A ROBUST UART ARCHITECTURE BASED ON RECURSIVE RUNNING SUM FILTER FOR BETTER NOISE PERFORMANCE

Introduction

Serial communication is an essential to computers and allows them to communicate with the low speed peripherals devices such as keyboard the mouse, modems etc. Thus the Universal Asynchronous Receiver Transmitter is the most important component required in serial communication.

The Universal Asynchronous Receiver/Transmitter (UART) controller is the key component of the serial communications subsystem of a computer. The UART takes bytes of data and transmits the individual bits in a sequential fashion. At the destination, a second UART re-assembles the bits into complete bytes.

Serial transmission is commonly used with modems and for non-networked communication between computers, terminals and other devices.

There are two primary forms of serial transmission: Synchronous and Asynchronous. Depending on the modes that are supported by the hardware.

Some common acronyms are:

• UART Universal Asynchronous Receiver/Transmitter

• USART Universal Synchronous-Asynchronous Receiver/Transmitter

Universal Asynchronous Receiver Transmitter (UART) is used for asynchronous serial data communication between remote embedded systems. Standard UART cores utilize three mid-bit samples to decode the serial data bit and the sampling rate is derived from external timer module. But if the physical channel is noisy then data bits get corrupted during transmission and it leads to wrong data decoding at receiver. To overcome the noise problem a digital low pass filter based architecture is proposed. Recursive Running Sum (RRS) is simple low pass filter, it can be used to remove noise samples from data samples at receiver. Serial receive data signal is directly sampled with system clock and samples are fed to RRS filter. The window size of the filter is user programmable and it decides baud rate.   

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