did, and I think that really made this project special for me. It showed me that I really did grow this summer, and even more by applying that knowledge to another context. Overall, I hope to keep tweaking this turn signal so that I can use it daily on my bike rides to and from school/work. In fact, it's completely usable how it is right now! I just want to tweak some aspects, like the power supply issues, before permanently installing it on my bike. 

/*Zarmond D. Goodman (zdgoodma)

60-223 - Intro to Physical Computing

Fall 2025

Project 2: Bike Auto-Turn Signal

  A turn signal for my bike that automatically detects turns and shuts off once completed.

Pin mapping:

  Arduino pin | role  |  description

  -------------------------------------

  2            input    compass SDA

  3            input    compass SCL

  15           output   left LED data

  14           output   right LED data

  8            input    left DPDT signal

  9            input    right DPDT signal

*/

#include <Adafruit_NeoPixel.h>  // LED library

#include <QMC5883LCompass.h>    //compass library

QMC5883LCompass compass;  // create object for compass

#define LEFT_LED_PIN 15  // Which pin on the Arduino is connected to the NeoPixels?

#define RIGHT_LED_PIN 14

#define LED_COUNT 48  // How many NeoPixels are attached to the Arduino?

//variables for the pins connected to the DPDT switch

const int LEFTBUTTON = 8;

const int RIGHTBUTTON = 9;

bool hasTurned = false; //var that stores if turn has been made

// Declare NeoPixel strip objects:

Adafruit_NeoPixel leftPixels(LED_COUNT, LEFT_LED_PIN, NEO_GRB + NEO_KHZ800);

Adafruit_NeoPixel rightPixels(LED_COUNT, RIGHT_LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {

  pinMode(LEFTBUTTON, INPUT_PULLUP);

  pinMode(RIGHTBUTTON, INPUT_PULLUP);

  leftPixels.begin();  // initialize NeoPixel strip objects

  rightPixels.begin();

  Serial.begin(9600); // initialize for compass data and debugging (compass needs to write to serial)

  compass.init();  // initialize compass

}

void loop() {

  int leftState = digitalRead(LEFTBUTTON); //var storing left button presses

  int rightState = digitalRead(RIGHTBUTTON); //var storing right button presses

  // Read compass values

  compass.read();

  // Return Azimuth reading and store it in a var

  int azimuthVal = compass.getAzimuth();

  //Serial.println(azimuthVal);

  delay(250);

//When wanting to turn left:

  if (leftState == LOW) { //if left signal is pressed

    int startTurnPos = azimuthVal; //record current azimuth directional value

    while (hasTurned == false) { //until I turn, keep blinking the LEDs

      compass.read(); //read current compass values

      int currentPos = compass.getAzimuth(); //record my current position when the turn signal is initiated

      //Serial.println(currentPos);

      if (abs(startTurnPos - currentPos) > 20) { //if my azimuth changes by 20 in either direction then:

        delay(5000);

        hasTurned = true; //I have turned

      }

      //This for loop is what makes the LEDs continuously blink

      for (int i = 0; i < LED_COUNT; i++) {  // For each pixel...

        // pixels.Color() takes RGB values, from 0,0,0 up to 255,255,255

        // Here we're using a moderately bright green color:

        leftPixels.setPixelColor(i, leftPixels.Color(255, 0, 0));

        leftPixels.show();  // Send the updated pixel colors to the hardware.

      }

      delay(500);

      leftPixels.clear(); //this turns off the LEDs creating the blink effect

      leftPixels.show();

      delay(500);

    }

  }

//When wanting to turn right:

  if (rightState == LOW) { //if right signal is pressed

    int startTurnPos = azimuthVal; //record current azimuth directional value

    while (hasTurned == false) { //until I turn, keep blinking the LEDs

      compass.read(); //read current compass values

      int currentPos = compass.getAzimuth(); //record my current position when the turn signal is initiated

      //Serial.println(currentPos);

      if (abs(startTurnPos - currentPos) > 20) { //if my azimuth changes by 20 in either direction then:

        delay(5000);

        hasTurned = true; //I have turned

      }

      //This for loop is what makes the LEDs continuously blink

      for (int i = 0; i < LED_COUNT; i++) {  // For each pixel...

        // pixels.Color() takes RGB values, from 0,0,0 up to 255,255,255

        // Here we're using a moderately bright green color:

        rightPixels.setPixelColor(i, rightPixels.Color(255, 0, 0));

        rightPixels.show();  // Send the updated pixel colors to the hardware.

      }

      delay(500);

      rightPixels.clear(); //this turns off the LEDs creating the blink effect

      rightPixels.show();

      delay(500);

    }

  } else { //if nothing is pressed, then the signals stay off

    //    Serial.println("off");

    rightPixels.clear();

    rightPixels.show();

    leftPixels.clear();

    leftPixels.show();

  }

}

/*References:

https://forum.arduino.cc/t/qmc5883l-calibration/686843 for calibration help

https://kunkune.co.uk/soldering/how-to-interface-the-gy-271qmc5883l-compass-magnetometer-with-arduino/ intital compass setup help

*/