Bluetooth Profiles > Electronic Shelf Label Profile

Introduction

The Electronic Shelf Label (ESL) Profile specifies how Bluetooth® wireless technology is used to control and update Electronic Shelf Labels, including configuration management through the ESL Service in the Low Energy (LE) connection state, and one-to-many bidirectional communication in the Periodic Advertising with Responses (PAwR) synchronized state.

The ESL Profile requires that devices conforming to this specification shall support LE Secure Connections, PAwR, and Encrypted Advertising Data features.

Roles

The ESL Profile specifies two roles. A device shall support one of the following roles.

Electronic Shelf Label

An ESL role is a device that displays graphic information (e.g., price and product description) for merchandise and typically integrates sensors, Light Emitting Diodes (LEDs), and other components.

The responsibilities of the ESL role include:

• The ESL role shall act as a Generic Access Profile (GAP) Peripheral and send connectable advertisements before being configured by an AP role.
• The ESL role shall act as a PAwR Scanner, receive messages from the AP role in the synchronized state, and determine whether to send response data.
• The ESL role shall act as an ESL Server and provide characteristics for the AP role to access and configure.
• The ESL role may act as an Object Server to receive images from the AP role.
• The ESL role may implement the Device Information Service to support vendor-specific opcodes.

An ESL role shall be bonded with a maximum of one AP role at any one time.

Access Point

An AP role is a central device that exchanges data with multiple ESL roles.

The responsibilities of the AP role include:

• The AP role shall act as a GAP Central to actively discover and connect to ESL roles.
• The AP role shall act as a PAwR Advertiser to transmit encrypted messages in the synchronized state and receive response data sent by ESL roles.
• The AP role shall act as an ESL Client to read the display, image, sensor, and LED characteristic information of ESL roles and write configuration parameters.
• The AP role shall act as an Object Client to transfer images to ESL roles.

An AP role may bond with multiple ESL roles.

One-to-Many Communication Architecture

The AP role may decide whether to organize ESL roles into different groups based on actual requirements.

The AP role uses the PAwR feature to send messages to grouped ESL roles. Messages within the same group are identical, while messages between different groups may differ. A message may contain data addressed to one or more ESL roles within the same group.

An ESL role receives messages at specified moments. If the message contains data addressed to that ESL role, the ESL role determines whether to send response data based on the data content; if the message does not contain data addressed to that ESL role, the ESL role shall not send response data.

Advantages

Efficient Communication Mechanism for Large-Scale Deployment

• Configuring Phase: One-to-one communication based on LE connection. The AP role establishes the initial bonding relationship with an ESL role, reads the capability information of that ESL role, and writes configuration parameters.
• Updating Phase: One-to-one communication based on LE connection. The AP role performs parameter configuration, command control, and image transfer for bonded ESL roles.
• Synchronized Phase: One-to-many bidirectional communication based on the PAwR feature. The AP role performs batch management and status monitoring of large-scale ESL roles.

Standardized Configuration and Interoperability Assurance

Provides a unified and interoperable protocol foundation for large-scale ESL role deployment, enabling AP roles and ESL roles from different vendors to work cooperatively in device discovery, configuration, content update, and daily control without the need for proprietary protocols.

Security Mechanisms

• Connection Security: The AP role shall complete pairing and bonding with the ESL role (using LE Secure Connections with security level 2 or higher) before data communication can occur.
• Key Configuration: The AP role configures each ESL role with AP Sync Key Material (for encrypting PAwR synchronization packets) and ESL Response Key Material (for encrypting PAwR response packets).
• Replay Attack Prevention: The AP role uses a new Randomizer value in each PAwR synchronization packet. Even if an attacker captures an encrypted packet and retransmits it, the ESL role will not process that packet repeatedly.

Application Scenarios

Dynamic Price Management in Retail Stores

In retail stores, ESL roles can implement automatic price updates at preset time points (e.g., at the start of promotional periods) and cyclically display between regular prices and discount information.

Order Picking Assistance in Retail Warehouses

When pickers handle multiple customer orders simultaneously, the system can indicate target product locations through LEDs of different colors, enabling rapid identification and sorting of products across multiple orders, significantly improving picking efficiency.