All the images used in my presentation are belonging to their respective owners. I do not own any copyright. ------------------------------------------------------------------------------------- >> A presentation on Embedded System Interfaces in theoretical aspects. >> I2C, SPI and UART had been discussed here. >> Prepared for my M.Tech Seminar for Semester 2 subject named, "High-Speed Digital Design" >> Guided by Mr Jeyaraj U Kidav, Scientist/Engineer 'D', National Institute of Electronics and Information Technology, Calicut

1. ELECTRONIC COMMUNICATION
PROTOCOLS
09EC6656 – HIGH SPEED DIGITAL DESIGN
Seminar on
Theoretical Aspects
Prepared & Presented by:
HARIHARAN K
UCC18ECED08,M.Tech Scholar
Dept. of Electronics DesignTechnology,
NIELIT – Calicut.
Guided by:
JAYARAJ U KIDAV
Scientist/Engineer - ‘D’
NIELIT – Calicut.

2. OUTLINE
 Introduction
 Why we need Protocol?
 SPI, I2C
 UART
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3. INTRODUCTION
 Embedded System :
◦ HARDWARE + SOFTWARE to perform a desired application.
 SYSTEM takes INPUT, processes the same, provides
the desired OUTPUT
 COMMUNICATION is happening!
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4. - Examples: CAN, I2C, I2S, SPI, Serial, USART,
UART, USB, RS-232, RS-485, Bluetooth,Wi-Fi,
ZigBee, LIN, MQTT, RFID, NFC etc.,
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COMMUNICATION PROTOCOL
- A set of rules and regulations that allow
two electronic devices to connect to exchange
the data with one and another.
- RealWorld Applications:
- Remote Controlled Gadgets
- FileTransfer between PC and Mobile

5. CATEGORIES
 In terms of communication:
- Serial Communication
- Parallel Communication
 In terms of Peripheral Accessibility:
- Inter System Protocol
Ex: Between a CPU and a Embedded Development board :
USB, UART etc.,
- Intra System Protocol
Ex: Between two devices in a circuit board : SPI, I2C etc.,
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6. SERIAL vs. PARALLEL
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7. Contd.,
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8. Internals of Serial Comm.
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Serial Communication is all about Shift Registers!
Shift registers:
Some D-Flip-Flops serially connected while sharing the same
clock line.

9. How data is sent serially?
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Transmitter: loading data in
parallel to a shift register, and
shifting it out a bit at a time -
Parallel In Serial Out Shift
Register
Receiver: receiving data a single bit at
a time and when all bits are received,
the shift register can be read in
parallel - Serial In Parallel Out Shift
Register

10. SERIAL IO
 Serial communication is preferred,
because:
 Few number of wires, less space etc.,
 Cost effective for long distances
 No Crosstalk and Clock Skew effects
 SerialTransmission Modes:
 Synchronous Data Transfer
 Asynchronous DataTransfer
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11. Synchronous Data Transfer
 Generates the Data Clock and sends it to the receiver which
works accordingly in a synchronized manner.
 Faster and Reliable Mechanism
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12. Asynchronous Data Transfer
 Generates the data clock internally and no incoming serial clock
signal.
 Proper Communication:TX and RX must be using the same baud
rate - rate at which bits are being sent bps (bits per second).
 Uses Start Bit, Stop Bit and Parity Bit for data reliability.
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13. TERMINOLOGIES
 MSB/LSB : Sounds familiar, but it’s crucial!
◦ Asynchronous : LSB sent First
◦ Synchronous : MSB sent First
 SIMPLEX - HALF DUPLEX - FULL DUPLEX
 BAUDRATE - Number of symbols (group of bits)
transceived per second.
-TX and RX should obey same baud rate value!
 MASTER/SLAVE Concept: Usually Synchronous.Sometimes, Multi
Master/Slave too!
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14. SPI
 Serial Peripheral Interface by Motorola in mid-1980’s
 Intra System - Full Duplex, Sync. Serial Communication
Protocol
 4 Pins - 4 wire communication protocol
SCK - Serial Clock
MOSI - Master Out, Slave In
MISO - Master In, Slave Out
CS/SS - Chip Select/Slave Select
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15. SPI - Two key terms
 CPOL - Clock Polarity
 CPHASE - Clock Phase
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16. SPI - Two key terms
 CPOL - Clock Polarity
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17. SPI - Two key terms
 CPHASE - Clock Phase
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18. Contd.,
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19. SPI CONFIGURATIONS
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20. Contd.,
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21. Contd.,
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22. Problem under Multi Slave
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23. Advantages & Disadvantages
 Advantages:
◦ High Speed Protocol & Full Duplex
Communication
◦ No complexity - Address of the Slave Device
◦ Best Suited for Single Master Single Slave
Configuration
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24. Advantages & Disadvantages
 Disadvantages:
◦ Pin Count is directly proportional to the
Number of Slave Devices
◦ No Acknowledgement!
◦ Slow speed device determining the speed
Example Devices: LM74 and TMP125
Temperature Sensors with SPI Interface
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25. I2C
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 Inter Integrated Circuits by Philips in mid-1980’s
 Intra System - Half Duplex Sync. Serial Communication
Protocol
 2 Pins - 2 wire topology
SCK - Serial Clock
SDA - Serial Data

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I2C

27. I2C - Data Format
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- Register Address + Data

28. I2C - Advanced Logics
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29. Advantages:
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30. Disadvantages:
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31. I2C Real World Devices:
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32. I2C vs SPI:
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33. UART
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Inter System - Async. Serial Communication Protocol

34. UART - Connection
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35. UART - Frame
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36. Advantages
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37. Disadvantages
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38. USB vs UART vs USART
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39. REFERENCES
 “Serial I-O”, Dinesh K. Sharma Electrical Engineering
Department I.I.T. Bombay Mumbai 400 076, (version July 11,
2016)
 https://deepbluembedded.com/uart-pic-microcontroller-
tutorial/
 https://i2c.info/
 https://www.slideshare.net/EmertxeSlides/communication-
protocols-31945098
More References are available in Google andYouTube! Practical
experiments are needed to understand the concepts clearly!
Just search these keywords 
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40. THANKYOU!
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