18.6.2024
Meshtastic is an open-source project that utilizes LoRa (Long Range) technology for wireless communication. LoRa is an ideal solution for places where electricity, internet connection, or mobile signal is not available. Do you have a remote cabin in the mountains? With a small photovoltaic panel, a Meshtastic device can run 24×7×365. If you connect a PIR sensor and a thermometer to the device, you will have constant information about the temperature and any unwanted visitors.
The "mesh" in the name means "network" – individual nodes in the network can relay messages to each other. If your cabin is in a deep mountain valley, another Meshtastic device on the nearest hill can facilitate the connection. When the zombie apocalypse comes, the Meshtastic network will be the only one capable of transmitting messages over long distances.
The 868 MHz network is currently used mainly for "radio amateur" purposes. It's fun, especially when you take a Meshtastic device with built-in GPS on a hike through the hills. Despite its community nature, the potential of the Meshtastic network is quite large. The network operates in the unlicensed shared band of 434 and 868 MHz along with car keys, cordless phones, garage door openers, and similar devices, but it introduces long-distance communication.
The Meshtastic network can use different frequencies – conditions in the USA are different from those in the EU. In Europe, the network can operate on two different frequencies:
Both frequencies have their pros and cons. The 868 MHz frequency is more useful because the network is denser, and where there is no direct visibility, other network nodes can facilitate the connection. On 434 MHz, such an option usually does not exist.
The transmitted messages can be very small (about the size of an SMS), and their number and transmission speed are limited. Meshtastic is by no means a replacement for an internet connection or mobile network. However, it can transmit a lot of simple information or commands:
Drivers for meteorological and electrical information are part of the firmware, and the devices themselves are connected via the I²C bus. Other devices, such as motion detectors or light controls, can be connected via GPIO, transmitting only simple on/off information.
Any other device can be connected via a serial port using an auxiliary CPU, such as an Arduino or ESP32. Commands are transmitted as text messages. This way, practically anything can be connected: electricity meters, water level monitoring in a well, etc.
Connecting an external device is very easy; making an LED blink or triggering a siren requires just a bit of skill with a soldering iron.
We tested several different devices:
All hardware works well, except for the Lora V1 – in the list, I have marked this device with three question marks. The manufacturer does not acknowledge the board, and no documentation or firmware can be found. After a long struggle, I managed to modify the firmware so that the device works. Liligo devices are generally strange – the biggest problem is identifying what exactly I am holding in my hand for each device.
Heltec devices work excellently. We created an enclosure for the Heltec V3 and Heltec Tracker; with a 26650 battery, the device can operate for two days without issues. The enclosure can be downloaded from Printables.com.
Small photovoltaic panels are perfect for powering Meshtastic devices. A typical small panel measuring 10×10 cm with a 5 Ah battery is usually sufficient to power a device such as a remote thermometer, especially in areas with low traffic on the band. However, during the winter season, it can occasionally happen that the battery runs out due to shorter days and limited sunlight. To ensure reliable operation under these conditions, it may be useful to have a larger battery capacity and a larger panel.
Powering a router that serves as a central communication point requires a larger photovoltaic panel because its consumption is higher. A typical frequent router located on a hill may have a continuous consumption of around 100 mA. In this case, it is advisable to use a larger photovoltaic panel that ensures sufficient power even during winter months, for example, a panel measuring 50×20 cm. The battery should also have a capacity of 10 to 20 Ah.
