M5Stack Kmeter Isolation Unit with Thermocouple Sensor (MAX31855)

M5Stack MAX31855 Isolated K-Type Thermocouple Unit

The M5Stack KMeter-ISO Unit combines K-type thermocouple acquisition, digital conversion, isolation, and I2C communication. It uses an STM32F030F4P6 controller, MAX31855KASA+T 14-bit thermocouple converter, and CA-IS3641HW signal isolation device.

The module supports K-type thermocouple probes across a specified -200°C to 1350°C range, while the included probe is rated for a narrower -50°C to 250°C range. The host reads temperature data through I2C at address 0x66.

Measure High Temperatures with Replaceable K-Type Probes

K-type thermocouples are widely used for ovens, heat-treatment equipment, power electronics, machinery, and industrial process monitoring. Choose the probe construction, insulation, connector, and rated temperature for the actual environment rather than assuming every K-type probe can use the module's full converter range.

14-Bit Conversion and Fault Detection

The MAX31855 path provides 0.25°C resolution and supports fault detection for conditions such as open circuit and short-circuit states. Use fault flags in firmware rather than treating every numeric reading as valid.

Isolated Signal Path

The CA-IS3641HW isolation device improves separation between the sensing and controller sides. Complete system safety still depends on thermocouple insulation, grounding, supply ratings, creepage and clearance, enclosure design, and the voltages present at the measurement point.

Validate the Installed Temperature Chain

Final accuracy depends on the thermocouple probe, cold-junction conditions, connector materials, cable routing, electrical noise, installation depth, thermal contact, and calibration. For process control or protection thresholds, compare the installed system with an appropriate reference method.

Technical setup details are available in the M5Stack KMeter-ISO documentation.