Bluetooth GPS Module

Introduction

Bluetooth technology is a wireless data and voice communication of the open global norms, is used to replace mobile devices or fixed electronic devices to connect cables between the proximity of the Wireless Link, Bluetooth work in the global 2.4GHz Band, data rate of 1mb/s, using the time Division duplex transmission technology to achieve full duplex transmission.

As a short distance wireless communication technology that replaces the data cable, Bluetooth supports point-to-point and point-to-point communication, wirelessly connects various data and voice devices in the home or office into a pico-net (pico-net), and several Pico nets can further interconnect, form a distributed network (scatter-net) to enable fast and convenient communication between these devices. This paper introduces the realization of Bluetooth interface in the embedded digital signal processor OMAP5910, the DSP carries on the sampling to the analog signal, and processes the digital signal after a/D transform, transmits to the receiving end through the Bluetooth interface, similarly, the DSP receives the digital signal to receive the D/a transformation, becomes the analog signal.

Bluetooth module BRF6100

Bluetooth signal transceiver is realized by Bluetooth module BRF6100. BRF6100 is the TI company recently introduced to follow the Bluetooth V1.1 standard wireless signal transceiver chip, its upgrade model BRF6150 support V1.2 Standard, BRF6100 main features are: Digital wireless processor in-chip DRP (Digitalradioprocessor), CNC oscillator, Chip RF transceiver switch switch, built-in ARM7 embedded processor and so on.

The internal function of BRF6100 is shown in Figure 1, when receiving the signal, the transceiver switch is placed in the receiving State, the RF signal is received from the antenna and transmitted directly to the baseband signal processor via the Bluetooth transceiver. Baseband signal processing includes lower frequency and sampling, and BRF6100 adopts 0 if structure. The digital signal is stored in RAM (32KB) for ARM7 processor invocation and processing, ARM7 the processed data from the coding interface to other devices, the signal process is the reverse process of signal collection, in addition, the BRF6100 also includes clock and power management module and multiple general I/O ports. For use by different peripherals. BRF6100 host interface can provide a duplex universal serial port, can easily and PC RS232 communication, but also with the DSP buffer serial communication. (Computer science)

System hardware Structure

The whole system is composed of DSP, BRF6100, audio ad/da, LCD, keyboard and flash, hardware connection as shown in Figure 2, DSP is the core control unit, the audio ad is used to convert the collected analog speech signal into digital speech signal, and the audio DA converts the digital speech signal into the analog speech signal. Output to headphones or speakers. Audio AD and Da Front-End and back-end have amplification and filter circuits, in general, audio AD and Da integrated into a chip, the system using TI Company's TLV320AIC10, set the sampling frequency of 8KHz, keyboard for input and control, LCD display a variety of information, Flash Save the DSP required program for the DSP on the electricity call; JTAG is the DSP simulation interface, DSP also provides HPI port, this interface can be connected with the computer, you can download files in the computer and through the DA Play, you can also transfer digital voice signal to the computer to save and processing.

The DSP in the system adopts OMAP5910, the DSP is the embedded DSP which is launched by TI Company, has the dual processor structure, the chip integrates arm and DSP processor. ARM is used to control peripheral devices and DSP is used for data processing. The DSP in OMAP5910 is based on the tms320c55x core processor, which provides 2 multiplication (MAC) units, a 40-bit arithmetic logic unit and a 16-bit arithmetic logic unit, because the DSP uses the double ALU structure, most of the instructions can run in parallel, Its working frequency is up to 150MHz, and the power consumption is lower.

The arm in OMAP5910 is a ti925t processor based on the ARM9 kernel, which includes 1 coprocessor with a command length of 16 bits or 32 bits. DSP and ARM can work together, through MMU control, can share memory and peripherals, OMAP5910 can be used in a variety of areas, such as mobile communications, video and image processing, audio processing, graphics and image accelerators, data processing. The system uses OMAP5910 for personal mobile communications.

Hardware design of BRF6100 and OMAP5910

The connection between the BRF6100 and OMAP5910 is the focus of the hardware connection of the system, and its specific connection, as shown in Figure 3, uses the MCSI interface of OMAP5910 to connect to the BRF61001 voice interface. The Mcsi interface is a OMAP5910-specific multi-channel serial interface (MULTICHANNELSERIALINTERFACE), which has a bit synchronization signal and a frame synchronization signal. The system uses main mode, namely OMAP5910 provides 2 clock to the Bluetooth module BRF6100 voice interface's bit and the frame synchronization clock signal, the MCSI interface maximum transmission frequency can reach 6MHz, the system because transmits the speech signal, sets the frame synchronization signal to 8KHz, The sampling frequency of the OMAP5910 external audio ad is consistent. The bits transmitted per frame can be set to 8 or 16 bits as needed, the corresponding bit synchronization clock is 64KHz or 128KHz, and these settings can be changed by setting the internal register of OMAP5910, which is very convenient and flexible to use.

OMAP5910 and BRF6100 communications are implemented using asynchronous serial ports. As shown in Figure 3 of the RX1 and TX1 signals, in order to ensure the reliable and real-time communication between the two sides, using RTS1 and CTS1 pin as the two sides of the communication handshake signal, the asynchronous serial port communication frequency can be set to 921.6KHz, 460.8KHz, 115.2KHz or 57.6KHz four kinds. The rate can be changed by setting the internal registers of the OMAP5910, and the BRF6100 asynchronous serial port rate is set by OMAP5910.

Since both OMAP5910 and BRF6100 have an arm core, the real-time clock signals of both sides can use a common clock signal to ensure the consistency of the two sides ' real-time clocks, in Fig. 3, the clock signal from the OMAP5910 output 32.768KHz to BRF6100 Slow_ CLK PIN. The 32.768KHz signal is provided by an external crystal, the stability of the crystal must meet the requirements of both sides, and the general stability requirement is 50x10-6 order of magnitude.

In Figure 3, OMAP5910 uses a gpio pin to control the BRF6100 reset, and when necessary OMAP5910 can reset the Bluetooth module. OMAP5910 use another Gpio pin control BRF6100 WP Signal, WP for BRF6100 eeprom write protection signal, in normal working state will the pin set high, ensure that the EEPROM will not overwrite the data.

BRF6100 RF antenna can be used Taiyoyuden Company's AH104F2450S1 model of the Bluetooth antenna. The antenna performance is good, has been applied to many Bluetooth devices, in order to verify the effectiveness of the antenna, you can add a section of the design phase of the antenna test circuit, as shown in Figure 4, the use of control signals to control switching switches, control signals can be from BR6100 or OMAP5910. When testing, switching switches connect J2 and J3, antenna signal connected to coaxial cable, can be further connected to test equipment, can easily detect the various indicators of the antenna, in practice, switching switches connected J2 and J1, or the circuit removed, the antenna signal directly connected to the BRF6100 of the RF signal pins.

Software design of OMAP5910

The whole system software design method has three kinds, according to the different application situation and the system responsible program uses the different design method, under normal circumstances, the simple system may adopt the conventional software design method, the more complex system may use the DSP simulation software CCS to provide the Dsp/bios design method (dsp/ The BIOS is an embedded software design method specially designed for DSP in TI Company, and the most complicated system needs to be designed by embedded operating system. At present, OMAP5912 support operating system including wince, Linux, nucleus and vxworks, can choose different operating system according to the need, this system uses the conventional software design method, its realization is most simple and convenient.

The software structure of the system is shown in Figure 5, the software structure includes initialization module, keyboard and LCD display, data and voice communication, Flash read and write and Bluetooth signal transceiver modules, in the initialization process set the keyboard scan time, voice sampling frequency, display status and other parameters, the whole system after initialization, program into the monitoring module, monitoring module at any time to determine the status of each module, and into the corresponding processing procedures, data communication module control OMAP5910 and Bluetooth module of the interface, Voice Communication module control OMAP5910 and audio Ad/da interface, Bluetooth Interface Transceiver Control OMAP5910 and Bluetooth module signal transceiver, flash read and write module control OMAP5910 on its external flash reading and writing, when necessary, some important data transmission to flash, in addition, OMAP5910 on the Electric boot program is also stored in Flash, Keyboard and Display module control system of human-computer interface, PC Communication module control system and PC connection.

Because OMAP5910 has C55 series of DSP core, some digital signal processing algorithms can be easily implemented, for speech signal, can be filtered to improve voice quality, if the transmission of music signals, you can add music processing algorithms, such as reverberation, edge, cutting peaks and other processing, Speech compression can be transferred to the PC, or after decompression to play a wide range of voice signals, making the application of the system more extensive and practical.

Summarize

In the OMAP5910 Bluetooth interface design, the OMAP5910 serial port is used to connect the Bluetooth module BRF61001 audio interface, and the OMAP5910 asynchronous serial port is connected with the Bluetooth module communication port. The Bluetooth module can avoid the transformation of RF signal to intermediate frequency signal, so the system is simple and simple to realize. Because of the processor with DSP kernel, the system can be easily applied to all kinds of speech signal processing.