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[HiFiBerry DAC+ DSP] GPIOs connector to Raspberry Pi and data reception/transmission from/to Raspberry Pi

Pedro Albergaria

July 01, 2021 09:32

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Hi,

I am using the HiFiBerry DAC+ DSP platform connected with the Raspberry Pi 4 Model B board.

In my project, I have a I2S microphone connected to the connector P6, namely the digital inputs and outputs 1. I am programming the project with the Analog Device's SigmaStudio.

For the project, I need to transmit and receive signals to/from the RaspBerry Pi. My first question is what are the GPIOs, amonsgt the 40-pin connector, that I can access in order to transmist/receive data? My second question is how can I do this with SigmaStudio?

I found this link for the Beocreate, but I couldn't similar information for the HiFiBerry DAC+ DSP platform. Also there is this link, but this also does not provide all the information that I need.

Best regards

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5 comments

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  HiFiBerry team July 02, 2021 05:55

  As the DSP and teh Pi run on independent clocks, this needs to be connected via an ASRC. To enable an input on the Pi, you can use the dacplus-dsp driver as the default driver only offers an output, no inputs.

  You don't have to deal with GPIOs on the Pi, that's just something that ALSA will handle.

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  Pedro Albergaria July 07, 2021 11:02

  Hi,

  Thank you for the response!

  I still don't understand how to connect the SigmaStudio project with ALSA. What are the IO signals on the SigmaStudio project for this to work? 

  Edited by Pedro Albergaria July 07, 2021 11:02
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  HiFiBerry team July 08, 2021 16:08

  Input and output are both connected to the first channel of the DSP. However, you can't simply connect these directly, but you have to route it via the ASRC. The DSP needs to be clock slave slave for both.

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  Pedro Albergaria July 08, 2021 16:45

  Hi, 

  Thank you for your help.

  Input and output are both connected to the first channel of the DSP

  So I have to connect the microphone to SDATA_IN1 (and the other required I2S signals, of course) and the output is SDATA_OUT1, correct?

  You don't have to deal with GPIOs on the Pi, that's just something that ALSA will handle

  I already have the dacplus-dsp driver as the default driver. How can I capture the microphone's audio with ALSA? 

  Another question is how I can send audio to the HiFiBerry from the RaspBerry Pi? What are the inputs on DSP for the SigmaStudio project? 

  Best regards

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  HiFiBerry team July 08, 2021 16:49

  It seems that you're trying to build something from scratch. Don't try this. Use one of the projects we supply as a template:

  https://github.com/hifiberry/hifiberry-dsp/tree/master/sample_files/dspproj
  
  To understand ALSA, have a look at the ALSA audio web site:

  https://www.alsa-project.org/wiki/Main_Page