How to Use MAX6675 Module: Examples, Pinouts, and Specs

The MAX6675 module is a digital thermocouple temperature sensor designed to measure temperatures ranging from 0°C to 1024°C. It provides a digital output via the Serial Peripheral Interface (SPI), making it an ideal choice for applications requiring precise temperature measurements. Common use cases include industrial temperature monitoring, HVAC systems, and scientific research.

1. Power Supply: Connect the VCC pin to a 3.0V to 5.5V power supply and the GND pin to the ground.
2. SPI Interface: Connect the SCK, CS, and SO pins to the corresponding SPI pins on your microcontroller.
3. Thermocouple Connection: Attach the thermocouple to the module's designated input terminals.

• Thermocouple Type: Ensure you are using a K-type thermocouple, as the MAX6675 is calibrated for this type.
• Noise Reduction: Keep the thermocouple wires away from high-power lines to minimize noise interference.
• Temperature Range: Do not exceed the specified temperature range to avoid damaging the sensor.

#include <SPI.h>

// Define the MAX6675 module pins
const int CS_PIN = 10;
const int SCK_PIN = 13;
const int SO_PIN = 12;

void setup() {
  // Initialize the Serial Monitor
  Serial.begin(9600);
  
  // Set the SPI pins
  pinMode(CS_PIN, OUTPUT);
  pinMode(SCK_PIN, OUTPUT);
  pinMode(SO_PIN, INPUT);
  
  // Initialize the SPI interface
  SPI.begin();
  
  // Set the Chip Select pin high
  digitalWrite(CS_PIN, HIGH);
}

void loop() {
  // Read temperature from MAX6675
  float temperature = readTemperature();
  
  // Print the temperature to the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  
  // Wait for 1 second before the next reading
  delay(1000);
}

float readTemperature() {
  // Select the MAX6675 module
  digitalWrite(CS_PIN, LOW);
  
  // Read 16 bits from the module
  uint16_t value = SPI.transfer16(0x00);
  
  // Deselect the module
  digitalWrite(CS_PIN, HIGH);
  
  // Check for thermocouple connection error
  if (value & 0x4) {
    return NAN; // Return NaN if there's an error
  }
  
  // Extract temperature data
  value >>= 3; // Remove the last 3 bits
  float temperature = value * 0.25; // Convert to Celsius
  
  return temperature;
}

1. No Temperature Reading: Ensure all connections are secure and the thermocouple is properly attached.
2. Incorrect Temperature: Verify that you are using a K-type thermocouple and that it is within the specified temperature range.
3. SPI Communication Failure: Check the SPI connections and ensure the correct pins are defined in your code.

• Check Connections: Double-check all wiring and connections to ensure they are correct and secure.
• Use a Multimeter: Measure the voltage at the VCC and GND pins to ensure the module is receiving power.
• Verify Code: Ensure the code is correctly uploaded to the microcontroller and that the SPI pins are correctly defined.

By following this documentation, users should be able to effectively integrate and utilize the MAX6675 module in their projects, ensuring accurate and reliable temperature measurements.