Offset 11D0 (TAT)

[Edoradar]

Hello Peter, I noticed that using this offsets, it behaves in a strange way when goin on low temperatures.

When approaching TAT of 0 degrees, the offset normally decreases till 0 and then suddenly jumps to 65353 and as the temperature decrease also this values decrease. Basically once converter / 256, if above 0 degrees it works ok, while when at or below 0 degrees, you have to subtract 255 from the final value. Is it at you thought to model it or should it be corrected?

I use also SAT offset and that one works normally...

Thanks

Edoardo

[Pete Dowson]

When approaching TAT of 0 degrees, the offset normally decreases till 0 and then suddenly jumps to 65353

Temperatures are SIGNED values -- they have to be, of course! 65353 is the unsigned interpretation of -183 (i.e. -0.715 degrees).. You must always treat numbers in the correct way or you will be bound to get wrong answers! In a 16-bit word, signed values go from -32768 to +32767, unsigned from 0 to 65535. There is no such value as 65353 in a 16-bit signed word.

Pete