From: theom+news@chiark.greenend.org.uk   
      
   The Natural Philosopher  wrote:   
   > It would seem from the pin states that it gets permanently stuck in   
   >   
   > while(!gpio_get(ULTRASONIC_IN))   
   >                 ;   
   >   
   > Which as understand it is waiting for the module (HCSR04) to *start* to   
   > send a pulse.   
      
   Can you scope it to see if the module is actually sending a pulse?   
      
   Is the pulse perhaps too short for the Pico to detect?  eg if the loop or   
   gpio_get() function took some time, it could be the signal goes 0-1-0 in the   
   middle of a loop iteration and so the gpio_get() never sees it go 1.   
      
   Theo   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)