Newbie question?

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designer2k2
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Re: Newbie question?

Post by designer2k2 »

easy debugging :D

just interesting that there are quite some problems with this ic´s :?
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bme30
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Re: Newbie question?

Post by bme30 »

yeah some times being careful isn't enought, but now all looks fine.

I have already tested some functions and on the temperature reading from a vdo sender i am getting a big diference in the temperature value, that is comparing the reading from the temp sensor T1 ( for example) and the reading from the vdo sender.

Using a analog termometer to compare i made a test using hot water, the thermometer was at +/- 40 Cº the temperarute sensor T1 was at +/- 40Cº too and the vdo was reading just about 28Cº, its a big diference and i now that's must be just a case of calibration but i have no idea how to do it, i had done some research but didn't foud a good example to go for.

I am using this sender http://prosportgauges.com/temperature-sender.aspx that reads from 100Fº( 38Cº) at 32 oHms to 302 Fº(150Cº) at 925 oHms and will read the engine oil temperature.
also have the oil pressure sender http://prosportgauges.com/performance-o ... ender.aspx reads from 0 bar at 3 oHms to 10 bar at 160 oHms , i haven't tested that yet so i don't know if also needs calibration.

Another thing that i have notice is that in some connectors if you have noting there the numbers keep bouncing back and foward and some even when conecter doesnt stop , is that normal ? :?
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designer2k2
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Re: Newbie question?

Post by designer2k2 »

the code is written for VDO sensors, your sensor have a different slope so it shows wrong values...

do you have a datasheet from the sensors? i can calculate you then the new lookup tables for them!

all Inputs are floating, means unconnected pins will read crap ;)
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bme30
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Re: Newbie question?

Post by bme30 »

Thanks for the help once more .

I have made some changes to the code for the temperarure sensor and now i am getting some more accurate readings, on the tab functions were you have the code for the temp sensor i have change the LokedupValue from -30 to -12 and the reading band form -40/999 to -12/170 somehow after testin i got beter accuracy maybe +/- 1 cº of error compare to an analog termometer.

I do not have the datasheet for the sensor, i only now that reads from 38cº to 150cº and 32(@28cº) to 925(@150cº), but for now it seems prety good accurate after the changes i have made. After instaling it in the car i wil compare using either the obd or other temperature reading device, either way, it is not very critical de acuracy since that the importante is betwen 80-150 even 150 degrees its a bit too mutch because if your oil temperature reaches that its not a good thing and normaly stays between 90-120 degrees.
The only thing that could hapen (not sure) is that if i conect a diferent sensor, it will not read well if is a diferent one . But for now i'll keep with this one, don't need another for the moment.
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designer2k2
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Re: Newbie question?

Post by designer2k2 »

oh thats an easy change to get it working :up:

and with the good prices from those sensors (VDO´s are around 20€ to 60€) they are a real alternative :)
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bme30
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Re: Newbie question?

Post by bme30 »

well guess i need some help again :( !
All Parts Ready but...
Before i start instaling the MD on the car i have made some final tests mainly to the turbo pressure sensor and oil pressure sensor, after some calibration i got the turbo pressure sensor working like a charm but on the other hand the oil pressure sensor seems not to like me :( .
The sensor that i have reads from 0 to 10 bar @ 3-160 ohms but when i tested and compared it, i get a big diference in the readings and i have already tuned a litle the lookup table but only got good readings til 3.5 bar max .
I contacted Prosportgauges from were i got the sensor and the reply was this:

bar - Volt

1 - 0.5
2 - 1
3 - 1.5
4 - 2
5 - 2.5
6 - 3
7 - 3.5
8 - 4
9 - 4.5
10 - 5

this is the only information that they gave to me about it and i hope that some one can help me figuring out the values for the lookup table, because i have no idea how do to do that.
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designer2k2
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Re: Newbie question?

Post by designer2k2 »

do you have the possibility to attach the sensor to a variable air pressure supply (like a air compressor) ?

if so, attach it and crank up the pressure in steps of 0,5 or 1 Bar and read the resistance from it.

The table they provide cant work as this sensor is only a resistor... I think you will be faster if you measure it yourself ;)
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bme30
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Re: Newbie question?

Post by bme30 »

Yes after i wrote the previous reply i attached the sensor into a air compressor and using at the same time a pressure gauge i was able to figure out the values and now reads prety good, only at 2 bar makes 0.3 error and the rest stays at 0.1 error.
Not a big deal begause the oil pressure does not oscilate very fast like the turbo and 0.3 error isn't very importante.
After calibration of all the sensors all is working well .
For those that are interested is using the same oil sensor from prosportgauges here is my current values:
6 , //0
155, //0.5
390, //1
750, //1.5
870, //2
1093, //3
1160, //3.5
1280, //4
1340, //4.5
1395, //5
1500, //5.5
1899, //6

The sensor is a cheap alternative and reads toa max of 10 bar, mine was set to read only to a max of 6 bar and that is enought, with a 0.1 error and only at 2.0 bar makes a 0.3 error, i will possibly refine that a litle more for more accuracy in the future but for now it works fine.
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