NTC calibration

🎄🎄☃️🎄🏂🎄 (documentation)

Table of contents

• Introduction
• Running the application
• Other methods to retrieve the voltage from the ADC signal
• Calibration results
• Contributing

Introduction

Makes use of the Steinhart-Hart equation to calibrate thermistors. This is achieved by:

• Retrieving an analog to digital converted signal via a microcontroller, This value is related to the resistance of the micro controller.
• Fetching the resistance of the Thorlabs TSP01 temperature logger.

Afterwards, these values are feeded into the Steinhart-Hart class and will be used to calibrate the coefficients.

Running it

Make sure that you've installed the requirements

pip install -r desktop/requirements.txt

Just run with your python3 interpreter:

python main.py

NOTE: Some users will not be able to detect the torlabs TSP01 sensor, this can be caused by:

• Not having the pyusb library installed (see link for install instructions)
• The current user on you desktop is not able to see the devices
  • Try adding your current user to the dialout group
  • run main.py with superuser permissions

Other method to retrieve the voltage from the ADC signal

If your circuit doesn't make use of a (simple) voltage devider, you will need another conversion method. This can be achieved by: Creating a method in config.py

Calibration results

Al the values (reference temperature, ntc_resistor value, predicted temperature, the coefficients, ...) will be stored in a .csv file. This can be used in e.g. Jupyter Notebook to analyse the quality of the calibration.

The succeeding table gives an overview which data elements are stored

RNTC	Tprobe	Tcalc	A	B	C	T1	R1	T2	R2	T3	R3
Ω	°C	°C	\	\	\	°C	Ω	°C	Ω	°C	Ω

Column	description
RNTC	The calculated resistance (via the retrieved ADC value) of the thermistor
Tprobe	The temperature of the TSP01 temperature probe
Tcalc	The calculated temperature of the termistor, based on RNTC and the Steinhart-Hart coefficients
A	Steinhart-Hart coefficient A
B	Steinhart-Hart coefficient B
C	Steinhart-Hart coefficient C
T1	The first reference temperature used for calculating the coefficients
R1	The first resistance used to calculate the Steinhart-Hart coefficients
T2	The second reference temperature used for calculating the coefficients
R2	The second resistance used to calculate the Steinhart-Hart coefficients
T3	The third reference temperature used for calculating the coefficients
R3	The third resistance used to calculate the Steinhart-Hart coefficients

Contributing

If you have some amazing ideas, just create a pull request ¯\_(ツ)_/¯.