Tutorial - Air Ride Suspension - Page 2

wrxyboy · 02-24-2009, 02:41 AM

thank you now explaining that and now everything is beginning to make sense. I couldnt make out how the equation would work and cause the values to be negative. Now you you said that 5v will equal 600psi, how is that possible with the sending unit only being able to have a max of 400psi or is it that the unit will never reach 5v thus 600psi will never be obtained. Thank you once again for all your help and great product.

2k1Toaster · 02-24-2009, 02:45 AM

the sensor will never give out a resistance that could possibly equal 5v input, so you would never get 600psi read in. If you for some strange reason did get 5v in, the actual pressure would be off since the equation blows up outside of its bounds, which in reality are closer to 3.3v instead of 5v since that is the max it can handle.

If you want to be more accurate then all you do is measure more data points and create a larger polynomial series.

wrxyboy · 02-24-2009, 03:31 AM

So would this air module function work with the 400psi sending unit or only the 150psi sending unit. I think i may need to purchase the dakota digital reading unit to make the equation more accurate.

2k1Toaster · 02-24-2009, 05:46 PM

Quote: Originally Posted by wrxyboy

So would this air module function work with the 400psi sending unit or only the 150psi sending unit. I think i may need to purchase the dakota digital reading unit to make the equation more accurate.

No it only works with the 150psi one.

If you want to use the 400 one then you would need to write a seperate function that would calibrate that

GizmoQ · 02-24-2009, 06:43 PM

Quote: Originally Posted by 2k1Toaster

No it only works with the 150psi one.

If you want to use the 400 one then you would need to write a seperate function that would calibrate that

Can you check my math on the 400psi polynomial from the other air pressure thread?

KennyKen · 03-17-2009, 11:23 AM

Hi All

Can i just check my wiring here as im in the middle of setting this up. Does this look right:

And is that the correct size resister for the 150psi Dakota unit?

Thanks in advance
Ken

greenman100 · 03-17-2009, 01:58 PM

resistor size doesn't really matter, as long as you use one around 100 ohms. you then use the voltage divider formula and resistance to PSI conversion posted above in MDX to get PSI

greenman100 · 03-17-2009, 01:58 PM

nick might make a function that does this automatically... would be pretty sweet.

greenman100 · 03-17-2009, 01:58 PM

like a curvefitting function

KennyKen · 03-17-2009, 02:01 PM

Are you talking about the
airridepressuresensormodule.xml
airridepressuresensormodule.designer
files

As far as i was aware they do the job of taking the input (voltage) and converting it to the Output (Psi).

Is that not correct?

Thanks
Ken

greenman100 · 03-17-2009, 03:43 PM

those will work if Nick posts the resistor he used while building those files

greenman100 · 03-17-2009, 03:48 PM

nick confirmed: his code is based on a 100ohm resistor.

KennyKen · 03-18-2009, 04:57 AM

perfect. thanks for that

KennyKen · 04-12-2009, 05:15 AM

Hmm ive got this thing wired up like my diagram above and i am getting a reading of 452, surely on a 150psi unit that's not possible.

edit
This is the airridepressure function:

KennyKen · 04-12-2009, 01:47 PM

Ok im going back to basics here.

Forget PSI for the moment, lets just work with voltage, if i open up the standard skin and plug in the sensor on its own with no resistor and no PSI converter i get 4.87 which is the volts obviously

However if i then install the 100ohm resistor, that voltage should still change to a much lower figure surely, well this doesn't change at all which leads me to assume ive got something wired incorrectly.

Is there anyone out there who has actually got a pressure sensor working on this FB board?

Ive got it exactly wired as in my picture above, can anyone shed any light on the subject as ive hit a wall right now.

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