A data handling system for an automobile comprises an odometric data generator which provides odometric data corresponding to the travel distance of the automobile. A nonvolatile memory stores total odometric data, an adder receives the odometric data provided from the odometric data generator and the previous total odometric data provided from the nonvolatile memory, and a control circuit controls the writing of data into the nonvolatile memory in accordance with the state of a key switch. The adder receives the present odometric data and the previous odometric data, to thereby provide total odometric data up to the present time. This total odometric data is displayed by an appropriate display device. In response to the turn-off of the key switch, the total odometric data provided from the adder is written into the nonvolatile memory. Thus, an odometer can be implemented in electronic circuit form.
A microprocessor transfers into a first so-called "fixed" zone of the memory the intermediate total distance travelled since the vehicle was put on the road and, in a second so called "journey" zone of the memory the successive partial distances travelled between each power supply cut off, the successive partial distances being transferred into the cells of the journey zone of the memory each time the power is switched off.
An electronic odometer employing a non-volatile memory is used to indicate the total distance traveled by a vehicle such as an automobile. The total distance traveled by the vehicle, calculated by an arithmetic unit 3 from signals from a pulse generator 1, is written piece-by-piece sequentially into a non-volatile memory 7 which has N locations for storing the data on total distance. To read the data, the maximum value of the total distance data is found from the N locations storing total distance data of the non-volatile memory 7. When the difference between the maximum value and the data item written immediately before the maximum value is equal to a preset distance, the maximum value is indicated as the total distance traveled on digital display unit 8.
In an electronic odometer for a wheeled vehicle, a non-volatile memory circuit includes a main memory having 256 cells in sequence for non-volatilely storing first data indicative of a unit mileage of the vehicle upon each application of the first data to the memory circuit. The memory circuit also includes an auxiliary memory having 32 cells in sequence for non-volatilely storing second data indicative of 256 times of the unit mileage upon each application of the second data to the memory circuit. A microcomputer repetitively determines the unit mileage in relation to the actual vehicle speed to search each cell of the main memory as to storage of the first data in each cell of the main memory. The microcomputer applied the first data to the memory circuit upon each search of no storage of the first data in at least one cell of the main memory and also applies the second data to the memory circuit upon each search of storage of the first data in each cell of the main memory. Upon application of the second data to the memory circuit, the first data is erased from each cell of the main memory. A display indicates a total mileage of the vehicle based on the contents in the memory circuit.
An electronic odo/trip meter for automobiles has a display for displaying a travel distance, a counter for enumerating the travel distance data, a non-volatile memory which is provided in the counter so as to prevent elimination of the travel distance data, and a control circuit which controls data transfer and includes a first detection circuit for detecting voltage-drop of a power supply and a second detection circuit for detecting resumption of the power supply. In the device according to the invention, the travel distance data of the counter can be stored in the non-volatile memory only when the first detection circuit detects a drop in the power supply, and the travel distance data of the non-volatile memory can be transferred into the counter only when the second detection circuit detects the resumption of the power supply.
An electric testing device is provided for the final testing of vehicle combination instruments. The vehicle combination instruments comprise display means (1-7) consisting of segments, a display control in a microcomputer (8) for activating the segments as a function of measured values, for analog measured values an analog-digital converter (14) arranged in front of the display control, and possibly an input network (13) arranged in front of said converter. The testing device and combination instruments are intended for final testing in a plurality of final test phases. Tolerance values of a critical display value are stored for each measurement value in the microcomputer (8). These tolerance values can be compared, in a first final test phase of a manually actuatable final-test operating mode, with a simulated measurement value which is fed into the microcomputer via the analog-digital converter and possibly the resistance network. A display value which represents the result of the comparison and is also fed into the microcomputer is transmitted, as a function of the result of the comparison, to the display means (3). Predetermined segment combinations can then be activated in succession by the display control in further final-test phases by operating a switch of the testing device. In the latter, there are provided equivalent resistors (35-37) which simulate the measurement value, as well as switches (33, 34) for calling up the final-test operating mode and for the further switching of the final-test phases.
