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68hc11 and z85230

Discussion in 'Electronic Design' started by giovanni, Apr 21, 2006.

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  1. giovanni

    giovanni Guest

    Hi all,

    has anyone tried to successfully connect the motorola 68hc11 to the
    zilog z85230?
    I am trying to make them work together but it seems I am able to read
    but not to write.

    data from 68hc11 are directly connected to the data lines on the
    z85230. Control signals rd and wr come from 68hc11. chip enable and d/c
    come from a PLD.

    I am thinking about delaying the write signal, in order to make it fit
    the z85230 timing constraints: could this help?

    Thanks in advance for your time and considerations.
  2. James Beck

    James Beck Guest

    I have no clue what a z85230 is, but first and foremost is to make sure
    you make the /RD and /WR using the HC11 RW line and the HC11 E clock,
    then any chip selects need to be ANDed with the E clock.

    In other words :
    /RD = !(RW & E)
    /WR = !(!RW & E)
    All address decoding needs to be ANDed with the E clock also.

    I usually use a small PLD to create the /RD and /WR signals along with
    the inverted reset some of the peripherals need and any odd address
    decoding that is needed.

    Hope this helps

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