UART(universal asynchronous receiver transmitter ) PPT

UART – Stands for Universal Asynchronous Receiver Transmitter It is a piece of hardware  that acts as a bridge between the processor and the serial communication protocol or port (RS-232). It performs parallel – to – serial data conversion at the transmitter side and serial – to – parallel data conversion at the receiver side.Asynchronous serial communication.
A serial communication can be done using fewer wires as compared to its parallel counterpart. It is a cheapest communication device with a single wire for transmitting the data and another wire for receiving. When the high-speed data transfer is not required UART is used. In a simple serial communication, 3 pins are used: TxD, RxD and GND.
At Transmission side (i.e. From Microcontoller), one can write data into UART Data Register (e.g. UART0_DR) by using software code.
These 8 bits of data from Data Register is passed to Tx FIFO Buffer. After that, the data is sent out(one at a time) from Tx Shift Register.
TxFIFO flag = 1 (Buffer full) TxFIFO flag = 0 (not full - Software can write to Data Register)
At Receiver end, there is Rx FIFO Buffer.
RxFIFO Empty flag = 1 (Buffer is empty) RxFIFO Empty flag = 0 (Buffer has data to be read)
A frame is the unit of transmission in serial communications
Start bit: To declare the start of transmission.
Data bits: 4,5,6,7, or 8 bits of useful data bits.
Parity bit : To check for transmission errors.
Stop bit: To declare end of frame
Parity bit is used to check the integrity of a frame and signal if an error occurred during transmission.
It is an extra bit added to the end of a frame.
Even parity :The number of ‘1’ symbols inside a frame must always be even.
Odd parity : The number of ‘1’ symbols inside a frame must always be odd
The configuration settings at both ends of Txd and Rxd:
Full or half-duplex operation
Data length
Start/Stop bits
Transmission speed.
EX:-198 = 11000110
Transmission speed
Common speed = 9600 bits/sec
1/9600 = 104 us.
After detecting start it will count 104us and complets start bit.
Then begins sampling the input bits after 52us with equal count of 104us between each bit untill the next stop bit with high pulse.
Advantages
Requires minimum wires
No need for clock or any other timing signal.
Parity bit ensures basic error checking.
Disadvantages
Size of the data in the frame is limited.
Can connect only two devices at a time
Speed for data transfer is less compared to parallel.
Transmitter and receiver must agree to the rules of transmission and appropriate baud rate must be selected.
if we are looking for a device to device serial communication then UART proves itself the best as it is easy to deal with and also widely used in many peripheral devices.

1. UART Presented BY G. Sai praneeth kumar

2. contents Introduction Block diagram How it works Frame parity Configuration Example Advantages & disadvantages C onclusion

3. Introduction UART – Stands for Universal Asynchronous Receiver Transmitter It is a piece of hardware  that acts as a bridge between the processor and the serial communication protocol or port (RS-232) It performs parallel – to – serial data conversion at the transmitter side and serial – to – parallel data conversion at the receiver side . Asynchronous serial communication.

4. WHY UART A serial communication can be done using fewer wires as compared to its parallel counterpart. It is a cheapest communication device with a single wire for transmitting the data and another wire for receiving. When the high-speed data transfer is not required UART is used.

5. Block diagram

6. Block diagram

7. UART TxD

8. UART RxD

9. DESCRIPTION In a simple serial communication, 3 pins are used: TxD , RxD and GND. At  Transmission  side (i.e. From Microcontoller ), one can write data into UART Data Register (e.g. UART0_DR) by using  software  code. These 8 bits of data from Data Register is passed to  Tx FIFO Buffer . After that, the data is sent out(one at a time) from Tx Shift Register. TxFIFO flag = 1 (Buffer full) TxFIFO flag = 0 (not full - Software can write to Data Register ) At Receiver end, there is  Rx FIFO Buffer. RxFIFO Empty flag = 1 (Buffer is empty) RxFIFO Empty flag = 0 (Buffer has data to be read)

10. How UART works

11. FRAME A frame is the unit of transmission in serial communications Start bit: To declare the start of transmission. Data bits: 4,5,6,7, or 8 bits of useful data bits. Parity bit : To check for transmission errors. Stop bit: To declare end of frame

12. PARITY Parity bit is used to check the integrity of a frame and signal if an error occurred during transmission. It is an extra bit added to the end of a frame. Even parity :The number of ‘1’ symbols inside a frame must always be even. Odd parity : The number of ‘1’ symbols inside a frame must always be odd

13. Transmisson and reception Transmission Reception

14. configuration The configuration settings at both ends of Txd and Rxd : Full or half-duplex operation Data length Start/Stop bits Transmission speed.

15. Example EX:-198 = 11000110 Transmission speed Common speed = 9600 bits/sec 1/9600 = 104 us.

16. Example After detecting start it will count 104us and complets start bit. Then begins sampling the input bits after 52us with equal count of 104us between each bit untill the next stop bit with high pulse.

17. Advantages & Disadvantages Advantages Requires minimum wires No need for clock or any other timing signal. Parity bit ensures basic error checking. Disadvantages Size of the data in the frame is limited. Can connect only two devices at a time Speed for data transfer is less compared to parallel. Transmitter and receiver must agree to the rules of transmission and appropriate baud rate must be selected.

18. Conclusion if we are looking for a device to device serial communication then UART proves itself the best as it is easy to deal with and also widely used in many peripheral devices.

19. Thank you