Assignment: Morse Code LED Controller with Variable Brightness

Objective

Extend a basic text-to-Morse-code converter to implement LED signaling with brightness control using a potentiometer.

Learning Outcomes

• Understanding ADC (Analog-to-Digital Conversion) configuration and usage
• Implementing PWM (Pulse Width Modulation) for LED brightness control
• Working with hardware peripherals in embedded systems
• Real-time signal processing and timing management

Hardware Requirements

1. Raspberry Pi Pico
2. LED (with appropriate current-limiting resistor)
3. Potentiometer
4. Breadboard and jumper wires

CMake Configuration

Don't forget to add appropriate libraries to CMakeLists.txt.

Implementation Tasks

1. Hardware Configuration (25 points)

• Choose appropriate GPIO pin for LED
• Select suitable ADC input for potentiometer
• Determine appropriate PWM frequency (consider LED characteristics)
• Choose PWM wrap value based on required brightness resolution

2. ADC Configuration (25 points)

• Initialize ADC hardware for potentiometer reading
• Configure GPIO for analog input
• Implement proper value scaling from ADC (0-4095) to PWM range

3. Morse Code Functions (50 points)

• Implement display_dot() with variable brightness
• Implement display_dash() with variable brightness
• Implement display_character() with proper handling of:
  • Uppercase and lowercase letters
  • Spaces between words
  • Invalid characters
• Ensure proper timing ratios between symbols
• Read potentiometer value during display for real-time brightness control

4. Code Quality and Integration (additional grade)

• Proper error handling
• Clear code organization
• Well-documented functions
• Smooth brightness transitions
• Comments

Technical Specifications

Timing Requirements

• Dot duration: 200ms
• Dash duration: 3 × dot duration
• Space between parts of letter: 1 × dot duration
• Space between letters: 3 × dot duration
• Space between words: 7 × dot duration

Starter Code

A base implementation is provided in 'morse_code_base.c'. You need to implement:

1. Functions marked with TODO comments
2. PWM initialization and control
3. ADC reading and scaling
4. LED brightness control

Testing Guidelines

1. Basic functionality:

   • Verify correct Morse code timing
   • Check LED on/off operation

2. Brightness control:

   • Test minimum brightness (potentiometer at 0)
   • Test maximum brightness (potentiometer at max)
   • Verify smooth brightness transitions

3. Error conditions:

   • Handle invalid input characters
   • Manage boundary conditions for ADC/PWM values

Troubleshooting Tips

1. No LED output:

   • Check physical connections
   • Verify PWM initialization
   • Confirm GPIO configuration

2. Incorrect brightness control:

   • Verify ADC readings
   • Check scaling calculations
   • Test PWM duty cycle range

3. Timing issues:

   • Use oscilloscope
   • Add debug print statements
   • Verify timer calculations