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MAX31865 RTD Temperature Sensor Module — PT100 / PT1000 for Arduino & Raspberry Pi
MAX31865 RTD Temperature Sensor Module PT100 / PT1000 for Arduino & Raspberry Pi
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MAX31865 RTD Temperature Sensor Module — PT100 / PT1000
The MAX31865 module is a precision RTD-to-digital converter that interfaces PT100 and PT1000 platinum resistance temperature detectors (RTDs) with any SPI-capable microcontroller. It provides significantly higher accuracy and stability than NTC thermistors or thermocouples in the −200°C to +850°C range, making it the preferred choice for 3D printer heated bed/hotend monitoring, industrial process control, laboratory temperature logging, and sous vide cooking controllers.
Key Specifications
| Parameter | Value |
|---|---|
| IC | MAX31865 |
| Compatible Sensors | PT100 and PT1000 RTDs (2-wire, 3-wire, 4-wire) |
| Temperature Range | −200°C to +850°C |
| Accuracy | ±0.5°C (typical) |
| ADC Resolution | 15-bit |
| Interface | SPI (4-wire: SCK, SDI, SDO, CS) |
| Supply Voltage | 3.3V / 5V compatible |
| Fault Detection | Open/short circuit detection with fault register |
| Origin | CN |
Why Choose RTD over Thermocouple or NTC?
| Feature | PT100 RTD (MAX31865) | Thermocouple (MAX6675) | NTC Thermistor |
|---|---|---|---|
| Accuracy | ✅ ±0.5°C | ❌ ±3°C typical | ❌ ±1–3°C |
| Range | ✅ −200 to +850°C | ✅ 0 to +1024°C | ❌ −50 to +150°C |
| Stability | ✅ Excellent long-term | ❌ Drift over time | ❌ Moderate |
| Cost | ❌ Higher | ✅ Lower | ✅ Lowest |
Typical Applications
- 3D printer heated bed and hotend temperature monitoring (replacement for NTC 100K)
- Industrial process temperature control and PID loops
- Laboratory temperature data logging
- Sous vide and precision cooking temperature controllers
- HVAC and refrigeration system monitoring
- Cryogenic temperature measurement (down to −200°C)
Frequently Asked Questions
Q: What is the difference between PT100 and PT1000?
Both are platinum RTDs with the same temperature coefficient (0.00385Ω/Ω/°C). PT100 has a resistance of 100Ω at 0°C; PT1000 has 1000Ω at 0°C. PT1000 is less sensitive to lead wire resistance, making it better for long cable runs. The MAX31865 module can be configured for either by changing the reference resistor (select the correct module variant).
Q: What Arduino library should I use?
Use the Adafruit MAX31865 library, available in the Arduino Library Manager. It supports 2-wire, 3-wire, and 4-wire RTD configurations and includes fault detection handling.
Package Contents
- 1× MAX31865 RTD Amplifier Module (PT100 or PT1000 variant per selection)
