The MAX31865 Platinum PT100 RTD Temperature Sensor Amplifier Module is designed to provide accurate temperature measurements using PT100 RTD (Resistance Temperature Detector) sensors. This module offers high precision and reliability in temperature sensing applications, making it ideal for industrial, scientific, and research purposes. The MAX31865 IC on the module is specifically engineered for interfacing with PT100 sensors, which are known for their stability and wide temperature range.

Key Applications:

• Industrial temperature monitoring
• Laboratory experiments and equipment
• HVAC systems
• Environmental control systems
• Automotive temperature sensing

Features:

• Precise Temperature Measurement: Converts the resistance of PT100 RTD sensors into a digital temperature reading with high accuracy.
• Wide Temperature Range: Compatible with PT100 sensors, which can measure temperatures from -200°C to +850°C.
• Digital Interface: Communicates with microcontrollers or processors via SPI (Serial Peripheral Interface) for easy integration into various systems.
• Built-in Filtering: Includes noise reduction features to ensure stable and reliable readings.
• Easy Calibration: Simple calibration process for accurate temperature readings.

Specifications:

• Sensor Type: PT100 RTD (Resistance Temperature Detector)
• Temperature Range: -200°C to +850°C
• Resolution: 0.0625°C (16-bit resolution)
• Accuracy: ±0.5°C (typical)
• Interface: SPI (Serial Peripheral Interface)
• Supply Voltage: 3.3V to 5.5V
• Current Consumption: Typically 1.5mA
• Operating Temperature: -40°C to +125°C
• Package Type: 8-pin SOIC (Small Outline Integrated Circuit)
• Dimensions: Varies depending on the module design (usually compact and suitable for various mounting options)

Connection Pinout:

• VDD: Power supply pin (3.3V to 5.5V)
• GND: Ground pin
• SCK: Serial Clock for SPI communication
• SDI: Serial Data Input
• SDO: Serial Data Output
• CS: Chip Select for SPI communication
• RTD+ / RTD-: PT100 sensor connections

How to interface with Arduino?

To interface an Arduino with the MAX31865 Platinum PT100 RTD Temperature Sensor Amplifier Module, you will follow these steps:

1. Wiring the MAX31865 to Arduino

Here’s how you connect the MAX31865 module to the Arduino:

• MAX31865 Pin | Arduino Pin
  • VCC | 5V (or 3.3V, depending on your module's operating voltage)
  • GND | GND
  • SCK | Pin 13 (SPI Clock)
  • MISO | Pin 12 (SPI Master In Slave Out)
  • MOSI | Pin 11 (SPI Master Out Slave In)
  • CS | Pin 10 (SPI Chip Select)
  • (Some modules may have an additional pin for RTD excitation, which is typically connected internally)

Note: Ensure that the module’s power supply matches the Arduino’s voltage level to avoid damaging the components.

2. Install Required Libraries

You’ll need the Adafruit MAX31865 library to interface with the sensor. You can install it using the Arduino Library Manager or download it from the Adafruit GitHub repository.

To install via the Library Manager:

1. Open the Arduino IDE.
2. Go to Sketch > Include Library > Manage Libraries.
3. Search for Adafruit MAX31865.
4. Click Install.

3. Sample Code

Here’s a simple example to read the temperature from the MAX31865 using the Adafruit library:

#include <Wire.h>
#include <Adafruit_MAX31865.h>

// Define the pin for CS (Chip Select)
#define MAX31865_CS 10

// Create an instance of the MAX31865 class
Adafruit_MAX31865 max31865 = Adafruit_MAX31865(MAX31865_CS);

// Configuration settings
#define MAX31865_RTD_NOMINAL 100.0  // PT100
#define MAX31865_RTD_RESOLUTION 430.0 // 430 ohm for PT1000, adjust if needed

void setup() {
  Serial.begin(9600);
  max31865.begin(MAX31865_RTD_NOMINAL, MAX31865_RTD_RESOLUTION);
}

void loop() {
  uint16_t rtd = max31865.readRTD();
  
  // Calculate temperature in Celsius
  float temperature = max31865.temperature(100.0, 430.0);
  
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" C");
  
  delay(1000); // Delay for a second
}

4. Explanation of Code

• Adafruit_MAX31865 max31865 = Adafruit_MAX31865(MAX31865_CS); initializes the MAX31865 sensor with the Chip Select pin.
• max31865.begin(MAX31865_RTD_NOMINAL, MAX31865_RTD_RESOLUTION); sets up the sensor with the nominal resistance of the PT100 sensor and the resolution.
• max31865.readRTD(); reads the raw RTD value.
• max31865.temperature(100.0, 430.0); converts the RTD value into temperature in Celsius. Adjust the nominal resistance and resolution based on your specific PT100 sensor and its configuration.

5. Calibration and Adjustments

• Ensure the sensor is correctly calibrated for accurate readings. The nominal resistance and resolution values should match your specific PT100 sensor and the MAX31865 settings.
• For different configurations or types of RTDs, you might need to adjust the MAX31865_RTD_NOMINAL and MAX31865_RTD_RESOLUTION values accordingly.

By following these steps, you should be able to interface the MAX31865 with an Arduino and read temperature values from a PT100 RTD sensor. If you encounter any issues or need more customization, refer to the library documentation or datasheets for more details.