Off-Grid Wireless Communication with the ARMACHAT

Doomsday text communication device enabled by LoRa.

James Lewis
a month agoCommunication

When all the communication networks go down, how will you keep in touch with friends and family across town? Bobricius of PeMi Technology has an off-grid solution for you. His doomsday communicator project, ARMACHAT, enables peer-to-peer wireless communication without relying on an infrastructure service provider. The secret is LoRa.

LoRa is a low-power wide-area network technology. Depending on the country, it operates on unlicensed frequency bands like 433MHz or 915MHz. It is possible to implement a mesh network with LoRa, but currently, ARMACHAT does not.

There are two versions of his device: desktop and pocket, with the pocket reminding us of a BlackBerry from their heyday. Both have a full QWERTY keyboard implemented as a matrix. ARMACHAT is powered by a SAMD 21 Arm Cortex-M0 processor, which is similar to the one found in 32-bit boards like the Arduino Zero. That means you can program the communicator with the Arduino IDE.

What can you do with ARMACHAT?

All of the hardware features gives many options for extensibility. ARMACHAT lets you learn how to do RF communication with LoRa, interface with sensors like GPS over I2C, manage power with sleep states, and display graphics on the LCD screen.

In what might be a first for us at Hackster, the project details include a full Strength, Weakness, Opportunity, and Threat (SWOT) analysis. In that SWOT, bobricius brings up the ESP32 as a competitor. The ESP32 would be ideal in situations where WiFi or Bluetooth Low Energy (BLE) hosts are readily available. The impressive thing with this LoRa-based design is that bobricius achieved communication across 500 meters without a direct line-of-sight.

Some LoRa radios are capable of much longer distances. We were happy to see that if ARMACHAT becomes a product that the radio would come unpopulated. Such a move means you can tailor the radio to frequencies used in your country and perhaps use one with different power levels.

For now, the project is still in active development. You can follow along with bobricius' progress on the ARMACHAT project page.

James Lewis
Enginerd at night. Electrical Engineer on paper. Fan of making things that blink, fly, or beep. Creator of: http://addohms.com. KN6FGY.
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