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Can I get me some of that sweet Line-in Audio (ala the Propeller Backpack)? — Parallax Forums

Can I get me some of that sweet Line-in Audio (ala the Propeller Backpack)?

Tim T.Tim T. Posts: 5
edited 2010-06-24 18:23 in Propeller 1
I see what appears to be a fine specimen of an audio line-level input circuit incorporated into the Propeller Backpack. I would like to adapt it for use on my proto-board project... but the code for the prop_backpack_adc is written in assembly (still greek to me), and doesn't seem to include the usual fine comments that help me to understand what the code is doing. Can't seem to find an example/demo Spin program that uses the functions either. How, why, when (wut)?

Help this prop-newbie get a bead on using what seems to be a good thing just out of reach.

Maybe a demo like the microphone to speaker (with delay) using Line-In instead of a Mic?

Post Edited (Tim T.) : 6/24/2010 12:34:14 AM GMT

Comments

  • StefanL38StefanL38 Posts: 2,292
    edited 2010-06-24 06:54
    This forum is very kindly to help.
    But you should provide more information like:

    - an url to the schematic of the propeller or the schematic as attachment to a posting

    the main difference between a microphone and a line in is HARDWARE

    A microphone creates a much lower signal (2-20 Millivolts) than Line-IN 500-700 millivolts and there is a difference in the "inner" resistance of a mic and line-in

    So the hardware has to be adapted to these different values.

    working with microcontrollers means to have knowledge about software AND hardware

    best regards

    Stefan
  • Tim T.Tim T. Posts: 5
    edited 2010-06-24 07:37
    The Propeller Backpack is a Parallax product:

    http://www.parallax.com/Store/Microcontrollers/PropellerDevelopmentBoards/tabid/514/CategoryID/73/List/0/Level/a/ProductID/602/Default.aspx?SortField=ProductName,ProductName

    I am interested in using both the circuit and code for the Delta-Sigma ADC for Audio Line-In on my Protoboard project, however the code is not very user friendly (no comments).
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-06-24 15:58
    Tim,

    The program you want to be looking at is the "Modem, Bell 202" object in the OBEX. It uses the line in capabilities of the Backpack and is copiously commented. The ADC object available on the Backpack product page is more general purpose and not as well-suited for audio line-in apps.

    -Phil
  • Tim T.Tim T. Posts: 5
    edited 2010-06-24 18:23
    Thanks Phil!

    I'll look that over this weekend.
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