this presentation contains all sort of information regarding USCI(Universal Serial Communication Interface) UART, SPI, I2C etc. this will be very helpful to the people those who are planning or starting projects or want to get idea how devices interfaced.

1. Presentation By:
Mohit Panchal
Guided by:
Prof. S.V. CHARATE
DR. S.K. JAIN

2.  DATA COMMUNICATION TYPES
 SYNCHRONOUS AND ASYNCHRONOUS
TRANSMISSION
 SERIAL COMMUNICATION IMPLEMENTATION
 TERMS USED IN SERIAL COMMUNICATION
 UART
 USART
 USB
 BIBLIOGRAPHY

3. 1. Parallel
2. Serial
(i) Synchronous
(ii) Asynchronous

4. Serial versus Parallel Data Transfer
FIG.1

5.  In parallel transmission, all the bits of data
are transmitted simultaneously on separate
communication lines.
 Parallel transmission is used for short
distance communication.
 In order to transmit n bit , n wires or lines
are used.
 More costly.
 Faster than serial transmission.
 Data can be transmitted in less time.

6.  Many lines of communication, synchronized
bursts of data
Time
Transmitter Receiver
FIG.2

7. Bit by bit transmission of information in series
A B
Travels in series
FIG.3

8.  One line of communication, long string of
data
Time
Signal

9.  In serial transmission , the various bits of
data are transmitted serially one after the
other.
 It requires only one communication line
rather than n lines to transmit data from
sender to receiver.
 Thus all the bits of data are transmitted
 on single lines in serial fashion.
 Less costly.
 Long distance transmission.

10.  Data sent at one time multiple bytes.
 Start and stop bit not used.
 Gap between data units not present.
 Data transmission speed fast.
 Cost high.
 Transfer of data between two computer.
 Synchronization between sender and
receiver required.

11.  Sends only one character at a time (one byte
of data at a time)
 Synchronize two devices using Start Bit and
Stop Bit.
 Start bit refers to the start of the data.
Usually 0 is used for start bit.
 Stop bit indicates the end of data.more than
one bit can be used for end.

12.  Popular implementation is known as the
RS-232 serial connection found in
microcomputers
 Newer type of serial connections
◦ Universal Serial Bus (USB)
◦ IEEE 1394 serial connection that is also dubbed as
the Fire Wire connection

13.  The most popular standard
 Conforming serial ports
◦ Micro
◦ Minis and mainframes
 Sometimes these ports are also known as
the asynchronous ports
 It is also possible to conduct synchronous
transmission through these ports as well

14. SerialInterface
Parallel Digital
Data
Serial Digital Data
OutIn
Expansion
Bus
FIG.4

15. FIG.5

16. Source: Black BoxFIG.6

17.  Big Endian- MSB first, less significant bytes in
descending order
 Little Endian- MSB last, data in ascending
order
 Endian type determines how the data is
interpreted, and how it should be sent in both
serial and parallel communication.

18.  As cable lengths increase, signal quality
degrades
 As data transfer speed increases, signal
quality degrades much faster for increasing
length
TABLE-1

19.  Number of possible on/off switches per
second, based on the clock.
 Faster clock, faster bit rate
 Standard bit rates
Some typical bit rates
FIG.7

20.  Number of actual data bits per second
 Different from Bit Rate because of required
setup bits per word transmitted.

21.  BAUD register, sets speed
◦ TCLR : Clear baud rate timing chain bit
◦ SCP : Baud rate pre-scale select bits
◦ RCKB : Baud rate clock test bit
◦ SCR : SCI baud rate select bits
01234567
Read: 0 0
Write: TCLR RCKB SCR1 SCR0SCP00 SCP1 SCR2

22. ◦ SCCR1 : Serial Communication Interface Control
Register 1
◦ R8 : Receive data bit 8
◦ T8 : Transmit data bit 8
◦ M : SCI character length bit
◦ WAKE : Wakeup method select bit
◦ Bits 0 - 2 & 5 are not used (always 0)
01234567
Read:
Write:
R8
T8 M Wake
0 0 0 0

23. SCCR2 : Serial Communication Control Register 2
TIE : Transmit interrupt enable bit
TCIE : Transmit complete interrupt enable bit
RIE : Receive interrupt enable bit
ILIE : Idle-line interrupt enable bit
TE : Transmit enable bit
RE : Receive enable bit
RWU : Receiver wakeup bit
SBK : Send break bit
01234567
Read:
Write:
RWU SBKTIE TETCIE RIE ILIE RE

