M5Stack Unveils Atomic DTU LoRaWAN-US915 with STM32WLE5, RS485, and Modbus Support for Industrial IoT

M5Stack is known for its ESP32-based building blocks for the IoT with Wi-Fi & Bluetooth wireless connectivity, I/O headers, and block-specific features like a tiny color display, a speaker, a touchscreen display, a camera, and more.

The company’s latest product is the M5Stack Atomic DTU LoRaWAN-US915, based on the ultra-low power wireless MCU with LoRa support (STM32WLE5), as well as the low-power long-range transceiver module (RAK3172) and one RS485 communication interface (SP3485EN) that allows for industrial communication, notably with the Modbus protocol. Based on the STM32WLE5CC chip, the Atomic DTU LoRaWAN Base supports LoRaWAN Class A, B, and C modes and comes in US915, EU868, and CN470 variants to meet regional frequency standards for low-power, long-range IoT communication.

M5Stack Atom DTU LoRaWAN-US915 Specifications:

• Wireless SoC: STM32WLE5 LoRa SoC with 256KB Flash and 64KB RAM
• LoRa module: RAK3172 transceiver module based on STM32WLE5CC
• Operating frequency: US915 (902 ~ 928 MHz)
• LoRaWAN protocol: Supports LoRaWAN 1.0.3, Class A, B, and C modes
• Communication modes: LoRaWAN and LoRa P2P (point-to-point)
• Activation modes: OTAA and ABP supported
• Transmit power: Up to +21 dBm
• Receiver sensitivity: Up to -137 dBm (SF12/BW125KHz)
• Antenna: 195mm rubber-duck stick antenna (50 Ω, 0.5 dBi, SMA male)
• Serial interface: UART @ 115200 baud, AT command support via ESP32
• LoRaWAN server compatibility: Works with TTN, ChirpStack, Actility, Tencent Cloud, and others
• Industrial I/O:
  • RS485 interface using SP3485EN transceiver
  • 12V DC input with integrated 5V step-down DC-DC
  • Modbus Master/Slave support
• Expansion:
  • 1x I2C Grove connector
  • 1x HT3.96 4P wiring terminal
• Standby current (RS485 powered):
  • 9V @ 167.98µA
  • 12V @ 178.09µA
• Active current (RS485 powered):
  • 500kbps RX: 9V @ 50.32mA | TX: 9V @ 51.56mA
  • 125kbps RX: 9V @ 49.94mA | TX: 9V @ 102.79mA
• Dimensions: 65.3 x 28.7 x 24.0 mm
• Weight: 20 grams
• Operating temperature: 0°C to 40°C

Typical applications for the Atom DTU (Data Transmission Unit) include automatic remote meter reading, intelligent traffic, intelligent parking lot, smart agriculture, industrial monitoring, and environmental monitoring node deployments. The unit is also compatible with the M5Stack ATOM-S3, a wireless programmable controller based on the ESP32-S3 IoT platform.

Like most M5Stack products, the Atom DTU LoRaWAN US915 module supports development environments such as UiFlow1, UiFlow2, and the Arduino IDE. More information on the hardware documentation, including schematics, can be found on the M5Stack documentation website, and the company provides a C++ API and a sample Arduino sketch connecting to a LoRaWAN gateway using the OTAA method on GitHub.

Each unit includes the DTU module, stick antenna, and HT3.96‑4P wiring terminal. All models are priced at $22.90 and are available from the M5Stack shop.

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