Receiving radiosondes with MySondy GO

MySondy GO is a project to facilitate the search for Radiosondes in the field. Using a TTGO ESP 32 (433 Mhz) module and a simple smartphone, it is possible to receive the radio signal directly from the probe. The geographical position of the probe is displayed on a map using the smartphone in Bluetooth connection with the module.

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The TTGO ESP32 module and the smartphone in Bluetooth connection with ESP32

Tutorial also in spanish translated by Miguel (ea4bas)

MySondyGO (spanish)Télécharger

Modificación de la antena TTGO para el rango de 400 a 406 MHz (spanish)Télécharger

The main advantage of the system is that you don’t need a laptop. The TTGO module fits in a matchbox. The author of the system is Mirko Dalmonte, IZ4PNN.

The development board called TTGO is equipped with an Esp32 microcontroller well known by the « Makers » and a SX1276 or SX1278 modem.

Pinout of the TTGO ESP32 module

For the moment, the MySondy GO project does not use Wi-Fi connection with the smartphone but only Bluetooth. Nevertheless, the author specifies that the use of Wi-Fi will be available in future software versions.

To test the project, I bought a TTGO module for 22€ on a well-known website. Be careful not to make a mistake in the frequency range when ordering, be sure to choose the 433Mhz version.

Then just download the firmware via the author’s links and programming utilities to get a functional set very quickly. So far, I used the MySondyGO140.bin firmware.

Summary of downloaded files:

MySondyGO manual	Instruction manual
MySondyGO_2_00	Programming Utility, drivers and firmware
MySondyGO.bin	Firmware to be programmed in ESP32

Even if the instruction manual is in Italian, the different screenshots do not pose any problem of comprehension. As soon as the TTGO module is connected to the PC with a microUSB cable, the drivers are automatically installed under Windows10. For Windows7 the drivers have to be installed beforehand (CP210xVCPInstaller). In the case of Linux, the name of the communication port should be /dev/ttyUSB0

Use the provided utility (Esp32 download tool) to implement the MySondyGO.bin firmware in esp32

ESP32 Programming Utility (i programmed previous version 1.40, now it is 2.0)

In case of difficulty programming the firmware under Windows, connect a wire between ground (GND) and pin GPIO0. This « forces » the programming mode. Under Linux, this wire is useless using the esptool command line utility and the following command lines:

python esptool.py –port /dev/ttyUSB0 erase_flash

python esptool.py –port /dev/ttyUSB0 write_flash -z 0x0000 MySondyGO.bin

Once the firmware is implemented in the ESP32, the module’s mini OLED display should produce this display

Start by performing Bluetooth pairing with ESP32

Then download the MySondy GO application with Google PLAY

When MySondy GO starts up, the smartphone asks for the necessary permissions to access the Bluetooth device, and for geolocation. Then the application searches for the available TTGO if it has been paired before. When the connection is made, the screen must match the OLED display of the module. From this moment on, the TTGO is constantly synchronized with the smartphone and is able to control and receive all necessary data. Don’t forget to activate the 4G connection in order to obtain the Openstreetmap mapping.

The MySondy GO application and the various menus at the top left of the screen

The interface is very ergonomic. The SET button is used to select the receiving frequency and the radiosonde model. I placed an M10 radiosonde in the garden for testing. Decoding is immediate. The software indicates precisely the distance between the probe and the smartphone with the course to follow.

M10 Radiosonde

The flashing yellow icon indicates the user’s position and signals that the TTGO is communicating correctly with the smartphone. Conversely, a flashing red light indicates that the TTGO is not connected or the Bluetooth connection is not stable.

When a probe is received, an additional button appears in the upper right corner. This is the share menu which allows you to send the sensor’s coordinates to the smartphone’s GPS navigation software or to share the sensor’s position with different software or messaging services (WhatsApp, etc.).

The software is very easy to use; Mirko’s work is remarkable

Using the button in the top left corner, the main menu allows you to access the application’s preferences and to customize the software.

In the parameters sub-menu, it is possible to change the hardware configuration of the pins (TTGO PINS), the battery management of the module and finally the radio parameters.

Configuration of pins, battery and reception parameters

Yes, it works !

Conclusion:

Falling by chance while surfing the Internet on the project, I immediately liked the concept and the ease of implementation, the main difficulty being to implement the firmware in the ESP32 according to the operating system used on the PC. The trick of connecting the GPIO0 pin to ground should make it easier. For packaging, many STL files for 3D printers can be downloaded from the Internet. This small module is really very handy and will quickly become indispensable for any radiosonde hunter. A Facebook group has been created (8).

73 and happy hunting!

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