Arduino Morse Code Decoder - WA6PZB

Monday, September 1, 2014

Arduino Morse Code Decoder

I came across this Arduino Morse Code Decoder Sketch by Budd WB7FHC HERE and it look interesting and very well documented so I thought I would try it out and run some tests on it because I may have an application for such a decoder. Using a straight key with it was a little tough but I was able to get it to copy me fine as long as I was sending perfectly at about 10 WPM. I tried increasing the speed but it seems to get easily confused requiring a reset. I then decided to connect a keyer to it so it was receiving perfect machine generated Morse. I used my WINKEYER USB. I started at 10 WPM and was able to increase the speed in 2-3 WPM increments and it was able to copy 100% all the way to 99 WPM! I still need to do more testing but the way the code is built, it seems to needs to start at a slow speed before handling higher speed code. I did find that from a reset it will copy perfectly at 10 WPM every time with virtually no training. It seems the training part of the code is more useful when dealing with a straight key and the variation that a human may cause. I came across some minor issues in the code while I was running it regarding decoding punctuation. The fix required a change to the "mySet" array and also the punctuation code. If you look at the printPunctuation code on Budds original sketch and compare to my code below I just did a direct print instead of assigning it to "pMark". I also made it so when it decodes a "@" sign it sends a newline to the terminal. There are some other changes I would like to make that would enable this code to work in an application I am pondering... a CW transponder. The idea would be to send it my call-sign and a command, it would decode it and if correct would respond with an appropriate CW response back (transpond). For example, if I send it... WA6PZB WA6PZB CMD WX CMD WX it would respond back with WA6PZB WA6PZB RESP 72F RESP 72F. Here I am requesting the temperature or weather (WX) and it is responding with 72 degrees F. I am expecting to send everything twice in and attempt to get the signal through under varying conditions since Morse has no error correction. /* Barnacle Budd's Morse Code Decoder v. 0.1 (c) 2011, Budd Churchward - WB7FHC Minor modification by WA6PZB 8/30/2014 Hook a button or telegraph key up to your Arduino and this program will copy your Morse Code and display the characters in your Monitor window. The program will automatically adjust to the speed of code that you are sending. The first few characters may come out wrong. The software tracks the speed of the sender's dahs to make its adjustments. The more dahs you send at the beginning the sooner it locks into solid copy. After a reset, the following text is very difficult to lock in on: 'SHE IS HIS SISTER' because there are only two dahs in the whole phrase and they come near the end. However, if you reset and then send 'CALL ME WOODY' it will match your speed quite quickly. */ int myKey=14; // We are borrowing Analog Pin 0 and using it as digital int speaker=11; // Speaker will be hooked between pin 11 and ground int val=0; // A value for key up and down int myTone=640; // Frequency of our tone boolean ditOrDah=true; // We have a full dit or a full dah int dit=100; // If we loop less than this with keydown it's a dit else a dah int averageDah=150; // Start with this value we will adjusted it each time he sends a dah boolean characterDone=true; // A full character has been sent int myBounce=2; // Handles normal keybounce but we needed to do more later int downTime=0; // We are going to count the cycles we loop while key is down long FullWait=10000; // This value will be set by the sender's speed - the gap between letters long WaitWait=FullWait; // WaitWait is for the gap between dits and dahs long newWord=0; // For the gap between words int nearLineEnd=40; // How far do you want to type across your monitor window? int letterCount=0; // To keep track of how many characters have been printed on the line int myNum=0; // We will turn the dits and dahs into a data stream and parse // a value that we will store here // The place a letter appears here matches the value we parse out of the code char mySet[] ="##TEMNAIOGKDWRUS##QZYCXBJP#L#FVH09#8###7#:###/#61#######2###3#45"; void setup() { pinMode(myKey, INPUT); pinMode(speaker,OUTPUT); // initialize the serial communication: Serial.begin(9600); } void loop() { val=digitalRead(myKey); // Is it up or is it down? if (val) keyIsDown(); // Any value here means it is down. if (!val) keyIsUp(); // Should be 0 when it is up. } void keyIsDown() { tone(speaker,myTone); // Turn on the sound WaitWait=FullWait; // Reset our Key Up countdown downTime++; //Count how long the key is down if (myNum==0) { // myNum will equal zero at the beginning of a character myNum=1; // This is our start bit - it only does this once per letter } characterDone=false; // we aren't finished with the character yet, there could be more ditOrDah=false; // we don't know what it is yet - key is still down delay(myBounce); // short delay to keep the real world in synch with Arduino } void keyIsUp() { noTone(speaker); // Turn off the sound if (newWord>0) newWord--; // Counting down to spot gap between words if (newWord==1) printSpace(); // Found the gap, print a space but only once next time it will be 0 if (!ditOrDah) { // We don't know if it was a dit or a dah yet, so ... shiftBits(); // let's go find out! And do our Magic with the bits } if (!characterDone) { WaitWait--; // We are counting down if (WaitWait==0) { // Bingo, keyUp just timed out! A full letter has been sent WaitWait=FullWait; // Reset our keyUp counter printCharacter(); // Go figure out what character it was and print it characterDone=true; // We got him, we're done here myNum=0; // This sets us up for getting the next start bit } downTime=0; // Reset our keyDown counter } } void printSpace() { letterCount++; // we're counting the number of characters on the line if (letterCount>nearLineEnd) { // when we get past our threshold we do this: Serial.println(); // jump down to a new line letterCount=0; // reset our character counter return; // Go back to loop(), we're done here. } Serial.print(' '); // print a space on the monitor window } void printCharacter() { FullWait=averageDah*100; // the keyUp counter gets reset based on sender's speed newWord=FullWait*5; // word gap counter is also adjusted by sender's speed letterCount++; // we're counting the number of characters on the line if (myNum>63) { printPunctuation(); // The value we parsed is bigger than our character array // It is probably a punctuation mark so go figure it out. return; // Go back to the main loop(), we're done here. } Serial.print(mySet[myNum]); // Print the letter that is in this spot in our character set } void printPunctuation() { byte pMark='#'; // Just in case nothing matches if (myNum==71) Serial.print(":"); if (myNum==76) Serial.print(","); if (myNum==84) Serial.print("!"); if (myNum==94) Serial.print("-"); if (myNum==101) Serial.println(); // the @ sign used for newline if (myNum==106) Serial.print("."); if (myNum==115) Serial.print("?"); } void shiftBits() { ditOrDah=true; // we will know which one in two lines if (downTime<dit/3) return; // ignore my keybounce if (downTime<dit) { // We got a dit myNum = myNum << 1; // shift bits left myNum++; // add one because it is a dit } else { // We got a dah myNum = myNum << 1; // shift bits left // The next three lines handle the automatic speed adjustment: averageDah=(downTime+averageDah)/2; // running average of dahs dit=averageDah/3; // normal dit would be this dit=dit*2; // double it to get the threshold between dits and dahs } } Posted by WA6PZB Blog at 1:45 PM Email ThisBlogThis!Share to XShare to FacebookShare to Pinterest

1 comment:

1. Steve CookOctober 1, 2020 at 12:21 PM

   Prat.

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