If you want I can help you make the "hacked" smoothieware to display the raw data and help you get the curve and formula to plug in IMO I don't care about that much precision as RTD's themselves are very inprecise so first or second way are imo best Second easy way would be to attach a 200k pot instead of the RTD, tweak smoothieware a bit to display "raw" data instead of "temperature" and then make your own curve by comparing temp from the table for 100k rtd and data you get from the smoothiewareīest, but not easy, way would be to read the schematic (I have posted it already on the forum, if you can't find I Can post it again) of the amplifier UP motherboard is using and calculate exactly the transformation between RTD value and ADC value you get on the smoothie cpu. Well easiest way would be to change the 100k RTD to PT100 and use my fork of smoothieware where it works :D Any thoughts on how to use the new sensor since it's not compatible with the signal conditioning for the PT100? I have a third party hotend I've adapted to the up mini but it has a 100K RTD instead of the PT100 element. You have a fair amount of experience with the smoothiware MCU and I was hoping you might still be around these forums. The Up mini now prints PLA without issue and the up mini is useful again Thanks to Arhi and tinyfab for their contributions. After that, the config.txt was modified to inform Smoothieware that the sensor was now a thermistor with a Beta of 3950 and from that point on PLA prints perfectly. A 10uF capacitor was also connected to the junction and ground to stabilize the reading. Then a simple 4.7Kohm pullup resistor was added that connected to a 3.3 Volt source on the MCU to the orange wire from the ribbon and this was connected to the connection at P1.9 on the MCU header. Then the pin on the tinyfab MCU for the extruder sensor (P1.9) had to be cut to isolate the pin from the up mini circuitry. This required cutting the ribbon from the extruder to the main board in order to break out the non-grounded wire for the temperature sensor (orange wire in the ribbon). The stepper/heater assembly purchased was a simple swap except that the new temperature sensor is a 100K type PTC thermistor versus the PT100 NTC sensor on the stock up mini. I previously tried far too many mods thinking the PLA printing issues were a result of the stepper running too hot or the feed gear being too aggressive for the filament but in the end the true issue was heat traveling up the tube from the heater to the throat causing too much pressure for the stepper feed assembly to overcome. It required replacing the extruder assembly with a generic one purchased off of Ebay that uses a PTFE liner in the throat between the stepper feed and the heater. I managed to get the up mini to print PLA reliably with the custom MCU running smoothieware. so it will not be table 10 by 10C but with bunch of random points on the curve but same thing. You don't need super accurate resistors, get a bunch of them between 100 and 250R, you measure resistance, you use the table (or online calculator like: ) you enter the resistance you measure, you check the temperature it represents and then you see what your ADC is reading :D. anyhow, any dmm that will show you 100.00 is good enough, even 100.0 is acceptable. you push 1mA trough resistor and you measure voltage across resistor and you get super accurate resistance value :). This you can do for few bucks, check vast internet knowledge for schematic or ping me I'll draw one for you :). You don't need super accurate anything, any decent dmm is accurate enough at these values, and if you have any electronics knowledge and will to play with it you can make yourself a great precision ohm meter :D. There's always a huge error in temp transfer between a probe and a measured spot, adding a second probe is doubling the error (actually way more then double as you cannot position probe properly) so it's not advisable method. I just have to be sure not to let the heater run away -) I don't have easy access to a super accurate multimeter or a 100 turn pot now I'm a softie not an electronics guy, but I do have a reasonably accurate -50 to 1100C K-type thermocouple meter (thanks to £10 spent on Amazon!) and klipper has a debug console I can use to control the heater then watch the returned adc values as well as the thermocouple measurements to get a calibration curve that way.
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