【正文】 the times and the development of electronic industry, the timer is used more and more widely. The traditional mechanical timer, electric timer is drived through the spring, AC synchronous motor or quartz stepper motor .The accuracy of this timer is not high and the error is large. Compared with the former two timer, electroni c timer has small volume, light weight, low cost, high precision, long service life, and electronic timer is safety and reliability, convenient adjustment, suitable for frequent use. The topic of this design is timer design based on the DSP paper designs a timer with the core of TMS320F28335 DSP microcontroller. Generating a timer interrupt and counting retrogradely by using the internal timer 0 and PIE peripheral interrupt expansion module. Communicate between DSP and 74HC164 through the SPI serial peripheral interface, so as to achieve displaying time on the digital tube by dynamic scanning. The system is turned on and paused through the matrix keyboard. In the timer pause,initial value can be inputed through the keyboard . When the timing is over, system will alarm through LED lights flashing, prompting the end of timing. Key Words: timer ,DSP ,TMS320F28335 ,SPI, matrix keyboard 第 3 頁(yè) 目 錄 1 緒論 .......................................................................................................................... 1 系統(tǒng)背景 ........................................................................................................ 1 定時(shí)器的分類(lèi) .................................................................................... 1 定時(shí)器的應(yīng)用 .................................................................................... 2 定時(shí)器系統(tǒng)概述 ........................................................................................... 2 定時(shí)器設(shè)計(jì)及實(shí)現(xiàn)的功能 ........................................................................... 2 設(shè)計(jì)過(guò)程 ............................................................................................ 2 定時(shí)器方案的確定 ............................................................................ 3 定時(shí)器的功能 .................................................................................... 3 2 定時(shí)器系統(tǒng)的硬件設(shè)計(jì) .......................................................................................... 4 總體硬件設(shè)計(jì) ............................................................................................... 4 DSP 微控制器 ............................................................................................... 5 定時(shí)器中斷的實(shí)現(xiàn) ........................................................................................ 6 DSP 內(nèi)部定時(shí)器 ................................................................................ 6 PIE 外設(shè)中斷擴(kuò)展模塊 ...................................................................... 7 數(shù)碼管顯示電路 ........................................................................................... 8 SPI 串行外設(shè)接口 .............................................................................. 9 74HC164 ........................................................................................... 12 數(shù)碼管 .............................................................................................. 13 按鍵控制電路 .............................................................................................. 16 第 4 頁(yè) 矩 陣鍵盤(pán)的概述 .............................................................................. 16 矩陣鍵盤(pán)的硬件設(shè)計(jì) ...................................................................... 16 按鍵接口的消抖 .............................................................................. 17 LED 顯示電路 ............................................................................................. 18 3 定時(shí)器軟件的設(shè)計(jì) ................................................................................................ 19 主函數(shù)程序設(shè)計(jì) ......................................................................................... 19 SPI 的初始化 ............................................................................................... 19 定時(shí)器、數(shù)碼管，按鍵及其他外設(shè)的初始化 ......................................... 21 定時(shí)器的初始化 .............................................................................. 21 其他外設(shè)的初始化 .......................................................................... 21 cpu 中斷及其 PIE 的設(shè)置 ........................................................................... 22 設(shè)置定時(shí)器 0 的周期、打開(kāi)定時(shí)器、看門(mén)狗和開(kāi)中斷 ......................... 22 設(shè)定定時(shí)器的周期 .......................................................................... 22 打開(kāi)定時(shí)器 ...................................................................................... 22 開(kāi)中斷 .............................................................................................. 23 開(kāi)啟看門(mén)狗 ...................................................................................... 23 主要功能的實(shí)現(xiàn) ......................................................................................... 23 定時(shí)器中斷子程序的設(shè)計(jì) .............................................................. 23 SPI 通信與數(shù)碼管顯示程序的設(shè)計(jì) ................................................ 24 矩陣鍵盤(pán)程序設(shè)計(jì) ........................................................................... 26 核心功能的設(shè)計(jì) .............................................................................. 29 4 總結(jié) ........................................................................................................................ 33 第 5 頁(yè) 參考文獻(xiàn) .................................................................................................................... 34 致謝 ............................................................................................................................ 35 第 1 頁(yè) 1 緒論 系統(tǒng)背景 人類(lèi)最早使用的定時(shí)工具是沙漏或水漏，但在鐘表誕生發(fā)展成熟之后，人們開(kāi)始嘗試使用這種全新的計(jì)時(shí)工具來(lái)改進(jìn)定時(shí)器，達(dá)到準(zhǔn)確控制時(shí)間的目的。 通過(guò) SPI 串行外設(shè)接 口在 DSP 和74HC164 之間進(jìn)行通信，進(jìn)而 實(shí)現(xiàn)在數(shù)碼管上 通過(guò)動(dòng)態(tài)掃描 顯示定時(shí)時(shí)間 。相對(duì)于前兩種定時(shí)器，電子式定時(shí)器體積小、重量輕、造價(jià)低、精度高、壽命長(zhǎng)、而且安全可靠、調(diào)整方便、適于頻繁使用。 第 1 頁(yè)