Luminary Micro provides an analog-to-digital converter (ADC) MODULE on some members of theStellaris microcontroller family. The hardware resolution of the ADC is 10 bits; however, due to noiseand other accuracy-diminishing factors, the true accuracy is less than 10 bits. This application noteprovides a software-based oversampling technique, resulting in an improved Effective Number OfBits (ENOB) in the conversion result. This document describes methods of oversampling an inputsignal, and the impact on precision and overall system performance.
基于單片機(jī)控制的二氧化碳濃度測(cè)試計(jì):基于CDM4161二氧化碳?xì)怏w濃度測(cè)試模塊以及ATtiny26單片機(jī),提出了一種二氧化碳濃度測(cè)試計(jì)的設(shè)計(jì)方案。該方案具有硬件電路簡(jiǎn)單、成本低、可靠性高、測(cè)量準(zhǔn)確等優(yōu)點(diǎn)，具有較高的實(shí)用價(jià)值。 Abstract: Abstract：A desigh scheme of CO2 concentration meter based on CDM4161carbon dioxide concentration test MODULE and ATtiny26micro-controller is presented in this paper.The design scheme features simple hardware circuit,low-cost,high reli-ability，accurate measurement and it has a high practical value.
基于USB接口的數(shù)據(jù)采集模塊的設(shè)計(jì)與實(shí)現(xiàn)Design and Implementation of USB-Based Data Acquisition MODULE路 永 伸(天津科技大學(xué)電子信息與自動(dòng)化學(xué)院，天津300222)摘要文中給出基于USB接口的數(shù)據(jù)采集模塊的設(shè)計(jì)與實(shí)現(xiàn)。硬件設(shè)計(jì)采用以Adpc831與PDIUSBDI2為主的器件進(jìn)行硬件設(shè)計(jì)，采用Windriver開(kāi)發(fā)USB驅(qū)動(dòng)，并用Visual C十十6.0對(duì)主機(jī)軟件中硬件接口操作部分進(jìn)行動(dòng)態(tài)鏈接庫(kù)封裝。關(guān)鍵詞USB 數(shù)據(jù)采集Adpc831 PDNSBDI2 Windriver動(dòng)態(tài)鏈接庫(kù)Abstract T hed esigna ndim plementaitono fU SB-BasedD ataA cquisiitonM oduleis g iven.Th ec hips oluitonm ainlyw ithA dpc831a ndP DTUSBD12i sused for hardware design. The USB drive is developed場(chǎng)Wmdriver, and the operation on the hardware interface is packaged into Dynamic Link Libraries場(chǎng)Visual C++6.0. Keywords USB DataA cquisition Adttc831 PDfUSBD12 Windriver0 引言US B總 線 是新一代接口總線，最初推出的目的是為了統(tǒng)一取代PC機(jī)的各類(lèi)外設(shè)接口，迄今經(jīng)歷了1.0,1.1與2.0版本3個(gè)標(biāo)準(zhǔn)。在國(guó)內(nèi)基于USB總線的相關(guān)設(shè)計(jì)與開(kāi)發(fā)也得到了快速的發(fā)展，很多設(shè)計(jì)者從各自的應(yīng)用領(lǐng)域，用不同方案設(shè)計(jì)出了相應(yīng)的裝置[1,2]。數(shù)據(jù)采集是工業(yè)控制中一個(gè)普遍而重要的環(huán)節(jié)，因此開(kāi)發(fā)基于USB接口的數(shù)據(jù)采集模塊具有很強(qiáng)的現(xiàn)實(shí)應(yīng)用意義。雖然 US B總線標(biāo)準(zhǔn)已經(jīng)發(fā)展到2.0版本，但由于工業(yè)控制現(xiàn)場(chǎng)干擾信號(hào)的情況比較復(fù)雜，高速數(shù)據(jù)傳輸?shù)目煽啃圆蝗菀妆槐ＷC，并且很多場(chǎng)合對(duì)數(shù)據(jù)采集的實(shí)時(shí)性要求并不高，開(kāi)發(fā)2.0標(biāo)準(zhǔn)產(chǎn)品的成本又較1.1標(biāo)準(zhǔn)產(chǎn)品高，所以筆者認(rèn)為，在工業(yè)控制領(lǐng)域，目前開(kāi)發(fā)基于USB總線1.1標(biāo)準(zhǔn)實(shí)現(xiàn)的數(shù)據(jù)采集模塊的實(shí)用意義大于相應(yīng)2.0標(biāo)準(zhǔn)模塊。
針對(duì)傳統(tǒng)集成電路（ASIC）功能固定、升級(jí)困難等缺點(diǎn)，利用FPGA實(shí)現(xiàn)了擴(kuò)頻通信芯片STEL-2000A的核心功能。使用ISE提供的DDS IP核實(shí)現(xiàn)NCO模塊，在下變頻模塊調(diào)用了硬核乘法器并引入CIC濾波器進(jìn)行低通濾波，給出了DQPSK解調(diào)的原理和實(shí)現(xiàn)方法，推導(dǎo)出一種簡(jiǎn)便的引入?仔/4固定相移的實(shí)現(xiàn)方法。采用模塊化的設(shè)計(jì)方法使用VHDL語(yǔ)言編寫(xiě)出源程序，在Virtex-II Pro 開(kāi)發(fā)板上成功實(shí)現(xiàn)了整個(gè)系統(tǒng)。測(cè)試結(jié)果表明該系統(tǒng)正確實(shí)現(xiàn)了STEL-2000A的核心功能。
Abstract:
To overcome drawbacks of ASIC such as fixed functionality and upgrade difficulty, FPGA was used to realize the core functions of STEL-2000A. This paper used the DDS IP core provided by ISE to realize the NCO MODULE, called hard core multiplier and implemented CIC filter in the down converter, described the principle and implementation detail of the demodulation of DQPSK, and derived a simple method to introduce a fixed phase shift of ?仔/4. The VHDL source code was designed by modularity method , and the complete system was successfully implemented on Virtex-II Pro development board. Test results indicate that this system successfully realize the core function of the STEL-2000A.
