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SPI wiring

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  • Murat Artun
    Hello, I have possibly an easy to solve problem about SPI wiring. When interfacing two hc11 boards as one to be master the other to be slave how will our
    Message 1 of 2 , Nov 1, 2002

      Hello,

      I have possibly an easy to solve problem about SPI wiring. When interfacing two hc11 boards as one to be master the other to be slave how will our wiring be? We set MSTR bit in SPCR for the master board and clear it for the slave. Do we also need to assign a logic one to SS pin of the master board (PD5) by pulling it up to 5V with a pull-up resistor? Or will we leave it unconnected to anywhere?

      thanks for any help...



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    • aslarorb@free.fr
      ... two hc11 boards as one to be master the other to be slave how will our wiring be? We set MSTR bit in SPCR for the master board and clear it for the slave.
      Message 2 of 2 , Nov 1, 2002
        On Fri, 1 Nov 2002, Murat Artun wrote:

        > Date: Fri, 1 Nov 2002 07:45:07 -0800 (PST)
        > From: Murat Artun <artunmm@...>
        > Reply-To: gnu-m68hc11@yahoogroups.com
        > To: gnu-m68hc11@yahoogroups.com
        > Subject: SPI wiring
        >
        >
        > Hello,
        >
        > I have possibly an easy to solve problem about SPI wiring. When interfacing
        two hc11 boards as one to be master the other to be slave how will our wiring
        be? We set MSTR bit in SPCR for the master board and clear it for the slave.
        Do we also need to assign a logic one to SS pin of the master board (PD5) by
        pulling it up to 5V with a pull-up resistor? Or will we leave it unconnected
        to anywhere?
        >
        > thanks for any help...
        >

        Your SS pin can have any use you want if the SPI system works as
        master.
        You might want to use it as a general purpose output, as these are
        rather scarce on the HC11.
        I suppose that your port is configured as open-drain (wired
        OR); you'll not forget that it is true for the entire port, and not
        forget the pull-up resistor. Unless you use some good old TTL logic
        chips.

        Jean-Paul

        --
        Outside of a dog, man's best friend is a book.
        Inside of a dog, it's too dark to read. (Groucho Marx)
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