LoRa Walkie-Textie

As a kid decades ago, if you wanted to communicate over the air with your friends in the neighborhood, you could use a walkie-talkie to squawk out messages to each other. For several reasons, this rarely worked well, but today there’s a new wireless technology on the block: the LoRa long-range, low-bandwidth wireless protocol. It's great for text messages, but not so much for voice communication.

Prolific hacker David Johnson-Davies (DJD) built a simple text communicator based on the LoRa protocol called the Walkie-Textie – as opposed to a voice-based walkie-talkie. The handheld device is brilliant in its simplicity. The body is a pair of screwed-together PCBs, and it features a 128x64 pixel monochrome I2C OLED display as its main visual interface. It also has an LED and a piezo beeper to indicate when a message is received. Input is via a 12-button interface for multi-tap texting, similar to how cell phone text input (rather annoyingly) worked a decade or two ago.

LoRa communication is handled by a HopeRF RFM95W module, while everything is controlled by an ATtiny814. The device is meant to be used with a LiPo battery, though other power sources can be implemented with the proper JST plug, plus a simple firmware modification to adjust the Walkie-Textie’s battery sensing routine.

A lot more details can be found on DJD’s Technoblogy post, including code and board files. Notably, messages can, in theory, be read by anyone in receiving range, so you’ll want to keep sensitive information – like the location of your secret hideout – off the air, or implement an encryption routine. The Walkie-Textie looks like a lot of fun to build and use, and it’s neat to see another device implementing LoRa technology!