Embedded Software Experiments

Programs created while experimenting and learning embedded software. Written in C for AVR ATmega328P microcontroller on Arduino Uno development board and STM32F446re on STNucleo development board. ATmega328P programs are compiled with avr-gcc and flashed to arduino with AVRDUDE. STM32F4 Programs use cube ide

Highlights

• Analog to Digital Conversion

  • Created ADC hardware abstraction layer (HAL)
    • Reads values from selected ADC on ATmega328P
  • Designed simple voltage divider circuits with LDRs and rotary potentiometers to manipulate ADC readings
    • Turned on board arduino light if LDR reaches a certain light level (adc_experiments / adc_read.c and adc_experiments / adc_hal_test.c)
    • Controlled servo position based on ADC readings from rotary potentiometers or LDRs. (adc_experiments/servo_integration.c)

• Servo Control

  • Generated PWM signals to control servo position
    • servo_experiments/pwm_gen.c
  • Implemented state machines to create simple systems
    • 2 sweeping servos, only one active at a time. Press a button to switch between them. Press another button to turn on / off. (servo_experiments/two_servos_state_machine.c)
    • 2 servos controlled by ADC reading from potentiometer voltage divider. Press a button to save current position. Press another button to switch between saved position and potentiometer position. (adc_experiments/save_state.c)

• UART Communication

  • Created interrupt-based UART HAL (serial_communication_interrupt/lib/serial_hal)
    • Sends and receive messages over UART
    • Uses a ring buffer to store tranmission data (serial_communication_interrupt/lib/ring_buffer)
    • Used for simple test program that would reply with the same message that was sent from serial monitor

• I2C Communication

  • Used polling and interrupt based methods to send messages over I2C (I2C/interrupt_i2c_transmit.c, I2C/polling_i2c_transmit.c)
    • Used Analog Discover 3 logic analyzer for debugging / analysis of working drivers
  • Created interrupt-based I2C HAL
  • Created I2C-LCD driver using my I2C HAL
    • Control of backlight, cursor position, and character at each position
    • Higher-level functions that handle backlight, cursor, and characters to print messages to screen

• STM

  • Interfaced with DAC and ADC using STM32 HAL to created proof of concepts of digital audio effects later used for digital guitar pedal project