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Thread: First Project - Questions about Audio Adaptor Board

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    First Project - Questions about Audio Adaptor Board

    Hi, I'm about to start my first build, a sample player in a footswitch. I have the majority of the parts already, and just have a couple questions as this is my first project with a Teensy.

    First off, I purchased these to attach the Teensy and Audio Adaptor Board, and now that I have them, I'm completely at a loss as to how I'm supposed to solder anything between the two insulators. Am I supposed to be able to slide one of the insulators off and put it back on? https://www.pjrc.com/store/header_14x1_d.html

    Secondly, I'm planning on using the line out, and very rarely if ever using the headphone jack. It seems like from what I've read that the volume control only effects the headphone jack, which is fine for my purposes. If I want to use that pin on the Teensy for something else, is it best to not solder it to the Audio Board? Could I then attach a physical volume control to the Audio Board for the occasional headphone jack use in the future, or is that pin on the Teensy required for the volume control to work?

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    Senior Member PaulS's Avatar
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    Quote Originally Posted by AaronVAudio View Post
    Am I supposed to be able to slide one of the insulators off and put it back on?
    No you don't, see this image on how the boards are mounted [ignore the second audio board on the bottom].

    If I want to use that pin on the Teensy for something else, is it best to not solder it to the Audio Board?
    If you don't solder a potmeter on the audio board, than pin 15/A1 is free for your own use.

    Paul

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    Quote Originally Posted by PaulS View Post
    No you don't, see this image on how the boards are mounted [ignore the second audio board on the bottom].
    Ahh, that makes more sense. Thank you.

    If you don't solder a potmeter on the audio board, than pin 15/A1 is free for your own use.
    So there won't be any adverse effects if pin 15 is soldered to the Audio Board but there's no volume pot?

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by AaronVAudio View Post
    Ahh, that makes more sense. Thank you.



    So there won't be any adverse effects if pin 15 is soldered to the Audio Board but there's no volume pot?
    As long as you don't use pin 15, it shouldn't be a problem. Note, there is a resistor and capacitor on pin 15, that may or may not cause an issue if you use pin 15 for something else than analog read.

    Note as it says in the audio adapter page, you want to use revision C of the adapter with the Teensy 3.2, 3.5, and 3.6 processors. You want to use revision D of the adapter for the Teensy 4.0 and 4.1. The audio adapter is not usable with the Teensy 2.0 and 2.0++ processors. The Teensy LC can use the adapter in a fairly limited fashion, but in general you want to stick with Teensy 3.x and 4.x processors. If you have the retired Teensy 3.0, it cannot be used with the adapter. If you have the retired Teensy 3.1, it works exactly the same as the Teensy 3.2.

    If you hook up a SPI display to your project, note that the Teensy 3.x processors have to use non-standard pins for SPI devices. The Teensy 4.x processors use the standard SPI pins. Avoid using pins 6 and 10. Pin 6 is for the optional flash memory that can be soldered to the adapter, and pin 10 is for the micro SD card reader. If you have a Teensy 3.5, 3.6, or 4.1, the built-in card reader will be faster than the card reader in the autio adapter.

    Good luck!

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    Quote Originally Posted by MichaelMeissner View Post
    As long as you don't use pin 15, it shouldn't be a problem. Note, there is a resistor and capacitor on pin 15, that may or may not cause an issue if you use pin 15 for something else than analog read.

    Note as it says in the audio adapter page, you want to use revision C of the adapter with the Teensy 3.2, 3.5, and 3.6 processors. You want to use revision D of the adapter for the Teensy 4.0 and 4.1. The audio adapter is not usable with the Teensy 2.0 and 2.0++ processors. The Teensy LC can use the adapter in a fairly limited fashion, but in general you want to stick with Teensy 3.x and 4.x processors. If you have the retired Teensy 3.0, it cannot be used with the adapter. If you have the retired Teensy 3.1, it works exactly the same as the Teensy 3.2.

    If you hook up a SPI display to your project, note that the Teensy 3.x processors have to use non-standard pins for SPI devices. The Teensy 4.x processors use the standard SPI pins. Avoid using pins 6 and 10. Pin 6 is for the optional flash memory that can be soldered to the adapter, and pin 10 is for the micro SD card reader. If you have a Teensy 3.5, 3.6, or 4.1, the built-in card reader will be faster than the card reader in the autio adapter.

