Implementation of Non-stringed guitar using ATmega128 Myeongsu Kang, Sangjin Cho, Jongmyon Kim, Uipil Chong School of Computer Engineering and Information Technology University of Ulsan, Ulsan 680-749 Korea Phone: +82-52-259-1650 E-mail: sjcho75@ulsan.ac.kr Abstract When guitarists play the guitar for music concert, they need to change guitar strings and tune guitar prior to the concert. In this paper, we propose non- stringed guitar to improve these troublesome things. Non-stringed guitar consists of three parts: chord glove, processor and sound processing software. First, the chord glove composed of FSR and FLEX sensors representing guitar chords. Second, the processor, ATMega128 recognizes guitar chords. Finally, each of sound pitches is transmitted to the sound processing software called Max/MSP. Therefore, Max/MSP can play guitar chords at certain pitch by using graphical object, such as ‘serial’ object, ‘open’ object and so on. Also, up and down stroke can be expressed by using different delay. Keywords: Non-stringed guitar, Chord glove, AVR board, Max/MSP. 1. Introduction At the end of the 18C, the first guitar that has six steal string invented and many great guitarists appeared as many as it is called 'golden age of guitar'. There were lots of music concerts playing the guitar and many guitars have been developed. Today, there are variety of guitars, such as semi folk guitar with pick-up, electric guitar and so on. There are many chances to use guitar for music concerts. Guitar players must tune guitar and change guitar strings prior to the concert. If players use the non-stringed guitar, they can avoid these troublesome things. This is why we develop the non-stringed guitar in this paper. Non-stringed guitar consists of three parts. First, it is necessary to implement a chord glove in which Force Sensing Resistor (FSR) and FLEX sensors are embedded to express guitar chords. Sensor signals generated in the chord glove are changed into the specific values through the AVR board. These values are transmitted to the computer in real-time. Sound processing software Max/MSP can play guitar sounds at certain pitch by using graphical objects because all of open string sounds are mapped into the Max/MSP in advance. 2. Implementation 2.1 Structure of acoustic guitar As shown in Fig. 1, Guitar consists of head, nut, neck, fret, fretboard, sound hole, string, bridge and so on. When players stroke on the guitar, the sound vibrates and then the sound is amplified on the sound hole. That is the principle how the guitar sound generates. Moreover, guitar has a variety of sounds which is expressed by fret. There is a semitone gap between first fret and second fret. Therefore, the twelfth fret is exactly one octave higher than the open string. Fig. 1 Structure of acoustic guitar 2.2 Overall system of the non-stringed guitar Non-stringed guitar basically consists of three parts as shown in Fig. 2. The first part is a chord glove that expresses guitar chords. The second part is an AVR board which ATmega128 processor is embedded into the board and it is for recognizing guitar chords. The third part is a Max/MSP which is sound processing software for playing guitar chords in real-time. Fig. 2 Overall system of the non-stringed guitar