![]() ![]() Those purchased prior to then will have Blue on Pin 3 and Green on Pin 4. Thus, at the end, the net voltage supplied is 3 V as it was required.Īs of 1/2010, the pins in the datasheet are correctly labeled. Now, 5 V at anode is opposed by 2 V in opposite direction and the net voltage is taken as:.Using the formula, 102 gets converted into analog voltage of 2 V. Thus, the value of 'blueBrightness' is 102.153 is entered in serial monitor, the difference is 255 - 153 = 102.Serial.println(blueBrightness) //Prints value on the serial monitorĪnalogWrite(blue, blueBrightness) //sends analog signals to blue LEDįor example: We want to supply 3 V to blue LED. Here, the value is taken and the difference between value and 255(peak value) is stored in the variable. You need to comment out some code lines for the common cathode RGB LED and uncomment the code lines written for the common anode.BlueBrightness = 255 - Serial.parseInt() Note: If you're using a common anode RGB LED, please read the comments inside the code. It allows you to monitor the RGB decimal value or the duty cycle of PWM signals through the serial monitor of the Arduino IDE. The other lines in the code are for monitoring purposes. Another way to tell which lead is the anode and which is the cathode is to look at the two plates at the end of the leads inside the body of the LED. The cathode is marked on the rim of the LED body with a flat area shown in the diagram. These lines program the Arduino Uno to adjust the duty cycle of the PWM signals based on the voltages across the ADC channels. On the physical LED, the longer lead (or leg) of the LED is the anode. Then it converts the values into a (0-255) range since the ADC uses 10-bit resolution which ranges from (0-1023) but the PWM function of the Arduino Uno uses a (0-255) range. This part of the code tells the Arduino Uno to read the voltage across the wiper terminal of the potentiometers/trimmers through channels A0, A1, and A2. These lines configure the digital pins D9, D10, and D11 to be the PWM output pins. Int RGBLED_BluePin = 11pinMode(RGBLED_RedPin, OUTPUT) Previous_PWMValue_GreenPin = Pot_GreenPin If (Threshold_PWMValue_RedPin >= 10 || Threshold_PWMValue_GreenPin >= 10 || Threshold_PWMValue_BluePin >= 10) Threshold_PWMValue_BluePin = abs(Pot_BluePin - Previous_PWMValue_BluePin) Threshold_PWMValue_GreenPin = abs(Pot_GreenPin - Previous_PWMValue_GreenPin) Threshold_PWMValue_RedPin = abs(Pot_RedPin - Previous_PWMValue_RedPin) Sometimes you get unstable output due to jumper wires not properly connected, poor quality breadboard, or poor quality potentiometers. ![]() This section is for serial printing the RGB decimal values. Use this code for RGB LED COMMON ANODE and comment the code for COMMON CATHODEĪnalogWrite(RGBLED_RedPin, 255-PWMValue_RedPin) ĪnalogWrite(RGBLED_GreenPin, 255-PWMValue_GreenPin) ĪnalogWrite(RGBLED_BluePin, 255-PWMValue_BluePin) Use this code for RGB LED COMMON CATHODE and comment the code for COMMON ANODEĪnalogWrite(RGBLED_RedPin, PWMValue_RedPin) ĪnalogWrite(RGBLED_GreenPin, PWMValue_GreenPin) ĪnalogWrite(RGBLED_BluePin, PWMValue_BluePin) Serial.begin(9600) // initialize serial communications at 9600 bps That way, you can have a balance between the brightness of the internal LEDs. But if you have access to the datasheet of the RGB LED that you're using, check the forward voltages of internal LEDs and from that, you can calculate the right resistance of the resistors that you're going to use. Note: In this example, we just used the same resistance value for the RGB LED series resistors. The cathode pin of the RGB LED is connected to the GND pin of the Arduino Uno. The D10 pin controls the intensity of the green LED and D11 controls the intensity of the blue LED. As you can see in the image above, the D9 pin controls the intensity of the red LED of the RGB LED. The ADC of the Arduino Uno reads the analog voltage across the wiper terminal of the potentiometers/trimmers and based on that voltage, the Arduino Uno adjusts the duty cycle of the PWM signals generated at the PWM pins D9, D10, and D11. Basically, what happens here is that we have 3 potentiometers/trimmers connected to the A0, A1, and A2 ADC channels of the Arduino Uno. They're all connected through the jumper wires that we have. We have here a common cathode RGB LED, an Arduino Uno board, 3 potentiometers/trimmers, and 3 resistors. ![]()
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