基于FPGA的无创伤血液成分光谱采集系统设计

血液成分检测是健康诊断的重要手段，常规的血液成分检测采用抽血的方法，不仅给病人带来痛苦，还存在交叉感染的风险。近红外光谱技术是无创伤血液成分检测中的研究热点。为满足近红外无创伤血液成分检测仪器对其光谱数据采集系统提出的高速、多通道和高信噪比的要求，设计了一种基于现场可编程门阵列(FPGA)的高速、多通道光谱数据采集系统。该系统采用Altera公司Cyclone IV系列的FPGA芯片作为其微控制器，控制两片8通道的A/D芯片并行采集16通道的人体血液脉搏波光谱信号，采集到的数据在FPGA的控制下首先缓存在FPGA内部建立的乒乓RAM中，然后转存至外部SRAM芯片中，最后经USB总线传输至计算机。实验结果表明，在19 531 Hz的采样频率下，该系统能够高速并行采集16个通道的信号，重复性信噪比可达40 000∶1。此外，在该采样率下，系统可以采集到高信噪比的人体血液脉搏波信号，采集速度能够达到每秒305幅光谱图。该系统满足近红外无创伤血液成分检测仪器对于光谱数据采集系统的基本要求。该研究的主要创新点为将FPGA应用于近红外无创伤血液成分检测仪器的数据采集系统中，FPGA能够同时控制两片AD芯片进行16路人体血液脉搏波数据的高速并行采集，解决了单片机作为微控制器时无法实现多通道大量数据高速采集和储存的问题，使仪器的采集速度大大加快;同时使用FPGA内部资源建立乒乓RAM进行数据的缓冲，实现了不同位数数据从AD芯片到SRAM芯片的无缝连续传输。

Design of Noninvasive Blood Constituent Spectrum Data Acquisition System Based on FPGA

Blood constituent examination is an important means of health diagnosis.For blood constituent examination,we usu-ally adopt the method of drawing blood,which bring pain and the risk of cross infection to the patient.Near infrared spectrum spectroscopy (NIRS)is a research hotspot in noninvasive blood constituent examination.The spectral data acquisition system of existing instruments is using a Single Chip Microcomputer (SCM)as its microcontroller.The spectral data acquisition system cannot realize the high speed multi-channel acquisition and storage of large amounts of data because of the SCM itself has certain deficiency.So a high speed multi-channel spectral data acquisition system based on Field Programmable Gate Array (FPGA)was designed in this paper in order to realize the system of high speed,multi-channel and high signal-to-noise ratio (SNR)in the area of noninvasive blood constituent examination by near infrared spectroscopy.An Altera Cyclone IV series FPGA was used as the microcontroller in this spectral data acquisition system,which simultaneously controlled two pieces of eight channels AD conver-sion chip acquiring 1 6 channels blood pulse wave signal parallel.Under the control of FPGA,the data was cached in FPGA inter-nal ping-pong RAM first,after that it was transferred to an SRAM chip,finally it was sent to the computer via the USB port. Experiment result shows that the spectral data acquisition system can collect 1 6 channels signal parallel and fast under the sam-pling frequency of 19 531 Hz and the repetitive signal-to-noise ratio is over 40 000∶1.The system can collect 305 spectrograms per second,more over it can get high SNR human body blood pulse wave signal under the same circumstances.The spectral data acquisition system satisfies the basic requirements of the noninvasive blood constituent examination instrument by NIRS and it can make the instrument collect the human body blood pulse wave data at a high speed.The main innovation point of this article is applying FPGA to the spectral data acquisition system of near infrared noninvasive blood constituent examination instrument. FPGA is able to simultaneously control two pieces of eight channels AD conversion chip acquiring 1 6 channels blood pulse wave signal parallel.By using FPGA as the microcontroller of the spectral data acquisition system,we solve the problem that SCM as the microcontroller can’t realize multi-channel high speed data acquisition and storage of large amounts of data.The acquisition speed is greatly faster than the system before.The second innovation point of this article is we use FPGA internal resources es-tablish a ping-pong RAM buffer.The spectral data from the AD chip is 24 bit,however,the SRAM chip has only 16 bit data bus.Via the ping-pang RAM buffer,the spectral data can transfer from AD chip to SRAM chip.The ping-pong RAM can real-ize different digits data seamless transfer from AD chip to SRAM chip.