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TFASPDIMU01 - sdp3x differental pressure sensor and IMU 9-axis unit

.github/workflows/KiCad.yml

ThunderFly TFASPDIMU01 is SPI/I2C sensor board equipped with a differential pressure sensor (Senserion SDP3x) and 9-axis motion tracking sensor (ICM-20948). Board is equipped with 7pin JST-GH connector. The sensor board is designed for multiple uses. It can be used as a self-adjusting anemometer WINDGAUGE03 or as an airspeed sensor for UAVs with optional function as the external magnetometer.

TFASPDIMU01 PCB

TFASPDIMU is commercially available from ThunderFly s.r.o., write an email to [email protected] or shop at Tindie store.

Specification

  • Type: Differential and 9-axis motion sensor board
  • Mass: 3 g
  • Size: 36 x 14 mm
  • Power: +5 V
  • Connection: 7pin JST-GH connector, custom pinout

SDP3x

  • Range: +/- 125/500 Pa (depending on exact sensor type)
  • Excellent accuracy and repeatability, even below one Pascal
  • No zero-point offset, no temperature drift
  • Calibrated and temperature compensated
  • Fast sampling time of 2kHz at 16 bit resolution
  • I2C address: 0x21 (d33)

ICM-20948

  • 3-axis gyroscope, 3-axis accelerometer, 3-axis compass (magnetometer)
  • Onboard Digital Motion Processor (DMP)
  • On-Chip 16-bit ADCs and Programmable Filters
  • 7 MHz SPI or 400 kHz Fast Mode I²C
  • Digital temperature sensor
  • Default I2C address: 0x68 (0d104), can be changed to 0x69 (0d105) by moving the resistor R2->R1.

Example of uses

WINDGUAGE01

Ground control station anemometer WINDGAUGE03

TFSLOT01 - UAV airspeed sensor

Our TFSLOT senzor is an airspeed sensor for use mainly on UAV. Due to 3D printed case it is possible to optimalize part according to the location of sensor on UAV and tune their characteristics. First use of this sensor was on our autogyro TF-G2.

TFSLOT01 sensor

More details about this solution is available in the repository TFSLOT01.

TFPIPE01 - UAV airspeed sensor

Symmetric variant of TFSLOT sensor for different mounting options TFPIPE01.

TFVENTUFO - omnidirectional anemometer

This anemometer should also based on venturi effect. Thanks to an clever design, it will measure the wind speed from all directions (without knowing the direction).

Angle of Attack sensor

In case of mounting on rotation slip-ring bearing the sensor could sense air AoA of the vehicle. Due to ability to turn in direction of airflow. The turnig direction could be sensed differentialy to position of aircraft by IMU embedded in the TFASPDIMU01 sensor.

Hardware

TFASPDIMU01 sensor

Eletronic schema

Full schema is avialible in PDF schema

Hardware layout

** IMG - technical draft **

Pinout

Pin # I2C SPI
1 +5V +5V
2 SCL SCK
3 -- MISO
4 SDA MOSI
5 -- CS
6 INT INT
7 GND GND

Due to the possible wider use of the sensor, a standard pixhawk pinout is not used.

PixHawk autopilot cable

To increase the transmission quality, it is recommended to create pairs SDA,GND and SCL,+5V on the cable (as shown in image)

I2C jstgh

TFASPDIMU01 Pin Sigal Pixhawk Color
1 +5V 1 Red
2 SCL 2 Yellow
4 SDA 3 Green
7 GND 4 Black

Pixhawk pinout is listed according to the Pixhawk connector standard.

Usage

Python

For reading data from the sensor, we have prepared a python script in PyMLAB library that uses the pySMBus to readout data. It can be used directly from a computer with a corresponding converter (for example MLAB USBI2C01A) or with one-board computers (Odroid, raspberry and similar) that have own smbus output.

Calibration vertification

Calibration can be verified by mounting of an anemometer to car roof and comparing it to speed obtained from GPS (gpsd). This needs to be done in windless weather.

PX4

We are now working on implementation of driver into PX4 stack.

Main usage of this sensor is as airspeed sensor. It can be also used as an external magnetometer and thermometer.

Ardupilot

We are currently unable to implement the sensor in the Ardupilot flight stack. However, we will be happy to provide assistance with implementation. You can contact us

configuration

TODO

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