What is spp profile in bluetooth

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What are SPP and GATT Bluetooth profiles
What’s SPP profile?
What’s GATT profile?
1. What is SPP?
2. Bluetooth configuration file structure
3. Configuration file stack
4. Configuration and roles
5. User needs and scenarios
6. Profile Basics
What is spp profile in bluetooth
What is spp profile in bluetooth
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What are SPP and GATT Bluetooth profiles

As we know, the Bluetooth module is divided into two types: Classic Bluetooth (BR/EDR) and Bluetooth Low Energy (BLE). There are many profiles of Classic Bluetooth and BLE: SPP, GATT, A2DP, AVRCP, HFP, etc. For data transmission, SPP and GATT are the most frequently used Classic Bluetooth and BLE profiles respectively.

What’s SPP profile?

SPP (Serial Port Profile) is a Classic Bluetooth profile, SPP defines the requirements for Bluetooth devices necessary for setting up emulated serial cable connections using RFCOMM between two peer devices. The requirements are expressed in terms of services provided to applications, and by defining the features and procedures that are required for interoperability between Bluetooth devices.

What’s GATT profile?

GATT (Generic Attribute profile is a BLE profile, it defines specifications for two BLE devices to communicate through Service and Characteristic, the two parties of GATT communication are Client/Server relationship, Peripheral is GATT Server, Central is the GATT Client, all the communications, both are initiated by Client, and receive the response from Server.

SPP+GATT combo

SPP and GATT are playing the role of transmitting data, we should notice that when using the Bluetooth module for communicating with the mobile app, for iOS smartphone, the BLE (GATT) is the only supported two-way data transmission profile that is free to use, for Android smartphone, it supports both SPP and GATT, so how important is a module supports both SPP and GATT.

When a Bluetooth module supports both SPP & GATT, it means that it’s a Bluetooth dual-mode module. Any recommended Bluetooth duial-mode modules?

These two modules are not very suitable for your application? Don’t hesitate to contact Feasycom now!

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1. What is SPP?

The Serial Port Profile defines the protocols and procedures that devices that use Bluetooth for RS232 (or similar) serial cable emulation should use.

The scenarios covered by this profile deal with legacy applications that use Bluetooth as a cable replacement through the virtual serial port abstraction (which itself is OS dependent).

2. Bluetooth configuration file structure

3. Configuration file stack

The diagram below shows the protocols and entities used in this configuration file.

Baseband, LMP, and L2CAP are Bluetooth protocols for OSI layers 1 and 2.

RFCOMM is the bluetooth adaptation of GSMTS07.10, which provides transmission protocol for serial port emulation.

SDP is the Bluetooth Service Discovery Protocol.

The port emulation layer shown in Figure 2.2 is an entity that emulates a serial port or provides an API to an application.

The applications on both sides are usually legacy applications that can and want to communicate (in this case emulated) over a serial cable. However, legacy apps cannot be aware of the bluetooth program that sets up the simulated serial cable, which is why they need help from some kind of bluetooth-aware helper app on both sides. (Similarly, non-legacy applications wishing to perform serial communications over Bluetooth must obey the behavior specified in this profile. This is true whether they use the Bluetooth-aware assistant described above, or other interfaces to the Bluetooth stack .This ensures that all combinations of legacy and non-legacy applications remain interoperable at the Bluetooth level.

4. Configuration and roles

The image below shows one possible device configuration for this profile

Device A (DevA) — This is the device that is actively connected to another device (DevA is the initiator of the row in the GAP).

Device B (DevB) — This is the device that waits for another device to actively connect. (DevB is the GAP receiver).

Note that the order of connections (from DevA to DevB) is not necessarily related to the order in which traditional applications are started.

Information Note: In order to map the serial port configuration file to the traditional serial port architecture, both DevA and DevB can be Data Circuit Endpoint (DCE) or Data Terminal Endpoint (DTE). (The RFCOMM protocol is designed to be independent of DTE-DCE or DTE-DTE relationships.)

5. User needs and scenarios

The scenarios covered by this profile are as follows:

Set up a virtual serial port (or equivalent) on both devices (e.g. a PC) and connect via bluetooth, simulating a serial cable between the two devices. Any legacy application can run on either device, using the virtual serial port as if there was a real serial cable connecting the two devices (using RS232 control signals).

This profile only needs to support single-socket packets. This means that this profile ensures that data rates up to 128kbps can be used. Support for higher prices is optional. the

In this profile, only one connection is processed at a time. Therefore, only point-topological configurations are considered. However, this should not be interpreted as imposing any restrictions on concurrency; multiple executions of this profile should be able to run concurrently on the same device. This also includes taking on two different roles (like DevA and DevB) at the same time.

6. Profile Basics

Security features such as authorization, authentication, and encryption are optional for executing this profile. Support for authentication and encryption is mandatory so that, if a request is made from a peer device, the device can participate in the corresponding process. If security features need to be used, the two devices are paired during the connection establishment phase (if not earlier).

No bindings are explicitly used in this configuration file, therefore, support for bindings is optional. The link establishment is initiated by DevA. The service discovery process must be performed before an emulated serial cable connection can be established.

There is no fixed master-slave role.

RFCOMM is used to transmit user data, modem control signals and configuration commands.

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