2 replies to this topic

[B9Brew]

Hello users,

I've been working through the Get Started with Netduino e-book using the Netduino Plus. All projects have worked fine until the "Mixing Colors" project in chapter 6. I've tried with the maker shield and with the breadboard and in both cases my RGB LED acts like its common is an anode rather than a cathode - i can't get the LED to light up unless i put a GIO_Pin_D9 (or 5 or 6) on the common with the ground on a leg (after a resistor). Do I need to initialize something? the code is simple:

        public static void Main()
        {
            // write your code here
            PWM redLed = new PWM(Pins.GPIO_PIN_D9);
            PWM greenLed = new PWM(Pins.GPIO_PIN_D6);
            PWM blueLed = new PWM(Pins.GPIO_PIN_D5);

            
            redLed.SetDutyCycle(100);
            greenLed.SetDutyCycle(30);
            blueLed.SetDutyCycle(60);

            Thread.Sleep(Timeout.Infinite);
        }

[Chris Walker]

Hi B9Brew, Can you explain your scenario in a bit more detail? Perhaps take a photo of the part, provide its part number, etc.? If your pin is common anode rather than common cathode, PWM may not work for you (unless you modify the native code underneath to cycle between high-z and output low). You really want a common cathode RGB LED. Chris

[CW2]

For common anode RGB LED, connect the anode to V_CC and R/G/B cathodes to Netduino PWM pins (through the resistors), PWM will work inversely: 0% duty cycle = on, 100% = off (the LED is on when the pin output is logic low). Also make sure you don't exceed Netduino max pin current, you'd probably need transistors...