changing brightness using serial comm of 3 leds - arduino

Question

So far I have wrote code so that if 1 then enter pressed or send clicked, and then 1 again and enter pressed or send clicked causes LED one to turn on, if ‘1’ ‘0’ is entered in a similar way then LED 1 turns off, and so on for LEDs two and three, ie: ‘2’ ‘1’ turns on LED 2, ‘3’ ’0’ turns off LED 3.
int incomingVal;
int ledPin = 16;
int ledPin2 = 15;
int ledPin3 = 14;
void setup()
{
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
Serial.println("starting");
pinMode(ledPin,OUTPUT);
pinMode(ledPin2,OUTPUT);
pinMode(ledPin3,OUTPUT);
}
void loop()
{
if (Serial.available() > 0 ) //then chars are in the serial buffer
{
incomingVal = Serial.parseInt();
Serial.print("You entered: ");
Serial.println(incomingVal);
if (incomingVal == 10)//turns off led 1
{
digitalWrite(ledPin, LOW);
}
if (incomingVal == 11)//turns on led 1
{
digitalWrite(ledPin, HIGH);
}
if (incomingVal == 20)//turns off led 2
{
digitalWrite(ledPin2, LOW);
}
if (incomingVal == 21)//turns on led 2
{
digitalWrite(ledPin2, HIGH);
}
if (incomingVal == 30)//turns off led 3
{
digitalWrite(ledPin3, LOW);
}
if (incomingVal == 31)//turns on led 3
{
digitalWrite(ledPin3, HIGH);
}
}
}
How could i change the code so i can enter a third value to change the brightness from 0 to 250? For example, typing “2,1,125” would make LED 2 to light up at 50% brightness.

Answer 1

To make the LED light up at half brightness you need to use pulse width modulation. Make sure that the pins you are using have ~ next to them (pins 3, 5, 6, 9, 10, 11 on the Uno).
I would change your input method slightly, because 0 brightness is essentially the same as turning the LED off, you should only need 2 numbers. The first number corresponds to the LED, the second number corresponds to the brightness.
int led_pins[3] = {9,10,11};
int incomingVal;
int brightness;
int parsed_value;
int x = 0;
void setup()
{
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
Serial.println("starting");
pinMode(led_pins[0],OUTPUT); // You could also use a loop here
pinMode(led_pins[1],OUTPUT);
pinMode(led_pins[2],OUTPUT);
}
void loop()
{
if (Serial.available() > 0 ) //then chars are in the serial buffer
{
incomingVal = Serial.parseInt();
Serial.print("You entered: ");
Serial.println(incomingVal);
//figure out which LED we selected
parsed_value = incomingVal;
while (parsed_value > 9){
/*
because of integer division, this line will remove the last
number from the integer. ie 11 / 10 = 1 (the result is rounded down)
The loop will continue until only 1 digit remains
*/
x++;
parsed_value = parsed_value / 10;
}
// x represents the number of times parsed_value was divided by 10
// this line removes the first digit of the incoming value, leaving
// the brightness
brightness = incomingVal - pow(10,x)*parsed_value;
/*parsed_value will be 1 greater than the array key value because
the array is 0 based.*/
//set the LED to the right brightness
analogWrite(led_pins[parsed_value-1],brightness);
}
}