Open-hardware wireless beehive weighting
Beehive monitoring - solves data acquisition from load cells placed under the beehives, data transport to server and data visualization for user.
Master unit consist of a Raspberry Pi with a CAN shield with RJ12 connector.
CAN shield is a board with SPI MCP2515 CAN controller and SN65HVD23x CAN transceiver.
The system is powered through a 18V solar panel, charging 12V battery.
Enclosure with master unit has power management board for charging circuit with under-voltage protection, as well as 5V USB ports for output.
20W solar panel was selected for a prototype, due to it’s ability to supply sufficient energy even during cloudy days for a Raspberry Pi.
Under each beehive, assuming that whole chain of beehives is no longer than 100m, is placed platform with load cells for measuring the weight and bus unit in an enclosure. First beehive in chain contains Master and Bus unit at once.
Bus unit has STM32F042F6P6 in an TSSOP20 package with CAN transceiver and two RJ12 connectors for daisy-chaining to other bus units, as well as two holders for HX711 breakout boards. Converters boards can be purchased through eBay or AliExpress.
Schematics & board design can be found in boards directory.
As an ADC with differential amplifier was selected chip HX711 integrated on a beakout board with all the necessary electronics around.
Simple two-rail platform consists of three components:
Middle bars may be optional, depending on the situation:
As the platform was not part of the project assignment, contact me in case of interest.
During development, Zemic L6E were selected. For deployment, L6G are used.
Several beehives can be chained together with a telephone cable with RJ12 jack through Bus unit under beehive, while master unit is sending captured data wirelessly to server through WiFi (3G/GSM modem option was tested and implemented, but is not further described, wvdial utility & whole ecosystem of linux drivers for modems make it diffucult for set-up).
Raspberry Pi 3 running Raspbian system, with an SPI overlay, provides can0 network interface which can be easily interfaced through linux socket. Main program is written in Haskell and is basically flipping frames received on CAN bus to HTTP requests to webservers where the data are further processed.
STM32F042 MCU on board has 32kB of Flash memory and 6kB SRAM. Ivory language has been selected for generation of the C code, and Ivory framework as a hardware abstraction layer, message passing and RTOS interaction. Therefore whole project is 100% Haskell except the web. Firmware can be found HERE.
Web interface provides charts for all sensors connected to the network as well as dashboard defined by user for aggregated statistics. Each setup requires separate instance of the web with database. Source code can be found HERE
System is deployed on a few beehives, needs a bit more tweaking (grounding of the metal platform with beehives, as interference is generated during thunderstorm) and better cable management.
candump can be seed on monitor of the laptop of the deployment set. Battery is already charging from solar panel.
Due to over-engineered solution, next iteration will be with SIGFOX - one module per beehive (just load cell cable connected to small box, 2xAA battery, optionally DS18B20 temperature sensor). Currently waiting for a better signal coverage in Slovakia, which is the reason SIGFOX was not considered from the beginning.