Introduction The design based on the ATT7022 chip aims to achieve a reasonable design and a cost-effective product, particularly with breakthroughs in measurement range. The current measurement range is 0–500A, with automatic smooth switching between multiple ranges, and manual conversion between three-phase four-wire and three-phase three-wire is possible. Measurement accuracy reaches 0.2 and 0.5 levels. The sampling frequency is 3.2kHz–25.6kHz, and the mutual inductance ratio, disk rotation count, and measured rotation count can be input from the keyboard as required, with real-time correction. The LCD screen displays parameters such as error percentage, three-phase voltage, three-phase current, phase, power factor, vector diagram, power, and energy in real time. A menu is displayed when not in operation. Figure 1 shows the internal circuit block diagram of the ATT7022. As shown in Figure 1, the internal circuit of the ATT7022 mainly includes a power monitoring circuit, an ADC, and a metering module. The power monitoring circuit monitors the analog power supply (AVcc), and the chip is reset when the power supply voltage drops below 4V±5%. The ATT7022 integrates six 16-bit ADCs with dual-ended differential signal input. The maximum input voltage is 1.5V, meaning the maximum effective value of a sinusoidal signal that can be input is 1V. It is recommended to select an input of approximately 0.5V for the voltage channel Un and approximately 0.1V for the current channel Ib. Figure 2 shows the overall system diagram and hardware implementation scheme. The overall system design is shown in Figure 2. The system mainly consists of five parts: a front-end acquisition module, a processing module, a storage module, a keyboard input module, and a display module. [align=center]Figure 3 shows the input interface circuit[/align] The front-end acquisition module uses clamp-on current transformers and three ATT7022 metering chips to simultaneously acquire data. It judges and identifies the data based on the magnitude of the acquired current, automatically switching between data transmission and reception. The current transformers selected in this paper have primary current ratings of 0-500A and 0-10A, secondary current ratings of 10mA and 2mA, and an accuracy class of 0.05. The load is 20Ω. The voltage transformers are rated at 220V/0.5V. The input interface circuit is shown in Figure 3. The processing module uses a Winbond W78E516B to communicate with the ATT7022 chip, and performs corresponding calculations, drives the LCD display, controls keyboard input, stores data, and communicates with the USB chip. The W78E516B microprocessor supports a wide voltage range, greatly increasing the chip's anti-interference performance. It is fully compatible with the industry-standard 80C51 microprocessor series, including four 8-bit bidirectional parallel ports, one additional 4-bit addressable I/O port (Port 4), three 16-bit timers/counters, one watchdog timer, and one standard UART. It contains 512B of RAM and 64KB of flash memory, with 64KB of program memory address space and 64KB of external data memory address space. The dual data addressing pointer clock operates at a frequency of up to 40MHz. The storage module uses 8KB of RAM (HM6264B) for data buffering and 4KB of EEPROM (AT28C64B) for data storage. The display module uses the Jingdian Pengyuan SED1335 graphic LCD driver module with a 320×240 color LCD screen, driven by a microcontroller. The communication module uses RS-232 and USB (CH375) interfaces to enable the computer to write current clamp calibration parameters and meter calibration parameters, and to control the output of display data. System Software Implementation **Driver Programs:** Display Driver: The LCD display driver is primarily responsible for hardware-related operations such as displaying real-time data size, position, color, chroma, blinking speed, and cursor handling, acting as a carrier between the display data and the hardware. Keyboard Driver: Primarily handles scanning, key value return, and key press count determination. Storage Driver: Primarily handles the storage and retrieval of integer, real, and floating-point data, completely shielding hardware and data type differences. Sampling Driver: Primarily handles the reading of effective parameters related to the ATT7022 circuit, such as power, energy, RMS value, power factor, and frequency measurements, as well as the input of power-on calibration data. Calculation Program: Primarily handles comparisons of the input sampled signal values, calculation of error percentages, routine proportional calculations, and non-routine data processing. Display and Menu Algorithm: Handles graphic and Chinese character display initialization and data display, dynamic graphics processing, multi-level menu processing, menu switching, and storage location definition. 　The communication and exception handling programs primarily handle communication with the ATT7022 and data communication with the host computer for calibration parameters. Conclusion The online wide-range energy measuring instrument based on the ATT7022 designed in this paper can achieve accurate online measurement of energy across a wide range (different current and voltage ranges), and can perform online real-time error comparison and analysis with other measuring devices to calculate the error percentage. Relevant data is displayed in real time. Actual testing shows that the system operates well. Editor: He Shiping