Creating the GeoMCU Network

WiFi Configuration

The GeoMCU board is based on an ESP8266, which gives us a few requirements for the WiFi network the sensors will connect to:

• Only 2.4 GHz WiFi can be used. The chip is compatible up to Wi-Fi 4/802.11n, but can still connect to a newer access point since they’re backwards compatible.

• The Arduino-based software can connect to WPA2-secured networks or lower, but is NOT compatible with WPA3

Because of these two requirements, most University networks will NOT work directly, and you will most likely need to manually configure the router or access point. We most commonly use one of:

• GL-iNet GL-B1300

• GL-iNet GL-A1300

for compatibility and configurability, but any Wi-Fi 4 router should work. Just make sure to manually configure a 2.4 GHz network with a password using at most WPA2 security. The SSID and password need to be set in the firmware configuration.

Gateway Computer

• For testing or short-term, contained use, a laptop will suffice, as long it can connect to the MQTT Broker.

• For remote or longer term deployments, we usually use an embedded Single-Board Computer, such as as a Raspberry Pi.

Recommended SBCs

• Raspberry Pi 3, 4, or 5

  • The community around these is very large, so it’s generally easy to find help when you run into problems

  • The Pi5 is very new (as of 2024) and much more powerful than the 3 or 4, with the same tradeoffs as the Rock4.

• Radxa Rock4

  • This board has a more robust processor than the RPi 3 or 4, and the added benefit of an NVMe slot for SSDs. However, it does consequently consume more power and put out even more heat.

• Olimex A20-OLinuXino-Lime2

  • This board is very low-powered, but has an on-board SATA port for a hard drive or SSD. Sometimes will struggle with memory usage or processing power with a large number of sensors (>30) and/or when archiving sensor data. That said, it’s also battle-tested and out-of-the-box compatible with just about any flavor of Linux you can think of, which leads to more stability compared with most SBCs.

MQTT Broker

You’ll need an MQTT Broker for the sensor nodes and the Gateway/Data Aggregator to connect to. As long as all of the sensors and the aggregator software can connect to it, data will flow wirelessly. This is technically optional when using External Data Acquisition, but we recommend keeping at least the sensors connected even this case for stability and easier configuration.

• We recommend mosquitto(8), and provide example configuration and service files among the System Scripts.

• If your WiFi AP is running OpenWRT, you could instead use the router or access point itself as the MQTT broker.

Note

Using a public MQTT broker should be technically possible, but would require modifying the firmware to securely log into the broker.