ATOMIC DTU NB-IoT2 Global Version v1.1 (SIM7028)

The M5Stack Atom DTU NBIoT2 v1.1 is a programmable SIM7028-based NB-IoT DTU for global Cat-NB bands, with SMA antenna support, UART AT control, power/voltage monitoring via ADC, and expandable RS485 and I2C/Grove interfaces—ideal for remote monitoring, tracking and control.

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The M5Stack Atom DTU NBIoT2 v1.1 is a programmable NB-IoT wireless Data Transmission Unit (DTU) designed to work across global Cat-NB frequency bands. This upgraded version adds an IO expansion chip, allowing control of the communication module’s power enable and software reset. This helps reduce power consumption and makes it possible to reset the SIM module without fully power cycling if abnormal conditions occur.

An ADC monitoring circuit has also been added, supporting real-time measurement of the input power voltage from the HT3.96-4P interface for power status monitoring. The unit integrates the SIM7028 communication module and communicates via UART, controlled through an AT command set. For stable connectivity, it includes an SMA external antenna interface, improving signal quality and reliability.

Unlike conventional DTUs that only provide transparent data transmission, the Atom DTU series uses a more open architecture, with reserved expansion interfaces including RS485 and I2C / custom Grove interface for quickly connecting sensors and actuators. It also features a built-in DIN rail mounting structure for installation in industrial control environments. This makes it well suited to low-latency, low-throughput applications such as remote control, asset tracking, remote monitoring, telemedicine, and shared bicycles.

Features

• Global version / multi-band support, suitable for worldwide use
• SIM7028 module, AT command control
• Micro-SIM IoT card
• IO expansion chip for communication module power enable and software reset control
• ADC monitoring circuit supporting power status monitoring
• External SMA antenna interface
• Reserved RS485, I2C / custom Grove interfaces
• Data rate (kbps): 127 (DL) / 159 (UL)
• Supports multiple network protocols such as MQTT and HTTP
• Multiple power supply methods

Specifications

Communication Module	SIM7028
Supported Cat-NB Band	B1/B2/B3/B4/B5/B8/B12/B13/B14/B17/B18/B19/B20/B25/B26/B28/B66/B70/B85
Network Protocol	TCP/UDP/HTTP/TLS/DTLS/DNS/NTP/PING/LWM2M/COAP/MQTT/MQTTS/SSL
Carrier	Deutsche Telekom / Vodafone / Telefonica / China Telecom / China Mobile / China Unicom
Communication Method	UART 115200bps @ 8N
IO Expansion Chip	M5IOE1
Antenna Specification	Size 108 x 10mm, connector type SMA (male thread, female pin), operating band 850 ~ 1900 MHz, gain 2.0 ± 0.5, VSWR ≤ 3.0
Power Supply	RS485 port (HT3.96R-4P interface): 9 ~ 24V USB Type-C: 5V
Power Consumption	SIM module powered off: 24V@9mA (RS485 power); [email protected] (USB power) Standby: [email protected] Working (continuous TX/RX): [email protected]
Grove Load Capacity	DC [email protected] (RS485 power supply)
Operating Temperature	0°C ~ 40°C
Installation Method	DIN rail mounting / mounting holes
Product Size	64.3 x 24.0 x 28.7mm
Product Weight	30.0g

Resources

• Documents

Package Contents

• 1 x Atom DTU NBIoT2 v1.1
• 1 x 850 ~ 1900 MHz SMA rubber antenna
• 1 x Hex Key L-Shape 1.5mm (For M2 Screw)
• 1 x M2 * 16mm cap head machine screw
• 1 x HT3.96-4P Terminal
• 1 x I/O Sticker