Summary of Morse-Code Trainer Using Arduino
This project is a Morse code trainer designed with an ATtiny85 microcontroller to help kids learn Morse code. Powered by a 3-AA battery pack, it drives a piezo beeper to output Morse messages. The device is programmed via an Arduino acting as an ISP programmer, using the familiar Arduino environment for ease. On startup, it waits 3 seconds, then continuously broadcasts a preset Morse code message. The compact, low-cost design makes it a fun educational tool with a hidden Lego prize as motivation.
Parts used in the Morse code trainer:
- ATtiny85 microcontroller
- Piezo beeper
- 3-cell AA battery pack
- Strip-board (for circuit assembly)
- 6-pin ISP header (for programming)
- Arduino (used as ISP programmer, not part of final device)
My kids are learning Morse code this summer, so I threw together this little circuit to help them learn. And to make it more fun…
It uses an ATtiny85 ($2.26 at digikey.com) to drive a piezo beeper (≈ $3.50 at Radio Shack.) The ATtiny85 takes 5.5V max, so I built the circuit on a piece of strip-board so as to fit onto the back of a 3-AA-cell ($3 or so at Radio Shack) battery pack.
To program it, I used MIT’s “High-Low Tech” ATtiny85 core using an Arduino as an ISP programmer. I actually built a 6-pin ISP header into the board, so I don’t have to pull the chip out to reprogram it as you would with MIT’s instructions, but that’s neither here nor there. Using an Arduino core allows me to use all the Arduino tools I’m familiar with, but I don’t have to spend $20 or more on a full Arduino when all I really need is one output pin and a couple kb of program space. The ATtiny85 is perfect for this: plenty of memory and dirt cheap. (Actually, an ATtiny25 would work with the amount of memory this program takes, but ATtiny85s are so cheap you don’t save much buying the ATtiny25.)
Here’s the code. When the device is powered up, it waits 3 seconds then puts out the message at the desired speed. The message repeats until power is removed. Currently the message is “SOS the moon rover has broken down and I am stuck in the trash can in the garden shed.” Once the kids decode it, they’ll find a small Lego moon rover there as a prize.
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