Basic Uart

BASIC UART

April 7, 2023 BASIC UART 1

PREPAID BY:RAHUL TIWARIROLL NO: 36

CONTENT

History Introduction Block diagram Working Structure Timing diagram Advantage and Disadvantage Application

2BASIC UARTApril 7, 2023

HISTORY

Need: A mean to connect peripherals RS-232 Serial Port UART First Applications: Teletypes or Visual

Display Units (VDU), Printers and Modems 8250: The first “PC” UART made by National UART Evolution:

8250 16450 16550 16C650A 16C850 Driven by Modem speeds, later by other applications Currently: sophisticated devices with numerous features

3April 7, 2023 BASIC UART

INTRODUCTION

It is a type of "asynchronous receiver/transmitter“, communication standards such as EIA RS-232, RS-422 or RS-485. data format and transmission speeds A UART is usually an individual (or part of an) integrated circuit used for

serial communications over a computer or peripheral device serial port. types of UART

A dual UART, or DUART, combines two UARTs into a single chip.


BLOCK DIAGRAM

5BASIC UARTApril 7, 2023

WORKING /OPERATION

takes bytes of data and transmits the individual bits in a sequential fashion. At the destination, re-assembles the bits into complete bytes

Transmission line are held high while no transmission/reception is taking place.

In the transmission of a sequence ,the active low start bit to the receiving UART that a new sequence of data is on its way. Lastly, a high stop bit is used to indicate the end of a block


Frame Structure

UART is capable of transmitting/receiving 7 or 8 bits of data plus 2 or 3 framing bits.

One start bit, eight data bits and one stop bit, is the common configuration.


Fig: General Form.

Fig: example of showing transmission of character ‘A’.

TRANSMITTER


Transmitter output

RECEIVER


ASMD CHART OF RECEIVER

RECEIVER OUTPUT

UART REGISTERS

I. Control Register - Contains settings for the UART. LCR: line control register(read/write) FCR:FIFO control register(write-only) IER: Interrupt enable register(read/write) MCR: Modem control register

II. Status Register - From its name, this contains information about the UART's condition or state.

IIR: Interrupt identification register(read-only) LSR: Line status register MSR: Modem status register(read-only)


III. Receive Register - This is the where received data is temporarily stored. RBR: Receiver buffer register RHR : Receive Holding Register (read-only)

IV. Transmit Register - A buffer register/s for temporarily storing data to be sent.

THR: Transmitter holding register(write-only)


Baud Rate Generator

UART clock =16 times original clock. The UART contains a programmable Baud Generator . Two 8-bit latches store the divisor in a 16-bit binary format.

DLL, divisor latch LSBDLM, divisor latch MSB(read/write)



Fig: block diagram of baud rate generator

The baud rate generator is a frequency divider that generates baud rates according to the following equation:

Here: 1. BAUD = Baud rate2. f CK = Crystal Clock frequency3. UBR = Contents of the UBRRHI and UBRR registers, (0-4095)

BAUD GENERATOR OUTPUT

ADVANTAGE

The UART system can tolerate a moderate amount of system noise without losing any information.

Supports all data rates from 9600 to 921600 band Internal diagnostic capabilities:

- Loop-back controls for communications link fault isolation- Break, parity, overrun, framing error simulation


DISADVANTAGE

As we increase the baud rate, distance of communication will decrease.

Due to asynchronous transmission, it is not accurate compared to synchronous transmission.


APPLICATION

Inter board communications Simple PC to Board interface For all serial communications Industrial

Heating-Ventilation-Air-Conditioning (HVAC),Security, Telemetry, Sensors, Medical, Test & Measurement, Data Terminals, Video Conf. Systems, Copiers, Printers, Data Recorder, Avionic, Robotic.

Telecom:Network Server Management (24/7, QoS, Redundancy), Hub, Router, Switch, Console Management, Keyboard-Video-Mouse (KVM) Switches, Home Networks, Bluetooth Devices, PDA Modules. Point of-Sale (POS)

Credit Authorization Systems, Handheld and Inventory Terminals, Banking ATM, Ticketing and Vending, Tolls Collection Systems, Car Parking Systems.


Inter board communication:


Telecom Application:

Server Management: Easy connections Simple protocol Chain to other systems or peripherals via RS-232/485


REFRENCE

http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_111%20What%20is%20UART.pdf

http://layadcircuits.com/layad_articles/UART_Basics.htm http://www.cse.sc.edu/~jimdavis/Courses/CSCE-612(Spring03)/

CSCE612-Project-2-uart8251-030214.pdf http://www.seminarprojects.com/Thread-basic-uart-full-report http://www.rosehulman.edu/~simoni/Classes/EC551/ProjectInfo/

UARTChallenge.pdf http://www.xmos.com/system/files/uart-tutorial.pdf http://www.mikroe.com/eng/chapters/view/43/chapter-10-uart-module/ http://www.exar.com/uploadedFiles/ICI/UARTIntro_100_030507.pdf http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter www.cosmiac.org/pdfs/T4_UART_TUTORIAL_vf.doc


Thank You


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