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8 Bit or 32 Bit Microcontroller

Discussion in 'Microcontrollers, Programming and IoT' started by pavankukkala, Jul 15, 2016.

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  1. pavankukkala


    Mar 25, 2014
    I have 1 question guys
    8 bit microcontroller is working 32Mhz Frequency and 32 Bit icrocontroller is working with 8 Mhz frequency,which one is better in real time systems.
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    This question can' be answered conclusively. It depends very much on the application and other parameters like:
    • Which peripherals are included?
    • How much memory (Flash, RAM) is included?
    • Last not least: What are you going to do with the controller?
  3. pavankukkala


    Mar 25, 2014
    Actually this question was asked for me interview today
    I got the point what you are saying
    One more doubt , if the peripherals are same , same amount of flash memory and same task on both the microcontrollers
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    It still depends on the application.
    Do you want to blink an LED, do you want to control a washing machine or do you want to build a small media player?
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Also, for doing lots of math with big numbers, a 32 bit µC has advantages as it can handle 32 bit numbers in one inxtruction (cycle) easily whereas an 8 bit µC will need more instructions (and cycles).
  6. Amar Dhore

    Amar Dhore

    Dec 2, 2015
    your question is like: A bus that can carry max 8 people with 32 MPH vs a bus that can carry 32 people with 8 MPH, which one is better.

    Even though the 32bit micros are the best in the market but still you will have to chose what is best for your application.

    if 8 bit is running at 32MHz and 32bit is running at 8MHz, I would prefer 32 bit, because of its lower frequency, the power consumption is less and in the backgrounds I will have a less codes.
    hevans1944 likes this.
  7. NorthGuy


    Mar 24, 2016
    Next time you're asked a question which starts from "What is better", ask "what is your definition of 'better'?"

    There are many considerations when choosing an MCU, and two things which are of the least concerts are "number of bits" and nominal MHz speed. These are marketing things. However, since hiring is done by technically-illiterate HR people, you have little chance to be hired unless you say these things are very important. In real life, the most important thing is periphery - in embedded world you can achieve better performance doing things in parallel, rather than pipelining sequential software threads.

    As to the speed, consider these examples:

    16-bit dsPIC33 running at 70MIPS doing FIR will leave most of the super-fast 32-bit processors in the dust because FIR is exactly the task it was made for,

    Little 8-bit PICs have predictable command timing and can be used for fast big-banging. Since most fast 32-bit processors use caches and pipelines, you can no longer rely on command timing and must use a timer instead, and hence you will require a processor with 5-10 times faster nominal MHz speed to achieve the same result.
    Harald Kapp likes this.
  8. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    I think the interviewer is trying to determine whether or not you know anything about microprocessors. The answer is probably NOT "This processor is better because... yada, yada, yada." They are probably looking for an answer that describes the in-depth considerations you would make before choosing a processor, thereby demonstrating that you actually know something about processors that wasn't simply a quotation from one of your lecture notes or text books.

    Well, at least I would be looking for that kind of answer if I was interviewing you. There are a lot of pretenders out there with glib responses to questions, but no actual knowledge or experience that is of any practical use if they are hired. I have no objection to on-the-job training (OJT), but I would like to know before hiring just how much time for OJT will be required. If you have zero experience and are looking for your first job after graduation, you need to find some positive things to talk about that emphasize your current abilities and strengths. Activities outside of school that are related to the profession you wish to pursue can be a positive indication: electronic hobbyist work at home, a summer internship, voluntary part-time work in an appropriate industry can be mentioned in addition to whatever formal education you bring to the interview table.
    Last edited: Jul 15, 2016
    Harald Kapp and Amar Dhore like this.
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