Problem with Titan Aero Thermistor

Discussion in 'Titan' started by Lambi, Mar 15, 2019.

  1. Lambi

    Lambi Member

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    Ok, so this will probably a rather long post, but I hope someone is able to help me with my issue. In short: I can't get the thermistor from the Titan Aero to provide any usable output.

    I am using a Up Mini printer from Tiertime. Originally, these are closed source, but some smart user managed to hack them and created a new CPU for it running smoothieware firmware, providing wireless access via esp3d. I ordered and installed it, and after some inital tinkering it ran fine with the stock extruder (I attached the original config for the stock extruder to this post).
    Then decided to upgrade the extruder to a Titan Aero (24v). Created a custom mount, assembled and mounted the extruder, everything fine so far. Configured the firmware as per the instructiones; however, when I start up the printer and connect via the esp3d-webui, I do not get correct temperature values from the thermistor. It either reads 84°C (if no homing command was sent yet), or "inf", if the printer has been homed.
    First suspected a bad thermistor, so took it out and tried to get some readings with a multimeter. When set to 20k, I get a reading of about 110 on the multimeter, which seems fine to me; so the thermistor seems to be in good shape.
    Then tried different configuration settings, nothing has worked so far.
    Temporarily re-attached the old thermistor from the stock extruder, and get correct readings again, so it doesn't seem to be an issue with the specific pin.
    The only possible issue left I can think of is a connection problem between the plug from the Titan thermistor and the small PCB on the extruder (this printer has a rainbow cable running from the motherboard to a small PCB on the extruder to which the electronics of the extruder are connected), but I am not particularly confident, that this is actually the problem.

    The configuration part for the hotend within the smoothie-config looks like this:
    # First hotend configuration
    temperature_control.hotend.enable true
    #temperature_control.hotend.sensor pt100
    temperature_control.hotend.thermistor_pin 0.23
    temperature_control.hotend.thermistor Semitec # see http://smoothieware.org/temperaturecontrol#toc5
    #temperature_control.hotend.ampmod1_pin 1.20 # UP! printer uses this to "energize" the RTD
    #temperature_control.hotend.ampmod2_pin 1.21 # set as nc if you don't need to energize RTD
    #temperature_control.hotend.slope 0.0257604875
    #temperature_control.hotend.yintercept -18.54
    temperature_control.hotend.heater_pin 2.7
    temperature_control.hotend.set_m_code 104
    temperature_control.hotend.set_and_wait_m_code 109
    temperature_control.hotend.designator T
    temperature_control.hotend.max_temp 290
    temperature_control.hotend.min_temp 0

    # Safety control is enabled by default and can be overidden here, the values show the defaults
    # See http://smoothieware.org/temperaturecontrol#runaway
    #temperature_control.hotend.runaway_heating_timeout 1200 # How long it can take to heat up, max is 2040 seconds.
    #temperature_control.hotend.runaway_cooling_timeout 0 # How long it can take to cool down if temp is set lower, max is 2040 seconds
    #temperature_control.hotend.runaway_range 50 # How far from the set temperature it can wander, max setting is 63°C

    ## PID configuration
    ## See http://smoothieware.org/temperaturecontrol#pid
    temperature_control.hotend.p_factor 22 #23.0
    temperature_control.hotend.i_factor 1.047 #1.104
    temperature_control.hotend.d_factor 115 #120

    #temperature_control.hotend.max_pwm 255 # max pwm, 64 is a good value if driving a 12v resistor with 24v.​

    I commented (removed) everything from the stock extruder configuration, that (in my mind) wasn't necessary for the new hotend (original configuration see attached).

    Due to my testing of the thermistor and the plugs on the PCB I do not suspect a mechanical issue, so the only thing I can think of is a missing / wrong setting in the configuration file.
    Anybody got any idea what I am doing wrong?

    Thanks!
    Florian
     

    Attached Files:

  2. Lambi

    Lambi Member

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    Searched around a bit, and I think I might be on to the root of the problem: my board and stock extruder originally used a PT100 temperature sensor, the Titan Aero of course comes with a Semitec thermistor. It looks like to me the board cannot immediately read the input from the semitec...

    Anybody got an idea on how to make a semitec thermistor work in this circumstance? Otherwise I'll have to get another pt100 (can't remove the old one) to replace the semitec in the titan.
     
  3. jfb

    jfb Well-Known Member

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    I'm not aware of any easy way to do that. The linearity is completely different, so even if you added, say, a resistor to bring the thermistor's resistance at ambient temperature into line with a PT100, as soon as the termperature goes up the readings will be totally different. If your firmware allows you to specify the temperature table (x resistance = y temperature) then you may be able to do it that way. Otherwise you'd need a small circuit to do the translation for you - more or less like the boards that work the other way to allow use of a PT100 with boards that expect a thermistor.

    Really, the best option is to just buy a PT100.
     
  4. Lambi

    Lambi Member

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    I assumed as much, thanks for the input (had hoped there was a possibility to somehow translate the values, but didn't find any information on the web...). Already ordered a PT100 which should fit the Titan heater block, let's see if that was actually the issue in the first place.

    Thanks!
     

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