lamaPLC: MLX90614 (GY-906) infrared non-contact thermometer

The Hailege MLX90614 is an infrared thermometer for non-contact temperature measurements. Both the IR-sensitive thermopile detector chip and the signal conditioning ASIC are integrated in the same TO-39 can. Integrated into the MLX90614 are a low-noise amplifier, a 17-bit ADC, and a powerful DSP unit, thus achieving high accuracy and resolution for the thermometer.

The thermometer comes factory-calibrated with a digital SMBus output, providing full access to the measured temperature across the complete temperature range(s) with a resolution of 0.02°C.

The user can configure the digital output to use pulse-width modulation (PWM). By default, the 10-bit PWM continuously transmits the measured temperature in the range of -20 to 120°C, with an output resolution of 0.14°C.

MLX90614 Features

• Factory calibrated in a wide temperature range: -40 to 125°C for sensor temperature and -70 to 380°C for object temperature
• High accuracy of 0.5°C over a wide temperature range (0..+50 C for both Ta and To)
• Medical accuracy of 0.1°C in a limited temperature range available on request
• Measurement resolution of 0.02°C
• Single and dual zone versions
• SMBus-compatible digital interface for rapid temperature readings and building sensor networks
• Customizable PWM output for continuous reading
• Available in 3.3V and 5V versions
• Simple adaptation for 8 to 16V applications
• Power saving mode
• Different package options for applications and measurement versatility
• Automotive grade

If you are using the blue breakout board, the pins are typically labelled on the back:

• VIN / VCC: Power supply. Most modules support 3.3V to 5V because they include a voltage regulator.
• GND: Ground reference.
• SCL: Serial Clock for I²C communication.
• SDA: Serial Data for I²C communication.

Important Wiring Notes

• Logic Levels: The RP2040-ETH uses 3.3V logic. Ensure your sensor's VIN is connected to the RP2040's 3V3 pin to avoid damaging the GPIOs.
• Pull-up Resistors: I²C communication requires pull-up resistors (typically 4.7 kΩ or 10 kΩ) on the SDA and SCL lines. Most GY-906 modules have these built-in.
• I²C Address: The default factory address for the MLX90614 is 0x5A

Read MLX90614 sensor values to RP2040_ETH over Micropython to serial: CODE.

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