【正文】 lso independent type key electric circuit, the dynamic state shows an electric circuit etc.. It not only can carry out various function of number electronics clock, if have to pare, adjust, in fixed time, alarm clock etc. function, and can also carry out the function that the fixedpoint tells the time.Key words ：MCU,The single slice of machine makes bell clock, code, segment code, showForeword: Actually and always the clock can provide second, cent, , the day, week, month and year are small can automatically adjust, and have leap year repair function with 31 weathers for a month. This design is still additional the fixedpoint tells the time of function, thus and further pleted automatically a design of telling the time the system. In brief described the work principle of hardware system first in the text, and attached diagram with the design frame of the hardware system, discuss this graduation design connects the function and work process that a people39。s technique and each one connect a people mold piece various hardware applying, and concrete described to circumscribe electric circuit to connect of soft, the hardware adjust to try.1. Single slice of machine total design way of thinking(1) Design minimum hardware system of a single slice of machine of ability normal work, the outer circle electric circuit includes to establish a keyboard, the monitor of LCD or LED。 (2) Carry on a software design, make use of single slice of machine system the clock design the internal clock system of high accuracy first, minimum and accurate time is period 1。 (3) Design on second foundation that counts a machine for a 24 hours, clock, and design some in fixed time function。 (4) Design a dozen of bells performance organization, plete an auto to beat bell function.2. The alternative of hardwareAutomatically tell the time system, it needs to be walked accurately, pare, adjust, in fixed time, the fixedpoint tell the time etc., therefore what I chose is one AT89 C51 list slice machine chip, then go together with with the DS12 C887, key electric circuit, crystal flap electric circuit and reset electric circuit and LED dynamic state of display, can carry out. The key connects, is pleted by , , and , four functions of keys respectively BE: One is the function key K1。 One is a number to adjust the key K2。 One is cancel to establish the key K3, use to establish time。 One is K4 keyses, use to establish in fixed time time. Seven type figures tubes drive mold piece, buzzer to drive a mold piece and reset a mold piece, keyboard mold piece and crystal to flap to concuss an electric circuit mold a piece five parts to constitute. And all pass AT89 C51 to carry out. seven type figures tubes drive a mold piece Adopt a dynamic state scanning method, through a set of single slice of machine port drive to merge together of LCD give out light a tube of on carrying(total Yin or total sun carry), LCD gives out light another feet of tube to connect to use an I/O and control it bright put out. The method can drive more LCD and control a way more vivid, and economical list the resources of the slice machine. buzzers drive a mold piece The adoption presses electricity type buzzer and presses an electricity type buzzer to be mainly flapped by many Xies to concuss a machine and press to give or get an electric shock Feng to blare slice, resistance to match machine and sympathy box, and outer shell...etc. to constitute. Many Xies flap to concuss the machine constitutes to176。from the transistor or the integrated circuit, when after connecting the power( V direct current work electric voltage), many Xies flap to concuss machine to flap and output the audio frequency signal with ~ khzs, the resistance matches a machine push to press to give or get an electric shock Feng to blare a slice of phonation. Reset a mold pieceList slice machine while switching on or make procedure lose control because of interference in the work, or the procedure in the work is placed in a certain dead circulating status and all needs to be reset in this case. The function of resetting is the beginning that makes CPU CPU and other function partses all resume to an assurance to start status, and restart a work from this status. The 89 S51 list slice machine resets to depend an external electric circuit realization, the signal is led a feet importation by RESET(RST), Gao Dian Ping is effective, while flapping to concuss a machine work, as long as keeping RST to lead feet two machine periods of Gao Dian Ping, single slice of machine namely reset. After resetting, the PC procedure counts the contents of machine as 0000 Hs, the contents is constant in RAM inside the slice. Resetting electric circuit to generally have to up wire reply, move a switch to resetting and automatically reset electric circuit is 3 kinds of, this adoption hand moves to reset a way. Keyboard mold piece Keyboard structure: The keyboard can is divided into 2 types: independent conjunction type and determinant(matrix type), each press it translate a code method and can is divided into code and don39。t code two, here use an independent conjunction type don39。t code a keyboard, the advantage of this kind of keyboard structure is that the electric circuit is simple。 The weakness is to be key to count more, take up more I/O line. The crystal flaps to concuss an electric circuit mold piece The crystal flaps the function quartz crystal of concussing the machine to flap to concuss a machine to also call quartz crystal the Xie flaps a machine, it uses to the stable frequency and the choice frequency, being 1 kind can replace the crystal Xie that the LC Xie flaps a back track to flap a ponent, this is crystal to flap the quartz that the electric circuit chooses crystal flap frequency to 6 Mhzs. The clock period is a single slice of machine to circumscribe crystal flap of reciprocal, for example 12 Ms of crystal flap, its time the period is a