LaunchPad Serial Morse Transmitter

Inspired by this, I decided to build a morse transmitter and add some cool features to it.

This project show how to build a little morse transmitter using an MSP430G2231 MCU.
The device can transmit in two modes:
   - serial, getting the characters from a COM port  and translating them into morse code; 
   - manual, using the key switch.

In serial mode, one character at a time is read from the COM port and transmitted as morse at 15 WPM. To better understand how morse code works, read this .

Morse keying is achieved toggling an output pin connected to the oscillator power pin, thus getting a pure CW mode.

The device is powered with 2xAA batteries, and the power consumption is kept to a minimum thanks to the Low Power Mode when not transmitting. You may add a second 4xAA supply for the octal buffer in order to increase RF power.

Step 1: BOM & Tools needed

Here's what you'll need to build this project:

BOM:
  - 1x MSP430G2231 Texas Instruments MCU
- 1x 74HC240 Octal buffer
- 1x Oscillator (operating frequency should be in the 10/12m CW band (24/28 MHz))
- 2x 220 ohm resistors
- 2x 1 kohm resistors
- 2x LED (different colors are better)
- 2 push-buttons (included in the Launchpad, you may want to use a better switch for morse keying)
- 2 AA batteries (you may want to use a separate 6V (4AA) supply for 74HC240)
- 1m electrical wire (9 AWG)

TOOLS:
- soldering iron
- solder
- wire stripper
- breadboard or stripboard
- TI's Launchpad board
- mini-usb cable
 

Comments

[RayBurne]

FYI:
"The hard part came when I needed to build a lookup table for the morse code, as there's no known algorithm capable of encoding a character directly into morse."

Not true anymore!  Magic Morse provides encoding and decoding capability.  

Encoding:  http://www.instructables.com/id/Orb-Flashes-Temperature-in-Morse-Code/

Decoding: http://www.instructables.com/id/Morse-Code-Magic-An-Algorithm/

Ray Burne

[Matz]

Nice job! I'm just starting out with the Launchpad and have found your Instructable to be quite informative.

[jbiggs12]

any news on a receiver? :)

[js12345]

This transmitter is not legal without an output filter. Please do not put this on the air without a proper output filter. This will transmit harmonics much higher than allowed by law.

Here are example filters:
http://www.gqrp.com/harmonic_filters.pdf

[rct]

If you watch the video, start with your audio turned way down, there is a loud noise at the very beginning.

[rct]

Isn't the 74HC240 Octal buffer just turning the (sine wave) output of the oscillator into an amplified square wave?

[AntzyP]

I thought of something on these lines for this contest as well... nice 1 though...