【正文】 1 Ratemeter and monolithic integrated circuit The traditional automobile rotational speed odometer39。s function has two。 first, with indicator instruction automobile travel instantaneous vehicle speed。 second, records the automobile travel with the mechanical counter the accumulation course. The modern automobile is developing to the high speed direction, along with the vehicle speed enhancement, the tradition speedometer which actuates with the flexible axle receives the unprecedented challenge, this is because of the flexible axle when high speed revolving, as a result of steel wire alternate stresses limit limit, but easy to break, simultaneously, the flexible axle will arrange long will have presented the deformation oversized or the movement sluggish and so on phenomena, moreover, regarding the different vehicle type, the rotational speed odometer39。s installment position will also receive the flexible axle length and bending limit. All these, causes based on the noncontact type tachometer generator39。s electronic formula rotational speed odometer to be able the rapidly expand. Present39。s automobile measuring appliance automaticity is very high, what the old style mechanical flexible axle transmission39。s measuring appliance already eliminated displaces is present39。s liquid crystal gauge board, is impossible through to dial the digital code wheel adjustment odometer again. When in the driver needs to increase the number of passes, runs the table with this kind to be possible very with ease to realize. This kind runs the table use medium scale integration design to bee, the volume is exquisite, the movement is stable, is suitable uses on each kind of electronic transducer39。s automobile. This kind of exquisite instrument has pared to the other similar products obvious merit: 1st, the circuit design is exquisite, strict. Has used the high performance integrated circuit and the electronic ponent, the guarantee circuit has the high quality。 The use optimization39。s circuit design, considered many disadvantageous use environment, enable the instrument as far as possible in the voltage, the temperature, the humidity, the dust pollution and so on under plex change factor many conditions to be able the steady work. 2nd, the reliability is good. In order to enhance the electric circuit work the reliability, not only the part passes through screens carefully, moreover passes through 2 2400 hours to roast machine the experiment, its outer covering is exquisite, may install conveniently in the pocket, momentarily may take the use. 3rd, simplicity of operator, easy to operate. Only needs to insert to the cigar lighter on, does not need to get out, all OK. 4th, the use security, felt relieved. Even if meets instead, also will not damage the instrument, will not damage on the vehicle anything. 5th, the speed may adjust. You may the speed regulation highest, may also adjust to a fixture, for instance 300 step. Is different based on the vehicle type, the speed differs from, may the speed knob change speed through the regulating instrument on. Monolithic integrated circuit AT89C2051 by its low price, the low power loss, the reliability high and easy to program and so on characteristics to be famous, X25045 is a MCS51 series monolithic integrated circuit electric circuit39。s auxiliary chip, mainly takes on the replacement, the voltage examination, the watchdog and the EEPROM function, this chip39。s use enhanced system39。s reliability greatly, reduced the periphery chip number, may realize the power failure which the course accumulates to save. LCM1010 is ten type belt back light liquid crystal display module, uses three serial interfaces, it has the power loss to be low and programming convenient characteristic. This demonstration is divided two lines of demonstrations, the first line of 6 demonstration accumulation course, second line of 4 (1 decimal) uses in demonstrating the subtotal course. In the chart K1 is the subtotal course reset key, R4 uses in adjusting liquidcrystal display39。s angle of view contrast gradient. Chip X25045 is Xicor Corporation promotes has programmable μP monitor39。s CMOS serial EEPROM, has 4096, according to 5128 organizes. It has 4 bytes pages to write the way and 100,000 use cycles, the data may preserve for 100 years. In order to guarantee the accumulation course unit the units place or su