UART is a transmission device & high speed soc is AHB bus. in this paper high speed components are interfaced to low speed components by using AHB bus.AHB bus is used to transmit data from DMA to memory& high speed components are connected by using this AHB bus. Compared to other system buses performance & processing time of soc is improved by using AHB bus. In serial communication UART controller plays a major role. Transmission of digital information through single wire is much more cost effective than transmitting through multiple wires. At the end of every link UART converts transmitted information between sequential & parallel form. For this purpose UART has shift registers. There are five main modules. Those are UART transmitter, UART receiver, DMA (direct memory