Today's bluetooth gains

Add Bluetooth support to EBox
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Open the command line shortcut
Set sysgen_bth_usb_only = 1
Exit from the command line to repeat blddemo clean-Q

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Bluetooth overview --- General description
Parameter: unlicensed 2.4 GHz ISM (industrial, scientific and medical)
Range: 10 meters
Why? --- Replace wired communication electronic devices with robust, low power consumption, and low cost. The bluetooth data rate is 1 Mb/s. The Time Division Duplex Transmission scheme is used for full duplex transmission.

Core Components of Bluetooth:
RF (radio frequency) Transmitter
Baseband-the frequency band of a transmitted message)
Protocol Stack

Bluetooth-based systems provide services that allow devices connected to each other to transmit different types of data.

Piconet:
All devices connected by Bluetooth are considered as a piconet. A piconet can be just two connected devices, such as a laptop and a mobile phone, it can also be eight connected devices. In a piconet, all devices have the same level of units and have the same permissions. However, when the piconet network was first created, one unit was defined as the master and other units were defined as the slave. Other slaves can be used as a reference based on the frequency and hopping pattern of the master.

Hop:
The ISM frequency band is an open frequency band for all radio systems. Therefore, an unpredictable interference source may occur when a frequency band is used. For example, some household appliances, cordless phones, car room door opener, microwave ovens, etc., may be interference. To this end, Bluetooth has specially designed fast validation and frequency hopping solutions to ensure link stability. The frequency hopping technique divides the frequency band into several hop channels. In a single connection, the radio transceiver follows a certain code sequence (that is, a certain rule, technically, it is called "pseudo-random code", that is, "fake" Random Code) constantly jump from one channel to another. Only the receiving and receiving sides communicate according to this rule, however, other interference may not be able to interfere according to the same rule. The instantaneous bandwidth of the frequency hopping is very narrow, but the narrow band width is expanded to a wide band by hundreds of times through the spectrum extension technology, this reduces the potential impact of interference.

Slot:
Physical channels are divided into time units, that is, slots. Data is transmitted in the device in the form of packets, and they are placed in these slots.

Physical link:
Through physical channel, a physical link is formed between two devices in any direction. There is a Phsical link between each slave and the master, but there is no direct connection between slave.

Each device in a piconet has an asynchronous connection (ACO) used as the transmission LMP protocol. For historical reasons, this is called ACL logical transport. When a device is added to a piconet, an ACL logical connection is created immediately.

The L2CAP layer on the baseband layer provides a channel-based abstraction for applications and services. L2CAP has a Protocol control channel that is transmitted to the L2CAP protocol through the honed ACL logical transport. The program sent to The L2CAP protocol should be transmitted by any logical link that supports the L2CAP protocol.

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Each of the four lowest layers is associated with a communication protocol. The bottom three layers (radio, LC, LMP) are usually encapsulated in a sub-system called bluetooth controller.

The Bluetooth core system provides services through some service access points. These services can be divided into three types:
1. Device Control Service. Modifies the status and working mode of a bluetooth device;
2. Transmission Control Service. Create, modify, and release transmission bearers (channels and links );
3. Data Service. It is used to submit data for transmission.
Generally, the first two are c-plane and the last one is u-plane.

HCI:
Host L2CAP and the rest of the Bluetooth Application
To ----------------------------------------------------------
Controller the lowest Thress Layers
Interface

Bytes -----------------------------------------------------------------------------------------------------------
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* Radio specification *
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Unlicensed 2.4 GHz ISM (industrial scientific medical) band.
Two working modes:
1 Basic Rate
2 Enhanced Data Rate
Both modes use TDD (Time Division Duplex) for full duplex transmission.

************************
* Baseband specification *
************************

**************************************** **************************************** ****************************

Bluetooth Operating System Development
Hardware considerations Bluetooth interface (USB, UART, bcsp, sdio, SC, and ambicom ).

The following considerations shoshould be taken into account when implementing this technology:

Only one Bluetooth controller is supported.
L2CAP links over unreliable channels are not supported.
Flush time-out is not supported by L2CAP. upper layers are supposed to fail the connection when flush time-out is not set to the default value or negotiated down to the default value.
L2CAP does not support dynamic reconfiguration, which allows the system to enter config mode when a connection has already been opened.
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Sysgen parameters:
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Sysgen_bth
Sysgen_bth_audio
Sysgen_bth_gateway
Sysgen_bth_modem
Sysgen_bth_utils
Sysgen_bth_ag
Sysgen_bth_hid_keyboard
Sysgen_bth_hid_mouse
Sysgen_bth_pan
Sysgen_bth_csr_only
Sysgen_bth_sdio_only
Sysgen_bth_usb_only
Sysgen_bth_uart_only

Pofile:
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