The TFHT01 hygrometer sensor offers flexible integration options, including direct connection to a Pixhawk autopilot with PX4 firmware, or utilization as a sensor for the TF-ATMON monitoring system.

Once mounted on a UAV, the sensor provides valuable data for various applications. Its ability to measure atmospheric temperature and humidity can help estimate that icing may form on aerodynamic surfaces or determine if the drone is operating within the recommended range. Furthermore, the sensor can also be utilized to measure the temperature of specific UAV components such as batteries, ESCs, motors, or bearings, identifying potential issues before they escalate and supporting proactive maintenance and repairs.

Choose the TFHT01 hygrometer sensor for unparalleled flexibility, precision, and versatility in data collection. Whether you require temperature and humidity data for agricultural or industrial equipment monitoring or need to monitor drone component temperatures for optimal performance, the TFHT01 has you covered.

What is it?

TFHT01 is a hygrometer and thermometer with an I2C interface for use on drones as an onboard weather station. Relative humidity and temperature are quantities that can affect both the flight characteristics of the drone and the execution of aerial works. At certain temperatures and relative humidity, icing can form on the lifting surfaces, worsening its flight characteristics or even causing a crash. Meteorological conditions can affect the payload as well - they can cause e.g. fogging on camera lenses, etc. It is therefore important to know about the presence of these phenomena during the flight.

How could be used

We developed the TFHT01 because we needed to know the temperature and humidity of the environment in which we operate our drones. At that time no such sensor was commercially available on the market.

Special features

The sensor is unique because it is ready to be immediately used on drones. It complies with the widely used dronecode standards and it is equipped with indicator diodes that help with quick diagnostics of the status of the sensor and its operating status.

Furthermore, the sensor has a specific construction that makes it possible to place it in the outdoor environment easily. Alternatively, the sensor can be used as a diagnostics probe for drone avionics’ (e.g. engines, regulators, or batteries).

Compatibility with autopilots

Our sensor is fully compatible with the dronecode standards. In terms of software, the sensor is supported by PX4 autopilot. The driver is programmed as a so-called multi-instance. Thanks to this it is possible to connect multiple TFHT01 sensors to the autopilot (they can be located in different parts of the drone or measure data from different drone’s components). This should be done concerning I2C bus properties, e.g. requirement of different addresses for each device on the bus.

Use with PX4

Complete settings and driver options under PX4 can be found in the documentation.

To start the driver automatically it is only necessary to connect the sensor to any I2C port and set the SENS_EN_SHT3x parameter to 1 (enabled). The sensor should initialize during the next start. The prerequisite is to use the PX4 firmware version newer than 2022/03.

You can check that the driver is running and the sensor is initialized, after turning the driver on, the LED ‘ALERT’ is off.

Data is logged locally in the drone’s onboard avionics and is sent via Mavlink to the ground station. The values can be viewed in real-time using control software e.g. QGC.

Another usage

The sensor can be used outside of drones and PX4 devices as well. The I2C interface is the 4-pin JST-GH connector. The sensor board also contains I2C pull-ups and that’s why the sensor can be connected to e.g. Arduino or other single-board computers and they can be used to read the data from the sensor. The suggested supply voltage is 5V.

What’s included?

• 1x TFHT01 with SHT35 sensor with PTFE membrane
• Optionally 1x JST-GH 4-pin I2C cable in accordance to cable style

Product changelog

The product is gradually evolving and improving based on user requirements. Currently (as of 11/2024), the TFHT01B revision is being shipped. In the development process, we keep backward compatibility, for example by keeping the same form factor or communication interface. The complete list of changes is in releases.

TFHT01B (from 11/2024)

Introduced the use of membrane-covered sensors, and 3D printed sensor housing to enhance environmental protection.

TFHT01B (from 10/2023)

PCBs are covered by shrink tubing to increase protection.

TFHT01B (from 05/2022)

PCB Thickness decreased to 0.8mm.

TFHT01A (from 09/2021)

Bare PCB version with 1.6mm thickness