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  • Pulling DMA low

    From Anthony Ortiz@21:1/5 to All on Tue Aug 23 10:53:12 2022
    Sorry for what might be a stupid question but I’ve been pulling the DMA line low by setting my gpio pin to output and clearing it, which sends a digital zero to the Dma line and that seems to work. However, searching online I see mention of simulating
    an open collector output by setting the gpio to input instead. I would like to do this the right way, so I’m wondering what the correct method is, and whether connecting it to ground will suffice.

    Thanks in advance!

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  • From Michael J. Mahon@21:1/5 to Anthony Ortiz on Wed Sep 7 00:41:04 2022
    Anthony Ortiz <[email protected]> wrote:
    Sorry for what might be a stupid question but I’ve been pulling the DMA line low by setting my gpio pin to output and clearing it, which sends a digital zero to the Dma line and that seems to work. However, searching online I see mention of simulating an open collector output by setting
    the gpio to input instead. I would like to do this the right way, so I’m wondering what the correct method is, and whether connecting it to ground will suffice.

    Thanks in advance!


    If I understand correctly, to assert /DMA you switch the GPIO to “output” and output “0”, and to de-assert it you switch the GPIO to “input”.

    This is the functional equivalent of using an open collector gate, so
    you’re fine!

    --
    -michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com

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  • From Anthony Ortiz@21:1/5 to All on Tue Sep 6 17:57:22 2022
    If I understand correctly, to assert /DMA you switch the GPIO to “output”
    and output “0”, and to de-assert it you switch the GPIO to “input”.

    This is the functional equivalent of using an open collector gate, so you’re fine!

    --
    -michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com

    Thanks Michael! You're the man!!

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