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1、电子式里程表摘 要里程表广泛应用于各类机车，传统的机械式里程表虽然稳定可靠，但功能单一、易受磨损。随着电子技术的迅猛发展，电子式里程表得以广泛应用，现在很多轿车仪表已经使用电子车速里程表，本设计介绍一种基于单片机的智能电子里程表。该电子式里程表是一种数字式仪表，主要由车速表和里程表两部分组成，其传感器采用无接触测量的光电传感器。它不仅可显示车辆行驶的总里程，也可显示一段时间的阶段里程，还可显示车速，以及实现超速报警等功能，并具有较强的再开发能力。它的实现方式是，通过安装在汽车转轴上的测量盘，用光电式转速传感器检测转速的脉冲信息，在脉冲状态下，将转速的变化转换成光通量的变化，再通过光电转换元件将
2、光通量的变化转换成电量的变化，接着通过频率测量电路将脉冲信号输入到单片机中，然后依据电量与转速的函数关系实现转速测量，再通过计算，从而得出里程、车速的信息，并由 LED 显示器显示出来。并且该电子式里程表累积的里程数字存储在非易失性的EEPROM 存储器内，在无电状态下数据也能保存。关键词：AT89S51单片机；里程表；光电传感器；LED显示器；存储器AbstractVehicle odometer is applied in each kind of motorcycle extensively, although the traditional machine type odometer
3、stable and credible, but the function of it is single and be easily worn away. Along with the technical fast fiercely develop in electronics, the electronic vehicle can be applied extensively. Recently, a lot of car appearances have already used the electronic vehicle odometer, this graduation thesi
4、s introduce a kind of intelligence electronic vehicle odometer, which is based on a Single-Chip Microcomputer system. The electronics type vehicle odometer is a kind of numerical type appearance, which mainly constitute with two parts, that is vehicle speed meter and odometer, it adopts the light se
5、nsor that the sensor has no contact measure. It not only can show the total mileage that vehicle drive, but also can show the stage mileage of a period of time. Moreover, Its can show the car speed, and the realization exceed the speed limit to report and so on. It also has the ability of strongerly
6、 develop again. The way of this vehicle odometer carry out is as follows: through the installed measure plate in the automobile shaft, use the light sensor to measure the rotational speed information. Under the pulse appearance, it make the variety rotational speed change to the variety of the light
7、 flux, after that the variety of the light flux convert to electricity quantity. Then through the light electricity convert component, we can make the pulse signal input to the Single-Chip Microcomputer by the frequency measure circuit. Then in terms of the function relationship of electricity quant
8、ity and rotational speed, we can realize the measure of rotational speed, after calculate by the Single-Chip Microcompute, we can obtain the information of mileage and vehicle speed. Moreover, This mileage and vehicle speed information can be displayed by the LED monitor. And the mileage numeral of
9、the electronics vehicle odometer accumulation is saving in EEPROM，which is not easily lost, the data also can keep under the no electric appearance.Keyword：AT89S51 Single-Chip Microcomputer；Odometer；Light sensor；LED ；Memory目 录引言 1 1 总体设计2 2 系统设计可行性分析22.1 总体设计分析22.2 硬件模块32.3 软件模块6 3 硬件单元电路设计73.1 传感器的
10、设计73.2 单片机与光电传感器的接口设计113.3 单片机与外部存储器的接口设计133.4 单片机与超速报警电路的接口设计133.5 单片机与键盘和7段显示器的接口设计 13 4 软件设计144.1 脉冲测量部分164.2 键盘输入部分174.3 数据处理部分184.4 存储器部分214.5 超速报警部分244.6 显示部分25 5 系统调试275.1 硬件单元电路调试275.2 软件程序调试295.3 整体调试32 6 系统使用说明32 7 系统功能的扩展33 8 结论33 谢辞 35参考文献36 附录37引言我国汽车工业走过了五十年的历程,与国际发达国家汽车工业相比,电子技术水平相对比较
11、落后,提高国产汽车的电子技术水平,增加汽车电子装备的数量,促进汽车电子化是夺取未来汽车市场的关键,提高我国的汽车电子技术已势在必行。随着中国的复关,国外汽车零部件厂商也大举进入中国参与竞争。电子式仪表及新型传感器是各类车型汽车的首选配套产品，通用性好，市场前景广阔。目前国外汽车车速里程表已广泛采用电子式机芯结构，而国内汽车仪表一直是机械式车速里程表的天下，少数采用动圈式电子仪表， 通过大量市场调研，我们清楚地看到进入 20 世纪以来汽车工业迅速发展，而电子产品则是汽车提高技术含量的晴雨表。国外电子产品占整车成本的 30%，然而我国汽车行业起步较晚，技术十分落后，电子产品仅占整车成本的 5%。例如国外汽车早已装配电子式仪表，而我国汽车仍在应用传统的机械仪表，可靠性很差。目前汽车仪表控制电子化是一种发展趋势，由先进的传感器与显示装置构成的电子仪表已开始全面取代传统的机电式仪表，成为现代汽车的明显标志。 一般汽车的常规仪表有车速里程表、转速表、机油压力表、水温表、燃油表、充电表等。仪表板中最常用的是车速里程表，目前很多轿车仪表已经使用电子车速表，它通过变速器上的速度传感器获取信号，通过脉冲
