How to control LED luminosity by entering number in Qt to Arduino

Macive Xiong

Hi everyone, I am a new learner of Qt. Recently, I am trying to develop a GUI to control the luminosity of LED thru Arduino by typing number (0~255) in Qt GUI.

Here is my Arduino code:

const int ledPin = 9;
int ledlum;

void setup() {
  pinMode(ledPin, OUTPUT);
  analogWrite(ledPin, 0);
  Serial.begin(9600);
}

void loop() {
  if (Serial.available()){
   ledlum = Serial.parseInt();
   write_led(ledlum);
}
}

void write_led(int lum){
  analogWrite(ledPin, 0 + lum);
 
}

My question is, how can I create a textbox or any box for number input to enter the number to control luminosity? I already know how to connect between Arduino and Qt. The part I don't know is, what's the code for textbox to send number from Qt to Arduino?
Thank you guys in advance:)

jsulm

@Macive-Xiong You can use QSpinBox to enter a number. Use QSpinBox::value() to get its value.
See http://doc.qt.io/qt-5/qspinbox.html

Macive Xiong

@jsulm thank you so much for your help:)

Macive Xiong

@jsulm Do you know any example for sending number to Arduino from Qt? I am not really sure how to write the code in Qt to send signal to Arduino thru SpinBox.

Thank you so much:)

jsulm

@Macive-Xiong No, I don't. How do you communicate with Arduino? Via serial port? If so then take a look at http://doc.qt.io/qt-5/qtserialport-index.html
In your first post in this thread you actually already have code to communicate with Arduino. I'm not sure what the problem is: get the value from QSpinBox calling its value() method. You can even use http://doc.qt.io/qt-5/qspinbox.html#valueChanged signal to get notified about a new value and then send it to Arduino.

Macive Xiong

@jsulm Thanks again for these info. I appreciate it:)