REYAX RYMR993 Lite

Presentation and Motivation

The RYLR993_Lite caught my attention because of its simplicity of integration.
All communication takes place through AT commands over UART — no complex software stack to embed, no need for FreeRTOS or any multitasking environment, no asynchronous SPI exchanges or concurrent task handling.

You work sequentially: one serial buffer, one command, one response.
No strict real-time requirements — as long as the UART port can be polled, everything runs smoothly.

This architectural choice makes it compatible with any microcontroller, even very basic ones.
Moreover, the RYLR993_Lite was designed with energy efficiency in mind, offering a low-power sleep mode capable of waking the MCU via an interrupt.

In short: the module handles the entire radio protocol — you focus on the application, not the infrastructure.

Package Contents

Two RYLR993_Lite modules and two 868/915 MHz antennas (U.FL → SMA), both of excellent build quality.
The breakout board is compact, includes LEDs to visualize module status, and can be easily mounted using a female header or Dupont wires for quick prototyping on a breadboard.

Specifications

• Frequency band: 820–960 MHz (EU868, US915, AS923, etc.)

• TX power: up to +22 dBm

• RX sensitivity: −148 dBm

• Supply voltage: 3.0–3.6 V (typ. 3.3 V)

• TX current: ~140 mA @ +22 dBm

• Sleep current (Class A): ~5 µA

• UART: 3.3 V logic only

• Operating temperature: −40 °C → +85 °C

• Built-in encryption: AES-128 CCM

• Minimal wiring: VDD, GND, RXD, TXD, NRST (all 3.3 V).
  No level shifter is required with an ESP32 or STM32 — just one UART port and a reset pin are enough.

Full specifications and integration resources are available here:
🔗 https://reyax.com/products/RYLR993_Lite

LoRa and LoRaWAN

The module can also operate in non-LoRaWAN (point-to-point) mode — ideal for quick tests or direct telemetry without relying on a public network.
Perfect for range and propagation experiments.

LoRaWAN mode is well documented and easy to configure, making it straightforward to join a public network.

Next Steps and Thanks

A LoRaWAN prototype will follow soon: environmental sensors, microcontroller, and data publication on a public network.
Nothing groundbreaking, perhaps — but a nice weather-station demonstrator in perspective.

Many thanks to REYAX for sending the two modules.
I’m genuinely impressed by their build quality and excellent documentation.