AtD conversion formulas
The Lazy Destroyer
Posts: 21
Hi, need some help!
I've been playing with doing ATD stuff but cannot figure out how to easily convert the digital data from the converter to the proper "reading" I need for my 2p40 project.
For example, if 0.60V is to equal 5.9 inches of vacuum on a sender, how does one go about converting the "492" (read from the 12 bit converter) output to "5.9", when the other values read do not seem linear? I graphed some of the values from a conversion chart I obtained for the sender and it has a wierd slope to it. It looks exponential but starts to slump over
On the sender I'm using, I get:
.3V (246) for "2.9 inches"
.6V (492) for "5.9 inches"
1.1V (901) for "8.9 inches"
1.7V (1393) for "11.8 inches"
2.2V (1803) for "14.8 inches"
2.7V (2213) for "17.7 inches".
I would figure there would be a multiplier and an offset for a conversion like this (example 5.9=492x+y) but this formula does not seem to work with all at once, so I'm assuming a non-linear equasion? It's been forever since I've done this kind of algebra, and I'm sure there is an easy "trick" to getting it, but how do the pro's convert that data? I've googled for a while and still have not found any worthwhile data on this.. there must be an easy way tho to find the conversion....
Any help is appreciated.
-Blake
I've been playing with doing ATD stuff but cannot figure out how to easily convert the digital data from the converter to the proper "reading" I need for my 2p40 project.
For example, if 0.60V is to equal 5.9 inches of vacuum on a sender, how does one go about converting the "492" (read from the 12 bit converter) output to "5.9", when the other values read do not seem linear? I graphed some of the values from a conversion chart I obtained for the sender and it has a wierd slope to it. It looks exponential but starts to slump over
On the sender I'm using, I get:
.3V (246) for "2.9 inches"
.6V (492) for "5.9 inches"
1.1V (901) for "8.9 inches"
1.7V (1393) for "11.8 inches"
2.2V (1803) for "14.8 inches"
2.7V (2213) for "17.7 inches".
I would figure there would be a multiplier and an offset for a conversion like this (example 5.9=492x+y) but this formula does not seem to work with all at once, so I'm assuming a non-linear equasion? It's been forever since I've done this kind of algebra, and I'm sure there is an easy "trick" to getting it, but how do the pro's convert that data? I've googled for a while and still have not found any worthwhile data on this.. there must be an easy way tho to find the conversion....
Any help is appreciated.
-Blake
Comments
Dave
Dave, the sender is a GM MAP sensor for vacuum readings. Hopefully the other senders I'm using (pressure and temp sensors) will be more linear.