I have a RAMPS 1.4 and an Arduino Mega 2560. The problem is with 100k NTC thermistor. I've tested it with a multimeter, it results in ~122kΩ.

I am using Marlin 1.0.2 (latest stable). I am using an MK8 extruder and do not receive temperature readings from the thermo-sensor - no matter how I connect it. However, on APrinter firmware it works flawlessly.

In configuration.h, I have tried most of the options, but found "1" is the best one for me.

Executing m105 on Marlin, I get following result:

ok T:0.0 /0.0 B:0.0 /0.0 T0:0.0 /0.0 @:0 B@:0

On APrinter, the result is different:

ok B:-inf /nan T:25.2076 /nan

I have not connected bed thermistor yet.


#define TEMP_0_PIN          1  // Extruder / Analog pin numbering
#define TEMP_BED_PIN        0  // Bed / Analog pin numbering


#define TEMP_SENSOR_0 1



After switching back and forth from Marlin to APrinter and back, Marlin stopped woking completely. I had configured the LCD (ReprapDiscount Smart Controller) and all the steppers were working. Right now, it does not even sends self test to Pronterface upon start/connection, or it hangs according to the log.

Pronterface output

Printer is now online.
echo: Last Updated: Jul 25 2016 17:12:39 | Author: (Rustam Rahimgulov, default config)
Compiled: Jul 25 2016
echo: Free Memory: 3971  PlannerBufferBytes: 1232
echo:Hardcoded Default Settings Loaded
echo:Steps per unit:
echo:  M92 X80.00 Y80.00 Z4000.00 E836.00
echo:Maximum feedrates (mm/s):
echo:  M203 X500.00 Y500.00 Z2.00 E25.00
echo:Maximum Acceleration (mm/s2):
echo:  M201 X9000 Y9000 Z100 E10000
echo:Acceleration: S=acceleration, T=retract acceleration
echo:  M204 S300.00 T3000.00
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s),  Z=maximum Z jerk (mm/s),  E=maximum E jerk (mm/s)
echo:  M205 S0.00 T0.00 B20000 X20.00 Z0.40 E5.00
echo:Home offset (mm):
echo:  M206 X0.00 Y0.00 Z0.00
echo:PID settings:
echo:   M301 P22.20 I1.08 D114.00
ec  (nothing more here, output just ends)
  • $\begingroup$ What happens if you manually request temperatures with M105? What is "aprintr firmware"? $\endgroup$ Jul 24, 2016 at 21:16
  • $\begingroup$ a) As far as I've encountered 100K thermistors, they usually give closely around 100K resisivity at room temperature. b) when you're talking about configuration.h, you mean in Marlin? Have you made sure that your Marlin is in working condition otherwise and has not been flawed during transfer? $\endgroup$
    – kamuro
    Jul 25, 2016 at 8:21
  • 1
    $\begingroup$ Do you have the thermistor plugged into the right socket? Perhaps aprintr is reading the temperature from a different pin than Marlin is configured to. $\endgroup$ Jul 25, 2016 at 12:21
  • 1
    $\begingroup$ I meant that you should check whether the pin that marlin is configured to read the temperature from (in pins_ramps_14.h) corresponds to the physical pin your thermistor is plugged in to. $\endgroup$ Jul 25, 2016 at 12:39
  • 1
    $\begingroup$ @TomvanderZanden There are so many redefinitions of the temp_0_pin that it's very hard to trace if it's correct or not. I can find lines that assign analogue pins 13 and 15 to bed and extruder sensors. $\endgroup$
    – hrust
    Jul 25, 2016 at 13:43

1 Answer 1


In the actual Marlin Firmware all supported printer boards are listed within the file "boards.h". This file contains the following entries for the RAMPS 1.4:

#define BOARD_RAMPS_13_EFB  33 // RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Bed)
#define BOARD_RAMPS_13_EEB  34 // RAMPS 1.3 / 1.4 (Power outputs: Extruder0, Extruder1, Bed)
#define BOARD_RAMPS_13_EFF  35 // RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Fan)
#define BOARD_RAMPS_13_EEF  36 // RAMPS 1.3 / 1.4 (Power outputs: Extruder0, Extruder1, Fan)

The most common version may be the variant . In this case you have to set the value as the following lines show.


Enable Display


Ok, it's time to make the adjustments specific to your 3d printer. You might first check the setting for the amount of extruders at around line 58. Most 3d printer rookies may start with one extruder, so the default entry of '1' is quite sufficient.

// This defines the number of extruders

#define EXTRUDERS 1

At around line 70 you have to set up the thermistors connected to the RAMPS for the extruder and the heatbed. Depending on your hardware configuration you have to change the last value in the defines.

#define TEMP_SENSOR_0 -1
#define TEMP_SENSOR_1 -1
#define TEMP_SENSOR_2 0

The define for TEMP_SENSOR_0 determins which thermistor type is assembled at the hotend of extruder 1. This termistor has to be connected to the first sensor input (see also wiring schema). The thermistor for the heatbed has to be connected to the second sensor input. The thermistor type is configured with the define line of 'TEMP_SENSOR_BED'. If you use a thermistor of the type EPCOS B57560G104F (100K, Beta = 4036), you write the value '1' into the matching define. In case you have a thermistor with 100k and Beta = 3950, you have to set the value '60' in the corresponding define. So the defines will look e.g.:

For EPCOS (Beta = 4036) on hotend and heatbed:

#define TEMP_SENSOR_0 1
#define TEMP_SENSOR_1 -1
#define TEMP_SENSOR_2 0

For Beta = 3950 on hotend and heatbed:

#define TEMP_SENSOR_0 60
#define TEMP_SENSOR_1 -1
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 60

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .