Posts Tagged ‘Morse Code’
Arduino Morse Tutor
September 20th, 2015 | 
Author: 
In a recent conversation with my good friend Lewis, we started discussing Morse code, training and the old equipment that was used to educate and teach the code to newcomers. In particular we discussed the old Datong D70 practice oscillators. Lewis carried on the tell me that his Datong like so many others started sending odd illegal characters and essentially rendered the kit useless. Of course you could whip of the lid and replace the logic chips, but I thought of recreating the Datong functionality in a new Arduino sketch.
So here is a breakdown of what the Datong offered:
- Either Mixed, letter or number combinations
- Groups of 5 characters
- Variable speed ( up to 37.5 word per minute)
- Variable character spacing (up to 4 seconds)
The Datong also allowed you to connect a telegraph key, and your headphones. But for now I will focus on the code generation element of the project.
The finished project has just a handful of components and can easily be created on a breadboard, or indeed if you have an old broken Datong you can reuse the box and panel to really replicate the old kit. The complete project includes 3 variable resistors (1K LIN) for Character speed, gap and volume. It also needs a 3 way switch to select the mode.
The Arduino I’m using is the UNO. Arguably the most popular Arduino on the market, but I have also tried the sketch on a Nano and it works fine – just some customisation of pin assignments is all that is needed.
On start up the Arduino checks to see which switch is LOW – it also saves the current mode and checks if the saved mode is the same as the current selected switch. If this is different, then the Arduino has had a change in the mode selection and resets.
When generating the tones, the Arduino randomly selects a character from an array. With that chosen letter – it calls a function and plays the corresponding tone functions. 2 functions exist as a DIT and a DAH.
The rest of the functions are dedicated to allowing the speed and gap to alter and also displaying the results on the LCD panel (completely optional).
Here is a short video of the kit working, and a link to the source code.
Arduino CW decoder – Conclusion
1. Line in or Microphone input
2. Easy to read display – all boxed neatly
3. An LED that shows the Zero beat
4. Easily accessible Reset Switch
5. Powered from a 12v supply.
I did want to create a usable PCB, something that could be used by a student or someone wanting to build the kit. So using the Fritzing application I set about laying out a circuit board.
This was my very first attempt at creating a PCB , so nerves were a wee bit on the tense side. I also wanted to box the project, so my rationale was to find a box first to work out the physical dimensions of the finished project.
As with the Vero Version – I created a layout that would fit on top of the UNO.
After submitting the design, and waiting a week I managed to get hold of 3 boards. They looked awesome. All white and exactly how I laid them out.
I did make 2 small errors on these boards. The first issue was sitting the capacitors a bit too close to the LM567 IC. That is an easy fix for the next version. But the 2nd and more serious issue is I forgot to ground 2 caps. They were floating and in parallel. I did fix this by attaching a wire to ground from one of the caps. That solved the issue, and I have already corrected the fault for the next batch of boards.
2 further observations of the boards & the project as a whole have highlighted 2 further improvements to the project. The location of the pins for the display / reset switch and audio OUT should be on the other side of the board. That would make a far better layout. Also adding in an audio oscillator / switch & plug to insert a key on the oscillator – then feed the output to the Arduino would immediately mean this kit could be used as a practice oscillator too. – that would show the letters as you transmit them out.
So here is a review of the project so far, and what I intend to do with the project going forward.
Arduino CW decoder – Conclusion
1. Line in or Microphone input
2. Easy to read display – all boxed neatly
3. An LED that shows the Zero beat
4. Easily accessible Reset Switch
5. Powered from a 12v supply.
I did want to create a usable PCB, something that could be used by a student or someone wanting to build the kit. So using the Fritzing application I set about laying out a circuit board.
This was my very first attempt at creating a PCB , so nerves were a wee bit on the tense side. I also wanted to box the project, so my rationale was to find a box first to work out the physical dimensions of the finished project.
As with the Vero Version – I created a layout that would fit on top of the UNO.
After submitting the design, and waiting a week I managed to get hold of 3 boards. They looked awesome. All white and exactly how I laid them out.
I did make 2 small errors on these boards. The first issue was sitting the capacitors a bit too close to the LM567 IC. That is an easy fix for the next version. But the 2nd and more serious issue is I forgot to ground 2 caps. They were floating and in parallel. I did fix this by attaching a wire to ground from one of the caps. That solved the issue, and I have already corrected the fault for the next batch of boards.
2 further observations of the boards & the project as a whole have highlighted 2 further improvements to the project. The location of the pins for the display / reset switch and audio OUT should be on the other side of the board. That would make a far better layout. Also adding in an audio oscillator / switch & plug to insert a key on the oscillator – then feed the output to the Arduino would immediately mean this kit could be used as a practice oscillator too. – that would show the letters as you transmit them out.
So here is a review of the project so far, and what I intend to do with the project going forward.
CW decoder – The Arduino
This is arguably the simplest part of the project. As mentioned Budd Churchward had created a series of videos on how he wrote the Sketch, created a PCB and published his code. (Budd’s Sketch is available here)
CW decoder – The electronics
CW decoder – The electronics
CW decoder – Introduction
If you do follow me on twitter (and if you don’t – you really should) you will have no doubt seen my recent tweets about constructing a CW decoder. After a number of retweets, and favorites from other very interested hams – I did promise that I would collate all my knowledge into a blog posts and share the details with you all.
So, for those who have not been following me on twitter – here is the sales pitch. I recently started looking at some projects that I could get my Arduino Uno involved in with the radio hobby. I have a number of reasons why I want to combine radio, Arduino and some electronics – more about this later.
I stumbled across a video on YouTube where Budd Churchward showed his Arduino copying and decoding CW straight off the HF band and at a reasonably high speed. I ventured further and wanted to know what electronics Budd was using to achieve this excellent little project.
I used the limited shared knowledge and discovered that the electronics is basally a LM567 – Tone decoder chip that (I have since discovered the chip is used in the ARRL book for Arduino Projects) I discovered takes an audio input and converts this to a HIGH / LOW output suitable for the Arduino to use as a signal for decoding.
Finding a suitable project for the LM567 and trying to work out how fellow constructors had configured their LM567s was not an easy task. This did indeed take quite a lot of chasing and head scratching. I will go into more technical detail on the next post – but for the reason why I wanted to complete this ? very simple. I w
ant to create a project that would “inspire” young electronically minded students that might have an interest in radio – (i.e the morse code) some coding experience and some construction / electronic interest. This project covers all 3 areas, and only lightly covers each subject area.
In the next post – I show the LM567, the schematic and give you the list of parts required.
