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REPLYADDR Pancho.Jones@proton.me
REPLYTO 3:770/3.0 UUCP
MSGID: a44348bb
REPLY: 2a461d54
PID: SoupGate-Win32 v1.05
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 ,
>> The Natural Philosopher 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 .
>
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
>
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.
--- SoupGate-Win32 v1.05
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