Design of Automatic Guitar Tuner using 8-bit Microcontroller

The guitar is a highly popular musical instrument. Tuning a guitar can be challenging for many, prompting the need for research into developing an automatic tuning tool. This device utilises the Arduino Uno to process audio signals, at a sampling rate of 38.5kHz. Achieving this rate involves configuring registers concerning ADC operations in Atmega328p (on the Arduino Uno), specifically ADMUX (ADC Multiplexer Selection Register), ADCSRA (ADC Control and Status Register A), and ADC Data Register. Frequency reading is determined by processing data from the ADC Arduino Uno to measure the time needed to complete one full wave. Upon obtaining the frequency value, the closest string frequency is calculated to determine if the frequency is accurate. If the frequency is found to be incorrect, the stepper motor will be rotated by several steps. The research concludes that the tool can tune effectively when the frequency is lower than the reference frequency, but its performance deteriorates when the frequency read is higher than the reference frequency.