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Altera_Forum's avatar
Altera_Forum
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12 years ago

using spi core

I want to use the spi core for adc peripheral AD9253. It has bidirectional SDIO. but spi core in nios has miso and mosi. so how do i tackle this. i want to read and write to the adc registers.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    A simple solution is driving SDIO in open collector mode using a tristate i/o buffer and a pull-up resistor.

    MOSI is connected to the active low buffer enable port, while the i/o buffer input is hardwired to gnd.

    MISO is connected to the same i/o pin.

    This way you simply put ones in the spi tx register for the bits you are supposed to receive.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    --- Quote Start ---

    A simple solution is driving SDIO in open collector mode using a tristate i/o buffer and a pull-up resistor.

    MOSI is connected to the active low buffer enable port, while the i/o buffer input is hardwired to gnd.

    MISO is connected to the same i/o pin.

    This way you simply put ones in the spi tx register for the bits you are supposed to receive.

    --- Quote End ---

    Hello, sherindeena!

    Did You try to make it this way?

    Here are another replies to this question:

    http://www.alteraforum.com/forum/showthread.php?t=26838

    http://www.alteraforum.com/forum/showthread.php?t=38228

    Which one is correct?

    I am interested because I am about to make the similar connection.