How to adjust values to a new range

[Demon]

This has been covered many many times on the forum so why not one more time...

You've explained it, using my own problem as example, and I still don't completely understand it. My eyes sort of gloss over when I've read these explanations on the forum. And it's not getting better as I get older.


I really do appreciate you holding my hand while you pound this into my skull.

[HenrikOlsson]

Allright...

[1] I believe you're with me for the 135/1023=0.132 part, right?

[2] IF the description for the */ operator WOULD have said "....resulting in an automatic division by 1000" then I think you'd see that the solultion WOULD be OutputValue = 100 + (InputValue */ 132), because 0.132*1000=132, correct?

[3] But since the */ operator "....resulting in an automatic division by 256" we must multiply 0.132 by 256 instead of 1000. Hence the value 34.

Makes sense? If not, which step?

[Demon]

I follow. I just could not have thought of this by myself.

[Ioannis]

Or maybe use a formula

X=135*256/1023

where X is the number you wan to use in the */

135 is the max scale value

1023 is the max ADC value

Ioannis

[amgen]

error posting

[Demon]

not to beat this up too much........

A horse is never too dead on the web.

... if you only need 135 output values, and you want to scale pot for 0 to 100%..... just use the top 8 bit from a/d and this trend line function that excel gave.

I can't believe I was playing with excel all that time and never thought of using the chart feature.

[Demon]

My ADC is only 10 bits, not 16.

So I just divide 10bits by 4 to reduce from 1023 down to 255, then slap it through your formula.

I haven't done any math yet (just thinking, while I work on my encoder logic), but this probably equates to what Ioannis is suggesting.

[amgen]

deleted because I realized the formula excel created was not correct...... me bad