What is it?

TFHT01 is a hygrometer and thermometer with I2C interface for use on drones as an on-board 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 bearing surfaces resulting in worsening of its flight characteristics or even causing its fall. 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 these phenomena during the flight.

Why did you make it?

We have developed the device 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.

What makes it special?

The sensor is unique in that 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 software.

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

What is the sensor’s 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).

Use with PX4

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

To start the driver automatically it is only necessary to connect the sensor into 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 tell that the driver is running and the sensor is initialized when, after turning the driver on, the LED ‘ALERT’ is off.

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

Other usage

The sensor can be used outside of drones and PX4 devices as well. I2C output from the sensor is realized through 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 one-board computers and they can be used to read the data from the sensor. The proposed supply voltage is 5.4V.

What’s included?

• 1x TFHT01A
• 1x JST-GH 4-pin I2C cable in accordance to cable style