Bluetooth Low Energy, also referred to as Bluetooth LE, BTLE or Bluetooth Smart, is a new communication protocol that has been added to the Bluetooth (BT) 4.0 specification. It is offered as supplement to the legacy Bluetooth protocol (now referred to as “Bluetooth Classic”). Bluetooth LE is intended to provide a lowpower use, low-speed alternative to Bluetooth Classic. The first Zebra® printer to offer Bluetooth LE as an option is ZQ500™ series.
Bluetooth LE operates on the same 2.4GHz band as BT Classic and Wi-Fi®. It uses a frequency-hopping scheme similar to Bluetooth Classic, but with fewer channels (37 vs. the 81 in Bluetooth Classic). Bluetooth LE is optimized for both power use and short data transmission events, so the connection process is extremely fast (0.01 seconds).
However, the Bluetooth LE specification requires that devices transfer data at significantly slower rates than those using Bluetooth Classic. Data transfer speeds to printers using Bluetooth LE have been benchmarked at 80 bytes per second when used in an isolation chamber. Given this, the Bluetooth LE protocol is best used for discovering devices and light-duty, data transfer events.
At typical Bluetooth LE data transfer rates, retrieving the printers “personality data” (using the allcv command) could take longer than 6 minutes. A firmware download could take up to 72 hours to complete, dependent on how many other Bluetooth LE devices are in the environment. Using Bluetooth Classic is recommended when data transfer times are the priority.
Bluetooth Classic used the concept of “Profiles” to describe the methods used to support a specific use case. For example, Zebra printers support the Serial Port Profile (SPP), which is used to enable devices to communicate with Zebra printers over Bluetooth Classic as if an RS-232 cable was being used. Bluetooth LE has replaced the “Profiles” concept with “Services”.
Bluetooth LE Services exist for a number of specific use cases. Since the Bluetooth LE specification does not have an equivalent to the Serial Port Profile, Zebra has developed a custom service to enable communication with the printer. This Service is called the “Zebra Bluetooth LE Parser Service”, described below.