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Difference between Brown out and Power on reset

Discussion in 'Microcontrollers, Programming and IoT' started by electronicsLearner77, Aug 10, 2017.

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  1. electronicsLearner77

    electronicsLearner77

    157
    1
    Jul 2, 2015
    I am bit confused with these terms as Brown out reset is set when the voltage is less than Vdd. So when you are powering ON it should go from lower voltage to Vdd. In this case how micro chip handles?
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    It would help if you told us what device you are talking about.

    Bob
     
  3. Amar Dhore

    Amar Dhore

    129
    12
    Dec 2, 2015
    Brown out reset flag gets set when the VDD drop below the operating voltage. It holds the reset high for some time. Check the datasheet for more information.
     
  4. electronicsLearner77

    electronicsLearner77

    157
    1
    Jul 2, 2015
    Sorry it is dspic33ev256gm106.
     
  5. electronicsLearner77

    electronicsLearner77

    157
    1
    Jul 2, 2015
    My Brownout reset flag is always set on after power On. Is it correct behavior? Please advise.
     
  6. hevans1944

    hevans1944 Hop - AC8NS

    4,595
    2,149
    Jun 21, 2012
    This is correct. See Section 6 RESETS in the datasheet, in particular this quotation:
     
  7. electronicsLearner77

    electronicsLearner77

    157
    1
    Jul 2, 2015
    Sorry but please explain me this scenario.
    1. I powered on the board for the first time. Will the brown reset flag will be set or not?
     
  8. hevans1944

    hevans1944 Hop - AC8NS

    4,595
    2,149
    Jun 21, 2012
    You should find that both POR and BOR bits <1:0> are set in RCON after initial power on. All other bits in RCON should have been cleared as a result of the power-on reset. As part of your program initialization after initial power on you should clear both POR and BOR bits so that the contents of RCON represent future events accurately.

    Have you read, and do you understand, the datasheet for this microprocessor? It appears to be quite sophisticated. It has been my experience with PIC micros that it is absolutely necessary to understand how each and every bit in all the registers functions before you can write correct code. The RCON register is just a status register to provide information to your program. Setting or clearing any of the bits in RCON will not create an actionable event for the microprocessor. This will not be true for other bits in other registers, whose state will determine what the microprocessor does. Read carefully and understand the purpose and function of each bit in every register. Consider using a higher level language, such as C, to shelter you from most of this.
     
    Last edited: Aug 11, 2017
    electronicsLearner77 likes this.
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