Baseband

The Class of Device/Service field

The Class of Device/Service (CoD) field has a variable format. The format is indicated using the “Format Type field” within the CoD. The length of the Format Type field is variable and ends with two bits different from “11.” The version field starts at the least significant bit of the CoD and may extend upward.

In the “format #1” of the CoD (Format Type field = 00), 11 bits are assigned as a bit-mask (multiple bits can be set), each bit corresponding to a high-level generic category of service class. Currently, seven categories are defined. These are primarily of a “public service” nature. The remaining 11 bits are used to indicate device type category and other device-specific characteristics.Any reserved but otherwise unassigned bits, such as in the Major Service Class field, should be set to zero.

Major Service Classes

The Major and Minor Service classes define the general families of devices with which Bluetooth SIG members want their applications to be associated. No assumptions about the specific functionality or characteristics of any application should be based solely on its inclusion within a Major or Minor device class.

Table 2: Major Service Classes

[Ref #1: See Generic Access Profile (please refer to the Generic Access Profile within the respective Core Specification)]

Major Device Classes

The Major Device Class segment is the highest level of granularity for defining a Bluetooth device. A device’s main function determines its Major Class assignment. There are 32 major classes. The assignment of this Major Class field is defined in the table.

Table 3: Major Device Classes

[Ref #2: Used where a more specific Major Device Class code is not suitable (but only as specified in this document). A device that does not have a major class code assigned can use the all-1 code until “classified.”]

The Minor Device Class field

The Minor Device Class field (bits 7 to 2 in the CoD) is interpreted only in the context of the Major Device Class (but independently of the Service Class field). Thus, the meaning of the bits may change, depending on the value of the Major Device Class field. When the Minor Device Class field indicates a device class, then the primary device class should be reported – e.g., a cellular phone that can also work as a cordless handset should use “Cellular” in the Minor Device Class field.

Minor Device Class field – Computer Major Class

Table 4: Sub-device Class field for the “Computer” Major Class

Minor Device Class field – Phone Major Class

Table 5: Sub-device Classes for the “Phone” Major Class

Minor Device Class field – LAN/Network Access Point Major Class

Table 6: The LAN/Network Access Point Load Factor field

The exact loading formula is not standardized. It is up to each LAN/Network Access Point implementation to determine what internal conditions to report as a utilization percentage. The only requirement is for the number to reflect an ever-increasing utilization of communication resources within the box. As a recommendation: a client locating multiple LAN/Network Access Points should attempt to connect to the one reporting the lowest load.

Table 7: Reserved sub-field for the LAN/Network Access Point

Minor Device Class field – Audio/Video Major Class

Table 8: Sub-device Classes for the “Audio/Video” Major Class

Minor Device Class field – Peripheral Major Class

Table 9: The Peripheral Major Class keyboard/pointing device field

Bits six and seven independently specify mouse, keyboard or combo mouse/keyboard devices. These may be combined with the lower bits in a multifunctional device.

Table 10: Minor Class bits two to five for Peripheral Major Class

Minor Device Class field – Imaging Major Class

Table 11: The Imaging Major Class bits four to seven

Bits four to seven independently specify display, camera, scanner or printer. These may be combined in a multifunctional device.

Table 12: The Imaging Major Class bits two and three

Bits two and three are reserved

Minor Device Class field – Wearable Major Class

The Minor Class segment is the lowest level of granularity for defining a Bluetooth Device. There are 64 different possible minor classes.

Minor Device Class field – Toy Major Class