【正文】 draw a diagram, PCB figure, through the Keil software keyboard to software programming, then the software and hardware debugging run and will burn to STC89C52 chip program. Operation of the system is stable and has the hardware circuit design simple, clear, and the cost is low, the software perfect function, control system firm, price higher advantages, has certain practical and reference value. Key words : stc89c52。 matrix keyboard 基于單片機(jī)的簡(jiǎn)易電子琴設(shè)計(jì) 目錄 摘要 .......................................................................................................................................... I Abstract.................................................................................................................................... II 1 緒論 ..................................................................................................................................... 1 設(shè)計(jì)的目的和意義 ....................................................................................................... 1 設(shè)計(jì)的主要內(nèi)容 ........................................................................................................... 1 2 系統(tǒng)概述 ............................................................................................................................. 2 系統(tǒng)工作原理 ............................................................................................................... 2 系統(tǒng)結(jié)構(gòu)組成 ............................................................................................................... 2 電源電路 ................................................................................................................ 2 控制部分 ................................................................................................................ 2 顯示部分 ................................................................................................................ 3 發(fā)聲部分 ................................................................................................................ 3 主要芯片及元件的介紹 ............................................................................................... 3 STC89C52 單片機(jī)簡(jiǎn)介 .......................................................................................... 3 芯片引腳介紹 ........................................................................................................ 4 STC89C52 時(shí)鐘介紹 .............................................................................................. 6 雙位 LED 數(shù) 碼顯示器簡(jiǎn)介 .................................................................................. 7 3 硬件電路的設(shè)計(jì) ................................................................................................................. 9 電源電路的設(shè)計(jì) ........................................................................................................... 9 復(fù)位電路的設(shè)計(jì) ......................................................................................................... 10 復(fù)位操作 .............................................................................................................. 10 復(fù)位信號(hào)及其產(chǎn)生 .............................................................................................. 10 鍵盤(pán)控制電路 ............................................................................................................. 11 矩陣式鍵盤(pán)的概述 .............................................................................................. 11 矩陣式鍵盤(pán)按鍵識(shí)別原理及方法 ...................................................................... 12 顯示電路 ..................................................................................................................... 13 4 系統(tǒng)軟件設(shè)計(jì) ................................................................................................................... 14 如何利用單片機(jī)實(shí)現(xiàn)音樂(lè)節(jié)拍 ................................................................................. 14 如何用單片機(jī)產(chǎn)生音頻脈沖 ..................................................................................... 14 音符和頻率的關(guān)系 .............................................................................................. 14 定義初值 .............................................................................................................. 15 音樂(lè)發(fā) 生 程序流程圖 ................................................................................................. 16 結(jié) 論 ..................................................................................................................................... 18 參考文獻(xiàn) ............................................................................................................................... 19 附錄一 電子琴源程序 ......................................................................................................... 20 附錄二 原理圖 ..................................................................................................................... 24 附錄三 PCB 圖 ...................................................................................................................... 25 附錄四 實(shí)物圖 ...