The TFHT02 hygrometer sensor offers flexible integration options. It can be directly connected to a Pixhawk autopilot with PX4 firmware, or it can be used as a sensor for the TF-ATMON monitoring system. The TFHT02 is optimized for fast response and reduced sensitivity to solar radiation, making it suitable for meteorological measurements of atmospheric profiles, where rapid environmental changes require fast response to maintain high measurement accuracy.
The TFHT02 sensor is designed for direct atmospheric sounding. Here is an example of measured data taken by TF-G2 autogyro.
The TFHT02 is commercially available from ThunderFly s.r.o.. For a commercial quotation or support, contact us by email at [email protected] or shop at Tindie store.
| Parameter | Value | Description |
|---|---|---|
| Sensing element | SHT45 | Other possible sensors are SHT40 or SHT41 |
| Typical accuracy | 1 %RH and 0.1 °C | |
| Repeatability | 0.15 %RH , 0.08 °C | The stated repeatability is 3 times the standard deviation (3σ) of multiple consecutive measurements at constant ambient conditions. |
| Operating temperature range | 0 °C - +65 °C | Sensor physically measures in range -40°C to +120°C with reduced accuracy |
| Operating humidity range | 0-100 % | At humidity above 80% the performance of the sensor could be degraded in case of prolonged periods |
| I2C connector | 4-pin JST-GH | The second connector could be installed on the opposite side |
| I2C address | 0x44 | |
| Storage temperature range | -20 °C - +40 °C | |
| Operational input voltage | 3.6 - 5.4V | Overvoltage is internally protected by zener diode |
| Mass | 2 g | PCB without cabling |
| Dimensions | 30 x 15 x 6.5 mm | PCB |
| Weather resistance | IP40 | External connectors fully occupied. |
The TFHT02 sensor is designed with an emphasis on fast response time and minimal sensitivity to solar radiation. This is achieved by reducing the thermal mass around the sensing element, allowing it to rapidly react to changes in ambient conditions. Additionally, the sensor is positioned in a way that maximizes its contact surface with the surrounding airflow, ensuring efficient heat exchange and accurate real-time measurements, which are critical for meteorological applications, especially for atmospheric profiling.
The PX4 autopilot firmware supports the sensor. Multiple sensors can be connected to one autopilot. The measured data could be sent to the ground station and at the same time logged in the onboard ulog file. Sensor support can be enabled by setting the SENS_EN_SHT4X parameter to 1.
CLI usage example:
sht4x start -X
Start the sensor driver on the external bus
sht4x status
Print driver status
sht4x values
Print the last measured values
sht4x reset
Reinitialize senzor, reset flags
sht4x <command> [arguments...]
Commands:
start
[-I] Internal I2C bus(es)
[-X] External I2C bus(es)
[-b <val>] board-specific bus (default=all) (external SPI: n-th bus
(default=1))
[-f <val>] bus frequency in kHz
[-q] quiet startup (no message if no device found)
[-a <val>] I2C address
default: 68
[-k] If initialization (probing) fails, keep retrying periodically
stop
status print status info
values Print actual data
reset Reinitialize sensor
In the Ardupilot firmware, the corresponding sht4x driver for TFHT02 is currently missing. The contributions are welcomed.