SunFounder ESP32 Starter Kit
Each thermistor has a normal resistance. Here it is 10k ohm, which is measured under 25 degree Celsius.
When the temperature gets higher, the resistance of the thermistor decreases. Then the voltage data is converted to
digital quantities by the A/D adapter.
The temperature in Celsius or Fahrenheit is output via programming.
Here is the relation between the resistance and temperature:
RT =RN expB(1/TK - 1/TN)
• RT is the resistance of the NTC thermistor when the temperature is TK.
• RN is the resistance of the NTC thermistor under the rated temperature TN. Here, the numerical
value of RN is 10k.
• TK is a Kelvin temperature and the unit is K. Here, the numerical value of TK is 373.15 + degree
Celsius.
• TN is a rated Kelvin temperature; the unit is K too. Here, the numerical value of TN is 373.15+25.
• And B(beta), the material constant of NTC thermistor, is also called heat sensitivity index with a
numerical value 4950.
• exp is the abbreviation of exponential, and the base number e is a natural number and equals 2.7
approximately.
Convert this formula TK=1/(ln(RT/RN)/B+1/TN) to get Kelvin temperature that minus 273.15 equals
degree Celsius.
This relation is an empirical formula. It is accurate only when the temperature and resistance are within
the effective range.
Learn More
You can also display the calculated Celsius and Fahrenheit temperatures on the I2C LCD1602.
Note:
• You can open the file 5.10_thermistor_lcd.ino under the path of euler-kit/arduino/5.
10_thermistor_lcd.
• After selecting the board (ESP32 Dev Module) and the appropriate port, click the Upload button.
• Always displaying “Unknown COMxx”?
• The LiquidCrystal I2C library is used here, you can install it from the Library Manager.
1.27 5.11 Toggle the Joystick
If you play a lot of video games, then you should be very familiar with the Joystick. It is usually used to move the
character around, rotate the screen, etc.
The principle behind Joystick’s ability to allow the computer to read our actions is very simple. It can be thought of as
consisting of two potentiometers that are perpendicular to each other. These two potentiometers measure the analog
value of the joystick vertically and horizontally, resulting in a value (x,y) in a planar right-angle coordinate system.
The joystick of this kit also has a digital input, which is activated when the joystick is pressed.
Required Components
In this project, we need the following components.
94 Chapter 1. For Arduino User
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