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???
05/22/04 08:04
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#70933 - Ultrasonics ranging
Hi

The soccer robot competition was over. During the three matches, one win, two lose, so I couldn't get into the final.

That's my last robot competition because I won't have that much of time to make the robots.

I don't need to make the robot now but, I still want to do some small projects. I've choosen the most difficult one for me, I think, Ultraonics sensor. The sensor is used to detect flat surface(wall), at about 10cm to 50cm. I've calculated the time need for sound to travel this distance(10cm:581uS, 50cm:2907uS) and wrote a program to measure the echo time. But it doesn't work, and I wonder maybe my way is wrong.

The program:
Initialize timer0, interrupt every 20uS;
Switch on the sonar for 120mS;
Switch off the sonar and start the timer at once;
{waiting for the echo}
After hearing the echo, stop the timer. The timer reading should not exceed the range 580uS and 2907uS.

But after running the program, the reading doesn't seems to be right. The led just flash "randomly". I want to know more details about ultrasonics ranging, not only the principle.

Stanley


List of 18 messages in thread
TopicAuthorDate
Ultrasonics ranging            01/01/70 00:00      
   RE: Ultrasonics ranging            01/01/70 00:00      
   RE: Ultrasonics ranging            01/01/70 00:00      
      RE: Ultrasonics ranging            01/01/70 00:00      
      RE: Ultrasonics ranging            01/01/70 00:00      
         RE: Ultrasonics ranging            01/01/70 00:00      
            RE: Ultrasonics ranging            01/01/70 00:00      
               RE: Ultrasonics ranging            01/01/70 00:00      
                  RE: Ultrasonics ranging            01/01/70 00:00      
                     RE: Ultrasonics ranging            01/01/70 00:00      
   Suggest me some words or phrases            01/01/70 00:00      
      RE: Suggest me some words or phrases            01/01/70 00:00      
   RE: Ultrasonics ranging            01/01/70 00:00      
      I use a pair of sonars.            01/01/70 00:00      
   RE: Ultrasonics ranging            01/01/70 00:00      
   ADC/Timer            01/01/70 00:00      
      RE: ADC/Timer            01/01/70 00:00      
         Hardwares respond            01/01/70 00:00      

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