Hello everyone,
I have a question about RGB LEDs.
Can I make an RGB LED fade without changing the colour?
For example, I have the RED=200, BLUE= 170 and GREEN=40 in 0 to 255 values.
Can I make the LED fade without chaging these colours?
Thanks.
Hello everyone,
I have a question about RGB LEDs.
Can I make an RGB LED fade without changing the colour?
For example, I have the RED=200, BLUE= 170 and GREEN=40 in 0 to 255 values.
Can I make the LED fade without chaging these colours?
Thanks.
Try a different colour space, like HSV.
What is HSV?
But if I want to treat the data from an app that sends rgb values to the arduino. Then I don't know how to treat the rgb values to hsv on the app.
An when the arduino reads the values, what do I have to do? Note that I've done some code for the rgb model, but know nothing about the hsv one.
#include <softwareserial.h>
#include <wire.h>//Include libraries: SoftwareSerial & Wire
SoftwareSerial BT(0,1); //Define PIN11 & PIN12 as RX and TX pins
//RGB LED Pins
int PIN_RED = 3;
int PIN_GREEN = 5;
int PIN_BLUE = 6;
//RED LED at Pin 13
int RED_LED = 13;
String RGB = ""; //store RGB code from BT
String RGB_Previous = "255.255.255)"; //preserve previous RGB color for LED switch on/off, default White
String ON = "ON"; //Check if ON command is received
String OFF = "OFF"; //Check if OFF command is received
boolean RGB_Completed = false;
void setup() {
Serial.begin(9600); //Arduino serial port baud rate:9600
BT.begin(9600);//My HC-05 module default baud rate is 9600
RGB.reserve(30);
pinMode(RED_LED, OUTPUT);
//Set pin13 as output for LED,
// this LED is on Arduino mini pro, not the RGB LED
}
void loop() {
// put your main code here, to run repeatedly:
//Read each character from Serial Port(Bluetooth)
while(BT.available()){
char ReadChar = (char)BT.read();
// Right parentheses ) indicates complet of the string
if(ReadChar == ')'){
RGB_Completed = true;
}else{
RGB += ReadChar;
}
}
//When a command code is received completely with ')' ending character
if(RGB_Completed){
//Print out debug info at Serial output window
Serial.print("RGB:");
Serial.print(RGB);
Serial.print(" PreRGB:");
Serial.println(RGB_Previous);
if(RGB==ON){
digitalWrite(13,HIGH);
RGB = RGB_Previous; //We only receive 'ON', so get previous RGB color back to turn LED on
Light_RGB_LED();
}else if(RGB==OFF){
digitalWrite(13,LOW);
RGB = "0.0.0)"; //Send OFF string to turn light off
Light_RGB_LED();
}else{
//Turn the color according the color code from Bluetooth Serial Port
Light_RGB_LED();
RGB_Previous = RGB;
}
//Reset RGB String
RGB = "";
RGB_Completed = false;
} //end if of check if RGB completed
} // end of loop
void Light_RGB_LED(){
int SP1 = RGB.indexOf('.');
int SP2 = RGB.indexOf('.', SP1+1);
int SP3 = RGB.indexOf('.', SP2+1);
String R = RGB.substring(0, SP1);
String G = RGB.substring(SP1+1, SP2);
String B = RGB.substring(SP2+1, SP3);
//Print out debug info at Serial output window
Serial.print("R=");
Serial.println( constrain(R.toInt(),0,255));
Serial.print("G=");
Serial.println(constrain(G.toInt(),0,255));
Serial.print("B=");
Serial.println( constrain(B.toInt(),0,255));
//Light up the LED with color code
//Because these RGB LED are common anode (Common positive)
//So we need to take 255 to minus R,G,B value to get correct RGB color code
analogWrite(PIN_RED, (255-R.toInt()));
analogWrite(PIN_GREEN, (255-G.toInt()));
analogWrite(PIN_BLUE, (255-B.toInt()));
}
Convert from RGB to HSV. Then reduce the V parameter then convert back from HSV to RGB and write that to the LED.
A simpler way to dim an RGB value is to multiply the red, green and blue component values by the same percentage. For example
Red: 240 * 50% = 120
Blue: 170 * 50% = 85
Green: 40* 50% = 20
When the dimming reaches the lowest levels, the colour may change, but there is nothing that can easily be done about this, because the Arduino's PWM control is normally only 8 bit.
Red: 240 * 5% = 12
Blue: 170 * 5% = 8 <-- ideally this would be 8.5 to maintain the same colour
Green: 40* 5% = 2
PS.
//Print out debug info at Serial output window
Serial.print("R=");
Serial.println( constrain(R.toInt(),0,255));
Serial.print("G=");
Serial.println(constrain(G.toInt(),0,255));
Serial.print("B=");
Serial.println( constrain(B.toInt(),0,255));
The above may appear to limit the r, g & b values to the range 0 to 255. But in reality it does nothing...