In-Depth Analysis of the UWB650 Module (Part 2): Mastering Core Functions: Configuration and Usage

Sep . 2025

By sdga:

This chapter serves as a comprehensive practical guide, systematically introducing how to configure and use the UWB650 module through its AT command set. The content will cover the three core functions—data transmission, high-precision ranging, and real-time positioning—and provide clear operational procedures for engineers, complete with command examples from the documentation.

AT Command Interface: Structure and Protocol

All configuration and operation of the UWB650 module are performed via serial AT commands. These commands follow a fixed format, starting with the prefix UWBRFAT and ending with a carriage return and a line feed . The module's responses follow a similar format, beginning and ending with .

During command interaction, the module uses an internal timeout timer of approximately 5ms to determine if the reception of serial data is complete. Adhering to this timing is crucial for writing stable and reliable automated control scripts, as it effectively prevents command parsing errors or loss due to commands being sent too quickly.

Data Transmission: Point-to-Point, Broadcast, and Enhanced Reliability

The module offers flexible and feature-rich data transmission capabilities, supporting various communication modes and enhancement mechanisms.

Network Addressing and Data Routing

Device Identification: Each UWB650 module is uniquely identified in the network by a 16-bit PAN ID (Personal Area Network Identifier) and a 16-bit Address. Communication is only possible between modules with the same PAN ID, and all modules within the same PAN ID must have a unique Address. These two parameters can be configured using the UWBRFAT+DEVICEID=, command.
Data Target: The UWBRFAT+TXTARGET=
command is used to set the destination address for data transmission. When
is a specific device address, the module will engage in point-to-point communication. When
is set to 0xFFFF, the module will transmit data in broadcast mode, and all modules with the same PAN ID in the network can receive it.

Reliability and Security Mechanisms

Clear Channel Assessment (CCA): The CCA feature can be enabled with UWBRFAT+CCAENABLE=1. When enabled, the module will listen to the channel to see if it is idle before sending data. If the channel is occupied, the module will abort the transmission and return CCA FAILURE via the serial port. In densely deployed UWB environments, this function is an effective means of avoiding data collisions and improving communication success rates.
Automatic Acknowledgment (ACK): The automatic acknowledgment request feature can be enabled with UWBRFAT+ACKENABLE=1. When enabled, unicast data frames sent by the module will include an ACK request. Upon successful receipt of the data, the receiving party will automatically reply with an ACK frame. If the sender receives the ACK within the specified time, the serial port returns ACK DETECTED; if it times out, it returns ACK WAIT TIMEOUT. This feature provides a link-layer confirmation mechanism for applications that require reliable data delivery.
Data Encryption (AES-128): AES-128 encryption can be enabled using the UWBRFAT+SECURITY=, command. When enabled, the Frame Payload portion of the transmitted data packet will be encrypted. It should be noted that encryption adds an overhead of 16 bytes, so the maximum single-packet data length that a user can transmit is reduced from 1012 bytes to 996 bytes. This is a clear trade-off between security and data throughput.

Power Management

Sniff Receive (SNIFF): For power-sensitive, battery-operated devices, SNIFF mode can be enabled with the UWBRFAT+SNIFFEN=1 command. In this mode, the module's receiver operates at approximately a 50% duty cycle (16µs on, 16µs off), significantly reducing the receive current from about 100 mA to 65 mA. The trade-off is the potential loss of some data packets. This is a typical trade-off between power consumption and performance.

SNIFF (Sniff Receive) Mode Timing Diagram

Transmission Performance

Thanks to the powerful 1023-byte transceiver buffer of the DW3000 chip, after accounting for the fixed data frame length, a user can transmit a maximum of 1023-11 = 1012 bytes of Frame Payload data in a single packet. Because the wireless transmitter starts sending after receiving a certain amount of data from the terminal device or after waiting for a certain period without new data, and the over-the-air transmission also takes time, there is a certain time delay for data to go from the transmitter to the receiver's output. Under the same conditions, this delay is fixed (the specific time is determined by the serial port rate, over-the-air rate, and the size of the data packet).

