thefekete / lm75 Goto Github PK

Hello!
First, let me thank you for uploading your library! :)

There seems to be a little problem with the power down mode on the LM75B from TI.

After enabling the shut down and then disabling it it will not update the temperature annymore.
The Thyst and Tost registers cann still be read and be written to though.
As far as i can make it out, it should work just fine, but i am not that smart ;^^

Maybe you can have a look, i am using the demo code from the library without anny changes.

Greetings,
Peter

Doesn't take negative temperature
Transformation isn't correctly executed

Hi,

First of all thank you very much for this library.

I think the library shows incorrect temperature when the temp is negative. According the LM75 datasheets the most significant bit (D15) contains 1 when value is negative.

In your case the temp value should be subtracted by 0x100 to get the right (negative) value.

float LM75::regdata2floattemp (word regdata)
{
  float temp = ((float)(int)regdata / 32) / 8;
  if (regdata >> 15) temp -= 0x100;
  return temp;
}

Also think that D0..D6 (don't care bits) should be masked. Not sure though...