ABOUT UART

UART

              Several devices collect data from sensors and need to send it to another unit, like a computer, for further processing. Data transfer/communication is generally done in two ways: parallel and serial. In the parallel mode, data transfer is fast and uses more number of lines. This mode is good for short range data transfer. 

Serial communication on the other hand, uses only one or two data lines to transfer data and is generally used for long distance communication. In serial communication the data is sent as one bit at a time.

Communication between two entities is important for the information flow to take place. In general the information transport system can be parallel in which the complete byte of data is sent at a time, with each bit having a separate dedicated line or it can be serial where only one communication line is available which is shared by all the bits sequentially. The pros and cons of these two systems are equivalent and selection between the two depends on the application.

Data can be exchanged using parallel or serial techniques. Setup for parallel data transfer is not cost effective but is a very fast method of communication. Serial communication is cost effective because it requires only a single line of connection but on the other hand is a slow process in comparison to parallel communication.          

             The Universal Asynchronous Receiver Transmitter (UART) is a popular and widely-used device for data communication in the field of telecommunication. There are different versions of ARTs in the industry. Some of them contain FIFOs for the receiver/transmitter data buffering and some of them have the 9 Data bits mode (Start bit + 9Data bits + Parity + Stop bits). This application note describes a fully configurable UART optimized for and implemented in a variety of Lattice devices, which have superior performance and architecture compared to existing semiconductor ASSPs (application-specific standard products).

This UART reference design contains a receiver and a transmitter.  The receiver performs serial-to-parallel conversion on the asynchronous data frame received from the serial data input SIN. The transmitter performs parallel-to-serial conversion on the 8-bit data received from the CPU. In order to synchronize the asynchronous serial data and to insure the data integrity, Start, Parity and Stop bits are added to the serial data.

The UART, or Universal Asynchronous Receiver / Transmitter, is a feature of our microcontroller useful for communicating serial data (text, numbers, etc.) to your PC. The device changes incoming parallel information (within the microcontroller/PC) to serial data which can be sent on a communication line. With the UART, you can add an LCD, boot loading, Bluetooth wireless, make a data logger, debug code, test sensors, and much more.

FEATURES:

• Functionally compatible with the NS16450 UART

• Faster performance than industry standard hardwired devices

• Inserts or extracts standard asynchronous communication bits (Start, Stop and Parity) to or from the serial data

• Holding and shifting registers eliminate the need for precise synchronization between the CPU and serial data

• Standard CPU Interface

• Separate interrupts lines for Data Received (RxRdyn) and Data Transmitted (TxRdyn)

• A common interrupt line for all internal UART Data and Error events. Interrupt conditions include: receiver line errors, receiver buffer available, transmit buffer empty and when a modem status flag change is detected.

• Fully prioritized interrupt system control

• MODEM interface functions (CTS, RTS, DSR, DTR, RI and DCD)

• Fully programmable serial interface characteristics:

- 5, 6, 7 or 8-bit characters

- Even, odd, or no-parity bit generation and detection

- 1, 1.5 or 2-stop bit generation and detection

It is really simple logic on UART to apply in our project but the user has to what kind of function is happened on the UART. So that is the reason why i made this post for the better understanding of UART. I future posts will be execution of UART regarding the microcontroller. So by configuring the register in the microcontroller the UART that is serial communication between two devices can be made. All the microcontrollers are having the inbuiuld UART.