Difference between a Bus and an Interface

Discussion in 'General Electronics Chat' started by Abhinavrajan, Aug 16, 2016.

  1. Abhinavrajan

    Thread Starter Member

    Aug 7, 2016
    I would like to know the difference between a Bus and an Interface.
    An interface is basically a bus, right ?

    Consider this example where I have microcontroller connected to a temperature sensor via an I2C bus.
    They communicate via the I2C interface.

    Inside the microcontroller, what protocol does the Control, Address and Data Bus follow ( Like whether they follow the I2C protocol, SPI protocol ) ?
    They data from the microcontroller moves through the data bus to the I2C interface. What protocol does the Data bus follow or what is the difference between the I2C bus and the data bus ( Which is present inside the microcontroller )

    I am just a beginner in electronics. So, I don't understand concepts clearly when said for the first time. Simple english with an example would really help me.
    Please send me any good links or PDFs on these topics i.e. Buses, Interfaces which can give me some really good clarity for a beginner.

    Thank you.
  2. crutschow


    Mar 14, 2008
    A bus is what carries the signal between two devices.
    The interface is the connection from a device to the bus or the protocol of that connection.
    Abhinavrajan likes this.
  3. hp1729

    Well-Known Member

    Nov 23, 2015
    Design 812 bus and interface.PNG
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  4. KeepItSimpleStupid

    AAC Fanatic!

    Mar 4, 2014
    Lets' go way basic and we can talk about the 5V BUS. It's any place that 5V exists.
    A BUS BAR does what?

    Wit simple memory, you have address its like An, An-1....A0. Each of these addresses e.g. A0 etc. is tied together for each chip, The NOT ENABLE signal generally becomes a CS or Chip Select). So, the "Interface" to this memory module includes the timing and set-up times that need to be present to talk to memory.

    You can have interfaces without busses. RS232 is an example although we have introduce Protocol too, The "Interface" is how RS232 is defined, the Protocol would include start, stop bits, parity, data bits and commands to given devices.

    RS485 is master/slave bus arrangement.

    So, BUS is more of a common element,
    Interface is more an electrical definition. We might say our computer has a USB interface or Port.

    I'm not sure what to call things like L/R Audio, Composite video, SPDIF optical, Coax optical or even 120/240 volt power cord.

    We can also talk about the "User interface" or HMI (Human Machine Interface), so it's not just electrical.
  5. kubeek


    Sep 20, 2005
    An interface is the endpoint, and bus is the thing that all interfaces are connected to.