為了解決磁放大器性能測試過程中，需要對其供給不同數(shù)值恒定電流的問題，設計了一種基于DAC7512和單片機的數(shù)控恒流源系統(tǒng)。該系統(tǒng)采用AT89C51作為主控器件，將計算機發(fā)送的電流控制字命令轉換為D/A轉換器控制字，通過模擬SPI通信接口，寫D/A控制字到DAC7512，從而控制其輸出相應數(shù)字電壓值，經差動縮放電路、電壓/電路變換電路和功率驅動電路，最后輸出恒定電流。實驗結果表明，恒流源輸出電流調節(jié)范圍為-45~+45 mA、精度為±0.1 mA，分辨率達0.024 4 mA，具有應用靈活，外圍電路簡單，可靠性高的特點。該數(shù)控直流恒流源也可為相關產品的測試系統(tǒng)研發(fā)提供參考。 Abstract: In order to solve the need to supply different values constant current for the magnetic amplifier in testing process， numerical control constant current source system was designed based on DAC7512 chip and microcontroller technology. The system used the AT89C51 as the main chip， which can convert the current control word from computer into to D/A control words. And the system wrote D/A control word into the DAC7512 chip to control the output voltage value by the SPI communication interface， which can output corresponding constant current figures by scaling circuit， the V/I converter and power drive circuit. Experimental results show that the current source output current adjustment range is -45~+45mA， accuracy is ± 0.1mA， and resolution ratio is 0.024 4mA
上傳時間： 2014-12-27
上傳用戶：invtnewer
1 FEATURES· Single chip LCD controller/driver· 1 or 2-line display of up to 24 characters per line, or2 or 4 lines of up to 12 characters per line· 5 ′ 7 character format plus cursor; 5 ′ 8 for kana(Japanese syllabary) and user defined symbols· On-chip:– generation of LCD supply voltage (external supplyalso possible)– generation of intermediate LCD bias voltages– oscillator requires no external components (externalclock also possible)· Display data RAM: 80 characters· Character generator ROM: 240 characters· Character generator RAM: 16 characters· 4 or 8-bit parallel bus or 2-wire I2C-bus interface· CMOS/TTL compatible· 32 row, 60 column outputs· MUX rates 1 : 32 and 1 : 16· Uses common 11 code instruction set· Logic supply voltage range, VDD - VSS: 2.5 to 6 V· Display supply voltage range, VDD - VLCD: 3.5 to 9 V· Low power consumption· I2C-bus address: 011101 SA0.
上傳時間： 2013-11-08
上傳用戶：laozhanshi111
第一章 序論……………………………………………………………6 1- 1 研究動機…………………………………………………………..7 1- 2 專題目標…………………………………………………………..8 1- 3 工作流程…………………………………………………………..9 1- 4 開發(fā)環(huán)境與設備…………………………………………………10 第二章 德州儀器OMAP 開發(fā)套件…………………………………10 2- 1 OMAP介紹………………………………………………………10 2-1.1 OMAP是什麼?…….………………………………….…10 2-1.2 DSP的優(yōu)點……………………………………………....11 2- 2 OMAP Architecture介紹………………………………………...12 2-2-1 OMAP1510 硬體架構………………………………….…12 2-2.2 OMAP1510軟體架構……………………………………...12 2-2.3 DSP / BIOS Bridge簡述…………………………………...13 2- 3 TI Innovator套件 -- OMAP1510 ……………………………..14 2-2.1 General Purpose processor -- ARM925T………………...14 2-2.2 DSP processor -- TMS320C55x …………………………15 2-2.3 IDE Tool – CCS …………………………………………15 2-2.4 Peripheral ………………………………………………..16 第三章 在OMAP1510上建構Embedded Linux System…………….17 3- 1 嵌入式工具………………………………………………………17 3-1.1 嵌入式程式開發(fā)與一般程式開發(fā)之不同………….