Sujet : Re: Need help with PI PICO...
De : tnp (at) *nospam* invalid.invalid (The Natural Philosopher)
Groupes : comp.sys.raspberry-piDate : 30. Mar 2024, 20:17:15
Autres entêtes
Organisation : A little, after lunch
Message-ID : <uu9kvb$1532r$1@dont-email.me>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14
User-Agent : Mozilla Thunderbird
On 30/03/2024 16:26, Pancho wrote:
On 30/03/2024 09:17, The Natural Philosopher wrote:
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:
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Maybe ascii art will help
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CONTROL=10µs
____| |________
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RETURN = wahatever
_____|^^^^^^^^^^^^|____________
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Assuming my bleary-eyed math is correct, 10µs is the length of one
cycle of ultrasound at 100,000 Hz.
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The width of that pulse is pretty much immaterial - its only a digital trigger, It doesn't send anything directly.
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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.
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Its a smart device .
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I think that is the part I was missing. I assumed it was like an analog device, out pin was for send and the in pin signalled it was receiving.
On reflection, the code makes sense if it is a smart device. The in pin just goes high (or low) for the period between sending and receiving a few micro seconds of the echo.
https://cdn.sparkfun.com/datasheets/Sensors/Proximity/HCSR04.pdf
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Not the most precise wording.
Having taken the trouble to understand. I might buy one to tell me if my garage door is open. Buy an echo device that is, not a PICO.
Well hook it to a pico and tell a server via wifi that the door is/isn't open!
It seems reiable so far.
Now running of 3 dry cells to see at what point the voltage gets too low for reliable pinging.
-- Canada is all right really, though not for the whole weekend."Saki"