Circuit Documentation

Summary

This circuit is designed to control a brushless motor using an Arduino UNO as the central processing unit. It includes a piezo buzzer for audible feedback, a pushbutton for user input, a speed controller to manage the motor's speed, and a current sensor to monitor the electrical current. Additionally, an SD module is incorporated for data logging purposes. The circuit is powered by a battery, and a resistor is used for pull-down configuration on the pushbutton.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Provides digital and analog I/O pins
• Includes communication interfaces such as SPI and I2C
• Operates at 5V

Brushless Motor

• Three-phase motor that requires an electronic speed controller (ESC)
• Typically used in applications requiring high power and efficiency

Speed Controller

• Electronic Speed Controller (ESC) for brushless motors
• Provides power to the motor and controls its speed
• Accepts signal input to set motor speed

Piezo Buzzer

• An electronic device that emits sound when voltage is applied
• Used for audible alerts or feedback

Pushbutton

• A simple switch mechanism for controlling some aspect of a machine or a process
• Normally open, closes the circuit when pressed

Resistor

• A passive two-terminal electrical component that implements electrical resistance
• Used here as a pull-down resistor for the pushbutton

Battery

• Provides power to the circuit
• Voltage and capacity are not specified in the provided information

SD Module

• A module that allows the Arduino to read from and write to SD cards
• Used for data logging purposes

ACS712 Current Sensor

• A hall effect-based linear current sensor
• Capable of measuring both AC and DC currents

Wiring Details

Arduino UNO

• D2 connected to Piezo Buzzer
• GND connected to common ground net
• 5V connected to common 5V net
• D10 connected to SD Module (CS)
• D13 connected to SD Module (SCK)
• D11 connected to SD Module (MOSI)
• D12 connected to SD Module (MISO)
• D4 connected to Pushbutton (via Resistor)
• D6 connected to Speed Controller (Signal)
• A0 not connected (reserved for current sensor)

Brushless Motor

• L1 connected to Speed Controller (OUT3)
• L2 connected to Speed Controller (Out 2)
• L3 connected to Speed Controller (Out1)

Speed Controller

• Signal connected to Arduino UNO (D6)
• 5V connected to common 5V net
• GND connected to common ground net
• V+ connected to Battery (+)
• Out1, Out 2, OUT3 connected to Brushless Motor

Piezo Buzzer

• pin 1 connected to Arduino UNO (D2)
• pin 2 connected to common ground net (via Resistor)

Pushbutton

• Pin 3 (out) connected to common 5V net
• Pin 1 (in) connected to Arduino UNO (D4) (via Resistor)

Resistor

• One end connected to Pushbutton, other end to common ground net and Arduino UNO (D4)

Battery

• + connected to Speed Controller (V+)
• - connected to ACS712 Current Sensor

SD Module

• CS connected to Arduino UNO (D10)
• SCK connected to Arduino UNO (D13)
• MOSI connected to Arduino UNO (D11)
• MISO connected to Arduino UNO (D12)
• VCC connected to common 5V net
• GND connected to common ground net

ACS712 Current Sensor

• 1 connected to Battery (-)
• 2 connected to common ground net
• GND connected to common ground net
• OUT not connected (reserved for analog input to Arduino)
• VCC connected to common 5V net

Documented Code

#include <SPI.h>
#include <SD.h>
#include <Servo.h>  // Include the Servo library

// Pin Definitions
const int buttonPin = 4;
const int buzzerPin = 2;
const int currentSensorPin = A0;
const int chipSelect = 10;  // Pin for the SD card module

// Program Variables
File dataFile;  // Create a file object to write to the SD card
Servo esc;  // Create a Servo object to control the ESC
bool programStarted = false;
bool buzzerStarted = false; // Ensures buzzer only activates after button press
bool buzzerOn = false; // Tracks if the buzzer should be on
unsigned long lastBuzzerTime = 0;
unsigned long lastThrottleTime = 0;
unsigned long lastSampleTime = 0;
int buzzerCount = 0;
int throttleValue = 1000;  // Start at 1000 µs (0% throttle for ESC)
bool holdingThrottle = false;  // Tracks if we're in the holding phase

void setup() {
  pinMode(buttonPin, INPUT);  // Button with pull-down resistor
  pinMode(buzzerPin, OUTPUT);
  esc.attach(6);  // Attach the ESC to pin 6
  esc.writeMicroseconds(throttleValue);  // Initialize PWM to 1000 µs
  digitalWrite(buzzerPin, LOW);  // Ensure buzzer is OFF initially
  Serial.begin(9600);  // For current data output

  // Initialize the SD card

  // Create a new file (or open an existing one)
  dataFile = SD.open("currentData.txt", FILE_WRITE);
  if (dataFile) {
    Serial.println("Writing to file...");
    dataFile.println("Time (ms), Current (A)"); // Header row
    dataFile.close();
  } else {
    Serial.println("Error opening file!");
  }
}

void loop() {
  // Check if the button is pressed to start the program
  if (digitalRead(buttonPin) == HIGH && !programStarted) {
    if (!SD.begin(chipSelect)) {
      Serial.println("SD card initialization failed!");
      return;
    }
    Serial.println("SD card initialized.");
    programStarted = true;
    buzzerStarted = true;      // Enable buzzer sequence only after button press
    lastBuzzerTime = millis(); // Start the buzzer timing
    buzzerCount = 0;           // Reset buzzer count at program start
  }

  // Buzzer Activation (5 times, 0.25 second ON, 0.5 second OFF) after button press
  if (buzzerStarted && buzzerCount < 5) {
    unsigned long currentMillis = millis();
    
    if (buzzerOn && currentMillis - lastBuzzerTime >= 250) {  // Buzzer ON duration
      digitalWrite(buzzerPin, LOW);  // Turn buzzer OFF
      buzzerOn = false;
      lastBuzzerTime = currentMillis;
      buzzerCount++;  // Increase beep count after each OFF period
    } 
    else if (!buzzerOn && currentMillis - lastBuzzerTime >= 500) {  // Buzzer OFF duration
      digitalWrite(buzzerPin, HIGH);  // Turn buzzer ON
      buzzerOn = true;
      lastBuzzerTime = currentMillis;
    }
  } 
  
  // Throttle Ramp-Up (1000 µs to 1250 µs over 5 seconds) after buzzer completes
  else if (programStarted && buzzerCount >= 5 && throttleValue < 1500 && !holdingThrottle) {
    if (millis() - lastThrottleTime >= 100) {
      lastThrottleTime = millis();
      throttleValue += 15;  // Increase PWM gradually to reach 1250 µs (approx. 25% throttle)
      esc.writeMicroseconds(throttleValue);  // Set ESC throttle
    }
  } 
  
  // Maintain 25% Throttle and Read Current Sensor Data (5 seconds at 50 Hz)
  else if (programStarted && throttleValue >= 1500 && !holdingThrottle) {
    holdingThrottle = true;  // Enter holding phase
    lastThrottleTime = millis();  // Reset timing for the hold duration
  }
  
  // Hold the throttle and read current sensor data for 5 seconds
  if (holdingThrottle && millis() - lastThrottleTime < 5000) {
    if (millis() - lastSampleTime >= 100) {   // Sample current sensor at 50 Hz
      lastSampleTime = millis();
      
      // Read and calculate current from ACS712 sensor
      int currentReading = analogRead(currentSensorPin);
      float current = (currentReading - 512) *-1* (5.0 / 1024.0) / 0.066;
      
      // Print current to Serial Monitor
      Serial.println(current);

      // Open the file to append the current reading with timestamp
      dataFile = SD.open("test.txt", FILE_WRITE);
      if (dataFile