150 PSI Air Pressure Sensor

**Ryann** · 12-13-2007, 02:24 AM

Thanks a million 2k, im going to have another play tonight, can i run it off the 12v to get a more broad range?

im a lil worried about accuracy with having only 5v range over 150psi.. this will be adjusting my airride so it will have to be rather accurate and hopefully pretty fast..

i think ill leave most of my final stuff until uber is ready..

**2k1Toaster** · 12-13-2007, 02:40 AM

You can run it off of 12v, but then you would need to divide it back down to 0-5v. The FB only supports 0v-5v input, so sending in 12v would release some magic smoke.

The resolution is determined by the PIC. We have 10bit resolution. Some people have 8bit, others 12 I believe (in a similar to 3 times price range, but they obviously go much higher, think premium sound cards

). So 10bit resolution is 1024 available steps. So 150PSI divided by 1024 (2^10) steps, means you have a 0.14PSI resolution no matter what. If it were 8bit, you would only have 0.6PSI/step resolution.

How accurate are you looking for?

And I have my final exams this week, and then I leave out of the country on the 20th, so I will try to get Uber "releasable" after exams, and before me leaving, as internet on the island is spotty at best. I think it is just a few satallite dish's splitting the internet over the whole island, so no uploading of big files, that is for sure.

**Ryann** · 12-13-2007, 03:05 AM

i would like to at least determine between 1-2 psi range.. max 5

even if i could adjust and set my ride heights at say 100 psi for front 2 and 50 for rear two..

them being within a 5psi range wouldnt really harm me.. wouldnt be noticable..

i want to be able to have presets were,

for the 10seconds following the click.. intialize the height, based off the bag pressures.. readjusting them.. then it wont check it until say 2min later were it will re-initialise... very similair to the dakota system.

having the range jumping over the place will be a problem, so maybe averageing them will be my best bet.

OK, with zero psi in my bag, im getting 0.313 and it fluctuates at times upto 0.391

with it at about 80-100psi unconfirmed (no pressure gauge on as yet) it was at 2.633 and it also fluctuated.

this sounding about right? how can i go about it just showing 2 decimal places?

also out of the inputs were does 0 start from?.. 0 and 9 are sharing the signal pretty much the same.

**greenman100** · 12-13-2007, 06:52 PM

Let me explain the "signal sharing".

The way the PIC works, is it connects a capacitor to the input in question. Then, it disconnects the input, and measures the capacitor. Then, it moves to the next input. If there's nothing connected to change the voltage level in the capacitor, some charge remains. The PIC should check inputs 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and back to 0 again.

**Ryann** · 12-13-2007, 08:33 PM

thanks greenman. Makes perfect sense now. I was worried that maybe having them all connected next to eachother was going to influence one another therefore making my readings less accurate.. But obviously this isnt the case.

**greenman100** · 12-18-2007, 01:06 PM

Originally Posted by Ryann

thanks greenman. Makes perfect sense now. I was worried that maybe having them all connected next to eachother was going to influence one another therefore making my readings less accurate.. But obviously this isnt the case.

nope, as soon as you attach a signal to a input, it'll charge that capacitor to that value, and teh reading will be correct.

**greenman100** · 02-29-2008, 03:24 PM

The ground (middle pin) of the fusion brain does not need to be connected as long as you have clean grounds on the sensor itself. This is very important.

see this thread regarding the importance of clean grounds:

http://www.ridetech.com/forum/showthread.php?t=3148

The others must be connected.

**Ryann** · 03-12-2008, 05:13 AM

Very helpful thread link green, my senders off my airline is right next to were my battery will lie, i may have to run the ground on the battery, or the VDO's at opposite ends or as fas as possible away by the sounds of it.

this is probably the reason i was getting funky readings whilst testing.. ill look into it.

**rgarjr** · 03-20-2008, 10:04 PM

I'm trying to understand how the FB can interface with the air sensors and the dakota digital meter that I currently have right now. Does this look right?

My setup includes 5 of 0-400PSI air sensors and I have the digital meter displaying the 5 different pressures.

**greenman100** · 03-20-2008, 11:41 PM

it's impossible to know if you can connect the dakota digital and the fusion brain at the same time without knowing how the dakota digital meter works.