TFHT02 - Fast response miniature UAV Humidity and Temperature Sensor

The TFHT02 is a compact and precise hygrometer and temperature sensor designed for atmospheric measurements by UAVs. It offers flexible integration options and can be directly connected to a Pixhawk based autopilot with PX4 firmware and used as a sensor for the TF-ATMON monitoring system. The fast response time and reduced sensitivity to solar radiation make it ideal for meteorological measurements, particularly in atmospheric profiling applications.

TFHT02A atmospheric profiling

Features

Designed for UAVs: Lightweight and compact construction
Fast Response: Optimized for real-time environmental changes
Broad Compatibility: Supports PX4 autopilot firmware
High Accuracy and repeatability: ±1% RH and ±0.1°C
Robust Design: Reduced sensitivity to solar radiation
Flexible Integration: Can be used with TF-ATMON and Pixhawk.

Where to Buy?

The TFHT02 is available from ThunderFly s.r.o..

For a quotation or support, contact us at sale@thunderfly.cz or visit our Tindie store.

Technical Specifications

Parameter	Value	Description
Sensing element	SHT45	Alternatives: SHT40 or SHT41
Typical accuracy	±1 %RH, ±0.1 °C
Repeatability	±0.15 %RH, ±0.08 °C	3σ of consecutive measurements at constant conditions
Operating temperature range	0 °C to +65 °C	Sensor measures from -40°C to +120°C with reduced accuracy
Operating humidity range	0-100 %	Accuracy degrades above 80% for prolonged periods
I2C Connector	4-pin JST-GH	Optional second connector on the opposite side
I2C Address	0x44
Storage temperature	-20 °C to +40 °C
Input voltage	3.6 - 5.4V	Overvoltage protected by Zener diode
Mass	2 g	PCB without cables
Dimensions	30 × 15 × 6.5 mm	PCB size
Weather resistance	IP40	When all external connectors are occupied

Design and Functionality

The TFHT02 sensor is built for fast response and minimal sensitivity to solar radiation. The sensing element has low thermal mass, allowing rapid adaptation to environmental changes. It is designed to maximize airflow exposure, ensuring accurate and efficient real-time meteorological measurements.

TFHT02A top view TFHT02A bottom view

Electrical Schematics

PX4 Autopilot Integration

The PX4 firmware supports TFHT02 out of the box. Multiple sensors can be connected to a single autopilot. The measured data could be sent to the ground station and logged in the onboard ulog file.

To enable support, set SENS_EN_SHT4X = 1.

Command Line Usage (CLI)

Start the sensor driver on the external I2C bus:

sht4x start -X

Check driver status:

sht4x status

Print last measured values:

sht4x values

Reinitialize the sensor:

sht4x reset

Full PX4 Driver Command Reference

sht4x <command> [arguments...]
 Commands:
   start
     [-I]        Internal I2C bus(es)
     [-X]        External I2C bus(es)
     [-b <val>]  Board-specific bus (default=all)
     [-f <val>]  Bus frequency in kHz
     [-q]        Quiet startup (no message if no device found)
     [-a <val>]  I2C address (default: 68)
     [-k]        Retry initialization periodically if probing fails

   stop          Stop driver
   status        Print driver status
   values        Print sensor data
   reset         Reinitialize sensor

Ardupilot Support

Currently, Ardupilot does not support the TFHT02 sensor as the sht4x driver is missing. Contributions to add support are welcome.