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TCPIP

Discussion in '8bit Microcontrollers' started by [email protected], Feb 7, 2005.

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  1. Guest

    For information purposes, I am curious about using a PIC to permit IP
    addressing of various devices in an application.

    A possible client is considering being able to talk to a dozen
    switches/boxes on site, using TCPIP.

    I see on the Microchip site that they offer a TCPIP stack, and that the
    more high end devices support this.

    I don't know that much about the software involved, so I cannot confirm if
    they can 'get there from here' with a PIC.

    Assuming I can find a programmer to help with this, am I on the right
    track? Anyone done this who can expand on what its all about, and how I
    can learn more about the application? Can the PIC handle the interface, or
    would each box need a NIC as well? The total amount of information moving
    back and forth would be minimal, as in "I am active, not active, my
    status, and turn on/turn off type of details"

    Kind of general topic, rather than specific details, so I hope it can
    stimulate some conversation :)

    Thanks,

    John
     
  2. Does this help?

    http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=
    1490&filterID=399

    Also, a search for "pic web server" will prove infomative

    Scott
     
  3. I have done two projects about TCP/IP embedded in AVR chips. I can say that
    it's not difficult to create a small TCP/IP stack for microcontrollers. The
    only thing you need is the right information and lot of time to debug :)

    Buy the book:
    TCP/IP Lean
    Web Servers for Embedded Systems
    Second edition
    ISBN: 1-57820-108-X

    I will give you some of my experiences. The difference between success and
    failure is the amount of RAM in the PIC. At least 3-4kbytes is needed in
    order to create a simple TCP/IP stack. I have created a TCP/IP stack with
    SLIP connection and 512 bytes RAM. I have also tried to improve the TCP/IP
    stack to use Ethernet but the project was not a success because 512 bytes
    RAM in the AVR was not enough to keep a packet in memory so there was a lot
    of buffer code and swapping between the Ethernet chip and the AVR
    microcontroller.

    The problem with the TCP/IP stack is that you sometime need to know the
    checksum and data length before you have created the data. Therefore the
    best thing is to have enough RAM space so you will be able to keep the
    data+headers in memory inorder to calculate the checksum and the length of
    the data. Both the length and the checksum is placed in the headers.

    In the book TCP/IP Lean there is a lot of solutions to all the different
    problems when you are implementing a TCP/IP stack in small microcontrollers.

    If you want to use low end PICs then you should look at RS485, CAN or LIN. A
    different approach is to use hardware implemented TCP/IP stacks. There is a
    ethernetchip with embedded TCP/IP stack can't remember the name of the chip.

    I wish you luck with the project.
    Rune Christensen
     
  4. Guest


    Well duh! I am pretty sure I pointed out where I am at, and solicted
    discussion on the matter so I can learn. It must be a wonderful advantage
    to be born all-knowing. The rest of us have to learn as we go.

    Everything is over everyone's head until they learn it.

    You have no frame of reference from which to judge me anyway. The more I
    think about what a crass comment that was..........

    Thanks anyway. Say hi to God up there on the mountain.

    John
     
  5. Tim H.

    Tim H. Guest

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