Overview on Electronic Communication Protocols


  • Protocol: A set of rules and regulations is called a protocol.
  • Communication: Exchange of information from one system to another system with a medium is called communication.
  • Communication Protocol: A set of rules and regulations that allow two electronic devices to connect to exchange the data with one and another.

Types of Electronic Communication Protocols:

There are two types of communication protocols which are classified below:

1. Inter System Protocol

2. Intra System Protocol

1. Inter System Protocol: The inter-system protocol using to communicate the two different devices. Like communication between computer to microcontroller kit. The communication is done through an inter bus system.


Inter System Protocol

Different categories of Intersystem protocol:

  • UART Protocol
  • USART Protocol
  • USB Protocol

2. Intra System Protocol: The Intra system protocol is used to communicate the two devices within the circuit board. While using these intra system protocols, without going to intrasystem protocols we will expand the peripherals of the microcontroller. The circuit complexity and power consumption will be increased by using intrasystem protocol. Using intra system protocols circuit complexity and power consumption, the cost is decreased and it is very secure to accessing the data.

Intra System protocol

Different categories of Intersystem protocol

  • I2C Protocol
  • SPI Protocol
  • CAN Protocol

UART Protocol:

UART stands for a universal asynchronous transmitter and receiver.UART Protocols is a serial communication with two wired protocols. The data cable signal lines are labeled as Rx and Tx. Serial communication is commonly used for transmitting and receiving the signal. It is transferred and receives the data serially bit by bit without class pulses. The UART takes bytes of data and sends the individual bits in a sequential manner. UART is a half-duplex protocol. Half-duplex means transferring and receiving the data but not at the same time. Most of the controllers have hardware UART on board. It uses a single data line for transmitting and receiving the data. It has one start bit, 8-bit data and one-stop bit mean the 8-bit data transfer one’s signal is high to low.

Ex: Emails, SMS, Walkie-talkie.

UART Protocol Data Flow
UART Protocol Data Flow

USART Protocol:

USART stands for a universal synchronous and asynchronous transmitter and receiver. It is a serial communication of a two-wire protocol. The data cable signal lines are labeled as Rx and TX. This protocol is used to transmitting and receiving the data byte by byte along with the clock pulses. It is a full-duplex protocol that means transmitting and receiving data simultaneously to different board rates. Different devices communicate with microcontroller to this protocol.


USART Protocol Data Flow
USART Protocol Data Flow

USB Protocol:

USB stands for universal serial bus. Again it is a serial communication of two-wire protocol. The data cable signal lines are labeled D+ and D-. This protocol is used to communicate with the system peripherals.USB protocol is used to send and receive the data serially to the host and peripheral devices.USB communication requires driver software which is based on the functionality of the system.USB devices can transfer data on the bus without any request on the host computer. Now a day’s most of the devices are using this technique for communicating with USB protocol. Like computer to communicate with ARM controller using USB. USB transfer the data different modes .first one is slow speed mode 10kbps to 100 kbps; the second one is full speed mode 500kbps to 10mbps, high-speed mode 25mbps to 400 Mbps.USB maximum cable length of 4 meters.

Ex: Mouse, Keyboard, Hubs, switches, pen drive.

USB Protocol Communication
USB Protocol Communication

Differences Between the Inter System Protocols:

communication protocol

I2C Protocol:

I2C stands for the inter-integrated circuit. I2C requires only two wires connecting all peripherals to microcontroller.I2C requires two wires SDA (serial data line) and SCL (serial clock line) to carry information between devices. It is a master to a slave communication protocol. Each slave has a unique address. The master device sends the address of the target slave device and reads/write flag. The address matches any slave device that device is ON, remaining slave devices are disabled mode. Once the address is match communication proceed between master and that slave device and transmitting and receiving the data. The transmitter sends 8-bit data, the receiver replies 1-bit of acknowledgment. When the communication is completed master issues the stop condition. The I2C bus was developed by Philips Semiconductors. Its original purpose is to provide an easy way to connect CPU to peripherals chips. Peripheral devices in embedded systems are often connected to the microcontroller as memory-mapped devices. I2C requires only two wires for connecting all the peripherals to the microcontroller. These active wires, called SDA and SCL, are both bidirectional. SDA line is a serial data line and the SCA line is a serial clock line.

I2C protocal data flow
I2C protocal data flow

I2C Pull-up Resistors:

Why given the pull-up resistors in I2C SCL and SDA line.

  • Both SDA and SCL lines are open-drain drivers.
  • It can drive output low canot driver it high.
  • For the lines to be able to go high you must provide pull-up resistors

SPI Protocol:

SPI stands for the serial peripheral interface. It is one of the serial communication protocol developed by Motorola. Some times SPI protocol is also called a 4-wire protocol. It requires four wires MOSI, MISO, SS, and SCLK.SPI protocol used to communicate the master and slave devices. The master first configures the clock using a frequency. The master then selects the particular slave device for communication by pulling the chip select button. That particular device is selected and starts the communication between master and that particular slave. The master select only one slave at a time. It is a full-duplex communication protocol. Not limited to 8-bit words in the case of bit transferring.

SPI protocol data flow
SPI protocol data flow

CAN Protocol:

CAN stands for the controller area network. It is a serial communication protocol. It requires two wires CAN High (H+) and CAN low (H-).  It was developed by the Robert bosh company in 1985 for in-vehicle networks. It is based on a message-oriented transmission protocol.

Differences Between the Inter System Protocols:

communication protocol in electPhotos Credit:


  1. Prashant Patil says:

    Which one is better protocol from above all protocol for communicating with microcontroller???
    Pls suggest

    1. Tarun Agarwal says:

      Hi Prashant
      I2C is better because it needs only two wires for connecting all peripherals to the microcontroller like serial data line and a serial clock line.

  2. Akshit Bhangale says:

    can you please suggest me some book to study these topics in depth

  3. mobile2computer says:

    Nice information will help me in the exams

  4. Nice piece of information but poorly worded making it difficult to understand, Needs improvement.

  5. Rajesh ch says:

    We can use UART as Full duplex also……

    1. Team ElProCus says:

      – Full duplex means both transferring and receiving data at the same time.
      – But in UART communication transferring and receiving data has different baud rates, where transferring data at 9600 baud rate and receiving data at 115220 baud rates. The UART communication clock synchronization is not at same time. ii will cause data corruption.
      – Most chips do not support it. Some UART’s support this kind of operation.
      – Only ZILOG microcontroller family is supported as per my knowledge.

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