Category: Netduino

I mashed together my Morse Blinker code with the noise making code from the Getting Started with Netduino book to make my Netduino buzz out text in Morse code.

Like the Morse Blinker program, it takes a string provided in the morseText variable and buzzes it out on the little speaker that comes with the kit. Morse code speed is adjusted by changing the beatsPerMinute variable. I haven’t done any testing to figure out how the beatsPerMinute value translates to Morse code words per minute (wpm), but a value of 500 sounds to me like something around 20 wpm.

using System;
using System.Threading;
using System.Collections;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
namespace MorseBuzzer
{
public class Program
{
public static void Main()
{
// Text to Morse code conversion table
Hashtable morse = new Hashtable();
morse.Add('a', "a1a3");
morse.Add('b', "a3a1a1a1");
morse.Add('c', "a3a1a3a1");
morse.Add('d', "a3a1a1");
morse.Add('e', "a1");
morse.Add('f', "a1a1a3a1");
morse.Add('g', "a3a3a1");
morse.Add('h', "a1a1a1a1");
morse.Add('i', "a1a1");
morse.Add('j', "a1a3a3a3");
morse.Add('k', "a3a1a3");
morse.Add('l', "a1a3a1a1");
morse.Add('m', "a3a3");
morse.Add('n', "a3a1");
morse.Add('o', "a3a3a3");
morse.Add('p', "a1a3a3a1");
morse.Add('q', "a3a3a1a3");
morse.Add('r', "a1a3a1");
morse.Add('s', "a1a1a1");
morse.Add('t', "a3");
morse.Add('u', "a1a1a3");
morse.Add('v', "a1a1a1a3");
morse.Add('w', "a1a3a3");
morse.Add('x', "a3a1a1a3");
morse.Add('y', "a3a1a3a3");
morse.Add('z', "a3a3a1a1");
morse.Add('0', "a3a3a3a3a3");
morse.Add('1', "a1a3a3a3a3");
morse.Add('2', "a1a1a3a3a3");
morse.Add('3', "a1a1a1a3a3");
morse.Add('4', "a1a1a1a1a3");
morse.Add('5', "a1a1a1a1a1");
morse.Add('6', "a3a1a1a1a1");
morse.Add('7', "a3a3a1a1a1");
morse.Add('8', "a3a3a3a1a1");
morse.Add('9', "a3a3a3a3a1");
morse.Add(' ', " ");
morse.Add('.', "a1a3a1a3a1a3");
morse.Add(',', "a3a3a1a1a3a3");
morse.Add('?', "a1a1a3a3a1a1");
morse.Add('!', "a3a1a3a1a3a3");
morse.Add('/', "a3a1a1a3a1");
// Hashtable to store the notes
Hashtable scale = new Hashtable();
scale.Add("c", 1915u);
scale.Add("d", 1700u);
scale.Add("e", 1519u);
scale.Add("f", 1432u);
scale.Add("g", 1275u);
scale.Add("a", 1136u);
scale.Add("b", 1014u);
scale.Add("C", 956u);
scale.Add("D", 851u);
scale.Add("E", 758u);
scale.Add("h", 0u);
// Text to play in Morse code. Change this to whatever you want
string morseText = "ab4ug";
int beatsPerMinute = 500;
int beatTimeInMilliseconds = 60000 / beatsPerMinute;
int pauseTimeInMilliseconds = (int)(beatTimeInMilliseconds * 0.1);
PWM speaker = new PWM(Pins.GPIO_PIN_D5);
while (true)
{
foreach (char c in morseText)
{
// Get the Morse "song" corresponding to the current letter
string song = (string)morse[c];
for (int i = 0; i < song.Length; i += 2)
{
// Extract the note from the string
string note = song.Substring(i, 1);
int beatCount = int.Parse(song.Substring(i + 1, 1));
uint noteDuration = (uint)scale[note];
// Play the note
speaker.SetPulse(noteDuration * 2, noteDuration);
Thread.Sleep(beatTimeInMilliseconds * beatCount - pauseTimeInMilliseconds);
// pause for 1/10th of a beat
speaker.SetDutyCycle(0);
Thread.Sleep(pauseTimeInMilliseconds);
}
// Pause for one beat between each character
speaker.SetDutyCycle(0);
Thread.Sleep(beatTimeInMilliseconds);
}
// Pause for five beats before repeating
speaker.SetDutyCycle(0);
Thread.Sleep(beatTimeInMilliseconds * 5);
}
}
}
}

The latest version is over in my Github. I’ll probably spend some time redoing Morse code translation table to make changing the tone easier.

