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Thread: Physical problem with new audio board?

  1. #1
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    Physical problem with new audio board?

    I've been experimenting with a Teensy 3.2 for several weeks and have been very impressed. I decided to add an audio board to work with FFT-based music analysis. However, after receiving and connecting the audio board to the Teensy, I'm stumped because I can't seem to get ANY audio through the headphone output or line out using the examples. And I get an "Unable to access SD card" error for any/all example files and sketches - even though I can play the sample files from the SD card using Audacity.

    I'm wondering if I've accidentally borked the audio board. Are there any very basic checks you could suggest to verify the audio board is working properly?

    Thanks// Chris Freeborn

  2. #2
    Senior Member PaulStoffregen's Avatar
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    The main thing to check is if the pins are all lined up properly. The bottom side of the audio board has the Teensy's pin numbers printed.

    Testing-wise, you could try measuring the 3.3V power. There's also a 1.8V regulator on board, which you could try checking.

  3. #3
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    I've checked power pins and all look OK. And example sketches seem to run fine - except those using specific audio board features such as the headphone jack, SD card and line out.

    Any other suggestions? Or should I just give up and decide whether to order another audio board?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Maybe post some photos? Perhaps we'll be able to see something...

  5. #5
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    One of my concerns is that I had to desolder the Teensy from a previous set of headers in order to attach the audio board; however, everything except audio board features seem to still be working fine on the Teensy. Here are some photos:

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  6. #6
    Senior Member+ Frank B's Avatar
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    i'd try to check the connection between the cpu (on the pins of the chip!, not on the pinheaders) and the audioshield with a DVM.

  7. #7
    Senior Member PaulStoffregen's Avatar
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    Desoldering often stresses the pads and breaks connections to the tiny traces.

    Obviously check the 3.3V power on the audio shield first.

    To start, I'd look at pin 11 (MCLK). Teensy should be sending an 11.3 MHz waveform to clock the SGTL5000. Nothing will work if that clock isn't connected.

    The next step would be checking I2C communication to see if the SDA and SCL signals are connected.

    Try running some of the SD card examples, like File > Examples > SD > listfiles. Don't forget to put SPI.setSCK(14) and SPI.setMOSI(7) into those examples, and use pin 10 on SD.begin.

    Then look at BCLK and LRCLK, which should be 1.4 MHz and 44.1 kHz. If you're playing audio from a file, the TX signal should be changing rapidly.

    My guess is one or more signals probably go severed. Hopefully this info helps you look for which ones are actually making it to the audio board.

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