….17 3-1.2 Cross Compiling的GNU工具程式……………………18 3-1.3 建立ARM-Linux Cross-Compiling 工具程式………...19 3-1.4 Serial Communication Program………………………...20 3- 2 Porting kernel………………………………………………….…21 3-2.1 Setup CCS ………………………………………….…..21 3-2.2 編譯及上傳Loader…………………………………..…23 3-2.3 編譯及上傳Kernel…………………………………..…24 3- 3 建構Root File System………………………………………..…..26 3-3.1 Flash ROM……………………………………………...26 3-3.2 NFS mounting…………………………………………..27 3-3.3 支援NFS Mounting 的kernel…………………………..27 3-3.4 提供NFS Mounting Service……………………………29 3-3.5 DHCP Server……………………………………………31 3-3.6 Linux root 檔案系統(tǒng)……………………………….…..32 3- 4 啟動及測試Innovator音效裝置…………………………..…….33 3- 5 建構支援DSP processor的環(huán)境…………………………...……34 3-5.1 Solution -- DSP Gateway簡介……………………..…34 3-5.2 DSP Gateway運作架構…………………………..…..35 3- 6 架設DSP Gateway………………………………………….…36 3-6.1 重編kernel……………………………………………...36 3-6.2 DEVFS driver…………………………………….……..36 3-6.3 編譯DSP tool和API……………………………..…….37 3-6.4 測試……………………………………………….…….37 第四章 MP3 Player……………………………………………….…..38 4- 1 MP3 介紹………………………………………………….…….38 4- 2 MP3 壓縮原理……………………………………………….….39 4- 3 Linux MP3 player – splay………………………………….…….41 4.3-1 splay介紹…………………………………………….…..41 4.3-2 splay 編譯………………………………………….…….41 4.3-3 splay 的使用說明………………………………….……41 第五章 程式改寫………………………………………………...…...42 5-1 程式評估與改寫………………………………………………...…42 5-1.1 Inter-Processor Communication Scheme…………….....42 5-1.2 ARM part programming……………………………..…42 5-1.3 DSP part programming………………………………....42 5-2 程式碼………………………………………………………..……43 5-3 雙處理器程式開發(fā)注意事項…………………………………...…47 第六章 效能評估與討論……………………………………………48 6-1 速度……………………………………………………………...48 6-2 CPU負載………………………………………………………..49 6-3 討論……………………………………………………………...49 6-3.1分工處理的經濟效益………………………………...49 6-3.2音質v.s 浮點與定點運算………………………..…..49 6-3.3 DSP Gateway架構的限制………………………….…50 6-3.4減少IO溝通……………….………………………….50 6-3.5網(wǎng)路掛載File System的Delay…………………..……51 第七章 結論心得…
上傳時間： 2013-10-14
上傳用戶：a471778
!方波信號是數(shù)字電路中非常重要的信號源!其產生方法有很多途徑"本設計是基于MPLAB平臺通過對方波信號發(fā)生器的電路分析!介紹了方波信號的產生原理和軟件實現(xiàn)過程!并利用’:.單片機的定時器#計數(shù)器技術對PIC16F877A進行編程$通過對TMRO模塊進行設置!使其分頻比改變!產生V種不同頻率的方波信號!同時改變初始值!產生任意頻率的方波信號"
上傳時間： 2013-10-23
上傳用戶：c12228
The SN65LBC170 and SN75LBC170 aremonolithic integrated circuits designed forbidirectional data communication on multipointbus-transmission lines. Potential applicationsinclude serial or parallel data transmission, cabledperipheral buses with twin axial, ribbon, ortwisted-pair cabling. These devices are suitablefor FAST-20 SCSI and can transmit or receivedata pulses as short as 25 ns, with skew lessthan 3 ns.These devices combine three 3-state differentialline drivers and three differential input linereceivers, all of which operate from a single 5-Vpower supply.The driver differential outputs and the receiverdifferential inputs are connected internally to formthree differential input/output (I/O) bus ports thatare designed to offer minimum loading to the buswhenever the driver is disabled or VCC = 0. Theseports feature a wide common-mode voltage rangemaking the device suitable for party-lineapplications over long cable runs.
