OpenSprinkler Forums Hardware Questions Want to add DAC to OSPI. Need access to GPIO pins?

  • This topic has 6 replies, 3 voices, and was last updated 7 years ago by Ray.
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  • #38929

    Anonymous
    Inactive

    I have my OSPI in my garage sucessfully running my 15 sprinkler stations. Since its in the garage, I thought I might as well use it as an mp3 player/media client. I have installed MPD, and also an UPnP renderer to listen to music both locally, and via my home network. Right now, I am using the mini stereo output hooked up to an old auto amp (12VDC, 25W), and then sent to some old truck box speakers. Obviously, the sound is not great, but good enough for now. I got to doing some research on DAC’s, and I’d like to get an I2S DAC.

    My setup now is OSPI on a Raspberry Pi 2, so, to hook up the DAC I would need access to the GPIO pins. I’ve included a pic with the pins I need, I think???

    The first question, is this even possible? If so, how?

    #38937

    Ray
    Keymaster

    Note that OSPi has a PCF8591 A/D D/A converter on-board, which provides 1 channel of DAC. Would this suffice for your need? I think it’s only 8-bit so I am not sure if the resolution is sufficient. PCF8591 uses I2C.

    I am not familiar with I2S — did you mean I2C?

    #38939

    Ray
    Keymaster

    On second thought: why do you have to use a DAC? Doesn’t RPi have an audio out connector? If so, you should be able to play MP3 directly, isn’t it?

    #38945

    Anonymous
    Inactive

    I am not familiar with I2S — did you mean I2C?

    I’m not sure? Still learning here. Did the picture make any sense to you? From what I’ve read, The rev 1 pi used an 8-pin header (P5 in the image), which is referred to as I2s. The ver. 2 incorporates this pins into the gpio. Most newer cards just mount directly to the gpio, which obviously is not an option.

    The audio out is only 11 bit. Looking for a little better. Just because😁

    #38946

    Anonymous
    Inactive

    DOH! JUst found the GPIO pin out on the OSPI board. 😳

    So, in theory, I could just add a header, and run the DAC from those pins, right?

    From the diagram in the screenshot, do you see anything that would interfere with the operation of the OSPI?

    #40309

    Jerome
    Participant

    Hello !

    when using PF8581 with python script, is there some special precaution to avoid interferences between opensprinkler services about RTC DS1307 and the new script that will use PF8591 in an asynchronous manner ?

    Thanks
    Jerome

    #40321

    Ray
    Keymaster

    The two chips have different I2C addresses, so there shouldn’t be any interference.

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OpenSprinkler Forums Hardware Questions Want to add DAC to OSPI. Need access to GPIO pins?