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B.... as in Y=MX+B (M is the multiplier and B is the offset, both were required to fit the line to the slope shown by two resistance values... ) Like Brundog says, polynomial would be better, but Pt (and Cu phaux-Pt) probes are both pretty flat.. I may do the polynomial someday... Right...

oh, and don't buy these 3-wire RTD's with quick disconnect from TOPINCN or CrocSee on amazon...... Why? because they are not really three from the sensor back, just the connector back

RTD Update...I received the 0.01% 100ohm and 0.1% 10 and 20 ohm resistors and made up three plugs and spent several hours testing and found a procedure to have a RTD amp calibrated in about a minute... Set up RTD SPI device in BC with multiplier, offset, RTD, and CtoF calibrations in that order...

yeah... I put my fingers on the 100 ohm and the BC displayed temp went *down* a few tenths... pretty much sums my whole experience... but I will get my calibration protocol documented, and it will include zeroing the amps in place where they will be used.

these were all with carbon resistors 100(single resistor), 110(100 soldered in series to 10), and 130ohm(100 soldered to 10 soldered to 20) The ambient change was noted when I brought a box in to my office to test it after testing out in the distillery, but same plugs were used and the new...

Maybe we can swap the RTD Amps, I am going to buy these precision resistors to test them, then put a piece of tape on them with the three raw numbers and the ambient temp. From there, we can add to each others collections of ones that are in the ballpark..

So on the RTD platforms, a few more observations. 1 - The ambient temp of the RTD Amp will raise the raw number about 1 for every increase in degrees F. (I brought a RTD box that was in 95 ambient into conditioned space that was about 80, and the average drop in the raw number was 13) 2 -...

OK, re-assembled after tinning leads that go into the RTD boards from the PG13 connectors, and I recorded raw numbers with ~100Ω and ~110Ω resistors, (in plugs). I will do a higher value later if needed, but I am pretty happy... The error(100Ω ∆ and 110Ω ∆) on both test plugs was pretty...

That picture was of the connector, I figured everyone would know what the image looked like with the resistor moved to the amplifier board. The right three columns have today's data. On GPIO12, it read 7577 for the raw value with the connector as shown, and it read 7576 without it. This...

The difference is 1-3 raw numbers, with an average of 3. (right three columns are raw readings of with and without connector, and the delta.) here is the resistor in the connector I made.

Yes, having the RTD not be autonomous is not ideal... hoping that is someday changed. If you are using PID and you have RTD on an interface that is glitchy, you will lose/gain a few seconds of heating, but the PID is designed to make up for this if properly tuned. more annoying to me are the...

To test the same resistor, I will make a plug connector that goes to screw terminals like the RTD amp boards have and test with the resistor directly in theRTD Amp, and then the plug with the same resistor attached, and test on all boards. Although it will take some time to check all 8 now that...

NTC is basically a 2-wire RTD with a very unlinear curve, the S-H calibrations for that curve make it readable.. even a copper RTD blows it away for linearity... Adafruit boards may have been the high quality ones in the past, but my previous post last December on this subject showed they were...

both terminals are the same in 3-wire mode. They are soldered together on the board at that point shown by the yellow arrow on the right in the phot you attached.

that diagram could be better... you want GPIO18, GPIO19, and GPIO23... in this diagram they are light green on the right VSPI CLK VSPI MISO VSPI MOSI

don't thank me yet, you know I will ask you to integrate it... question, I do not see it in the manual, can we add/delete/edit calibrations via script? @oakbarn - yes, along with fermentation temps of 65°F(wort) to93°F (Molasses) I need the absolute best I can get at the 170-180F range, at...

I am not sure why you would think the wiring is incorrect. A precise 100 ohm resistor measured with RTD would read 0C or 32°F and 99.4 ohms would be interpolated between 99.35 and 99.57 as being between 29°F and 30°F. What we are seeing here is just a small ∆t of less than 1°F All 8 on this...

edited inline to show that it was a single resistor (I did another resistor, and it was about 99.2ohms, and the readings were all about 1.15 degrees F below the 99.4 ohm resistor)... I thought about adjusting the SPI reference resistor value for the device, but not sure exactly how that...

OK, got the #8-32 standoffs in from digikey, 1/4" on the bottom, 7/8" in between and a hex nut on top, and I may just leave it with 2 standoffs, it will not be subject to movement or vibration when I am done. I wired her up and got 8 RTD's on one ESP32 (big thanks to @BrunDog for making this...

so *maybe* if the ESP32-to-tft is implemented the same..... :cool: