accessing port directly - Hewlett Packard

This is a discussion on accessing port directly - Hewlett Packard ; Hello all, I would like to build a card for the HP48. It requires that informations are exchanged between the card and the calculator via port 1 or 2. I have limited knowledge in asm and never made a program ...

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  1. accessing port directly

    Hello all,

    I would like to build a card for the HP48. It requires that
    informations are exchanged between the card and the calculator via
    port 1 or 2. I have limited knowledge in asm and never made a program
    that use port 1 or 2. Ideally I would like to use a pin of one of the
    port to transfer data to the card and another one to receive data, and
    finally a third one as clock (SPI interface to a SD card in fact). Is
    this possible ? I have looked to hpcalc and in the web but failed to
    retrieve information on this.

    Any help will be greatly appreciated !

    val

  2. Re: accessing port directly

    On Feb 21, 6:17*pm, val wrote:
    > Hello all,
    >
    > I would like to build a card for the HP48. It requires that
    > informations are exchanged between the card and the calculator via
    > port 1 or 2. I have limited knowledge in asm and never made a program
    > that use port 1 or 2. Ideally I would like to use a pin of one of the
    > port to transfer data to the card and another one to receive data, and
    > finally a third one as clock (SPI interface to a SD card in fact). Is
    > this possible ? I have looked to hpcalc and in the web but failed to
    > retrieve information on this.
    >
    > Any help will be greatly appreciated !
    >
    > val


    I'm no expert in electronics but I'm not sure what you want is
    possible (from the hardware point of view).
    And even if it was, the speed of the processor is probably not enough
    to initialize an SD card. Minimum clock frequency for communication I
    believe is 600 kHz for an SD card, even the best Saturn assembler
    programmer can't write software to send data with a 600 kHz clock. The
    Saturn works at 4 Mhz, and each instruction takes like 3 to 18
    cycles... forget it.

    If you really want to add an SD interface to an HP48, I suggest you
    buy an HP50G!!.
    That's the best help I can offer.

    Regards,
    Claudio

  3. Re: accessing port directly

    On 22 fév, 01:42, Claudio Lapilli wrote:
    > On Feb 21, 6:17*pm, val wrote:
    >
    > > Hello all,

    >
    > > I would like to build a card for the HP48. It requires that
    > > informations are exchanged between the card and the calculator via
    > > port 1 or 2. I have limited knowledge in asm and never made a program
    > > that use port 1 or 2. Ideally I would like to use a pin of one of the
    > > port to transfer data to the card and another one to receive data, and
    > > finally a third one as clock (SPI interface to a SD card in fact). Is
    > > this possible ? I have looked to hpcalc and in the web but failed to
    > > retrieve information on this.

    >
    > > Any help will be greatly appreciated !

    >
    > > val

    >
    > I'm no expert in electronics but I'm not sure what you want is
    > possible (from the hardware point of view).
    > And even if it was, the speed of the processor is probably not enough
    > to initialize an SD card. Minimum clock frequency for communication I
    > believe is 600 kHz for an SD card, even the best Saturn assembler
    > programmer can't write software to send data with a 600 kHz clock. The
    > Saturn works at 4 Mhz, and each instruction takes like 3 to 18
    > cycles... forget it.
    >
    > If you really want to add an SD interface to an HP48, I suggest you
    > buy an HP50G!!.
    > That's the best help I can offer.
    >
    > Regards,
    > Claudio


    Hi,

    One may use SD cards in SPI mode and this way there is no problems on
    communication speed (you set it using your dedicated clock line). My
    problem is more on finding a way to access directly the port 1 or 2
    pins to build the communication interface. I have a dead ram card that
    I want to use for this purpose. The SD card will be attached to a few
    pins of this ram card and the hp48 will talk to the SD card using pins
    of port 1 or 2, depending where I plug the card.
    If you want to write directly to memory in port 0 you may write, in
    asm :
    LC(2) XXh
    D0=(5)Adr
    DAT0=C , or smthg approaching.
    But what if the address is supposed to correspond to port 1 (or 2).
    I guess that in this latter case there is another way of writing in
    external memory. Do we have to use CONFIG, IN, OUT,...?
    Basically, does somebody know a way to physically assert/read pins on
    port 1 or 2, and which pins must be asserted in order to fake a valid
    card (CD, CE, and such).
    In fact any info on the way a hp48 reads/writes from or to a ram card
    will be helpful to me.

    Thanks for your help.

    val

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