Welcome to the training module on National Semiconductor Bluetooth ® Serial Port Micro Module. This training module is to introduce the LMX9830 Blutooth ® module.
Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmissions over short distances from fixed and/or mobile devices, creating wireless personal area networks (PANs). The intent behind the development of Bluetooth was the creation of a single digital wireless protocol, capable of replacing the cable connecting portable and/or fixed electronic devices. The Bluetooth operates in the unlicensed ISM band at 2.4 GHz. The core system consists of an RF transceiver, baseband, and protocol stack. The Bluetooth core system covers the four lowest layers and associated protocols.
National Semiconductor is making Bluetooth® technology easier to adopt than ever before. Each module in the Simply Blue family includes a complete embedded Bluetooth protocol stack, application-specific profiles, and a high-level command interpreter. The high-level command set effectively removes the need for Bluetooth expertise. Moreover, as the entire Bluetooth Stack and Profiles run in the module (not on the host processor), the host processor task loading for Bluetooth is rendered negligible and porting Bluetooth technology to proprietary host operating systems is no longer required.
The LMX9830 integrates a Bluetooth CMOS radio transceiver that delivers the highest level of RF integration available today and a Bluetooth baseband controller with cost efficient ROM memory. All hardware and firmware is included to provide a complete solution from antenna through the complete lower and upper layers of the Bluetooth stack, up to the application including the Generic Access Profile (GAP), the Service Discovery Application Profile (SDAP), and the Serial Port Profile (SPP).
Each Bluetooth device requires a unique 48-bit address known as the Bluetooth Device Address or BD_ADDR. The device- specific BD_ADDR plays a central role in the Bluetooth system, such as seeding algorithms required to implement the core functionality. It is used during physical connection establishment (paging) and discovery (inquiry).
Here shows a general block diagram of the LM9830. The next few pages will introduce some of functional block in detail.
Baseband and Lower Link control functions are implemented using a combination of National’s CompactRISC 16-bit processor and the Bluetooth Lower Link Controller. The on-chip application of the LMX9830 allows full standalone operation, without any Bluetooth protocol layer necessary outside the module. It supports the Generic Access Profile (GAP), the Service Discovery Application Profile (SDAP), and the Serial Port Profile (SPP). The module supports automatic slave operation eliminating the need for an external control unit. The device uses a pin to block unallowed connections. Acting as master, the application offers a simple but versatile command interface for standard Bluetooth operation like inquiry, service discovery, or serial port connection.
The LMX9830 provides one Universal Asynchronous Receiver Transmitter (UART). The UART interface consists out of Receive (RX), Transmit (TX), Ready-to-Send (RTS) and Clear-to-Send signals. RTS and CTS are used for hardware handshaking between the host and the LMX9830. The UART baudrate is configured during startup by setting option pins OP3, OP4 and OP5 for reference clock and baudrate.
The LMX9830 can be used to transport control data required for additional profiles on the host. With this it is possible to use the device for audio profiles like Headset Profile (HSP) or Handsfree Profile (HFP). The Advanced Audio Interface (AAI) is an advanced version of the Synchronous Serial Interface (SSI) that provides a full duplex communications port to a variety of industry-standard 13/14/15/16-bit linear or 8-bit log PCM codecs, DSPs, and other serial audio devices. The interface allows the support one codec or interface.
The integrated Digital Smart Radio utilizes a heterodyne receiver architecture with a low intermediate frequency (2 MHz) such that the intermediate frequency filters can be integrated on chip. The receiver consists of a low-noise amplifier (LNA) followed by two mixers. The intermediate frequency signal processing blocks consist of a poly-phase bandpass filter (BPF), two hard-limiters (LIM), a frequency discriminator (DET), and a post-detection filter (PDF). The received signal level is detected by a received signal strength indicator (RSSI). The transmitter utilizes IQ-modulation with bit-stream data that is gaussian filtered. Other blocks included in the transmitter are a VCO buffer and a power amplifier (PA).
The LMX9830 has an internal data area in RAM that includes the necessary operation parameters. After boot or reset, the module starts to check for different operation modes. The Automatic operation flag is checked after Reset/Boot-up and on incoming links. According to this flag, the firmware will initiate steps to automatically answer to service requests. In Non-Automatic Operation, the LMX9830 does not check the default connections section within the Data RAM. If connected by another device, it will not switch to transparent mode and continue to interpret data sent on the UART. The module provides transparent data communication from the UART interface to a bluetooth link. In normal operation, the LMX9830 will be a slave for any incoming link. But in Force Master mode, the LMX3980 tries to act like an Access point for multiple connections.
The LMX9830 supports different Low Power Modes to reduce power in different operating situations. The modular structure of the LMX9830 allows the firmware to power down unused modules. The low power modes have influence on UART transport layer an Bluetooth baseband activity. In certain usage scenarios the host is able to switch off the transport layer of the LMX9830 in order to reduce power consumption. Afterwards both devices, host and LMX9830 are able to shut down their UART interfaces.
The LMX9830 offers Bluetooth functionality in either a self contained slave functionality or over a simple command interface. The interface is listening on the UART interface. The commands have to be sent within a special package format. The LMX9830 implements a complete command set for bluetooth operation and local configuration. The command set is based on a request/confirm scheme meaning any command will be confirmed by an appropriate event including the same opcode.
Here is an example of point-to-point connection. The LMX9830 acts as slave and no further configuration is required. The SPP conformance of the LMX9830 allows any device using the SPP to connect to the LMX9830. Because of switching to transparent automatically, the controller has no need for an additional protocol layer; data is sent raw to the other Bluetooth device.
In this example, the LMX9830 modules are at both sides. Here the device #1 controls the link setup with a few commands. After establishing the SPP link and step 5 is executed, the stored default device is connected after reset (automatic mode only) or by sending the command “connect to the default device”.
In this application, the LMX9830 (Serial Device #1) acts as master for several slaves. Serial Devices #2 and #3 establish the link automatically as soon as they are contacted by another device. No controller interaction is necessary for setting up the Bluetooth link. Both switch automatically into Transparent mode. The host sends raw data over the UART. As the host has to decide to or from which device data is coming from, data must be sent using the “Send data command”. If the device receives data from the other devices, it is packaged into an event called “Incoming data event”. The event includes the device related port number.
The LMX9830 Bluetooth® serial dongle reference kit is a plug and play serial adapter for serial cable replacement applications and more. It is able to support more profiles than just the Serial Port Profile (including audio support with external codec boards). By using enclosed Simply Blue Commander software, it allows user to develop their own SW applications easily given the built in interpreter for HEX commands. SBsmart is a higher level application tool that provides buttons with the built in commands to easily set up or demonstrate different profile support using the Simply Blue SPP package.
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