Diagram of End-to-End Data Transmission Delay in the UWB Module

The total time for data to travel from the sending-end serial input to the receiving-end serial output is referenced in the table below:

Over-the-Air Data Rate	1-Byte Payload	1012-Byte Payload
6.8Mbps	1.905ms	12.330ms
850Kbps	2.316ms	20.885ms

High-Precision Ranging: Implementing DS-TWR Distance Measurement

The module's ranging function is based on the advanced Double-Sided Two-Way Ranging (DS-TWR) method, combined with a Single-Sided Two-Way Ranging (SS-TWR) scheme. DS-TWR accurately calculates the signal's time of flight through a three-message exchange between two devices. Its core advantage is its ability to effectively eliminate ranging errors introduced by crystal frequency differences (i.e., clock drift) between the two devices, thus achieving high-precision measurement without the need for complex network-wide clock synchronization.

DS-TWR (Double-Sided Two-Way Ranging) Timing Diagram

Role Definition: During ranging, devices are categorized as either an Initiator (master) or a Responder (slave). The Initiator actively starts the ranging request, and the Responder passively responds.
Command Operation:
- Initiator: The Initiator starts ranging one or more Responders by sending the command UWBRFAT+RANGING=,,,.... Here, is the quantity of target Responders, and is the list of Responder addresses.
- Responder: The Responder is in response mode by default and requires no special configuration. When it receives a ranging request from an Initiator, it automatically participates in the ranging process and outputs the result via the serial port upon completion.
Output Format Analysis: After the Initiator completes ranging, the received format is +RANGING=(),(). If the ranging fails, the distance value will be -1.
Performance: The ranging process is extremely fast. The table below shows the time consumed for ranging in different modes:

Over-the-Air Data Rate	Mode	Ranging Time
6.8Mbps	Initiator	4.819ms
	Responder	4.051ms
850Kbps	Initiator	5.545ms
	Responder	4.553ms

Engineers can accurately determine the start and end times of the ranging process by monitoring the level of the module's P011 pin.

Real-Time Locating System (RTLS): 2D and 3D Positioning Strategies

The module has a built-in complete location solving function, supporting both 2D planar and 3D spatial positioning.

Role Definition: In a positioning system, devices are categorized as either a Tag (a mobile target to be located) or an Anchor (a fixed reference point with known coordinates).
Anchor Setup: The first step in deploying a positioning system is to accurately set the coordinates of the Anchors. Use the command UWBRFAT+COORDINATE=,, to configure the position of each Anchor in a predefined Cartesian coordinate system, with units in centimeters. The final accuracy of the entire positioning system largely depends on the accuracy of the Anchor coordinate measurements.
Tag Operation: A Tag initiates a positioning request by sending the command UWBRFAT+LOCATION=,,.... The command must include the addresses of at least 3 Anchors (for 2D positioning) or at least 4 Anchors (for 3D positioning). The module will automatically range with each Anchor in the list, then use its built-in trilateration (more accurately, multilateration) algorithm to calculate its own (x,y,z) coordinates and output the result via the serial port.
State Mutex: The module's functional states are mutually exclusive. For example, when a module is acting as an Initiator to actively start ranging or positioning, it will temporarily be unable to respond to ranging requests from other Initiators. Similarly, during ranging or positioning, an enabled SNIFF low-power mode will be temporarily disabled to ensure that all ranging response frames can be received. This means that in systems with multiple active devices (multiple Tags or Initiators), a reasonable Medium Access Control (MAC) strategy, such as Time Division Multiple Access (TDMA), must be designed at the application layer to coordinate channel usage and avoid collisions and request failures. The module itself provides the physical layer capabilities, but stable system-level operation requires the assurance of upper-layer protocols.