Week 7: Input Devices
Add a sensor to a microcontroller board and read it

This week was much less painful compared to week 4 and 5. I think I have finally gotten over the initial learning curve of electronics design (using Fusion Eagle, finding components, making sure they are pointed to the right pins on your microcontroller) and electronics production (milling your board, soldering the components, and testing your board). This week was fun! I connected a MPU6050 which is an accelerometer / gyroscope to sense movement - this was my input device. Follow along to watch me set up and test the

I watched a few videos and used AI to figure out that I needed to install the MPU6050 Adafruit library on Arduino to test my sensor.

In this video, I viewed the motion data on the serial monitor in Arduino.

My final project involves using motion to then be visualized into light. I wanted to do a rough test this week to translate motion into changing the LED color.

Before connecting my MPU6050 - I watched a few videos (as mentioned above). In this screenshot, I used it to confirm that I connected the sensor to the right pins.

I used the multimeter to make sure the connector pins were connected to my MPU6050 properly.

Here is the first code I used to get the LED to blink when the MPU was moving. I didn't love the result because it would only turn red and not green. So I tweaked the thresholds for color change and told the LED to turn off when there was no motion detected.

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
Adafruit_MPU6050 mpu;
#define RED_PIN 3
#define GREEN_PIN 4
#define BLUE_PIN 5

unsigned long lastMotionTime = 0;    // Stores the time of the last detected motion
const unsigned long motionTimeout = 3000;  // Time in milliseconds to reset to yellow after no motion

void setup(void) {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println("Adafruit MPU6050 test!");

  // Initialize MPU6050
  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050 chip");
    while (1) delay(10);
  }
  Serial.println("MPU6050 Found!");

  // Set up motion detection
  mpu.setHighPassFilter(MPU6050_HIGHPASS_0_63_HZ);
  mpu.setMotionDetectionThreshold(1);
  mpu.setMotionDetectionDuration(20);
  mpu.setInterruptPinLatch(true);
  mpu.setInterruptPinPolarity(true);
  mpu.setMotionInterrupt(true);

  // Initialize RGB LED pins
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(BLUE_PIN, OUTPUT);
  // Start with yellow light for minimal motion
  setRGBColor(HIGH, HIGH, LOW);
  delay(100);
}
// Function to set LED color with digital control
void setRGBColor(int red, int green, int blue) {
  digitalWrite(RED_PIN, red);
  digitalWrite(GREEN_PIN, green);
  digitalWrite(BLUE_PIN, blue);
}
void loop() {
  // Check if motion interrupt status is true (motion detected)
  if (mpu.getMotionInterruptStatus()) {
    sensors_event_t a, g, temp;
    mpu.getEvent(&a, &g, &temp);
    // Update the last motion time
    lastMotionTime = millis();
    Serial.print("AccelX:");
    Serial.print(a.acceleration.x);
    Serial.print(",");
    Serial.print("AccelY:");
    Serial.print(a.acceleration.y);
    Serial.print(",");
    Serial.print("AccelZ:");
    Serial.print(a.acceleration.z);
    Serial.print(", ");
    Serial.print("GyroX:");
    Serial.print(g.gyro.x);
    Serial.print(",");
    Serial.print("GyroY:");
    Serial.print(g.gyro.y);
    Serial.print(",");
    Serial.print("GyroZ:");
    Serial.println(g.gyro.z);
    // Adjusted thresholds for minimal, moderate, and strong motion
    if (abs(g.gyro.x) > 2 || abs(g.gyro.y) > 2 || abs(g.gyro.z) > 2) {
      // Strong motion - green
      setRGBColor(LOW, HIGH, LOW);  // Solid Red
    } else if (abs(g.gyro.x) > 0.5 || abs(g.gyro.y) > 0.5 || abs(g.gyro.z) > 0.5) {
      // Moderate motion - red
      setRGBColor(HIGH, LOW, LOW);  // Solid red
    }
  }
  // Check if no motion has been detected for the timeout period
  if (millis() - lastMotionTime > motionTimeout) {
    // Set LED color to yellow for minimal movement
    setRGBColor(HIGH, HIGH, LOW);  // Solid Yellow
  }
  delay(10); // Short delay to avoid overloading the serial output
}

