【正文】 h the development of science and technology, the application of SCM increasingly mature. Single chip microputer high level of integration, processing powerful, low prices make it is widely used in various fields. At the same time the keyboards for science and technology and music mon development of the product, in the electronic information era, for music39。 matrix keyboard目錄摘要 ..........................................................................................................................................IAbstract ...................................................................................................................................II1 緒論 ......................................................................................................................................1 設計的目的和意義 .......................................................................................................1 設計的主要內(nèi)容 ...........................................................................................................12 系統(tǒng)概述 ..............................................................................................................................1 系統(tǒng)工作原理 ...............................................................................................................1 系統(tǒng)結(jié)構(gòu)組成 ...............................................................................................................1 電源電路 ................................................................................................................2 控制部分 ................................................................................................................2 顯示部分 ................................................................................................................2 發(fā)聲部分 ................................................................................................................2 主要芯片及元件的介紹 ...............................................................................................2 STC89C52 單片機簡介 ..........................................................................................2 芯片引腳介紹 ........................................................................................................4 STC89C52 時鐘介紹 ..............................................................................................7 雙位 LED 數(shù)碼顯示器簡介 ..................................................................................73 硬件電路的設計 ..................................................................................................................9 電源電路的設計 ...........................................................................................................9 復位電路的設計 .........................................................................................................10 復位操作 ..............................................................................................................10 復位信號及其產(chǎn)生 ..............................................................................................11 鍵盤控制電路 .............................................................................................................12 矩陣式鍵盤的概述 ..............................................................................................12 矩陣式鍵盤按鍵識別原理及方法 ......................................................................12 顯示電路 .....................................................................................................................134 系統(tǒng)軟件設計 ....................................................................................................................14 如何利用單片機實現(xiàn)音樂節(jié)拍 .................................................................................14 如何用單片機產(chǎn)生音頻脈沖 .....................................................................................15 音符和頻率的關系 ..............................................................................................15 定義初值 ..............................................................................................................16 音樂發(fā)生程序流程圖 .................................................................................................18結(jié) 論 ......................................................................................................................................19參考文獻 ................................................................................................................................20附錄一 電子琴源程序