Design and FPGA implementation of digital OSD controller

This paper discussed a design method of digital OSD (on screen display) controller. This OSD controller, synchronized with horizontal and vertical synchronization signals, operates the display property registers of characters and bitmap set by the user microcontroller application. The OSD image displays in LCD overlapping the input video signal, which is generated automatically by the image composition module. Logic functions and characteristics of this OSD controller are verified in FPGA (Field Programmable Gate Array). The results of temperature experimentation show that it can operate stably in -40-65°C. This OSD controller is applied to a military LCD successfully. The characteristic of this OSD controller is combining the two methods of OSD image composition together, and the methods are based on the character and the bitmap. So the functions are enhanced and the OSD image contains more information of figures and characters, and the parallel and serial interfaces improve its system compatibility.