The Electronic Shelf Label profile
The Electronic Shelf Label profile specification enables standardized, interoperable ESL products that use Bluetooth® LE are created.
The profile specification contains an addressing scheme and a set of commands and parameters that an AP can send to one or more ESL devices in a single packet sent during a PAwR subevent.
ESLs are members of groups, of which there can be 128, each with a numeric ID. Each group can have 255 ESL devices, each with a numeric ID. The unique address of an individual ESL across the entire network is a combined group ID and ESL ID, and as a result an ESL network can contain up to 32,640 electronic shelf labels, each of which can be managed from a single access point.
Before a new ESL can be used, it must go through a setup procedure. This means that the AP connects to the ESL, assigns it an address on the network, and typically transfers a series of images to it. Details of PAwR events and sub-events are passed to the ESL over the same connection. The assigned ESL Group ID determines the sub-event to use, while response slots are assigned dynamically, using standardized message processing logic.
ESL commands and responses are encrypted and verified using the AES-CCM algorithm to secure communications between the AP and ESLs. This capability is powered by another new Bluetooth LE feature called Encrypted Advertising Data.
ESL and PAwR in action
Figure 2 shows an exchange between an access point and different ESL devices over different sub-events.