Build a LoRa Mesh Radio Using an Adafruit Feather or TTGO ESP32 Module
This simple add-on for mobile phones enables SMS-like messaging in a group when outside cell coverage, or in disaster scenarios.
LoRa-based hardware has been utilized to create a myriad of different IoT projects that require long-range/low power communication. That said, it’s also a great platform that can be used to send SMS messages via a smartphone when cell signals are out of range, making them a great tool in disaster scenarios. Instructables user 'sqij' has uploaded a great tutorial on how to build a LoRa Mesh Radio using either Adafruit’s Feather M0 (with RFM95 LoRa Radio) or Lilygo’s TTGO LORA32 ESP32-based module.
Both boards will work in this scenario, but sqij states that the TTGO LORA32 module only gets about half the range of the Feather, so keep that in mind if you’re are looking to recreate his build. Beyond the boards, sqij offers some optional hardware choices — an on/off switch, a piezo buzzer, a 350mAh LiPo battery, and a USB OTG cable, all of which make sense if you plan to use the radio in an emergency setting.
While the TTGO LORA32 might not have as much range as the Feather offers, it does have some advantages, including the ability to connect to smartphones via Bluetooth Classic or LE, negating a need for a cable connection. It also comes with a handy 0.96-inch OLED display and a 915MHz spring antenna. The Adafruit Feather M0 is a barebones affair without Bluetooth or Wi-Fi but does come equipped with an ATSAMD21G18 MCU and a powerful RFM9x LoRa 868/915 MHz radio module, making it an attractive LoRa option.
On the software side, both boards utilize the Arduino IDE, as well as Ripple firmware, which allows users to SMS using an assignable numerical ID between 1 and 254. sqij provides a complete walkthrough for each board in his write-up, along with links to the Ripple firmware and even the files needed to 3D print a handy case that users can attach to their phones.