This seemed to work slightly better, but I still wasn't fully satisfied. (Motion detection code example provided by Adafruit and tweaked with AI to change the LED color)

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
Adafruit_MPU6050 mpu;
#define RED_PIN 3
#define GREEN_PIN 4
#define BLUE_PIN 5

unsigned long lastMotionTime = 0;    // Stores the time of the last detected motion
const unsigned long motionTimeout = 3000;  // Time in milliseconds to reset to yellow after no motion

void setup(void) {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println("Adafruit MPU6050 test!");

  // Initialize MPU6050
  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050 chip");
    while (1) delay(10);
  }
  Serial.println("MPU6050 Found!");

  // Set up motion detection
  mpu.setHighPassFilter(MPU6050_HIGHPASS_0_63_HZ);
  mpu.setMotionDetectionThreshold(1);
  mpu.setMotionDetectionDuration(20);
  mpu.setInterruptPinLatch(true);
  mpu.setInterruptPinPolarity(true);
  mpu.setMotionInterrupt(true);

  // Initialize RGB LED pins
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(BLUE_PIN, OUTPUT);
  // Start with yellow light for minimal motion
  setRGBColor(HIGH, HIGH, LOW);
  delay(100);
}
// Function to set LED color with digital control
void setRGBColor(int red, int green, int blue) {
  digitalWrite(RED_PIN, red);
  digitalWrite(GREEN_PIN, green);
  digitalWrite(BLUE_PIN, blue);
}
void loop() {
  // Check if motion interrupt status is true (motion detected)
  if (mpu.getMotionInterruptStatus()) {
    sensors_event_t a, g, temp;
    mpu.getEvent(&a, &g, &temp);
    // Update the last motion time
    lastMotionTime = millis();
    Serial.print("AccelX:");
    Serial.print(a.acceleration.x);
    Serial.print(",");
    Serial.print("AccelY:");
    Serial.print(a.acceleration.y);
    Serial.print(",");
    Serial.print("AccelZ:");
    Serial.print(a.acceleration.z);
    Serial.print(", ");
    Serial.print("GyroX:");
    Serial.print(g.gyro.x);
    Serial.print(",");
    Serial.print("GyroY:");
    Serial.print(g.gyro.y);
    Serial.print(",");
    Serial.print("GyroZ:");
    Serial.println(g.gyro.z);
    // Adjusted thresholds for minimal, moderate, and strong motion
    if (abs(g.gyro.x) > 2 || abs(g.gyro.y) > 2 || abs(g.gyro.z) > 2) {
      // Strong motion - green
      setRGBColor(LOW, HIGH, LOW);  // Solid Red
    } else if (abs(g.gyro.x) > 0.5 || abs(g.gyro.y) > 0.5 || abs(g.gyro.z) > 0.5) {
      // Moderate motion - red
      setRGBColor(HIGH, LOW, LOW);  // Solid red
    }
  }
  // Check if no motion has been detected for the timeout period
  if (millis() - lastMotionTime > motionTimeout) {
    // Set LED color to yellow for minimal movement
    setRGBColor(HIGH, HIGH, LOW);  // Solid Yellow
  }
  delay(10); // Short delay to avoid overloading the serial output
}

Time for a fresh board

Even though my old board worked, but I felt limited by RBG LED. I decided to make a second board which would allow me to connect a string of neopixels.

Here is my board design: 3 pins on the left to connect with my neopixel string and 4 connectors on the right to connect with my MPU6050.

See board re-milling above

Freshly soldered and tested board (using multimeter to confirm pin connections to components)

After attaching my components via the connector pins, I tested the neopixels - they worked wonderfully! They were far easily to program than LEDS and less prone to power issues.

Here is the code I used to test the neopixels before integrating with the MPU6050.

