Details about 89C51

Discussion in 'Embedded Systems and Microcontrollers' started by rahul_cracker, Jun 14, 2007.

  1. rahul_cracker

    Thread Starter New Member

    Jun 13, 2007
    3
    0
    hi
    I am a newbie here and about the programming of the 89C51 microcontroller.I have downloaded the data sheet avaliable on the www.atmel.com .But i really want to know more about the memory the internal hardware of the 89C51, i am unable to find anything in the stickies also .Please suggest a link to the above detail's ,i do have a book on 8051 programming so i am really interested in the hardware details like
    "bi-directional open drain " things in the data sheet .
    thank you in advance
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,155
    1,795
    You want the following two documents from the atmel website:

    Microcontroller Instruction Set
    http://www.atmel.com/dyn/resources/prod_documents/doc0509.pdf

    8051 Hardware Manual
    http://www.atmel.com/dyn/resources/prod_documents/doc4316.pdf

    The second document describes the hardware present in each of the 8051 variants. The datasheets for the individual parts document the additional features of the part.

    The key feature of the quasi-bi-directional port structure is that writing a one to an output port with a VERY WEAK pullup is equivalent to making that pin an input. The pin can only source 60 micro amps so any reasonable output driver can pull it low without damaging anything.

    The open drain structure on P0 means you have to provide an external pullup resistor for those pins which are to be outputs.

    After drinking from the firehose, feel free to ask more questions.
     
  3. KumaraGuruparan

    Member

    Aug 20, 2007
    19
    0
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