Weight, temperature and humidity measurement in a beehive using Arduino and LoRaWan (TTN).
Deutscher Text.
To support bee keepers in monitoring their bees with minimal interference, a set of sensors will measure and transmit the current state in short intervalls. Design goals:
- Energy efficiency. Devices should be able to run on batteries and solar cells for unlimited time.
- Low radiation. I do not know whether or not radio transmissions disturbe bees. Using a low-power technology like LoRa rather than GSM minimizes the effect.
- Low cost. Small microcontrollers are very affordable and sufficient for the task.
-
Arduino (alternatively Uno + Dragino LoRa Shield, Dragino LoRa Mini Dev, or CubeCell LoRa Dev)
A small microcontroller has enough power to measure every couple of minutes. A rechargeable battery serves as buffer to measure during night and cloudy weather.
The device works without any human intervention except a button to put it to a 'manual mode' when working with the beehive.- Several (e.g. 5) DS18B20 temperature sensors using 1-wire
- DHT11/22 temperature and humidity sensor
- Weight cell with HX711 converter
- LoRaWan connection (TTN)
- Solar power and rechargeable battery (LiPo)
- Push-Button with LED to disable temporary (manual mode)
- Evtl. slave devices with RS-485?
-
LoRaWAN TTN-Gateway/Network/Application
Beehives usually have no wired internet connection and high-speed connections using GSM and WLAN is avoided to keep radiation low.
TheThingsNetwork (TTN) is a global open LoRa network. If no gateway is available within some km near the beehives, an additional gateway can easily be installed.- Transmits messages from the LoRa gateways to the internet, handles authorization (OTAA/ABP) and encoding/decoding of messages
- Allows direct ThingSpeak integration (only 1 device per application with 1 channel)
- HTTP integration allows to address any possible backend (many devices per application, see below)
- see TTN application
-
Dashboard and visualization with ThingSpeak channel
This is the quick and simple way to display the sensor data.- Simple to setup and share ThingSpeak
- Mobile app available
- Matlab analysis possible
- Limited to 8 fields/channel
- No linking of multiple channels (beehives)
- Limited user interaction (drilldown)
-
Mapping and routing sensor data eg. using AWS (work in progress)
Alternative or extension to the ThingSpeak display. Such a back-end application can be used to collect the sensor data and to feed a web application.- see AWS serverless
- Forwarding to ThingSpeak channels as above, but allowing many devices/channels per TTN application
- Additionally storing sensor docs in DynamoDb, see AWS recording
- No restrictions of the number of fields or the way sensor data is displayed (own WebApp)
Three boards have been tested:
- Arduino Uno + Dragino LoRa Shield
- Needs 5V supply
- Many digital pins already used by shield
- Classic Uno size and MCU (16MHz ATMega328P, 32KB FLASH, 2KB SRAM)
- Dragino LoRa Mini Dev
- 3.3V (possible LiPo, not tested)
- Small size, LoRa transmitter integrated
- Classic Arduino MCU (16MHz ATMega328P, 32KB FLASH, 2KB SRAM)
- Heltec CubeCell LoRa Dev. My favorite!
- 3.3V (possible LiPo, integrated solar charging logic)
- Power efficient (1W solar cell with 230mAh LiPo loads on a single sunny day and has almost 2 weeks of buffer)
- Small size, LoRa transmitter integrated
- Stronger MCU (48 MHz ARM M0+, 128KB FLASH, 16KB SRAM)
Used pins:
| Pin Function | Wiring | Uno+Shield / Dragino | CubeCell |
|---|---|---|---|
| 1-wire Temp sensor | pull-up resistor 4k7 to VCC | D5 | GPIO5 |
| DHT-11/22 | pull-up resistor 4k7 to VCC | D4 | GPIO4 |
| HX711 Dout | A0 | GPIO2 | |
| HX711 Sck | A1 | GPIO3 | |
| Push-Button | to GND (active low, triggers interrupt) | D3 | GPIO7 (aka battery test control) |
| LED | to VCC (active low) | A2 | GPIO1 |
- The device measures about every 5 min
- Measures will be transmitted on significant changes or every 30 min (messages may get lost)
- Currently no uplink messages
- Fixed size and order of measured values
- Values are transmitted as short integer values with 2 digits (-327.67 .. 327.67)
- Reserved value to represent null (-327.68)
"sensor": {
"version": 0, // command id or version
"battery": 3.92,
"weight": 0.37,
"humidity": {
"roof": 47.5
},
"temperature": {
"drop": 20.68,
"lower": 19.5,
"middle": 19.93,
"outer": 20.62,
"roof": 22.2,
"upper": 19.37
}
}
Local installation of git and Arduino IDE assumed.
Install the CubeCell board: https://heltec-automation-docs.readthedocs.io/en/latest/cubecell/quick_start.html
(current version 1.3.0).
cd <project-root>
git clone https://github.com/joergkeller/beehive-sensor.git
cd beehive-sensor
git submodule init
git submodule update
To fetch the latest updates:
cd beehive-sensor
git stash
git pull
git submodule update
git stash pop
| Arduino Settings | Value |
|---|---|
| File > Preferences > Settings > Board Manager URLs | https://github.com/HelTecAutomation/CubeCell-Arduino/releases/download/V1.3.0/package_CubeCell_index.json |
| File > Preferences > Settings > Sketchbook location | C:\...\beehive-sensor |
| File > Open... | C:\...\beehive-sensor\arduino_beehive_sensor_lora\arduino_beehive_sensor_lora.ino |
| Tools > Board | CubeCell-Board |
| Tools > LORAWAN_REGION | REGION_EU868 or your region |
| Tools > LORAWAN_CLASS | CLASS_A |
| Tools > LORAWAN_DEVEUI | CUSTOM |
| Tools > LORAWAN_NETMODE | OTAA |
| Tools > LORAWAN_ADR | ON |
| Tools > LORAWAN_UPLINKMODE | UNCONFIRMED |
| Tools > LORAWAN_NET_RESERVATION | OFF |
| Tools > LORAWAN_AT_SUPPORT | OFF |
| Tools > LORAWAN_RGB | ACTIVE or DEACTIVE |
| Monitor baud rate | 115200 |
The project already includes all required libraries (that is the reason for the submodule commands and for the local sketchbook location).
Then
- Create free TTN account/application/device and enter OTAA/ABP authorization codes in
credentials.h - Create free ThingSpeak account/channel and a TTN ThingSpeak integration with the appropriate values
- Compile/upload sketch
- Activation with OTAA takes some time (even half an hour or so)
- Press button to enter 'manual mode'
- no LoRa messages sending, blinking LED instead
- continous weight measuring for calibration, calculate offset/scale (eg. see Excel sheet)
- for temperature compensation, measure weights at different temperatures also
- scanning 1-wire temperature sensors one by one, note ids
- press button again to start LoRa activation
- Enter 1-wire sensor ids and weight calibration to
calibration.h - Compile/upload sketch again
- Wait for OTAA activation
- First measure should appear in the local monitor, as TTN data and in ThingSpeak channel