Frequency detection (audio)

Results 1 to 23 of 23

Threaded View

  1. - 7th June 2012, 21:23 #13
    cncmachineguy's Avatar
    cncmachineguy
    cncmachineguy is offline Senior Member
    Join Date
    Aug 2010
    Location
    Maryland, USA
    Posts
    869

    Did you find this post helpful? Yes | No

    Default Re: Frequency detection (audio)

    Hank do the numbers below 900 seem to make sense? We should be able to predict the TMR output based on some simple math. You are running 4MIPS (16Mhz OSC). so that would be .25uS per instruction. If the timer is running from Fosc, a 1 K signal would have a count of 4000? 1/1000 = 1mS. 1mS/.25uS=4000. Assuming the ISR fires 1 time per cycle. Likewise we would expect a count of around 8000 for a 500Hz signal. But either you don't have it set up as I assume, or something is wrong that will require seeing more of your code.

    BTW, using my assumptions, 82.4Hz is 48,543.
    330Hz = 12,121
    600Hz = 6666
    650Hz = 6153

    I can't decide if that looks linear, but it should.

    Also try clearing the TMR1 high byte and low byte seperatly in the ISR. I don't think this should help, but it can't hurt
    Last edited by cncmachineguy; - 7th June 2012 at 21:36.
    -Bert

    The glass is not half full or half empty, Its twice as big as needed for the job!

    http://foamcasualty.com/ - Warbird R/C scratch building with foam!
« Previous Thread | Next Thread »

Members who have read this thread : 0

You do not have permission to view the list of names.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Forum Rules