上傳時間： 2013-10-13
上傳用戶：ytulpx
FEATURES400 MSPS internal clock speedIntegrated 10-bit DAC32-bit tuning wordPhase noise ≤ –120 dBc/Hz @ 1 kHz offset (DAC output)Excellent dynamic performance>75 dB SFDR @ 160 MHz (±100 kHz offset) AOUTSerial I/O control1.8 V power supplySoftware and hardware controlled power-down48-lead TQFP/EP packageSupport for 5 V input levels on most digital inputsPLL REFCLK multiplier (4× to 20×)Internal oscillator; can be driven by a single crystalPhase modulation capabilityMultichip synchronization
上傳時間： 2014-12-04
上傳用戶：axin881314
摘要：介紹一種基于單片機AT89C51和V/F轉換器LM331的壓力數(shù)據(jù)采集系統(tǒng)，該系統(tǒng)以AT89C51單片機為核心，實時測量由壓力傳感器MPXV5004G檢測的壓力。與傳統(tǒng)電路設計相比較，其外部硬件電路少，結構簡單，無較大的時延。只要對其功能進行擴展，能夠實現(xiàn)相應控制。關鍵詞：壓力傳感器，V/F轉換器，單片機，頻率測量，LM331
上傳時間： 2013-10-09
上傳用戶：atdawn
我們在做一個單片機系統(tǒng)時，常常會遇到這樣那樣的數(shù)據(jù)采集，在這些被采集的數(shù)據(jù)中，大部分可以通過我們的I/O口擴展接口電路直接得到，由于51單片機大部分不帶AD轉換器，所以模擬量的采集就必須靠A/D或V/F實現(xiàn)。下現(xiàn)我們就來了解一下AD0809與51單片機的接口及其程序設計。
上傳時間： 2013-10-19
上傳用戶：gaome
AVR單片機技術原理 AVR單片機介紹 單片機又稱單片微控制器，它是把一個計算機系統(tǒng)集成到一個芯片上，概括的講：一塊芯片就成了一臺計算機。單片機技術是計算機技術的一個分支,是簡易機器人的核心元件。 1997年,由ATMEL公司挪威設計中心的A先生與V先生利用ATMEL公司的Flash新技術, 共同研發(fā)出RISC精簡指令集的高速8位單片機，簡稱AVR。[編輯本段]AVR單片機的優(yōu)勢特征 單片機已廣泛地應用于軍事、工業(yè)、家用電器、智能玩具、便攜式智能儀表和機器人制作等領域，使產品功能、精度和質量大幅度提升，且電路簡單，故障率低，可靠性高，成本低廉。單片機種類很多，在簡易機器人制作和創(chuàng)新中，為什么選用AVR單片機呢？ 一、簡便易學，費用低廉 首先，對于非專業(yè)人員來說，選擇AVR單片機的最主要原因，是進入AVR單片機開發(fā)的門檻非常低，只要會操作電腦就可以學習AVR單片機的開發(fā)。單片機初學者只需一條ISP下載線，把編輯、調試通過的軟件程序直接在線寫入AVR單片機，即可以開發(fā)AVR單片機系列中的各種封裝的器件。AVR單片機因此在業(yè)界號稱“一線打天下”。 其次，AVR單片機便于升級。AVR程序寫入是直接在電路板上進行程序修改、燒錄等操作，這樣便于產品升級。 再次，AVR單片機費用低廉。學習AVR單片機可使用ISP在線下載編程方式(即把PC機上編譯好的程序寫到單片機的程序存儲器中)，不需購買仿真器、編程器、擦抹器和芯片適配器等，即可進行所有AVR單片機的開發(fā)應用，這可節(jié)省很多開發(fā)費用。程序存儲器擦寫可達10000次以上，不會產生報廢品。 二、高速、低耗、保密 首先，AVR單片機是高速嵌入式單片機： 1、AVR單片機具有預取指令功能，即在執(zhí)行一條指令時，預先把下一條指令取進來，使得指令可以在一個時鐘周期內執(zhí)行。 2、多累加器型，數(shù)據(jù)處理速度快。AVR單片機具有32個通用工作寄存器，相當于有32條立交橋，可以快速通行。 3、中斷響應速度快。AVR單片機有多個固定中斷向量入口地址，可快速響應中斷。 其次，AVR單片機耗能低。對于典型功耗情況，WDT關閉時為100nA，更適用于電池供電的應用設備。有的器件最低1.8 V即可工作。 再次，AVR單片機保密性能好。它具有不可破解的位加密鎖Lock Bit技術，保密位單元深藏于芯片內部，無法用電子顯微鏡看到。 三、I/O口功能強,具有A/D轉換等電路 1. AVR單片機的I/O口是真正的I/O口，能正確反映I/O口輸入/輸出的真實情況。工業(yè)級產品，具有大電流(灌電流)10～40 mA,可直接驅動可控硅SCR或繼電器，節(jié)省了外圍驅動器件。 2. AVR單片機內帶模擬比較器，I/O口可用作A/D轉換，可組成廉價的A/D轉換器。ATmega48/8/16等器件具有8路10位A/D。 3. 部分AVR單片機可組成零外設元件單片機系統(tǒng)，使該類單片機無外加元器件即可工作，簡單方便，成本又低。 4. AVR單片機可重設啟動復位,以提高單片機工作的可靠性。有看門狗定時器實行安全保護,可防止程序走亂(飛),提高了產品的抗干擾能力。 四、有功能強大的定時器/計數(shù)器及通訊接口 定時/計數(shù)器T/C有8位和16位,可用作比較器。計數(shù)器外部中斷和PWM(也可用作D/A)用于控制輸出，某些型號的AVR單片機有3～4個PWM，是作電機無級調速的理想器件。 AVR單片機有串行異步通訊UART接口,不占用定時器和SPI同步傳輸功能,因其具有高速特性，故可以工作在一般標準整數(shù)頻率下,而波特率可達576K。
上傳時間： 2013-10-18
上傳用戶：二十八號
I/O 型單片機使用手冊 目錄 間接尋址寄存器 – IAR, IAR0, IAR1 .............................................35間接尋址指針 – MP, MP0, MP1 ......................................................35存儲區(qū)指針 – BP .........................................................................36累加器 – ACC...................................................................................37程序計數(shù)器低字節(jié)寄存器 – PCL....................................................37表格寄存器 – TBLP,TBHP,TBLH....................................................37看門狗定時寄存器 – WDTS............................................................38狀態(tài)寄存器 – STATUS.....................................................................38中斷控制寄存器 – INTC,INTC0,INTC1 .........................................39定時/計數(shù)寄存器...............................................................................39輸入/輸出端口和控制寄存器...........................................................40UART 寄存器 .USR,UCR1,UCR2,TXR/RXR,BRG.......................40輸入/輸出端口..........................................................................................41上拉電阻............................................................................................41PA 口的喚醒......................................................................................41輸入/輸出端口控制寄存器...............................................................41引腳共享功能....................................................................................42編程注意事項....................................................................................45定時/計數(shù)器..............................................................................................46配置定時/計數(shù)器輸入時鐘源...........................................................47定時/計數(shù)寄存器 – TMR, TMR0,TMR0L/TMR0H,TMR1L/TMR1H,TMR2.....................................................................49定時/計數(shù)控制寄存器 – TMRC,TMR0C,TMR1C,TMR2C............50定時器模式........................................................................................53事件計數(shù)器模式................................................................................53脈沖寬度測量模式............................................................................54可編程分頻器(PFD)和蜂鳴器的應用..............................................55預分頻器(Prescaler)...........................................................................56輸入/輸出接口...................................................................................56編程注意事項....................................................................................57定時/計數(shù)器應用范例.......................................................................57中斷............................................................................................................59中斷寄存器........................................................................................59中斷優(yōu)先權........................................................................................62外部中斷............................................................................................63定時/計數(shù)器中斷...............................................................................64UART 中斷........................................................................................64編程注意事項....................................................................................65復位和初始化............................................................................................66復位....................................................................................................66目錄iii異步串行口——UART............................................................................74UART 特性..........................................................................................74UART 外部引腳..................................................................................74數(shù)據(jù)發(fā)送.............................................................................................75UART 狀態(tài)控制寄存器......................................................................75波特率發(fā)生器.....................................................................................79UART 設置與控制..............................................................................81UART 發(fā)送器......................................................................................83UART 接收器......................................................................................84接收錯誤處理.....................................................................................85接收中斷圖解.....................................................................................86地址檢測模式.....................................................................................86暫停模式下的UART 功能.................................................................87UART 應用范例.................................................................................87振蕩器........................................................................................................89系統(tǒng)時鐘配置....................................................................................89系統(tǒng)晶體/陶瓷振蕩器.......................................................................89系統(tǒng)電阻電容振蕩器........................................................................90內部系統(tǒng)電阻電容振蕩器................................................................90RTC 振蕩器........................................................................................91看門狗定時振蕩器............................................................................91暫停和喚醒................................................................................................92暫停.....................................................................................................92進入暫停.............................................................................................92靜態(tài)電流.............................................................................................92喚醒....................................................................................................92看門狗定時器............................................................................................94掩膜選項....................................................................................................96應用電路....................................................................................................97第二部份 程序語言.....................................................................99第二章 指令集介紹.................................................................................101指令集......................................................................................................101指令周期..........................................................................................101數(shù)據(jù)的傳送......................................................................................101算術運算..........................................................................................102邏輯和移位運算..............................................................................102分支和控制的轉換..........................................................................102位運算..............................................................................................102查表運算..........................................................................................103其它運算..........................................................................................103指令設定一覽表......................................................................................104慣例..................................................................................................104I/O 