The microcontroller programming equivalent of “Hello World” seems to be “Blink the LED”.

After going through some of the example code for my Netduino, I decided to expand a bit on the LED examples and come up with a simple little program that would make the onboard LED blink out Morse code.

After a few hours of futzing around trying to figure out the C# syntax and the relevant parts of the .NET Micro Framework, I finally came up with something that works pretty well. I called it MorseBlinker.

One of the problems I ran into was .NET Micro Framework API changes between 4.2 (which is what I had installed) and 4.1 which is what the examples in the Getting Started with Netduino book are written for. Also, apparently there’s a big difference between “a” and ‘a’ in C# (although I imagine it’s probably the same in C too). 

The string is hard coded into the program, so if i want to change what the Netduino blinks, I have to change the string and redeploy the app, which isn’t too difficult. Timing is also hard coded too (in the dit variable which specifies the duration of a dit in milliseconds), so changing the speed it blinks at also requires the app to be rebuilt and redeployed.

using System;
using System.Threading;
using System.Collections;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
namespace MorseBlinker
{
public class Program
{
private static void blinker(OutputPort p, string a)
{
// Make the LED blink a morse code string provided by a
// Change the duration of the blinking by adjusting the dit variable
int dit = 50;                    // dit length in milliseconds
int dah = dit * 3;                // dah length in milliseconds
int space = dit * 7;              // space length in milliseconds
foreach (char sym in a)
{
switch (sym)
{
case '.':
p.Write(true);
Thread.Sleep(dit);
p.Write(false);
Thread.Sleep(dit);
break;
case '-':
p.Write(true);
Thread.Sleep(dah);
p.Write(false);
Thread.Sleep(dit);
break;
case ' ':
p.Write(false);
Thread.Sleep(space);
break;
default:
break;
}
}
p.Write(false);
Thread.Sleep(dit * 3);    // space between characters
}
public static void Main()
{
// Text to Morse code conversion table
Hashtable morse = new Hashtable();
morse.Add('a', ".-");
morse.Add('b', "-...");
morse.Add('c', "-.-.");
morse.Add('d', "-..");
morse.Add('e', ".");
morse.Add('f', "..-.");
morse.Add('g', "--.");
morse.Add('h', "....");
morse.Add('i', "..");
morse.Add('j', ".---");
morse.Add('k', "-.-");
morse.Add('l', ".-..");
morse.Add('m', "--");
morse.Add('n', "-.");
morse.Add('o', "---");
morse.Add('p', ".--.");
morse.Add('q', "--.-");
morse.Add('r', ".-.");
morse.Add('s', "...");
morse.Add('t', "-");
morse.Add('u', "..-");
morse.Add('v', "...-");
morse.Add('w', ".--");
morse.Add('x', "-..-");
morse.Add('y', "-.--");
morse.Add('z', "--..");
morse.Add('0', "-----");
morse.Add('1', ".----");
morse.Add('2', "..---");
morse.Add('3', "...--");
morse.Add('4', "....-");
morse.Add('5', ".....");
morse.Add('6', "-....");
morse.Add('7', "--...");
morse.Add('8', "---..");
morse.Add('9', "----.");
morse.Add(' ', " ");
morse.Add('.', "·-·-·-");
morse.Add(',', "--..--");
morse.Add('?', "..--..");
morse.Add('!', "-.-.--");
morse.Add('/', "-..-.");
// Text to play in Morse code. Change this to whatever you want
string morseText = "ab4ug";
OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
while (true) {
// go through all the characters in morseText
foreach (char c in morseText)
{
// Blink the character in Morse code
blinker(led, (string)morse[c.ToLower()]);
}
// Delay 1s before repeating the text
led.Write(false);
Thread.Sleep(1000);
}
}
}
}

You can check out the latest version over at Github.

For my next trick, I think I’ll try to make a speaker buzz at the same time as the light flashes.