Walkie-Textie Wireless Communicator

Walkie-Textie Wireless Communicator

The Walkie-Textie is a simple handheld device with a 12-key keypad and OLED display that allows you to send and receive text messages using the LoRa wireless protocol. It's ideal for situations where there's no mobile signal, such as when you're camping or hiking in a remote area, when you don't want the cost of a mobile network, or for children to have fun without running up a bill:

The Walkie-Textie is a handheld device that allows you to send text messages

using the LoRa wireless protocol.

The circuit uses a low-cost LoRa module, the HopeRF RFM95W, controlled by an ATtiny814, which also drives a low-cost monochrome OLED display to show the messages, reads the keyboard, provides an audio alert, and reads the battery level.

Introduction

The Walkie-Textie uses the LoRa wireless protocol which is unsuitable for speech, but ideal for short text messages. LoRa can reach a range of up to 3 miles (4.8 km) in urban areas, and up to 10 miles (16 km) in rural areas. It uses license-free sub-gigahertz radio frequency bands: 433 MHz or 868 MHz in Europe, 915 MHz in North and South America, 868 MHz in India, and 915 MHz in Asia. The LoRa modules are available in two versions: one for 433 MHz, and one that can be tuned to either 868 MHz or 915 MHz.

Using the Walkie-Textie

The Walkie-Textie has a twelve-key keypad, and like early mobile phones uses a technique called multi-tap to compose messages, in which repeatedly pressing the same key cycles through the characters for that key:

The Walkie-Textie lets you write messages on a 12-key keypad

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