micro seconds per inch...

denno · 2025-11-25 18:24

Using the "PING" from Parallax. I'm just wondering what is being used for the above title. I have been using 72 uSec/inch. I'm making a digital readout for my diesel fuel tank for the furness up here...I do know that temperature can effect the numbers. But I am only sounding 24 inches..
Thanks

JonnyMac · 2025-11-26 21:30

I wrote the original Ping))) demo code for the BS2 when I worked for Parallax.

In the code I used 73.746 inches per microsecond. It's a specific number, so I must have looked it up somewhere.

RawToIn         CON     889             ' 1 / 73.746 (with **)

Now, we cannot [directly] divide by 73.746 so we have to use ** operator. How do we get 889? We take the fractional value and multiply by 65535.

(1 / 73.746) * 65535 = 888.658 (rounded up to 889)

The return pulse represents a round trip so we have to divide by two for the sensor-to-object value.

Get_Sonar:
  Ping = IsLow                          ' make trigger 0-1-0
  PULSOUT Ping, Trigger                 ' activate sensor
  PULSIN  Ping, IsHigh, rawDist         ' measure echo pulse
  rawDist = rawDist */ Scale            ' convert to uS
  rawDist = rawDist / 2                 ' remove return trip
  RETURN

JonnyMac · 2025-11-26 22:46

I did a quick query on Grok:

If you want to go with Grok's number, the RawToIn value would become 882. Now that you know the process, you can decide what's best for your code and adjust as needed.

denno · 2025-11-29 21:57

Wow, Jon, you have helped me again...I have been using stamps and pbasic since the very 2000's. I was really sorry to see the BS2sx go obsolete. Sort of like me, I guess. Anyway, living up here in the frozen north, I am using the PING in an opening, in the tank top, covered, snow, rain proof, to determine the diesel level inside the tank, for my furness. Having to go out in the winter's snow, and hand stick it got, well...no fun. Using a Parallax LCD for the readout. I used to use Scott Edward's LCD's, and he to is going out of business the end of this year. Thanks again...for your help.

Buck Rogers · 2025-11-30 05:33

@denno said:
Wow, Jon, you have helped me again...I have been using stamps and pbasic since the very 2000's. I was really sorry to see the BS2sx go obsolete. Sort of like me, I guess. Anyway, living up here in the frozen north, I am using the PING in an opening, in the tank top, covered, snow, rain proof, to determine the diesel level inside the tank, for my furness. Having to go out in the winter's snow, and hand stick it got, well...no fun. Using a Parallax LCD for the readout. I used to use Scott Edward's LCD's, and he to is going out of business the end of this year. Thanks again...for your help.

Hello!
That's a good application. You mean furnace. The word you used is someone's name, Furness as in an actress and a moderately famous one. Frozen north? One of my cats wants to know where that is.
Hungry mascot.

micro seconds per inch...

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