Parallel interface for 8-bit DAC



  • I'm investigating use of Spresense to drive a DAC (8-bit) for signal generation purposes, but it's not clear whether 5-10 MByte/sec is possible. Any pointers to appropriate interface spec and usage guidelines and/or has anyone done anything similar?

    Many thanks in advance.


  • DeveloperWorld

    @StepMaker what DAC is it that you would like to connect? Datasheet? And what interface on Spresense would you like to use?

    Br
    Karl



  • Hi Karl, I'm hoping to start using a TLC7524/AD7524 DAC which has an 8-bit, parallel interface, then increase number of bits in future depending on what's possible. Hence, I wondered what was possible using the GPIOs, but I'm open to other I/F suggestions. If I can't drive it directly via a parallel I/F, then using SPI and a shift register (74HC595) is another option as I should be able to get the speed I need (just!). Many thanks.


  • DeveloperWorld

    Hi @StepMaker

    I think that writing a driver in Nuttx would be the way to go.
    If you have a look SDK in a file sthat is called /nuttx/boards/arm/cxd560xx/spresense/src/cxd56_gpioif.c you will se how the board_gpio_write function is written.
    if you can find 8 GPIO pins that are access by the same register you should be able to write to all 8 of them with one register write. This I think should give you proper speed.

    This way is a little bit tricky but I think it should be doable.
    I would give it a try, and you can always come back if you have more questions.

    Br
    Karl

    @StepMaker said in Parallel interface for 8-bit DAC:

    I'm investigating use of Spresense to drive a DAC (8-bit) for signal generation purposes, but it's not clear whether 5-10 MByte/sec is possible. Any pointers to appropriate interface spec and usage guidelines and/or has anyone done anything similar?
    Many thanks in advance.



  • Many thanks again Karl. I'll give the gpio_write a go as well as I'll try using SPI interface and a shift register. I'll share progress.


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