MLX90640 Thermal Camera with ESP32

Thermal cameras are now more affordable, letting hobbyists and professionals explore various applications. One great option is the MLX90640 IR array with a 32x24 pixel resolution. By pairing it with an ESP32 board, you can make a thermal imaging device.

This guide will walk you through the process of connecting the MLX90640 to the ESP32, setting up the firmware, installing the necessary libraries, and obtaining temperature readings.

I was working on MLX90640 with different libraries and I had to make some adjustments to get some kind of reliability and accuracy. I’m so happy to share my experience with you.

Materials Needed

• MLX90640BAA IR Thermal Camera
• ESP32 Development Board
• Jumper Wires

Wiring the MLX90640 to the ESP32

Here’s a simple explanation of the wiring,

Installing Necessary Libraries

For this project, you’ll need the Adafruit MLX90640 library.

Follow these steps to install them:

• Go to Documents > Arduino> libraries.
• Download the library, unzip it, and add it to the “libraries” Folder.

Firmware

• Copy the following code

#include <Wire.h>
#include <Adafruit_MLX90640.h>

// Addresses and parameters
const byte MLX90640_address = 0x33; 
#define TA_SHIFT 8 

Adafruit_MLX90640 mlx;
float frame[32 * 24];

void setup() {
  Serial.begin(115200);
  Wire.begin();
  Wire.setClock(400000); 

  // Ensure the MLX90640 is properly reset and initialized
  if (!isConnected()) {
    Serial.println("MLX90640 not detected at default I2C address. Please check wiring. Freezing.");
    while (1);
  }
  Serial.println("MLX90640 online!");

  // Perform a soft reset of the MLX90640
  MLX90640_I2CWrite(0x33, 0x800D, 6401);
  delay(100);

  // Initialize MLX90640 using Adafruit's method
  if (!mlx.begin()) {
    Serial.println("Failed to initialize MLX90640!");
    while (1);
  }

  mlx.setResolution(MLX90640_ADC_18BIT);
  mlx.setRefreshRate(MLX90640_4_HZ);
  mlx.setMode(MLX90640_CHESS);

  Serial.println("MLX90640 initialized successfully.");
}

void loop() {
  // Get frame using Adafruit method
  delay(500);

  if (mlx.getFrame(frame) != 0) {
    Serial.println("Failed to get frame");
    return;
  }

  float tempMinRead = 1000;   // some high value
  float tempMaxRead = -1000;  // some low value
  float tempCenter = 0.0;     // Temperature at center

  // Update the minimum, maximum, and center temperatures read from the sensor
  for (int i = 0; i < 32 * 24; i++) {
    if (frame[i] < tempMinRead) {
      tempMinRead = frame[i];
    }
    if (frame[i] > tempMaxRead) {
      tempMaxRead = frame[i];
    }
    if (i == 32 * 12 + 16) {
      tempCenter = frame[i];
    }
  }

  Serial.print("T Min: ");
  Serial.print(tempMinRead);
  Serial.print(" C, T Max: ");
  Serial.print(tempMaxRead);
  Serial.print(" C, Tc: ");
  Serial.print(tempCenter);
  Serial.println(" C");
}

// Check if the MLX90640 is connected
boolean isConnected() {
  Wire.beginTransmission((uint8_t)MLX90640_address);
  if (Wire.endTransmission() != 0)
    return (false); // Sensor did not ACK
  return (true);
}

// Custom I2C read and write functions
int MLX90640_I2CRead(uint8_t slaveAddr, uint16_t regAddr, uint16_t len, uint16_t *data) {
  Wire.beginTransmission(slaveAddr);
  Wire.write(regAddr >> 8);
  Wire.write(regAddr & 0xFF);
  Wire.endTransmission(false);

  Wire.requestFrom(slaveAddr, (uint8_t)(len * 2));
  for (uint16_t i = 0; i < len; i++) {
    data[i] = Wire.read() << 8;
    data[i] |= Wire.read();
  }

  return 0;
}

void MLX90640_I2CWrite(uint8_t slaveAddr, uint16_t regAddr, uint16_t data) {
  Wire.beginTransmission(slaveAddr);
  Wire.write(regAddr >> 8);
  Wire.write(regAddr & 0xFF);
  Wire.write(data >> 8);
  Wire.write(data & 0xFF);
  Wire.endTransmission();
}

• Paste the code on an Arduino Script.
• And save and compile the code.
• Upload the code to Esp32

Output

Hope you enjoyed our article.

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Email: udara@protonest.co

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