    Good luck!
    Hi, maybe I'm misunderstanding, but it seems like this conflicts with what I've read elsewhere. I'd read that if you're not using the volume control or the optional flash memory then those pins are free to use for other I/O. The resistor and capacitor for pin 15 are on the Audio Board, correct? So if I want to use that pin on the Teensy, would a solution be simply not connecting pin 15 to the Audio Board?

    All my other I/O will be analog/digital (some footswitches and some LEDs, Line Out from the Audio Board, and a MIDI out jack) so I don't think I need to worry about SPI, unless I'm mistaken.

    I have the rev D and a Teensy 4.0, so I'm good there. I'll be using the card reader on the Audio Board since I'm not too worried about the speed, it will almost exclusively be used for playing a single sound file at a time.

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    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by AaronVAudio View Post
    I'd read that if you're not using the volume control or the optional flash memory then those pins are free to use for other I/O. The resistor and capacitor for pin 15 are on the Audio Board, correct? So if I want to use that pin on the Teensy, would a solution be simply not connecting pin 15 to the Audio Board?
    Best to refer to the audio board's schematic. It's on the audio board page, just scroll down to see it.

    Pin 15 has a capacitor connected to AGND, which is the GND pin between VIN & 3.3V. The 25K pot is only present if you add it. So if you use pin 15 for something else, remember the audio board adds that capacitor.

    You can also see on the schematic that pins 11, 12, 13 connect to both the SPI flash chip and SD card. If you don't solder a flash chip AND you do not put a SD card into the socket, then those pins aren't actually connected to anything and can be used for other purposes. But you said you're going to use a SD card, so even though you're not adding the flash chip, I hope you can see from the schematic how pins 10, 11, 12, 13 are indeed used by the SD card.

    When in doubt about these details, best to check the schematic to make sure.

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    Quote Originally Posted by PaulStoffregen View Post
    Best to refer to the audio board's schematic. It's on the audio board page, just scroll down to see it.

    Pin 15 has a capacitor connected to AGND, which is the GND pin between VIN & 3.3V. The 25K pot is only present if you add it. So if you use pin 15 for something else, remember the audio board adds that capacitor.

    You can also see on the schematic that pins 11, 12, 13 connect to both the SPI flash chip and SD card. If you don't solder a flash chip AND you do not put a SD card into the socket, then those pins aren't actually connected to anything and can be used for other purposes. But you said you're going to use a SD card, so even though you're not adding the flash chip, I hope you can see from the schematic how pins 10, 11, 12, 13 are indeed used by the SD card.

    When in doubt about these details, best to check the schematic to make sure.
    You seem to be misunderstanding my questions and where Iím at with this.

    I am aware of which pins the Audio Board uses for which things. Iím aware that if Iím not using the flash memory it frees up a pin for me.

    My question was simply if choosing to not solder the Teensyís pin 15 to the Audio Board would be possible, so that the capacitor and resistor on the Audio Board wouldnít be an issue when using pin 15 on the Teensy for something else.

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    Quote Originally Posted by AaronVAudio View Post
    You seem to be misunderstanding my questions and where I’m at with this.

    I am aware of which pins the Audio Board uses for which things. I’m aware that if I’m not using the flash memory it frees up a pin for me.

    My question was simply if choosing to not solder the Teensy’s pin 15 to the Audio Board would be possible, so that the capacitor and resistor on the Audio Board wouldn’t be an issue when using pin 15 on the Teensy for something else.
    Right, pin 15 is not needed, you can leave it unsoldered.

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    Quote Originally Posted by Frank B View Post
    Right, pin 15 is not needed, you can leave it unsoldered.
    Awesome, thanks!

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    Senior Member PaulS's Avatar
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    Mind you, "unsoldered" does not necessarily mean it does not make contact... you better cut that specific header pin instead of letting it protrude unsoldered through the audio board pin hole.

    Paul

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    Quote Originally Posted by PaulS View Post
    Mind you, "unsoldered" does not necessarily mean it does not make contact... you better cut that specific header pin instead of letting it protrude unsoldered through the audio board pin hole.

    Paul
    Yeah, that was the plan I had in mind. Definitely donít want it making intermittent contact.

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