24.  SCI status register
◦ TDRE : Transmit data register empty bit
◦ TC : Transmit complete bit
◦ RDRF : Receive data register full bit
◦ IDLE : Idle-line detect bit
◦ OR : Overrun error bit
◦ NF : Noise flag
◦ FE : Framing Error bit
◦ Bit 0 is not used (always 0)
01234567
Read:
Write:
TDRE TC RDRF IDLE OR NF FE 0

25.  SCI data register
◦ Two separate registers, same address
◦ Used to Read the Received data
◦ Used to Write the Transmit data
◦ R7 - R0 – Read bits
◦ T7 - T0 – Write bits
01234567
Read:
Write:
R7 R6 R5 R4 R3 R2 R1 R0
T7 T6 T5 T4 T3 T2 T1 T0

27.  UART (pronounced “You Art”) is an industry acronym
that stands for Universal Asynchronous Receiver
Transmitter. It is the interface circuitry between the
microprocessor and the serial port. This circuitry is
built in to the 8051 microcontroller.
 The UART is responsible for breaking apart bytes of
data and transmitting it one bit at a time (i.e. serially).
Likewise, the UART receives serialized bits and
converts them back into bytes. In practice, it’s a little
more complicated, but that’s the basic idea.

28. 7-
28
 Transmitter (Tx) - converts data from parallel
to serial format
◦ inserts start and stop bits
◦ calculates and inserts parity bit if required
◦ output bit rate is determined by the UART clock
Serial output
Parallel
data
UART Clock from
baud rate generator
Status information

29. 7-
29
1
0
Serial transmission is little endian (least significant bit first)

30. 7-
30
◦ synchronises with transmitter using the falling edge of the
start bit.
◦ samples the input data line at a clock rate that is normally a
multiple of baud rate, typically 16 times the baud rate.
◦ reads each bit in middle of bit period (many modern UARTs
use a majority decision of the several samples to determine
the bit value)
◦ removes the start and stop bits, optional calculates and
checks the parity bit. Presents the received data value in
parallel form.
Serial input
Status information
Parallel
data
UART Clock from
baud rate generator

31. 7-
31
Idle
waiting for
start bit
Start bit
1
First data bit
etc.
0
Start
detected

32.  Control registers
 Transmit
 Receive
 FIFO control
 Status
 Interrupt
 Interrupt enable
 Format control
 Baud rate control
7-
32

33.  Universal Synchronous Asynchronous
Receiver Transmitter
 used to send and receive small packets
(characters) over a serial line
◦ full or half duplex
 typically asynchronously
 5 – 9 bits of data
 2 or 3 framing bits
 start bit
 1 or 2 stop bits
 0 or 1 parity bits

34.  Must be agreed on by sender and receiver
before any exchanges can be made
 stop bit (1 to 0 transition)
 5 – 9 data bits
 0 or 1 parity bits (odd or even parity)
 1 or 2 stop bits (logic 0)

35.  Data input register
 Data output register
 Control register
◦ speed, data bits, parity, stop bits, start, stop
 Status register
◦ data ready, transmitting
 interrupts
◦ overflow, underflow, data ready, data sent

36.  Remember synchronization is on a character
by character basis
 check status
 load data register
 start transmit
 wait for transmission complete status or for
interrupt
 repeat

37.  poll status register for data ready or wait for
interrupt
 read data (save it)
 repeat

39. In 1994 a collaborative effort to design a
standard for peripheral devices was made
between Compaq, DEC, IBM, Intel, Microsoft,
NEC, and Nortel.

40. USB 1.0 was released January 1996. It has a
data transfer rate of 12 Mbit/s. However USB
did not become popular until its first revision,
in 1998. This revision featured the ability to
use either 12 Mbit/s(FS) or 1.5 Mbit/s(LS)
depending on the device being used.

41. April 2000, the specifications for USB 2.0 are
released. With a data transfer rate of 480
Mbit/s(HS) this revision was much more
superior than its predecessors. However, just
because this speed is manageable does not
mean that it is often met.

42.  http://en.wikipedia.org/wiki/usci
 www.technogyaan.com/serial_parallel_comm
 www.engineersworld.com/usci_facts
 www.engpaper.com/parallel_serial_interface

43. THANK YOU