Re: 8051 and sonar (depth finder)

From: Tim Wescott (tim_at_wescottnospamdesign.com)
Date: 12/29/04 

Date: Tue, 28 Dec 2004 17:33:36 -0800

jentzd@gmail.com wrote:

> Hi all,
>
> Recently I am stuck on my first microcontroller project. I think I have
> everything nailed down to the absolute last detail, but have not yet
> been able to find a solution to this - after about 6 weeks of looking.
>
> My 8051 microcontroller is trying to determine the ocean floor depth.
> To do this, it sends out a ping, enables a timer, and counts how long
> until the echo is returned. Simple enough - right?
>
> My problem is not in the sending of the ping - or in counting the echo
> return (I use timer0 and expect no overflows), it is simply in getting
> back a consistant echo. Echos that I do recieve range in time from 500
> ticks to 60000. When I turn off my labview echo simulator - I still get
> the wildly varying and inconsistent results! Help!
>
> I can provide schematics if necessery. For now I will keep it simple by
> saying I detect echo signals generated from the comparator1 interrupt.
> An active low indicates a echo.
> Any help would be greatly greatly appreciated.
> -David
>
Labview echo simulator?

Does the input signal look good on an oscilloscope? Are you _sure_
you're not getting overflows? If you're getting up to 60000 ticks on a
16 bit timer then you're darn close. Perhaps you have a prescaler set
incorrectly and you're just getting the remainder? 

-- 
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Relevant Pages

  • Re: 8051 and sonar (depth finder)
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