The core function of the LED asynchronous control card is to realize the display of multiple windows on a single screen at any position. The LED asynchronous control system mainly consists of PC application software, communication module, data processing module, scanning control module, drive module and LED screen. The controller includes three parts: communication module, data processing module and scanning control module. In terms of hardware architecture, there are different implementation schemes. A typical scheme in 2011 is based on a 32-bit ARM processor (such as LPC2214) and adopts a discrete module design. The data processing module consists of MCU, SRAM and FLASH memory; the scanning control module consists of CPLD and SRAM; the communication module includes Ethernet module and serial communication module, supporting RS232 and RS485 communication [11]. An integrated scheme in 2026 is based on NiosII 32-bit soft core processor and adopts a single-chip FPGA design. The data communication transmission module, data processing module and scanning control module are all implemented on FPGA. The data processing module consists of NiosII soft core CPU, SDRAM and Flash memory; the scanning control module consists of user-defined PWM IP core and SRAM. In terms of software architecture, both solutions are designed based on a real-time operating system (such as uc/OS-II), utilizing efficient task scheduling algorithms to manage multiple tasks, with each display window completed by an independent task [11-12]. For full-color screens, each pixel includes three primary colors: red, green, and blue. Each color has 256 gray levels, so each pixel requires 3 bytes of storage space. The data corresponding to the three colors (red, green, and blue) can be stored separately for easier operation. The gray level implementation method for LED displays is weighted scanning, which requires bit separation of color data, followed by recombination of bits with the same weight.
The development from discrete modules to single-chip integration has made screen displays richer and more flexible. A single asynchronous controller can replace multiple controllers, and the entire control system is completed on a single FPGA chip, effectively reducing system costs.
