Robert,

You're a year early I love that you didn't just stop with the LEDs, but added in the holiday tunes too. Cool.

Chris

That's another (better) way to look at it ;-) Thanks for the compliment.

I managed to find the schema (see attached). Now looking for the code.

Robert :-)

Hi all,

A bit late, but I finally got around to post about the netduino powered xmas tree I built. It has (randomly) blinking LEDs, which are fed from two 74HC595 shift registers. The shift registers are controlled through the library from Szymon Kobalczyk (the library for the shift registers is part of the code in the blog post).

It also plays xmas ringtones using the code from Omar. When it plays a ringtone, the LEDs blink in tune with the music.

The code is not optimized, but seems to work fine anyway ;-)

Here's a little video of it in action:
http://www.youtube.com/watch?v=Iz9dE39W1F8

I don't have access to the source or the schema I created, right now, but if anyone is interested, let me know.

Enjoy,
Robert :-)

Hi Omar,

Just had a look at your player for a little holiday project I'm working on and found that some notes couldn't be heard (I guess the same thing happens with the two notes you claim to have missing in the Mission Impossible ringtone).

After some investigation, what I found was that your PlayNote method allows the duration to be longer than the period, which I understand is not allowed. If I understand it correctly PWM sets a period (the total time of one cycle in the square wave) and the duration is the total time in that period that it's ON).

This means that the duration should therefore be less than the period. However, if you make the duration the same as the period or slightly less, it still drops off (you can still hear it, but only faint). I found that a max duration of 95% of the period worked well for me. I changed your PlayNote method as follows:

        public static void PlayNote(uint frequencyInHertz, uint durationMilliseconds)
        {

            if (frequencyInHertz != 0)
            {
                uint timbre = 50; // 50% = perfect square wave.
                pwm.SetDutyCycle(timbre);

                uint period = (uint)1000000 / frequencyInHertz; // 1000,000 instead of 1,000 because SetPulse duration is in microseconds, not in milliSeconds.

                //Duration needs to be less than the period. To make sure we have at least some sound, make sure we stay below 95% of the period:
                double maxDuration = 0.95*period;
                uint duration = (uint)(durationMilliseconds <= maxDuration ? durationMilliseconds : maxDuration);
                Debug.Print("Frequency -> " + frequencyInHertz + ", Period -> " + period + ", durationMilliseconds -> " + durationMilliseconds + ", Max Duration -> " + maxDuration + ", duration -> " + duration);
                pwm.SetPulse(period, duration);
            }

            //-- Wait for note (or silence) to play out, then be quiet --
            Thread.Sleep((int)durationMilliseconds);
            pwm.SetDutyCycle(0);
        }

Hope this helps. If anyone has some suggestions or want to tell me I'm completely wrong, please feel free. I'm an experienced .Net developer, but new to Netduino/electronics, so...

Robert :-)