Temperautre Defective at -50.88oC

edited November 2014 in Extruder & Bed
Hi All

I have a slight issue with trying to sense temperature and was wondering if anyone can please help.

I have a J Head with temp sensor in, this is an epocs sensor.

Resistance reading: around 100k
V reading out the T pins: around 4.5 to 5

When i heat up the temp sensor it changes the resistance also the voltage from the pins. That should mean that everything is working well, however on my software i am getting a reading of -50.88 degrees C

Please may someone help me fix this issue.

I have an Arduino mega with Ramps 1.4 using repetier firmware and host

Kind Regards
Josh


Comments

  • Make sure you have selected the right sensor type. If it doe snot change with heating extruder, the sensor pin in firmware does not match the pins where you connected.
  • hmm, I have tried a few different sensor types. What pin on the arduino does repetier look at for T0 please? I will try plugging it directly into there as a test.
  • T0 would be TEMP_0_PIN = analog pin 13. Be aware that T0 has an 4,7K resistor between 0v and 5v in addition to your thermistor.
  • OK well i have tried all of the above, and all i get is the minimum temp i set the thermoster to have, I have tried doing a generic table, working out my beta and testing, still not working. my thermistor definitely works. Is there something stupid that I am doing?

    I have tried using analogue 3 off to the side of the board too which also does not work.

    I must be doing something really wrong nobody else seems to get this same problem.

    It would be brilliant if someone could take a look at my code and check to see what I am doing wrong.

     

    Any help would be much appreciated. This the last hurdle to getting my printer extruding as everything else works.

  • Oh, I dont get -50.88 now  I usually get whatever the thermisters lowest value is on the settup. i.e. -20. This can also be held at 0.0 depending on which thermister i select. but none of them not even my custom tables actually give me a value that changes.
  • You can send 

    M105 X0

    tehn you see also the raw values. I guess they are 0 or 4095 every time meaning no sensor is attached to the pin you said it should read. The pin is defined by

    #define EXT0_TEMPSENSOR_PIN TEMP_0_PIN

    or whatever you selected there. Be aware to use an analog pin number, not a digital one.
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