Sensors and hardware
The app works from meteorological data and from what you write in the log. A sensor reads the plot directly: soil temperature, greenhouse temperature, moisture.
What works
- Soil temperature and moisture sensor — Our design and firmware. Soil temperature is the one thing no forecast gives you: it knows the air over a city, and sowing time is decided by the ground in your bed.
- Greenhouse air sensor — Temperature and humidity. Until now the app said plainly that its heat figures were outdoor ones — a greenhouse can now answer for itself.
- Hub — A single-board computer with a radio module, built from the instructions. It hears the sensors, stores readings and sends them on when the internet comes back.
Planned
A second hub for the LoRaWAN standard, so off-the-shelf sensors work: Dragino, Milesight and the rest. That is a separate device rather than a firmware update — someone else's sensor needs an eight-channel receiver, and that is hardware, not software.
How it works
The sensor speaks once an hour over LoRa radio — kilometres in the open, and no Wi-Fi needed out at the bed. The hub hears it, decrypts it and queues the reading.
A country plot does not always have internet, but it does have power. So the hub stores readings and sends them in a batch when the connection returns — each carrying the time it was measured, not the time it arrived. A week without a connection comes back as an unbroken series.
The app never talks to the hub at all: network setup and sensor pairing live on the hub, beds live in the app, and the server is what joins them.
Why through a hub
The sensor sends its readings over radio to the hub. A direct Bluetooth link to the phone does not work for this: Bluetooth reaches a few metres and only while the phone is beside the bed with the app open — iOS gives no reliable background polling. A reading would arrive exactly when you are standing there and can feel the soil with your hand.
A sensor is worth the opposite: knowing what is happening on the plot while you are away. So readings go through the hub — it listens to the sensors continuously and passes them to the server when the internet comes back.
The server is ours, not the sensor manufacturer's, and no account other than your Dachamatics one is needed.
What not to expect
- Automatic watering. Operating a water valve is a different kind of responsibility from displaying a number.
- A product in a box. For now this is a schematic, firmware and instructions, not something on a shelf.
- A verdict of "dry" from a home-built moisture sensor. Without factory calibration its output is not a percentage but its own units, so the app will show you the change and will not tell you whether it is time to water. Temperature needs no such caveat.
Until there are sensors
Watering, frost cover and feeding are worked out from the log, your plot's weather and published norms. That works and costs nothing to buy.