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FYSETC / FYSETC-SPIDER

FYSETC Board - 3d printer motherboard for VORON and other open source project.
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Klipper w/ PT100 amplifier, wrong temp #42

Closed Thelm76 closed 3 years ago

Thelm76 commented 3 years ago

Hi, I have a PT100 amplifier from triangle labs connected like this (to get 5V in amp board) : Sans titre

In klipper I tried "PT100 INA826" and "AD595" in sensor-type, with and without ADC voltage to 5V.

I even created my own sensor type using datasheet from E3D amp like this : image image

The temperature table : image

but even if I measure 1.20V-1.24V with a voltmeter on the signal pin (while connected to the board) the klipper displays around 190°C...

EDIT : I just realised my custom sensor was misconfigured, but the issue is still here with this config : image

Heating the hotend with a lighter raised the displayed temp to 213°C with 1.296V measured with voltmeter

Thelm76 commented 3 years ago

I managed to get correct measurements using "PT100 INA286" and removing this pullup resistor from the board (and the filter capacitor but I think it's not mandatory) : image

weirdly, the "adc_voltage" in klipper should remain configured to 5V to get the proper value my hypothesis is that the stm32 is reading the value between 0-3.3V and amp voltage is 3.3V so 3.3V/3.3V, but klipper expects a value betwene 0-5V so adc_voltage should remain to 5V to get this 1:1 ratio.

Further measurements will be needed just to be sure the sensor is properly calibrated

Thelm76 commented 3 years ago

By the way, the amplifier should not be connected to a pull-up pin, so @GerogeFu I have a suggestion, maybe for V1.2 : you should add a way to easily deactivate these pull-up resitors (little switch, or unweldable PCB track) in order to easily put an amp board for pt100