实现ADI ADSP-BF526C嵌入音频处理器的方案

　　美国模拟器件公司是的精密高性能模拟集成电路制造商，其产品广泛用于模拟信号和数字信号处理领域。公司总部设在美国马萨诸塞州诺伍德市，在约有9,000名员工，并且在马萨诸塞州、加利福尼亚州、北卡罗来纳州、爱尔兰和菲律宾都有制造厂。ADI公司的股票在纽约证券交易所上市，并被纳入标准普尔500指数（S&P 500 Index）。

　　ADI 公司的ADSP-BF52xC系列嵌入式处理器集成了低功耗高质量立体声音频CODEC,以及可编程输入增益放大器（PGA）和单声道麦克风输入，两个24位ADC和两个24位DAC. ADSP-BF52xC系列的处理器是高达600MHz的高性能Blackfin处理器，采用RISC类寄存器和指令模型，容易编程并支持友好界面。THD达-80dB,而DAC的SNR达90dB（A加重），THD为-80dB。 方框图和CODEC方框图以及采用SPI和TWI控制的应用电路图。

　　Embedded Processor ADSP-BF522C/523C/524C/525C/526C/527C

　　The ADSP-BF522C/523C/524C/525C/526C/527C adds a low power, high quality stereo audio codec for portable digital audio applications with one set of stereo programmable gain amplifier （PGA） line inputs and one monaural microphone input. It features two 24-bit analog-to-digital converter （ADC） channels and two 24-bit digital-to-analog （DAC） converter channels.

　　The CODEC can operate as a master or a slave. It supports various master clock frequencies, including 12 MHz or 24 MHz for USB devices; standard 256 × fS or 384 × fS based rates, such as 12.288 MHz and 24.576 MHz; and many common audio sampling rates, such as 96 kHz,16 kHz, 12 kHz, 11.025 kHz, and 8 kHz.

　　The CODEC can operate at power supplies as low as 1.8 V for the analog circuitry and as low as 1.8 V for the digital circuitry. The maximum voltage supply is 3.6 V for all supplies.

　　The CODEC software-programmable stereo output options provide the programmer with many application possibilities because the device can be used as a headphone driver or as a speaker driver. Its volume control functions provide a large range of gain control of the audio signal.

　　The VoIP challenge to the embedded-system designer is to choose a processing solution that is cost-effective, easy to deploy and scaleable in performance across market spaces. A “sweet spot” embedded-solution approach is to design with a platform that can implement a low channel count basic VoIP solution, yet retain sufficient capacity for value added capabilities and services – such as video, music, imaging and system control. Unlike traditional VoIP embedded solutions that utilize two processor cores to provide VoIP functionality, the ADSP-BF526C provides a convergent solution in a unified core architecture that allows voice and video signal processing concurrent with RISC MCU processing to handle network and user-interface demands. This unique ability to offer full VoIP functionality on a single convergent processor provides for a unified software development environment, faster system debugging and deployment, and lower overall system cost.

     IP protection has become a necessary part of today’s embedded computing applications. The ADSP-BF526C provides a security scheme which balances flexibility and upgradeability with performance through the inclusion of a firmware-based solution including OTP (One Time Programmable) memory to enable users to implement private keys for secure access to program code.

　　处理器特性：

　　Up to 600MHz high performance Blackfin processor

　　RISC-like register and instruction model for ease of programming and compiler-friendly support

　　Advanced debug, trace, and performance monitoring

　　Programmable on-chip voltage regulator （ADSP-BF523/525/527 processors only）

　　Embedded low power audio CODEC

　　289-ball （12 mm x 12 mm） CSP_BGA package

　　132K bytes of on-chip memory

　　External memory controller with glueless support for SDRAM and asynchronous 8-bit and 16-bit memories

　　Flexible booting options from external flash, SPI and TWI memory or from host devices including SPI, TWI, and UART

　　Code Security with LockboxTM Secure Technology

　　One-Time-Programmable （OTP） Memory

　　Memory management unit providing memory protection

　　2 dual-channel memory DMA controllers

　　ADSP-BF525/ADSP-BF526/ADSP-BF527 datasheet for additional peripherals

　　嵌入CODEC特性：

　　Stereo, 24-bit ADCs and DACs

　　DAC SNR: 100 dB （A-weighted）， THD: –80 dB at 48 kHz, 3.3 V

　　ADC SNR: 90 dB （A-weighted）， THD: –80 dB at 48 kHz, 3.3 V

　　Highly efficient headphone amplifier

　　Stereo line input and monaural microphone input

　　Low power

　　7 mW stereo playback （1.8 V supply）

　　14 mW record and playback （1.8 V supply）

　　Low supply voltages

　　Analog: 1.8 V to 3.6 V

　　Digital core: 1.8 V min

　　Digital I/O: 1.8 V to 3.6 V

　　256 × fS /384 × fS oversampling rate in normal mode;

　　250 × fS/272 × fS oversampling rate in USB mode

　　Audio sampling rates: 8 kHz, 11.025 kHz, 12 kHz, 16 kHz, 22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz