Hi Jim, > Im looking to understand why my temps are so high, > esp in comparison to values from my soekris as obtained from > http://phk.freebsd.dk/soekris/env4801/ > > VREF = 1.214 V245 = 2.450 > Temp 2 (status=0x81) 54 C > > in your code, > > data->in_vref = (i&0x02) ? 3025 : 2966; > dev_dbg(&new_client->dev, "Using %s reference voltage\n", > (i&0x02) ? "external" : "internal"); > > youve got 2 magical constants, where are they from ? > I cant find mention of them in the pdf, 3.025 is 1.235 * 2.45. Page 227 of the datasheet mentions internal Vref = 1.235V, and at page 180, section 11.3.2 has: "Analog input voltage is measured relative to 2.45 * Vref". In section 14.4.1, external Vref is given at 1.211V, and full scale is given at 2.097, which happens to be 1.211 * 2.45. This is where the numbers are coming from. Now I always found it strange that you could pick an external voltage with a *lower* value than the internale voltage, and not much lower at that. Remember that I do not have a PC87366 chip myself, so had no chance to measure the physical values at a chip's pins to confirm that the driver does the right thing. If you are using an external reference, and it is NOT 1.211 volt, then I am not surprised if your voltages are not correct. Note that the reference voltage is used to compute the voltages and the thermistor-based temperatures, NOT the diode-based temperatures. The TMS logical device is influenced by the reference voltage, but the value isn't used in computations AFAIR. > BTW, (since Im writing), my patchset for pc87366 sensors-dev-attrs > (done against rc4-mm1), also applies (clean, iirc) to rc5-mm1, and > works there. I'm sorry, I didn't have the time to look at it yet. I'm currently busy with i2c core changes and other drivers (i2c-viapro and it87.) Please be patient. -- Jean Delvare
