Question
Dear Sirs,
using the AD5259 digital potentiometer, I want to make sure, I use the contentsof the tolerance registers correctly if the sign bit is set.
How are negative values in the tolerance registers decoded? The first bit ofthe sign-and-integer byte is set. And then? Mask away the sign bit and use theresult as integer? Or is the encoding a 2's complement?
Unfortunately, the example in the data sheet handles only the case of apositive tolerance value.
Thank you very much for your help.
Answer
The most significant bit, D7 gives you the polarity of the tolerance and theremaining bits will give you the number.
For example,1. MSB=0 and next 7 bits=0011100 would represent +282. MSB=1 and next 7 bits=0011100 would represent -28