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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: Need help with PI PICO...
Date: Sat, 30 Mar 2024 09:17:46 +0000
Organization: A little, after lunch
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On 30/03/2024 02:04, Jim H wrote:
> On Fri, 29 Mar 2024 10:49:13 +0000, in <uu66b9$83pi$3@dont-email.me>,
> The Natural Philosopher <tnp@invalid.invalid> wrote:
> 
>> Maybe ascii art will help
>>
>> CONTROL=10µs
>> ____| |________
>>
>> RETURN = wahatever
>> _____|^^^^^^^^^^^^|____________
>>
> 
> Assuming my bleary-eyed math is correct, 10µs is the length of one
> cycle of ultrasound at 100,000 Hz.
> 
The width of that pulse is pretty much immaterial - its only a digital 
trigger, It doesn't send anything directly.

The unit does that, and senses a high to the output. Then it transmits a 
squawk., When it receives an echo it switches that to low.

Its a smart device .

https://cdn.sparkfun.com/datasheets/Sensors/Proximity/HCSR04.pdf


> So what frequency is your ultrasound? Maybe some ASCII art - to scale
> - of the waveform going down and back will reveal something.
> 
40Khz allegedly. see datasheet

> I admit total ignorance to whether your devices can send sound and
> receive at the same time, etc, etc, so this is my last potentially
> annoying input. Good luck.
> 
Ive no idea either, Its got two things that might be transducers,

> Spent many an evening with Z-80 assembler back in the late 70s. Good
> times.
> 
Yes. I finally connected the dots between hardware and higher level 
languages

Anyway the unit now appears to be stable, i've watched it fail to 
connect, and recover, I've watched it detect it had lost wifi and 
reconnect after that, and it hasn't crashed or locked up yet, so I think 
  that's as far as the code needs to go right now.

Next step is to concert to battery and check if the battery saver works, 
and see how long it lasts on batterries

-- 
"An intellectual is a person knowledgeable in one field who speaks out 
only in others...”

Tom Wolfe