ArduinoPIDCtrl : Simple Arduino PID Controller developped in C#

Screenshots

Features

This is greatly inspired by the "Dark room experiment" used to demonstrate the use of a PID controller : https://www.instructables.com/id/Arduino-PID-Library-Luminosity-Control/

• Setpoint (0-255), Sample time (ms) as well as P, I and D coefficients can be adjusted on the fly
• Setpoint, input (LDR) and output (LED) values are displayed on the graph

Project structure

• README.md -> that the file you are reading now
• Screenshots -> behavior of the app
• Schematics -> Fritzing schematics and captures
• ldr_read -> Arduino project
• PidCtrl -> Visual Studio project
  • PidCtrl\PidCtrl\bin\Debug\PidCtrl.exe -> latest version of the Windows app
• LDR_calc.xlsx -> File to test different resistor values for the LDR

Schematics

Wiring

• A0 - R1 - GND
• A0 - LDR - Vcc
• D3 - LED - R2 - GND

Resistor values

• R1 sets the range of the input and depends of the LDR used. Measure the LDR value when in the dark and illuminated by a bright light. For example for R1=100kΩ, R_high=800kΩ and R_low=5kΩ the voltages would be :
  • R_high/(R_high+R1)*Vcc = 800/(800+100)*5.0 = 4.44V
  • R_low/(R_low+R1)*Vcc = 5/(5+100)*5.0 = 0.24V
  • Keep in mind that the function is not linear (see LDR_calc.xlsx file)
• R2 limits the LED current : 220Ω is a good value and is calculed as follows :
  • R = (Vcc-Vf)/I = (5.0V-2.8V)/0.01A) = 220Ω
  • Vf being the forward voltage drop of the led (Red ~2.8V) and I the desired current (10mA), that's the worst case scenario as LEDs tends to have a higher voltage drop and the Arduino Nano can deliver up to 20mA per pin

Log

TODO

Known issues

• Reduce external light if oscillating occur (especially artificial like fluorescent tube)

Prerequisites (to upload Arduino code, open Visual Studio project and read Fritzing schematics)

Arduino IDE (free) can be found here :

https://www.arduino.cc/en/main/software

Visual Studio Community (free) can be found here :

https://visualstudio.microsoft.com

Fritzing (free) can be found here :

http://fritzing.org/download/

Developper infos

• Author : Jimmy Caille
• Email : [email protected]