José Carlos Dafonte VázquezFreeDSM (Free Dark Sky Meter)
This DIY photometer is part of the project Gaia4sustainability, funded by the Spanish MICINN through grant PDC2021-121059-C21/C22
The FreeDSM allows you to measure the quality of the sky background during your night observations. It is a photometric instrument that incorporates the Osram TSL2591 sensor, with two diodes: one will make a measurement in the infrared range and the other in the full spectrum. From the data proviced by those diodes, it calculates the mpsas measurements every minute (its range is 12-23 mpsas) but algo temperature and humidity (sensor AHT2x).
You can build your own FreeDSM with the information contained here, by assembling low cost and easily available components and some small parts for the chassis that you can create on any 3D printer. It resists weather, is small and incorporates a battery, which allows us to use it in a portable way, although you can also install it permanently, even ignoring the installation of the battery inside and its charge regulator. The software is based on Tasmota, making it easy to integrate data across a multitude of environments and to include hundreds of additional sensors. The license of the firmware is GPL3.0 and additional proccesing in Berry code run by FreeDSM.
This device is part of the Gaia4sustainability project and can provide measurement data to our open platform. We say can because FreeDSM allows the sending of data via MQTT messages to your own home automation platform (for example, Home Assistant), it can also save them in the memory of the device itself and, if you allow it, also send the data to our platform, where You can have your own profile and see your FreeDSM data in it.
We hope you enjoy it as much as we have designing and programming it. We also thank the community for their support during its development, and for them it is the result.
Description of the components and Do-It-Yourself process
Firmware releases
Here you will find the latest FreeDSM firmware and Berry script.
IMPORTANT: The firmware and berry script must much the first two digits. If you are performing an initial flash, the file includes firmware and script but the update by web interface DOES NOT update the berry script, it is mandatory to update it manually (web interface -> Console->File system upload)
- Latest Firmware v2.4 initial flashing (firmware.factory.bin, needed flashing by command line)
- Latest Firmware v2.4 web update (firmware.bin, flashing using the Tasmota web interface)
- Berry script v2.4.7 web update (autoexec.bec, to upload in the Tasmota filesystem)