1 Introduction A new type of level transmitter and 8031 ​​microcontroller are used to design an intelligent automobile fuel gauge. It is an intelligent version of the original automobile fuel gauge, and adds functions such as fuel accumulation, low fuel alarm, data communication, and power failure protection. Its measurement accuracy is far superior to that of the original automobile fuel gauge. 2 Working Principle The block diagram of the intelligent automobile fuel gauge is shown in Figure 1. It mainly consists of 6 parts: (1) The microcontroller expansion system consists of an 8031 ​​microcontroller, EPROM, latch and decoder driver. It is the core of the instrument. It mainly completes the storage and automatic execution of the application program. The EPROM is used as the external ROM unit of the 8031 ​​to store the control program of the instrument, which facilitates the software upgrade of the instrument. (2) The level transmitter is installed at the bottom of the automobile fuel tank. It converts the automobile fuel signal into an electrical signal and inputs it to the instrument. It is converted into a digital signal by an A/D converter to complete the signal detection. (3) The keyboard control circuit consists of two keys and a level judgment circuit to implement the interrupt service subroutine, which is used to display the current refueling amount and the total refueling amount, and is also used to set some parameters and functions. (4) The decoder driver consists of a decoder driver and a display unit composed of 5-digit LED digital tubes. The maximum display can reach 99999L. (5) The power supply and power-off protection circuit consists of a three-terminal integrated stable power-off protection circuit. The former converts the +12V battery voltage in the vehicle into a +5V regulated output. It serves as the V[sub]DD[/sub] power supply for the instrument integrated block. The latter works when the power supply fails, permanently saving data and preventing the loss of cumulative amount, refueling amount and other parameters, ensuring the reliability of the instrument. (6) The data communication port inputs the fuel gauge value in the instrument to the computer. It completes the management of fuel consumption of multiple vehicles. 3 Program Flowchart (I) The main program flowchart is shown in Figure 2: (2) The sampling program flowchart is shown in Figure 3: Fuel sampling is implemented with the following instructions: Other program flowcharts are not detailed here. 4. Uncertainty Analysis of Fuel Gauge Analysis shows that the error mainly comes from three aspects: (1) Error of the level transmitter: e[sub]1[/sub]=±2.0×10[sup]-3[/sup] (2) Error of the A/D converter: e[sub]2[/sub]=±1.0×10[sup]-3[/sup]±1 digit. (3) Fuel tank error can be compensated by software design, and its error: e[sub]3[/sub]=±5.0×10[sup]-3[/sup]±1 The root sum of squares method is used for error composition: It can be seen that the uncertainty of the fuel gauge is less than ±1.0%. 5. Development and Application Prospects The fuel gauge has high accuracy and can accurately display the amount of fuel added each time, which is convenient for car drivers and can realize transparent consumption. Simultaneously, a low fuel alarm can be set to remind drivers to refuel in time. Especially for fleet fuel consumption, the data communication port allows for intelligent management of the entire fleet's fuel consumption. With China's accession to the WTO approaching, the relatively late-starting automotive electronics industry will face global challenges and competition. Experts predict that in the next 5-10 years, a large number of cars will enter Chinese households, and the cost of automotive electronic products will account for 15% of the total vehicle price, with market sales exceeding 5 billion yuan. Therefore, the market potential is huge and the future is broad. The research, development, and application of intelligent automotive fuel gauges are in line with the development direction of China's automotive electronics industry and have development and application value. Intelligent automotive fuel gauges are novel, simple in structure, easy to operate, reliable in operation, and universal for different vehicle models, but their practical application still needs further development and improvement. References: 1. Xie Jianying, Microcomputer Control Technology. Beijing: National Defense Industry Press, 1985. 2. Bang Wenlong, Single-Chip Microcomputer Principles and Applications. Xi'an: Xi'an University of Electronic Science and Technology Press, 1993. 3. Xu Beiying, The automotive electronics industry has a broad future and should be given key support; strong measures should be taken to accelerate product development. China Science and Technology Information, 1993, 15(1)