**1 Introduction** With the continuous improvement of modern industrial automation, it is often necessary to centrally monitor multiple flow points. For example, in the process of oil water injection, in order to maintain the extraction effect, protect the underground environment, and subsequently analyze water injection data, it is necessary to monitor the water injection volume. Intelligent instruments are increasingly being used in oilfield systems to measure the oil production of wells. The accuracy of the measuring instrument directly affects the economic benefits of the enterprise. Currently, my country's flow meter industry started late, with a low starting point, and is still relatively backward. Flow meters developed using microcontrollers are very suitable as secondary instruments and greatly promote oilfield automation. **2 System Principle** In terms of overall structure, the flow meter mainly consists of a vortex flow sensor, a preamplifier, and a counting display unit. The vortex flow sensor mainly consists of a vortex generator, a vortex frequency detector, and a housing. Its function is to generate stable and strong vortices and detect the frequency of the generated vortexes and output an electrical signal proportional to the vortex frequency. The vortex generator is a crucial component of a vortex flowmeter. To generate a strong and stable vortex street and maintain a constant Strouhal number over a wide pipe Reynolds number range to ensure linear output, the vortex generator must have a specific shape, structure, and size proportions, which must be determined through practical application. Generally, because the signal output by the sensing element is relatively weak and contains noise, the preamplifier for various sensing methods should also include amplification, filtering, and shaping components; together, these are referred to as the primary instrument. The counting and display unit, also known as the secondary instrument of the flowmeter, is typically composed of a microcontroller system. It counts the signal output from the converter to record, store, calculate, and set the flow rate. Additionally, it controls the LCD display to show information such as the measured instantaneous flow rate and total flow rate. Some flowmeters also have a communication interface for data communication with a remote computer, enabling dynamic monitoring. Instruments developed using microcontrollers have multiple functions. The intelligent flow display instrument with software-adjusted nonlinear error is a secondary instrument配套 (matched) with various pulse-output primary flow measurement instruments, and has the following characteristics: ● Employs microprocessor technology for high reliability; ● Uses low-power devices for low power consumption, suitable for battery power; ● Can simultaneously display cumulative flow and instantaneous flow; ● Employs intelligent multi-segment flow software compensation technology for high measurement accuracy; ● Can store flow rate data. Its technical performance is as follows. The input signal is the frequency input signal of the primary instrument, connected to the flow sensor. After detection and amplification, the flow rate of the measured medium is obtained. The signal frequency is a pulse signal of 0MHz to 1000Hz. The length of the sensor connection cable is less than 1000m, the wire capacitance is less than 0.1μF, and the inductance is less than 10mH. The intelligent flow display instrument (secondary instrument) is placed in the metering room, which can accommodate 30 displays. There are two types of output signals: Cumulative flow display is an 8-bit floating-point display, initially showing 5 decimal places (0.00000m³) and ending with 3 decimal places (0000.000m³), representing the cumulative flow since the instrument started operating; Instantaneous flow display is a 4-bit floating-point display, initially showing 2 decimal places (00.00m³) and ending with 1 decimal place (000.0m³), representing the current instantaneous flow. Interference resistance: The display remains unchanged even when a 10kW~17kW motor is running. Accuracy: Approximately 3% without correction, ±0.01% after correction. Flow correction range: Compensation correction is performed in 8 segments across the entire process. Cumulative flow compensation coefficient setting: Up to 8 integer digits. Power supply: 4V~5V DC. Total power consumption: <1.0mW. Includes LB undervoltage indication. Ambient temperature range: -20℃~70℃. Relative humidity: <85%. Explosion-proof enclosure. **3 Hardware Composition** The core of the hardware is the AT89C51/LV51 microcontroller manufactured by Atmel Corporation. It is a low-power, low-voltage, high-performance 8-bit microcontroller with an on-chip 4KB Flash programmable and erasable read-only memory. It uses CMOS technology and Atmel's high-density non-volatile memory technology, and its output pins and instruction set are compatible with the MSC-51 microcontroller. The memory used to store the flow rate is the Atmel AT24C16 series, which is an electrically erasable, programmable read-only memory with 2KB Flash. The microcontroller's RXD and TXD ports are connected to its SCI and SDA pins respectively for read and write operations. During measurement, a 1-second hardware reset circuit is connected to the RE-SET pin to reset the microcontroller periodically. The microcontroller operates in power-saving mode, waiting to wake up after each input, accumulation, and display processing, resulting in very low power consumption. When setting the compensation coefficient, the reset pin is connected normally. The input pulse is divided and latched by a 74HC393 before being sent to the P2 port of the microcontroller. After processing by the microcontroller, the output display signal is sent to the P1 port (4 bits of data, 4 bits of selection signal). Four bits of the data are sent to the MC14543 (BCD latch/7-segment decoder/driver). There are 12 MC14543s in total, which control the display data of the LCD block connected to the 8-bit cumulative flow and 4-bit instantaneous flow respectively. The 4-bit selection signal is sent to the CD4514 decoder (4-bit latch, 4-to-16 line decoder) to select the MC14543 circuit receiving the data and the floating decimal point. The hardware is divided into two parts: the control part processes the flow signal to obtain the display data of cumulative flow and instantaneous flow, as shown in Figure 1; the display part sends the display data to the LCD screen, as shown in Figure 2. These two parts are connected through a 10-pin socket J1. [b]4 Software Design[/b] The main program flowchart is shown in Figure 3. [b]5 Usage Results and Improvements[/b] This intelligent flow meter has been used for field measurements for over 5 years, demonstrating reliable operation, accurate measurement, and a very high cost-performance ratio. It is also easily expandable. Flow alarm and flow rate control functions have now been added. When the flow rate exceeds the set alarm value, it can issue an audio alarm; after setting flow control parameters, it can automatically adjust the flow rate. This instrument can also be used in conjunction with industrial configuration software MCGS or KingSCADA to collect flow data as a lower-level machine and send it to a configuration server for processing. Editor: He Shiping