#include <Adafruit_NeoPixel.h>
#include <Wire.h>
#include <MPU6050.h>
#define NUM_PIXELS 60      // Number of NeoPixels in your strip
#define DATA_PIN 2         // GPIO pin connected to NeoPixel data line

Adafruit_NeoPixel pixels(NUM_PIXELS, DATA_PIN, NEO_GRB + NEO_KHZ800);
MPU6050 mpu;
void setup() {
  Serial.begin(115200);      // Begin serial communication for debugging
  pixels.begin();            // Initialize the NeoPixel strip
  pixels.show();             // Turn off all pixels initially
  Wire.begin();              // Begin I2C communication for MPU6050

  mpu.initialize();          // Initialize the MPU6050
  if (!mpu.testConnection()) {
    Serial.println("MPU6050 connection failed"); // Debug in case of issues
    while (1);               // Halt if connection fails
  }
}
void loop() {
  int16_t ax, ay, az;
  mpu.getAcceleration(&ax, &ay, &az); // Get accelerometer values

  // Map acceleration to RGB values
  int colorX = map(ax, -17000, 17000, 0, 255);  // Forward-backward
  int colorY = map(ay, -17000, 17000, 0, 255);  // Left-right
  int colorZ = map(az, -17000, 17000, 0, 255);  // Up-down

  // Update the NeoPixels with the mapped color
  setColor(colorX, colorY, colorZ);
  delay(100);  // Delay to allow time between sensor reads
}
// Function to set all pixels to a specific color
void setColor(uint8_t r, uint8_t g, uint8_t b) {
  for (int i = 0; i < NUM_PIXELS; i++) {
    pixels.setPixelColor(i, pixels.Color(r, g, b));
  }
  pixels.show(); // Push the color to the strip
}

Here is the code I used to connect color with motion. Colors were assigned to certain thresholds and as the MPU moved the color would mix and move based on that movement.

#include <Adafruit_NeoPixel.h>
#include <Wire.h>
#include <MPU6050.h>
#define NUM_PIXELS 60      // Number of NeoPixels in your strip
#define DATA_PIN 2         // GPIO pin connected to NeoPixel data line

Adafruit_NeoPixel pixels(NUM_PIXELS, DATA_PIN, NEO_GRB + NEO_KHZ800);
MPU6050 mpu;
void setup() {
  Serial.begin(115200);      // Begin serial communication for debugging
  pixels.begin();            // Initialize the NeoPixel strip
  pixels.show();             // Turn off all pixels initially
  Wire.begin();              // Begin I2C communication for MPU6050

  mpu.initialize();          // Initialize the MPU6050
  if (!mpu.testConnection()) {
    Serial.println("MPU6050 connection failed"); // Debug in case of issues
    while (1);               // Halt if connection fails
  }
}
void loop() {
  int16_t ax, ay, az;
  mpu.getAcceleration(&ax, &ay, &az); // Get accelerometer values

  // Map acceleration to RGB values
  int colorX = map(ax, -17000, 17000, 0, 255);  // Forward-backward
  int colorY = map(ay, -17000, 17000, 0, 255);  // Left-right
  int colorZ = map(az, -17000, 17000, 0, 255);  // Up-down

  // Update the NeoPixels with the mapped color
  setColor(colorX, colorY, colorZ);
  delay(100);  // Delay to allow time between sensor reads
}
// Function to set all pixels to a specific color
void setColor(uint8_t r, uint8_t g, uint8_t b) {
  for (int i = 0; i < NUM_PIXELS; i++) {
    pixels.setPixelColor(i, pixels.Color(r, g, b));
  }
  pixels.show(); // Push the color to the strip
}

In closing

This week was satisfying. This class has taught me how to mill a board, solder it, test it, and program it! Building little mini computers to do cool things. Just a few weeks ago I was terrified by microcontrollers and everything seemed so complicated. (To be fair - I still feel intimidated - but I'm building confidence at the same time too!)

Week 7: Input DevicesAdd a sensor to a microcontroller board and read it

Time for a fresh board

In closing

Week 7: Input Devices
Add a sensor to a microcontroller board and read it