From: tnp@invalid.invalid   
      
   On 28/03/2024 08:35, Björn Lundin wrote:   
   > On 2024-03-25 16:57, The Natural Philosopher wrote:   
   >> That is, some asynchrounous event in this sequence   
   >>   
   >>      gpio_put(ULTRASONIC_OUT,1);   
   >>      sleep_us(10);   
   >>      gpio_put(ULTRASONIC_OUT,0); //reset the input   
   >> //if asynch event lasting more than 100uS occurs here...   
   >>      // wait for echo pulse start   
   >>      while(!gpio_get(ULTRASONIC_IN))   
   >>          ;   
   >> //then the low-high-low echo pulse will never be detected.   
   >   
   >   
   > if you change the wait body to include a counter then you could realize   
   > that when the counter had reached a high number - you missed the pulse.   
   > Just try again then. Getting a reading is not that time sensitive - or?   
   >   
   That will be the next strategy.   
      
   I need to isolate exactly which bit is failing, and can remove all the   
   other debug code.   
   If it turns out to be a one in a thousand issue  it probably isn't worth   
   trying to avoid it, as you say, simply take another sample   
      
      
   > :START   
   >        int cnt = 0;   
   >        gpio_put(ULTRASONIC_OUT,1);   
   >        sleep_us(10);   
   >        gpio_put(ULTRASONIC_OUT,0); //reset the input   
   >   //if asynch event lasting more than 100uS occurs here...   
   >        // wait for echo pulse start   
   >        while(TRUE) {   
   >   
   >          if (! gpio_get(ULTRASONIC_IN)) {   
   >             cnt++   
   >          } else {   
   >            break;   
   >          }   
   >   
   >          if (cnt >= TOO_HIGH_VALUE) {   
   >             goto START;   
   >          }   
   >   
   >   
   >        }   
   >   
      
   --   
   “It is hard to imagine a more stupid decision or more dangerous way of   
   making decisions than by putting those decisions in the hands of people   
   who pay no price for being wrong.”   
      
   Thomas Sowell   
      
   --- SoupGate-Win32 v1.05   
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