型單片機使用手冊iv第三章 指令定義.....................................................................................107第四章 匯編語言和編譯器.....................................................................121常用符號..................................................................................................121語句語法..................................................................................................122名稱..................................................................................................122操作項..............................................................................................122操作數(shù)項..........................................................................................122注解..................................................................................................122編譯偽指令..............................................................................................123條件編譯偽指令..............................................................................123文件控制偽指令..............................................................................124程序偽指令......................................................................................126數(shù)據(jù)定義偽指令..............................................................................130宏指令..............................................................................................132匯編語言指令..........................................................................................136名稱..................................................................................................136助記符..............................................................................................136操作數(shù)、運算子和表達式..............................................................136其它..........................................................................................................139前置引用..........................................................................................139局部標號..........................................................................................139匯編語言保留字..............................................................................140編譯器選項..............................................................................................141編譯列表文件格式..................................................................................141源程序列表......................................................................................141編譯總結..........................................................................................142其它..................................................................................................142第三部份 開發(fā)工具................................................................... 145第五章 單片機開發(fā)工具.........................................................................147HT-IDE 集成開發(fā)環(huán)境............................................................................147盛群單片機仿真器(HT-ICE) ..................................................................149HT-ICE 接口卡.................................................................................149OTP 燒寫器.....................................................................................149OTP 適配卡.....................................................................................149系統(tǒng)配置..................................................................................................150HT-ICE 接口卡設置........................................................................151安裝..........................................................................................................153系統(tǒng)要求..........................................................................................153硬件安裝..........................................................................................153軟件安裝..........................................................................................154目錄v第六章 快速開始.....................................................................................159步驟一：建立一個新項目..............................................................159步驟二：將源程序文件加到項目中..............................................159步驟三：編譯項目..........................................................................159步驟四：燒寫OTP 單片機.............................................................160步驟五：傳送程序與掩膜選項單至Holtek ..................................160附錄............................................................................................... 161附錄A 特性曲線圖...................................................................................163附錄B 封裝信息.......................................................................................173
上傳時間： 2013-10-18
上傳用戶：blacklee
