When you have a hammer, everything looks like a nail

Log in or register to post comments
Go To Last Post
13 posts / 0 new
Author
Message
kk6gm
kk6gm's picture
Level: Raving Lunatic
Joined: Fri. Sep 11, 2009
Posts: 4022 View posts
Location: Sacramento, CA
#1
Posted by kk6gm: Thu. Dec 20, 2018 - 06:57 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 2

My son totally surprised me last week by texting that he wanted to learn Morse code.  He's been using an app, but he needs a CPO (code practice oscillator).  I looked in my stash for a 555 chip but didn't have any.  What I did have was a little tiny44A board that I've used for WS2812 LED projects, so I programmed it to be a CPO.

 

To make this somewhat forum-related, what allowed me to pull this off is that I had added a jumper with 2 extra GPIO connections, "just in case".  I never used them for the WS2812 projects, but they were necessary for the CPO.  So if you have extra GPIO, bring a few out to some pads, "just in case".

 

 

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
Top
ki0bk
ki0bk's picture
Level: 10k+ Postman
Joined: Mon. Sep 8, 2014
Posts: 10608 View posts
Location: Over the rainbow
Posted by ki0bk: Thu. Dec 20, 2018 - 07:15 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

-.-.--

Nice job, I was going to suggest the CPO kit by the 4 states QRP group. http://www.4sqrp.com/sscpo.php

 

 

-.-. --.-  -.-. --.-  -.. .  -.- .. ----- -... -.-

 

Jim

 

 

 

FF = PI > S.E.T

 

Top
kk6gm
kk6gm's picture
Level: Raving Lunatic
Joined: Fri. Sep 11, 2009
Posts: 4022 View posts
Location: Sacramento, CA
Posted by kk6gm: Thu. Dec 20, 2018 - 07:46 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Source code, in case anybody is interested.

 

#define F_CPU		1000000UL	// 1 MHz

#include <avr/io.h>
#include <util/delay.h>

#define SPKR_A		PA0
#define SPKR_B		PA1
#define KEY		PB0

#define CPO_FREQ	700	// hz
#define CPO_HALF_CYCLE	(F_CPU / CPO_FREQ / 2)


int main(void)
{
    DDRA = (1 << SPKR_A) | (1 << SPKR_B);
    PORTB = 1 << KEY;

    while (1) 
    {
	if (!(PINB & (1 << KEY)))	// key down
	{
	    PORTA = (1 << SPKR_A);	// pulse speaker +
	     _delay_us(CPO_HALF_CYCLE);	// 1/2 cycle
	     PORTA = (1 << SPKR_B);	// pulse speaker -
	     _delay_us(CPO_HALF_CYCLE);	// 1/2 cycle
	}
	else
	    PORTA = 0;			// no DC on speaker!
    }
}

 

Top
ajcashin
ajcashin's picture
Level: Wannabe
Joined: Sun. Dec 9, 2018
Posts: 79 View posts
Posted by ajcashin: Thu. Dec 20, 2018 - 08:46 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Is that a powered speaker? I don't see a supply - internal battery? Driving a low impedance speaker directly would draw too much current. I'm thinking there's more to it than meets the eye.

Top
kk6gm
kk6gm's picture
Level: Raving Lunatic
Joined: Fri. Sep 11, 2009
Posts: 4022 View posts
Location: Sacramento, CA
Posted by kk6gm: Thu. Dec 20, 2018 - 08:59 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

ajcashin wrote:

Is that a powered speaker? I don't see a supply - internal battery? Driving a low impedance speaker directly would draw too much current. I'm thinking there's more to it than meets the eye.

5V wall wart not in the picture.  Was using clip leads for power, but have since soldered on a power jack (which the board is designed to take.)  Not a powered speaker - there's a 330 Ohm resistor in the circuit behind the speaker.

Top
ajcashin
ajcashin's picture
Level: Wannabe
Joined: Sun. Dec 9, 2018
Posts: 79 View posts
Posted by ajcashin: Thu. Dec 20, 2018 - 09:03 PM (Reply to #5)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

kk6gm wrote:

ajcashin wrote:

 

Is that a powered speaker? I don't see a supply - internal battery? Driving a low impedance speaker directly would draw too much current. I'm thinking there's more to it than meets the eye.

