GFX-One Guitar Processor

1. GFX-One Guitar Processor Team Carpal Tunnel September 8, 2005 Capstone Fall 2005

2. Team Members • Mason Stone • Henock Negassa • Tony Sawyer • Nael Cassier Capstone Fall 2005

3. What is GFX-One? • GFX-One is a digital audio effects processor. • It is designed specifically for use with guitar, but can process any monaural analog audio input. Capstone Fall 2005

4. Functional Block Diagram Capstone Fall 2005

5. Digital Signal Processor Capstone Fall 2005

6. Why use a DSP? • Digital data is easier to manipulate • Implementing effects can be done using algorithms and subroutines as opposed to sophisticated analog hardware • DSP can be altered and maintained using software Capstone Fall 2005

7. Implementing Audio Effects • Flanger effect is present in a lot of guitar-driven music • It is accomplished by adding a signal to a time-varying, phase-modulated version of itself Capstone Fall 2005

8. Fixed Delay and Reverberation • Reverberation and echo are very common in audio engineering • Both can be synthesized in DSP using comb filters and re-circulating delay lines Capstone Fall 2005

9. Other Effects and Features • Parametric Equalization • Gain manipulation • Auto-Wah • Phaser • Noise-gating • Decimation (Aliasing) • Many other possibilities Capstone Fall 2005

10. DSP Interface • What We Need: • 25 MHz Oscillator • Flash Microcontroller • 256 MB SDRAM • FPGA • I/O Capstone Fall 2005

11. 25 MHz Oscillator • Used to synchronize digital circuitry. • With use of PLL, provides clock speed. • Will be connected to FPGA, then distributed. Capstone Fall 2005

12. Flash Microcontroller • Contains instructions for DSP. • Internal μcontroller programs chip automatically over HDD interface. • Internal code can contain image for FPGA. Capstone Fall 2005

13. SDRAM/FPGA • Operate over system bus: • 8 bits for Address • 8 bits for Data • Chip Enable • Read/Write Enable • Clock • IRQ Capstone Fall 2005

14. Input/Output • DSP means Digital Signal Processor, so we need a digital input and output. • A/D converter translates signal into DSP. • D/A converter translates signal out of DSP. • DSP has Multi-channel Audio Serial Ports (McASP) to accomplish this, but it can also be implemented using parallel interface. Capstone Fall 2005

15. Mixed Signal Interface • Signal from Analog amplifier is fed to A/D Converter. • Converts input voltage from analog signal in to Digital bit • Synchronized with 44.1KHz Clock • 16 Bit digital signal Capstone Fall 2005

16. Mixed Signal Interface • Digital to Analog (D/A) conversion methods • Data is fed from DSP to D/A Converter. • Standard D/A converters translate an array of digital bits into a bias voltage • Synchronized with 44.1KHz Clock • 16 Bit digital signal Capstone Fall 2005

17. Power • Regulated 3.3 and 2.5 V power buses from 9V DC adapter. • 5V • LCD • 3.3 V • Compact Flash • A/D and D/A converters • Data lines to and from FPGA • 2.5 V • FPGA Vcc Capstone Fall 2005

18. Analog Signal Mixer • A good recording mixer lets you route a variety of input signals and combine them into one signal. • For a potential Add-on output signal from MP3 player will mix with signal from D/A converter Capstone Fall 2005

19. Audio Op Amps • Analog signal from Mixer is going to be amplified and routed to speaker • Amplifier is transistor based • 1.6- to 3.6-volt speaker driver Capstone Fall 2005

20. Field Programmable Gate Array • Gateway of the user to all the other chips • Controls the Clock to other devices • Sends data to the DSP as well as the LCD • Flash will set the FPGA through the DSP • Program the FPGA through a JTAG Interface Capstone Fall 2005

21. User Interface Capstone Fall 2005

22. Schedule Capstone Fall 2005

23. Division of Labor Capstone Fall 2005

24. Tentative Budget Capstone Fall 2005

25. Possible Add-ons • Add another analog signal (MP3) • Amplifier + Speaker • Over Drive Circuit Capstone Fall 2005

26. Risks and Contingencies • Hardware Availability/ Damage • Difficulties Implementing FPGA • Difficulties Implementing LCD • Difficulties With DSP Interface Bus Capstone Fall 2005

27. Questions? Capstone Fall 2005