# How to setup 3.5k thermistor parametars in Marlin 2.1.2.1

Posted by lukaari
 How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 27, 2024 03:38AM Registered: 4 years ago Posts: 42
Hello,

I need help configuring the Marlin 2.1.2.1 to use thermistor which resistance is 3,5k at 25C.

I am using MKS Gen L board V1. I tested several options config file but I always got reading over the 100C.

I think you for any help or recommendation

Edited 2 time(s). Last edit at 01/28/2024 11:36PM by lukaari.
 Re: How to setup 4.7k thermistor parametarsin Marlin 2.1.2.1 January 27, 2024 08:29AM Admin Registered: 13 years ago Posts: 7,045
You need to generate your own thermistor table

Use the script buildroot/share/scripts/createTemperatureLookupMarlin.py
 Re: How to setup 4.7k thermistor parametarsin Marlin 2.1.2.1 January 27, 2024 12:37PM Registered: 4 years ago Posts: 42
Thank you very much
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 28, 2024 10:33PM Registered: 4 years ago Posts: 42
Hello,

I still need the help creating the thermistor lookup table.

Can thermistor lookup table be created form the known temperature and measured voltage on the thermistor?
Thermistor resistance R 3.5k @ 25c board pull up resistor 4.7K supply voltage 5V

I measured the temperature and voltage on the sensor, but I have trouble creating the table.

There is the formula but something is messing, I am not sure what, maybe scaling to the 1024 max?

Here is the table of the voltage vs temperature.

Thermistor resistance R 3.5k @ 25c pull up resistor 4.7K supply voltage 5V

Voltage: Celsius:

0.637 - 70c
0.786 - 65
0.940 - 60
1.090 - 50
1.395 - 45
1.556 - 40
1.741 - 35
1.921 - 30
2.126 - 25
2.421 - 20
2.878 - 15
3.095 - 10
3.30 ---- 5
3.40 ---- 0
3.69 ---- -5

Any help appreciated,

Thank you

Edited 1 time(s). Last edit at 01/28/2024 10:37PM by lukaari.
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 29, 2024 01:23AM Admin Registered: 13 years ago Posts: 7,045
covert voltages 0-5v to adc values 0-1023 ie voltage * (1023/5) and round the results to nearest Integer

eg

```constexpr temp_entry_t temptable_1[] PROGMEM = {
{ OV( 130 ), 70 },
{ OV( 161 ), 65 },
{ OV( 192 ), 60 },
{ OV( 223 ), 50 },
{ OV( 285 ), 45 },
{ OV( 318 ), 40 },
{ OV( 356 ), 35 },
{ OV( 393 ), 30 },
{ OV( 435 ), 25 },
{ OV( 495 ), 20 },
{ OV( 589 ), 15 },
{ OV( 633 ), 10 },
{ OV( 675 ),  5 },
{ OV( 696 ),  0 },
{ OV( 755 ), -5 }
}```

Edited 2 time(s). Last edit at 01/29/2024 01:43AM by Dust.
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 30, 2024 12:57AM Registered: 4 years ago Posts: 42
Perfect, it work nicely.

Question:

a) Is there any plan to add the cooler as a part of the existing temperature management with pid and pid autotune in the future development?

b) Is there any possibility of modifying any of the existing pid loops to accommodate the cooling mode? and what will be the process to make this addition?

Thank you very much,
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 30, 2024 01:59AM Registered: 4 years ago Posts: 42
Perfect, it work nicely.

Is there any plan to add the cooler as a part of the existing temperature management with pid and pid autotune in the future development?

Is there any possibility of modifying any of the existing pid loops to accommodate the cooling mode? and what will be the process to make this addition?

Thank you very much,
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 January 30, 2024 11:03PM Admin Registered: 13 years ago Posts: 7,045
Marlin already has a cooler function, but it does not use pid, it uses a simple hysteresis loop.

Marlin is community driven, there a very few actual plans, someone wants something and has the skills to add it simply adds it
 Re: How to setup 3.5k thermistor parametars in Marlin 2.1.2.1 February 02, 2024 11:46PM Registered: 4 years ago Posts: 42
Hello,
Unsure whether to create new topics or continue ..moved to the new topics, I appolologize .

Edited 1 time(s). Last edit at 02/03/2024 12:48AM by lukaari.
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