Bresser Station Gateway Board

A multifunctional board for our AMMS system and other Lora applications

Index

• Introduction
• The problem
• Searching for a possible solution
• Hardware
• Software
• Assembly and first tests
• Next developments
• Conclusions
• Glossary (work in progress)

Introduction

For our AMMS system we use a plethora of commercial weather stations, mainly from Bresser, which we implement in the network via our gateways that we told you about months ago in our dedicated article.

The system, which is always evolving, required further development from a prototype with flying wires to a more professional solution, with printed circuit board and components ordered and already calibrated to simplify gateway construction and software installation.

The problem

It was necessary to find a solution to the complexities of assembling the BSG (Bresser Station Gateway) system, which is still a prototype, by achieving a final product that simplified the installation of components and software, and solved the problems of instability and data reception from Bresser stations.

Searching for a possible solution

After months of work and development, we began to think about a definitive solution to all the problems of the Bresser-AMMS system, finding a number of focal points on which to concentrate our efforts, which can be summarised as follows:

• Change from Esp8266 to Esp32 to solve problems with system stability and data transmission.
• Standard antenna pre-fabricated on PCB to remove end-user difficulties in finding the correct wire size
• Creation of a compact PCB to simplify system assembly and improve aesthetics.
• Optimising the software by making it neophyte-proof.
• Ease of marketing.

Hardware

The hardware was the first major problem to be solved, as it previously consisted of an ESP8266-based devboard with an RFM95W module soldered on via flying wires and an antenna that had to be prepared by hand and correctly sized. The resulting system was therefore unsightly and complex to prepare, as apart from the skills of soldering electronic components, we had to deal with the antenna problem, a continual lottery to find the ideal antenna for our uses, i.e. picking up the 868MHz frequency of the Bresser weather stations and decoding them to send them into our AMMS database.

To overcome these problems, we made a number of considerations in combination with our software problems, opting for the use of WEMos esp32 mini modules, equipped with a powerful dual core Esp-Wroom-32 microcontroller, which allows us to decode and send without interfering with network connectivity, and considering the creation of a PCB dedicated to the project, also integrating a connector with an I²C for future expansion or user customisation.

This is how the BSG Board, an acronym that stands for Bresser Station Gateway, was born. Lora to Esp32This means that it is not only possible to pick up the 868MHz radio frequencies of commercial stations and send them via WiFi to the AMMS central server, but also to use the board as a Lora modem, a feature being developed by Joshua and Leonardowith a view to implementing it also in our base stations and weather nodes where the Internet does not arrive, thus exploiting radio waves.

The board has slight differences in terms of the ESP32 pinout compared to the original design, due to the implementation of the I2C output, however, it remains a fast project and one that we have decided to make opensource also to support the work of Matthias Prinke, author of the library BresserWeatherSensorReceiver from which we have taken our cue, and without which the AMMS would be without an important slice of weather stations and monitoring sites.

The software

Currently, the firmware is largely based on what we showed you in the previous article dedicated to this project, although an entirely different programme is currently being tested that also supports OTA updates and configuration via serial commands, by our programmer Giosuè, removing the configuration via WEB page that made the system unstable.

We have not released anything yet as we want to make sure it is stable and without bugs that would compromise the AMMS system, but you can test it by installing it on the BSG board using the online installer at ESP Launchpad at the following link and by contacting us from our telegram channel for subsequent configuration. When the firmware is complete, it will be released opensource on our GitHub, where you can already find the schematics of the board.

Assembly and first tests

Once the PCBs (ordered from JLCPCB) arrived, we started assembling the board, which proved to be very easy as we had thought when designing the product. The board also measures only 4cm by 5cm on each side, so it is easy to hide, however aesthetically unimpressive it may be. If you wish, you can further reduce the footprint by soldering the esp32 devboard directly onto the board, without using the headers, but in the event of mistakes it becomes easier to break something, so we do not recommend this as a thing to do. We suggest a 90° JST-XH connector to have all the connectors on one side, a connector that can be used for additional displays or sensors, or to connect other boards with microcontrollers in slave mode (we will release the source specifically to facilitate the development of further applications for this board).

Having loaded the software with the Launchpad, all we had to do was connect with the Arduino IDE to the serial monitor and send the SSID of the WiFi network, its password, and the token for our AMMS system to enter your station data. From here we began a test period lasting about a month where we verified the functioning of the system, its stability over time, and also the shooting distance of the antenna on the PCB, which is around 600m in optics, a very good result considering that this is the first time we have designed the antenna for one of our devices in house.
The tests have succeeded perfectly, in that not only does it work stably without the usual reboots that caused us to lose data after data, but we have worked on implementing further functions to the board, OTA and MQTT in primis, the former for automatic system updates, the latter to have compatibility with Home Assistant without losing the sending of data to the AMMS system, functions which are currently being tested but which are giving us satisfaction as the system holds up over time and does not 'lose connection' (for those who have been following the project for a longer time, the biggest problem we had was the automatic reconnection, which did not work and so the station was offline even though everything worked locally)

Next developments

We plan to turn this board into a multifunctional gateway, exploiting the potential of the RFM95W module. In fact, the BSG Board lends itself to acting as a Lora modem, i.e. communicating via radiofrequency with another receiving station the data fetched from the weather station or sensors/devices connected to the I2C port
Multi-station mode is also envisaged, i.e., having several Bresser stations interfaced to a single board, which would allow our system to expand much more extensively even in small towns or squares where there are several Bresser devices to be interfaced to a single system (perhaps with the advent of version 2.0 we will consider using an external antenna via connector to increase the reception range)

Conclusions

This board represents the turning point of our project, as we can now start working on a single board for multiple devices (you can find a list of compatible devices in the GitHub of the Matthias Prinke) and, above all, allows us to fulfil several needs that had been blocking the project's progress for some time, firstly a stable and lasting interface between station and database, and secondly a useful template to exploit the LoRa potential of the RFM95W module, which allows us to think in the future of more applications of the board (think of places where the Internet does not arrive and there are stations to be interfaced to the network), as well as already allowing a plethora of functions that greatly simplify the usability of the system, such as automatic updates and interfacing to Home Assistant (thus making the radio alarm device incorporated in the weather station unnecessary).