Passive matrix Micro-LED display driven by STM32 microcontroller using a two-wire serial transmission method

Abstract

In this study, the STM32 microcontroller is used to drive a passive matrix (PM) Micro-LED through two-wire serial transmission and row-column integration. STM32 exhibits superior properties, including simple-to-operate, cost-friendly, and flexible programming. Moreover, it has a lower cost and more straightforward implementation for testing the quality of the device and realizing the graphics. In this design, the connection between the STM32 and the PM array is realized by an LED driver board and flexible printed circuit (FPC) structure. The two-wire serial protocol and row-column integration are adopted, which not only optimizes the circuit structure but also avoids coupling problems. Compared to the existing structures, it is more concise that only four connecting wires are required to transmit data in display devices of any resolution. Besides, the problem of graphics distortion is solved through two buffers to form a data handshake. Using this method, the blue PM array, which has a resolution of 48 × 48, a refresh rate of 60 Hz, a pixel size of 300 μm, and a luminous area of 50 μm, is successfully realized. In addition, p-metal fractures caused by the bulge in the p-lines are also resolved by adding the GaN as a raised substrate.