Text to Morse Code

Project Overview

In this project I made a light blink in morse code. You are able to write to a text file and the corresponding morse code can be programmed into the memory of a microcontroller. PWM was used to when turning on and off light for smooth transitions. Input length was restricted by the program memory of the microcontroller. There is also a switch to turn off the morse code and keep the light on all the time.

Implementation

Microcontroller

Name: ATTiny13 Memory: 1k of program memory

Programming Languages Used

• C

  • Converting text to a binary code (morse code), expressed as hex in a ascii file.
  • textToMorse.c
  • This output file can be read directly by the assembler I used (avra)
  • The assembler writes the binary code into the program memory

• Assembly (for ATTiny13)

  • loads one byte at a time from the program memory
  • then sends one bit at a time to a pin using PWM to soften transitions
  • morseOut.asm
  • Pulse with Modulation(PWM): microcontroller has built in PWM
    • Accidentally chose pins with no built in PWM
    • To remedy this, implemented PWM in software

Dimming

• I wanted to be able to control the maximum brightness of the light so it could be used durring the day or at night.
• With only 8 bits of PWM on the microcontroller this would be impossible to achieve while keeping the transitions looking smooth even at low brightnesses.
• This is why I included the potentiometer and transitor
• It isn't a perfect circuit as it is tempurature sensitive and sensitive to changes in supply voltage, but I wasn't able to notice these issues when using the light.

PCB

I etched the PCB at home. Mixed through-hole and surface mount parts.

Components

• 1 transistor
• 5 LED's
• 1 potentiometer

Project Result and Takeaways

Results

• It worked ok. Storing morse code the way I did was not space efficient for long messages. Also the c program was very sensitive to white space, so you have to be carful with formatting. That could definitly use improvement.

• Video of Light Blinking on YouTube

Takeaways

I wish I had included reverse polarity protection. I created the pcb before finishing the code. However, there was no need for this. I could have got the circuit woringing on a breadboard before making the PCB and this would have prevented the mistake of using the wrong pin to control the leds. Alternativily I could have been more careful and not assumed all pins had PWM capability.

If I were to do this project again I would modify the pcb instead of software to deal with PWM error. I knew I was only making one so it seemed like a more eligant solution to keep the pcb intact, but now I dont think that was the best option. Its nice to have different programs to integrate.