八路智能搶答器的設(shè)計(jì)單片機(jī)外文翻譯單片機(jī)at89c-全文預(yù)覽
【正文】 tes to a port pin or to external memory. Figure 1. Oscillator Connections Figure 2. External Clock Drive Configuration 八路智能搶答器的設(shè)計(jì) 第 6頁(yè) 共 13頁(yè) Powerdown Mode In the powerdown mode, the oscillator is stopped, and the instruction that invokes powerdown is the last instruction executed. The onchip RAM and Special Function Registers retain their values until the powerdown mode is terminated. The only exit from powerdown is a hardware reset. Reset redefines the SFRs but does not change the onchip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize. Program Memory Lock Bits On the chip are three lock bits which can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the table lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random value, and holds that value until reset is activated. It is necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly. Programming the Flash The AT89C51 is normally shipped with the onchip Flash memory array in the erased state (that is, contents = FFH) and ready to be programmed. The programming interface accepts either a highvoltage (12volt) or a lowvoltage (VCC) program enable signal. The lowvoltage programming mode provides a convenient way to program the AT89C51 inside the user’s system, while the highvoltage programming mode is patible with conventional 第 7頁(yè) 共 13頁(yè) thirdparty Flash or EPROM programmers. The AT89C51 is shipped with either the highvoltage or lowvoltage programming mode enabled. The AT89C51 code memory array is programmed bytebybyte in either programming mode. To program any nonblank byte in the onchip Flash Memory, the entire memory must be erased using the Chip Erase Mode. 八路智能搶答器的設(shè)計(jì) 第 8頁(yè) 共 13頁(yè) AT89C51 主要性能參數(shù)： ? 與 MCS51 產(chǎn)品指令系統(tǒng)完全兼容 ? 4K 字節(jié)可重檫寫 Flash 閃速存儲(chǔ)器 ? 1000 次檫寫周期 ? 全靜態(tài)操作： 0HZ24MHZ ? 三級(jí)加密程序存儲(chǔ)器 ? 128*8 字節(jié)內(nèi)部 RAM ? 32 個(gè)可編程 I/O 口線 ? 2 個(gè) 16 位定時(shí) /記數(shù)器 ? 6 個(gè)中斷源 ? 可編程串行 UART 通道 ? 低功耗空閑和掉電模式 功能特性概述： AT89C51 提供以下標(biāo)準(zhǔn)功能： 4K字節(jié) Flash 閃速存儲(chǔ)器， 128 字節(jié)內(nèi)部 RAM， 32 個(gè)I/O 口線，兩個(gè) 16位定時(shí) /記數(shù)器，一個(gè) 5向量?jī)杉?jí)中斷結(jié)構(gòu)，一個(gè)全雙工串行通信口，片內(nèi)振蕩器及時(shí)鐘電路。 AT89C51是美國(guó) ATMEL公司生產(chǎn)的低電壓，高性能 CMOS的 8位單片機(jī)，片內(nèi)含 4k bytes的可反復(fù)擦寫的只讀程序存儲(chǔ)器（ PEROM）和 128 bytes的隨機(jī)存取數(shù)據(jù)存儲(chǔ)器（ RAM），器件采用 ATMEL公司的高密度、非易失性存儲(chǔ)技術(shù)生產(chǎn)，兼容標(biāo)準(zhǔn) MCS51指令系統(tǒng)，片內(nèi)置通用 8位中央處理器（ CPU）和 Flash存儲(chǔ)單元，功能強(qiáng)大 AT89C51單片機(jī)可為您提供許多高性價(jià)比的應(yīng)用場(chǎng)合，可靈活應(yīng)用于各種控制領(lǐng)域。 P0 口： P0 口是一組 8 位漏極開路型雙向 I／ O 口，也
研究報(bào)告相關(guān)推薦
鄂ICP備17016276號(hào)-1