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From: Theo <theom+news@chiark.greenend.org.uk>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: Need help with PI PICO...
Date: 24 Mar 2024 09:39:30 +0000 (GMT)
Organization: University of Cambridge, England
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The Natural Philosopher <tnp@invalid.invalid> 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