【文章內(nèi)容簡介】 P2口的口線 ~。 II、數(shù)據(jù)線的連接 外部程序存儲器 8位數(shù)據(jù)線 D0~D7與 P0口的口線 ~。 III、控制線的連接 RD(單片機片外數(shù)據(jù)讀信號 )和 RD(數(shù)據(jù)存儲器讀信號 )相連； ALE(單片機地址鎖存允許信號 )和 G(地址鎖存器鎖存信號 )相連； WR(單片機片外數(shù)據(jù)寫信號 )和 WE(數(shù)據(jù)存儲器寫信號 )相連； 單片機的相關地址線經(jīng)過線譯碼或地址譯碼和數(shù)據(jù)存儲器的片選信號相連。 采用 16 位地址線尋址外部數(shù)據(jù)區(qū)，這時可尋址空間為 64KB，采用下面 8位尋址指令來讀、寫此數(shù)據(jù)存儲區(qū)： MOVX A,@DPTR MOVX @DPTR,A 當外部 RAM容量較大 (大于 256B)時 ,采用此尋址方法。下圖即為 80c51與 62256 的連接圖。 綜合程序存儲器與數(shù)據(jù)存儲器，可以畫出存儲模塊的原理圖如下。 第 13 頁 共 24 頁 字模的制作與保存 本次設計設計的字模（ 32 32）都是使用 PCtoLCD2022 軟件來獲取的；如圖所示，為本次取字的字模。 取字原理：由于采用共陰極的 LED 顯示模塊，故在取字符時，取字符陰碼，即點亮 LED燈的信號為 1。取模順序是從左到右，逐行取位，即第一個點作為最高位。每取 8個點作為一個字節(jié)。取字的字體由軟件寫入時的字體決定，每個 LED燈的亮滅都是由一個數(shù)位來標志的。 以下為用 PCtoLCD2022 取的“太師學院計算機系”的字模： 太 (0) 師 (1) 學 (2) 院 (3) 計 (4) 算 (5) 機 (6) 系 (7) {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x03,0x80,0x00,0x00,0x03,0x00,0x00,0x00,0x03,0x00,0x00,0x00,0x03,0x00,0x00,0x00,0x03,0x00,0x00}, {0x00,0x03,0x00,0x00,0x00,0x03,0x00,0x10,0x00,0x03,0x00,0x38,0x1F,0xFF,0xFF,0xC0,0x00,0x03,0x40,0x00,0x00,0x03,0x40,0x00,0x00,0x02,0x40,0x00,0x00,0x06,0x20,0x00}, {0x00,0x06,0x20,0x00,0x00,0x06,0x10,0x00,0x00,0x0C,0x10,0x00,0x00,0x0C,0x18,0x00,0x00,0x18,0x0C,0x00,0x00,0x18,0x0C,0x00,0x00,0x34,0x06,0x00,0x00,0x33,0x03,0x00}, {0x00,0x61,0x83,0x80,0x00,0xC1,0xC1,0xC0,0x01,0x80,0xE0,0xF0,0x03,0x00,0x40,0x78,0x0C,0x00,0x00,0x3E,0x18,0x00,0x00,0x10,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*太 ,0*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x60,0x00,0x18,0x00,0x40,0x00,0x3C,0x00,0x47,0xFF,0xC0,0x10,0x40,0x08,0x00,0x0C,0x40,0x08,0x00}, {0x08,0x40,0x08,0x00,0x08,0x40,0x08,0x00,0x08,0x46,0x08,0x18,0x08,0x47,0xFF,0xF8,0x08,0x46,0x08,0x10,0x08,0x46,0x08,0x10,0x08,0x46,0x08,0x10,0x08,0xC6,0x08,0x10}, {0x08,0xC6,0x08,0x10,0x08,0xC6,0x08,0x10,0x08,0xC6,0x08,0x10,0x08,0xC6,0x08,0x10,0x08,0x86,0x08,0x10,0x08,0x86,0x08,0x10,0x09,0x86,0x08,0x10,0x11,0x86,0x09,0xF0}, {0x01,0x06,0x08,0x70,0x03,0x06,0x08,0x20,0x02,0x00,0x08,0x00,0x04,0x00,0x0C,0x00,0x08,0x00,0x0C,0x00,0x10,0x00,0x0C,0x00,0x20,0x00,0x0C,0x00,0x00,0x00,0x00,0x00},/*師 ,1*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x04,0x01,0x00,0x01,0x06,0x01,0x80,0x01,0x83,0x03,0x80,0x00,0xC3,0x83,0x00,0x00,0xE1,0x86,0x00,0x00,0x61,0x84,0x00}, {0x00,0x61,0x88,0x00,0x00,0x40,0x08,0x08,0x07,0xFF,0xFF,0xFC,0x0C,0x00,0x00,0x1C,0x0C,0x00,0x00,0x30,0x1C,0x00,0x00,0x60,0x38,0x00,0x06,0x00,0x11,0xFF,0xFF,0x00}, {0x00,0x00,0x1C,0x00,0x00,0x00,0x30,0x00,0x00,0x00,0x40,0x00,0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x30,0x3F,0xFF,0xFF,0xF8,0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x00}, 第 14 頁 共 24 頁 {0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x00,0x00,0x1F,0x80,0x00,0x00,0x07,0x00,0x00,0x00,0x03,0x00,0x00,0x00,0x00,0x00,0x00},/*學 ,2*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x18,0x00,0x08,0x30,0x1C,0x00,0x0F,0xF0,0x0C,0x00,0x08,0x60,0x08,0x30,0x08,0x67,0xF7,0xF8}, {0x08,0x44,0x00,0x30,0x08,0xCC,0x00,0x20,0x08,0x9C,0x00,0x40,0x08,0x80,0x00,0x80,0x09,0x01,0xFF,0xC0,0x08,0x80,0x00,0x00,0x08,0x40,0x00,0x00,0x08,0x60,0x00,0x00}, {0x08,0x30,0x00,0x30,0x08,0x37,0xFF,0xF8,0x08,0x10,0x62,0x00,0x08,0x10,0x62,0x00,0x08,0x30,0x62,0x00,0x0B,0xF0,0x62,0x00,0x08,0xE0,0x42,0x00,0x08,0x40,0x42,0x08}, {0x08,0x00,0xC2,0x08,0x08,0x00,0x82,0x08,0x08,0x01,0x82,0x08,0x08,0x03,0x02,0x0C,0x08,0x06,0x03,0xFC,0x08,0x18,0x03,0xF8,0x08,0x60,0x00,0x00,0x00,0x00,0x00,0x00},/*院 ,3*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x06,0x00,0x18,0x00,0x03,0x80,0x1C,0x00,0x01,0xC0,0x18,0x00,0x00,0xC0,0x18,0x00,0x00,0xC0,0x18,0x00}, {0x00,0x00,0x18,0x00,0x00,0x00,0x18,0x00,0x00,0x00,0x18,0x00,0x00,0x00,0x18,0x00,0x00,0x00,0x18,0x18,0x01,0x9F,0xFF,0xFC,0x3F,0x80,0x18,0x00,0x01,0x00,0x18,0x00}, {0x01,0x00,0x18,0x00,0x01,0x00,0x18,0x00,0x01,0x00,0x18,0x00,0x01,0x00,0x18,0x00,0x01,0x02,0x18,0x00,0x01,0x04,0x18,0x00,0x01,0x08,0x18,0x00,0x01,0x10,0x18,0x00}, {0x01,0x20,0x18,0x00,0x01,0x60,0x18,0x00,0x01,0xC0,0x18,0x00,0x03,0x80,0x18,0x00,0x01,0x80,0x18,0x00,0x00,0x00,0x18,0x00,0x00,0x00,0x18,0x00,0x00,0x00,0x00,0x00},/*計 ,4*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x18,0x00,0x01,0xC0,0x18,0x00,0x01,0x80,0x10,0x08,0x03,0x03,0x30,0x1C,0x03,0xFC,0x2F,0xE0,0x06,0x10,0x40,0xC0}, {0x04,0x18,0x80,0xC0,0x09,0x19,0x01,0x40,0x11,0xFF,0xFF,0x80,0x11,0x80,0x01,0x00,0x21,0x80,0x01,0x00,0x01,0xFF,0xFF,0x00,0x01,0x80,0x01,0x00,0x01,0x80,0x01,0x00}, {0x01,0xFF,0xFF,0x00,0x01,0x80,0x01,0x00,0x01,0x80,0x01,0x00,0x01,0x80,0x01,0x00,0x01,0xFF,0xFF,0x00,0x01,0x98,0x08,0x00,0x00,0x18,0x08,0x00,0x00,0x18,0x08,0x18}, {0x3F,0xFF,0xFF,0xFC,0x00,0x10,0x18,0x00,0x00,0x30,0x18,0x00,0x00,0x60,0x18,0x00,0x00,0xC0,0x18,0x00,0x03,0x80,0x18,0x00,0x0C,0x00,0x18,0x00,0x00,0x00,0x00,0x00},/*算 ,5*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x80,0x00,0x00,0x01,0x80,0x00,0x00,0x01,0x81,0x00,0x80,0x01,0x81,0xFF,0xC0,0x01,0x81,0x81,0x80,0x01,0x81,0x81,0x80}, {0x01,0x81,0x81,0x80,0x01,0x99,0x81,0x80,0x3F,0xE1,0x81,0x80,0x01,0x81,0x81,0x80,0x03,0x81,0x81,0x80,0x03,0x81,0x81,0x80,0x03,0xC1,0x81,0x80,0x03,0xB1,0x81,0x80}, {0x07,0x99,0x81,0x80,0x05,0x9D,0x81,0x80,0x05,0x89,0x81,0x80,0x0D,0x81,0x81,0x80,0x09,0x81,0x81,0x80,0x11,0x81,0x81,0x80,0x11,0x81,0x01,0x80,0x21,0x83,0x01,0x80}, {0x41,0x83,0x01,0x88,0x41,0x86,0x01,0x88,0x01,0x84,0x01,0x8C,0x01,0x8C,0x01,0x8C,0x01,0x88,0x01,0xFC,0x01,0x90,0x00,0xF8,0x01,0xA0,0x00,0x00,0x00,0x00,0x00,0x00},/*機 ,6*/ {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xE0,0x00,0x00,0x0F,0xF0,0x00,0x03,0xFC,0x00,0x03,0xFD,0x00,0x00,0x0C,0x03,0xC0,0x00,0x00,0x07,0x00,0x00}, {0x00,0x0C,0x03,0x00,0x00,0x18,0x07,0x80,0x00,0x60,0x0E,0x00,0x01,0xBF,0xF8,0x00,0x01,0xF0,0x60,0x00,0x00,0x00,0xC0,0x00,0x00,0x03,0x04,0x00,0x00,0x0C,0x03,0x00}, 第 15 頁 共 24 頁 {0x00,0x38,0x01,0xC0,0x00,0xE0,0x0F,0xE0,0x03,0xFF,0xF0,0x70,0x01,0xC0,0xC0,0x30,0x00,0x00,0xC0,0x20,0x00,0x10,0xC8,0x00,0x00,0x38,0xC6,0x00,0x00,0x60,0xC1,0x80}, {0x00,0xC0,0xC0,0xE0,0x01,0x80,0xC0,0x70,0x02,0x00,0xC0,0x38,0x0C,0x00,0xC0,0x38,0x10,0x18,0xC0,0x18,0x20,0x07,0xC0,0x00,0x00,0x01,0x80,0x00,0x00,0x00,0x00,0x00},/*系 ,7*/ 每個 LED 燈的亮滅都是由一個數(shù)位來標志的，那么存儲一個漢字 需要的空間就有： 32 32﹦ 1024b﹦ 128B；存儲 8個漢字就需要 1K 的空間。本次設計中使用的 62256可存儲的漢字字數(shù)是 256個。 當存儲的漢字較多時，比如顯示廣告或顯示其他信息時，需要的空間就迅速上升；而 80c51內(nèi)部的存儲空間是有限的，故需要對數(shù)據(jù)存儲器進行擴展，使字庫存儲在片外的存儲器上。另外，由于系統(tǒng)需要調(diào)用的程序和數(shù)據(jù)比較多，所以在外部