5V wall wart not in the picture.  Was using clip leads for power, but have since soldered on a power jack (which the board is designed to take.)  Not a powered speaker - there's a 330 Ohm resistor in the circuit behind the speaker.

I figured as much. Good to complete the picture if someone else copied the idea. Nice hack.

Top
avr-mike
avr-mike's picture
Level: Resident
Joined: Sat. Jul 21, 2018
Posts: 865 View posts
Location: U.S. Pacific
Posted by avr-mike: Thu. Dec 20, 2018 - 10:23 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You could also build the Real Thing!

 

Morse Code Sounder

 

An ATmega328P driving an (open-collector) MPSA13.

 

--Mike

 

Top
Paulvdh
Paulvdh's picture
Level: Raving Lunatic
Joined: Fri. Aug 3, 2001
Posts: 2802 View posts
Posted by Paulvdh: Thu. Dec 20, 2018 - 10:37 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

This does not seem to work very well:

https://translate.google.com/#view=home&op=translate&sl=auto&tl=en&text=-.-.%20--.-%20%20-.-.%20--.-%20%20-..%20.%20%20-.-%20..%20-----%20-...%20-.-

 

 

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

Top
kk6gm
kk6gm's picture
Level: Raving Lunatic
Joined: Fri. Sep 11, 2009
Posts: 4022 View posts
Location: Sacramento, CA
Posted by kk6gm: Thu. Dec 20, 2018 - 11:40 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Paulvdh wrote:

This does not seem to work very well:

https://translate.google.com/#view=home&op=translate&sl=auto&tl=en&text=-.-.%20--.-%20%20-.-.%20--.-%20%20-..%20.%20%20-.-%20..%20-----%20-...%20-.-

Shocking omission!

Top
Simonetta
Simonetta's picture
Level: Raving Lunatic
Joined: Wed. Mar 12, 2003
Posts: 3379 View posts
Location: Portland, Oregon USA
Posted by Simonetta: Fri. Dec 21, 2018 - 02:16 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Morse code is way to get complex information into an extremely simple basic AVR system when the only input/output that you have is a push-switch and an LED.

 

The Atmel Xpress boards come with a Morse code parser and generator as their demo program.  I'm still trying to convert it to Arduino.  Is Morse code still used for anything? besides prisoners tapping on drainpipes and  one button/one LED embedded systems?

Top
kk6gm
kk6gm's picture
Level: Raving Lunatic
Joined: Fri. Sep 11, 2009
Posts: 4022 View posts
Location: Sacramento, CA
Posted by kk6gm: Fri. Dec 21, 2018 - 02:24 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Simonetta wrote:

Is Morse code still used for anything? besides prisoners tapping on drainpipes and  one button/one LED embedded systems?

Still used on the ham bands, fairly heavily.  My son says it is used in video games, and that's what got him interested - that surprised me.  And definitely useful for debugging.

 

Should also be extremely valuable when the zombie apocalypse comes.

Last Edited: Fri. Dec 21, 2018 - 02:26 AM
Top
avrcandies
avrcandies's picture
Level: Raving Lunatic
Joined: Wed. Jun 30, 2004
Posts: 9030 View posts
Location: Cincinnati Oh
Posted by avrcandies: Fri. Dec 21, 2018 - 05:11 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Is Morse code still used for anything? besides prisoners tapping on drainpipes and  one button/one LED embedded systems?

I wonder how many vending machines have this hidden feature, where you can simply tap in "free candy" & then make your selection.  

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Top
Scroungre
Scroungre's picture
Level: Posting Freak
Joined: Wed. Apr 18, 2007
Posts: 1687 View posts
Location: Southern California
Posted by Scroungre: Fri. Dec 21, 2018 - 08:44 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

A friend of mine built a multi-strand cable tester that worked by sending a different Morse Code letter down each wire.  Clip up an earbud and listen to each one.

 

I have an AVR-driven gizmo that flashes my Xmas lights in Morse Code (using a 90s1200, of all things, and a relay.  (It ticks a lot.  An SSR or triac would have been better)).  The first season I put them up they said, "If you can read this send me email" and gave my email address.  Nobody did, so now I can make them say anything I like...  devil   (There's an RS-232 interface for programming the message).

 

-.- --. .. .. --     S.

Top