Hi Mark, On Wed, 11 May 2005 10:41:35 -0400, Mark Studebaker <mds at mds.gotdns.com> wrote: >Do you now think the formula is wrong or just hard to understand? Not wrong, hard to understand :) What do you think of this approach to calibration? set sensors to 1:1 for unknowns so we read sensor chip's values ask user for +12V, -5V, -12V BIOS or meter readings calculate 'y = mx + c' transforms for sensors.conf, based on discrete E24 resistor series: one decade for R1, two decades for R2: # ---o--> +12V # | # - # | | R2 ---------------------- -5V, -12V # | | | | ____ ____ # - | 3600mV Vref |--|____|--o--|____|--> # | Vin | | R1 | R2 # o-----------| 0..4096mV | | # | | 0..4096mV |---------- # - | W83697HF | Vin # | | R1 | | # | | ---------------------- # - | # | 0V | 0V # ---o----------------------o---------------------------------> The technique seems viable, and has accuracy better than chip A/D resolution. For those cases where mobo uses datasheet values this technique has no use for end user, but when their voltages are messed up, this technique will give a better answer being based on a discrete set of viable transform 'x' ratios. On reflection, end user doesn't want traceable transforms, that's for driver writers -- and since we scaling lower sensor voltages in user-space now, I doubt it worth changing unless I find errors in transforms. And it is difficult to goof up on 16mV / bit :) I think I now understand the 'datasheets not be trusted' related to their strange formulas, only one datasheet (lm81) had a decent transform, I've had to go back to basics to retrace path you guys already done. Is there a reason why sensors doesn't do the reverse transform for voltage set functions? (rather than the explicit dual compute) Thanks, --Grant.
