Abstract: This paper proposes a method for constructing an automotive electronic intelligent instrument using single-chip microcomputer technology and VFD display device. The instrument , with a PIC16C72A single-chip microcomputer as its core, displays and saves vehicle parameters such as vehicle speed, engine speed, water temperature, oil level, total mileage, and sub-mileage in real time, giving the car a "black box" function. Keywords: instrument cluster; VFD; single-chip microcomputer; hardware; software Keywords: Combined meter; VFD (Vacuum Fluorescent Display); Single-chip; Computer Hardware; Software 1 Design Concept The automotive instrument panel serves as the window and interface for information exchange between the driver and the vehicle, playing a positive and important role in improving the lifespan of the instrument panel and ensuring safe and economical driving. This design uses a PIC16C72A single-chip microcomputer as the core of the instrument panel. Existing automotive sensors do not need to be replaced. The sensor output signals are sent to the CPU after signal conditioning circuitry. The signal processed by the CPU is then displayed on the VFD display using time-division multiplexing technology. It displays real-time vehicle speed, engine speed, coolant temperature, fuel level, total mileage, and sub-mileage, and performs complex processing on this information to provide the driver with useful information such as average speed, fuel consumption, and remaining fuel range. Simultaneously, it records and stores instantaneous driving information, achieving a "black box" function; it provides voice alarm prompts for abnormal situations and reserves communication interfaces for future functional expansion. Compared to traditional automotive instrument panels, this instrument panel boasts advantages such as rich functionality, high reliability, high precision, excellent visibility, strong versatility, storage capabilities, no mechanical wear, and long service life. 2. Hardware Structure The automotive electronic intelligent instrument panel for passenger cars consists of sensors, signal conditioning circuits, a microcontroller processor, a voice alarm circuit, a display driver circuit, and a VFD display, among other components. As shown in Figure 1: Wherein: S1 is a photoelectric vehicle speed sensor, which converts the vehicle speed corresponding to 0-200 km/h into a pulse signal with a frequency range of 0-136.3 Hz; S2 is a pulse signal speed sensor, which converts the engine speed corresponding to 0-8000 rpm into a frequency signal of 0-260 Hz; S3 is a thermistor temperature sensor used to measure the temperature of the vehicle's coolant, converting changes in water temperature into changes in resistance and voltage; S4 is a float-variable resistance level sensor, converting changes in oil level into changes in resistance and voltage; Cn1 and Cn2 are the signal conditioning circuits for the vehicle speed measurement channel and the engine speed measurement channel, respectively. Since the vehicle speed and engine speed sensors output pulse frequency signals, the corresponding signal conditioning circuits shape, clamp/limit the sensor output signals to meet the CPU's requirements for the input signals. The water temperature and oil level sensors output analog signals. Their corresponding signal conditioning circuits Cn3 and Cn4 form a resistor transmission network that sends the sensor's output signal to the microcontroller's built-in A/D input. The CPU is the core of the entire instrument, controlling the acquisition, processing, and output of signals. The chip used is the Microchip PIC16C72A, an 8-bit microprocessor with an 8-bit 5-channel A/D converter, 4k x 14-bit program memory, 128 x 8-bit data memory, and 3 timers. The E²PROM uses a 93LCA6B three-wire serial electrically erasable programmable read-only memory with a capacity of 1k x 16 bits, an erase cycle of 1M times, a display speed of 2ms, and a data retention time of more than 40 years. The instrument cluster stores sub-mileage, total mileage, and current vehicle status data, ensuring data integrity even in the event of power failure, functioning as a "black box" for the car. ISD is a voice chip that stores all alarm messages and drives the alarm horn. DR1 and DR2 are VFD display driver/controller μPD16311 chips; one drives the VFD display showing engine speed and total mileage, while the other drives the VFD display showing vehicle speed, coolant temperature, fuel level, and sub-mileage. SP is the horn, providing a voice alarm when measured parameters such as vehicle speed, engine speed, coolant temperature, and fuel level exceed limits. VFD1 and VFD2 are fluorescent displays that display real-time vehicle speed, engine speed, coolant temperature, fuel level, total mileage, and sub-mileage. The DC/DC power converter transforms the car's original 12V battery power supply voltage into the three operating voltages required by the intelligent instrument cluster: +5V for the microcontroller, voice chip, and signal conditioning circuit; -32V for the anode and gate of the VFD display; and AC 4.2V for powering the VFD display filaments. The function selection switch is used for function selection and has two functions: ① Switching the display content of the multi-function display area. The multi-function display area can display three items: sub-mileage (km), sub-mileage driving time (hr:min), and remaining fuel driving range (km). The default display content is sub-mileage. ② Resetting the sub-mileage and sub-mileage driving time. Pressing the button for more than 3 seconds will reset the sub-mileage and sub-mileage driving time to zero. The brightness adjustment switch adjusts the brightness of the VFD display. 3. Software Design The instrument's software consists of four parts: the system clock program, the measurement and control program, the button/switch processing program, and the VFD display program. The system clock program processes four software timers, enabling functions such as setting the sampling time, setting the sub-mileage/driving time reset timer, setting the multi-function display timer, and setting the alarm interval timer. The measurement and control program mainly includes a data acquisition program and a data processing program, completing the acquisition, digital filtering, and calculation of various values ​​for vehicle speed, engine speed pulse signals, and water temperature and oil level sensor analog signals. The button/switch processing program handles the switching of the multi-function display area and the reset of sub-mileage and sub-mileage driving time. The VFD display program provides the functions of analog bar display of engine speed, water temperature, and oil level, and digital display of parameters such as vehicle speed, total mileage, sub-mileage, driving time, and remaining fuel driving range. The main program flowchart of the system is shown in Figure 2. The automotive instrument panel operates in a constantly changing environment; therefore, the design incorporates both hardware and software considerations to achieve anti-interference and reliable data storage. Regarding software anti-interference measures, firstly, considering that digital signals are easily affected by interference during transmission, leading to waveform degradation and potential errors at the receiving end, the coding design focuses on the coding structure, employing an interleaved convolutional code encoding method with strong anti-interference capabilities. To prevent infinite loops or crashes during program use, a watchdog circuit was designed to protect the software from hardware limitations. To eliminate errors caused by data acquisition, arithmetic average digital filtering was used for slowly changing signals such as those from oil level sensors to eliminate the impact of oil level fluctuations on the sampled values. References: 1. Dong Hui. Automotive Electronics Technology and Sensors [M]. Beijing: Beijing Institute of Technology Press, 1997. 2. Dou Zhenzhong. PIC Series Microcontroller Principles and Programming [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 1991. 3. 1997 Microchip Technical Library, Microchip Technology Inc. [M].