Digital Guitar Amplifier and Effects Unit Shaun Caraway, Matt Evens, and Jan Nevarez Group 5, Senior Design Spring 2014 Table of Contents 1. Executive Summary ....................................................................................... 1 2. Project Description ......................................................................................... 2 2.1. Project Motivation and Goals ................................................................... 2 2.2. Objectives ................................................................................................ 3 2.3. Project Requirements and Specifications ................................................ 3 3. Research ........................................................................................................ 4 3.1. Digital Signal Processing ......................................................................... 4 3.1.1. Requirements ................................................................................... 4 3.1.1.1. Sampling Rate ............................................................................... 4 3.1.1.2. Audio Word Size ............................................................................ 5 3.1.2. Processor Comparison ..................................................................... 5 3.1.3. Features ............................................................................................ 6 3.1.3.1. Programming Method .................................................................... 6 3.1.3.2. Real-Time OS ................................................................................ 6 3.1.3.3. Ports Available ............................................................................... 7 3.2. Analog ..................................................................................................... 7 3.2.1. Input .................................................................................................. 7 3.2.2. Output ............................................................................................... 8 3.3. Data Converts ......................................................................................... 9 3.3.1. Analog to Digital Converts ................................................................ 9 3.3.2. Digital to Analog Converts .............................................................. 10 3.4. Communication ..................................................................................... 11 3.4.1. UART .............................................................................................. 11 3.4.2. SPI .................................................................................................. 11 3.4.3. UPP ................................................................................................ 12 3.4.4. EMIF16 ........................................................................................... 12 3.4.5. SRIO ............................................................................................... 12 3.4.6. McBSP ............................................................................................ 13 3.5. Algorithms ............................................................................................. 13 3.5.1. K Method ........................................................................................ 14 3.5.2. Newton’s Method ............................................................................ 15 3.5.3. DK Method ...................................................................................... 16 3.5.4. DK Method Equations ..................................................................... 16 i 3.5.5. Impedance Decomposition ............................................................. 17 3.5.6. Component Models ........................................................................ 18 3.5.7. Vacuum Tube Models ..................................................................... 18 3.5.8. Diode Model ................................................................................... 20 3.5.9. Transformer Model ......................................................................... 20 3.5.10. Effects Algorithms ....................................................................... 23 3.5.10.1. Delay ........................................................................................ 23 3.5.10.2. Reverb ..................................................................................... 24 3.5.10.3. Chorus ..................................................................................... 25 3.5.10.4. Compression ............................................................................ 26 3.5.10.5. Speaker Cabinet Simulation ..................................................... 27 3.6. Printed Circuit Board ............................................................................. 29 3.6.1. Layer Consideration ....................................................................... 29 3.6.2. OrCad ............................................................................................. 30 3.6.3. Eagle .............................................................................................. 30 3.6.4. Upverter .......................................................................................... 31 3.7. User Interface ........................................................................................ 31 3.7.1. On Board ........................................................................................ 31 3.7.1.1. On Board LCD ............................................................................. 31 3.7.1.2. Microcontroller for the LCD ......................................................... 32 3.7.1.3. Alternate Solution ........................................................................ 32 3.7.2. Computer ........................................................................................ 33 3.8. Power Supply ........................................................................................ 33 3.8.1. Linear Power Supply ...................................................................... 33 3.8.2. Switching Power Supply ................................................................. 34 3.8.3. Power Management ....................................................................... 35 4. Design ......................................................................................................... 37 4.1. Audio Inputs and Outputs ...................................................................... 37 4.1.1. Unbalanced to Balanced Signal ...................................................... 38 4.1.2. Headphone Output ......................................................................... 40 4.1.3. Stereo Output ................................................................................. 43 4.2. Data Convert Design ............................................................................. 44 4.2.1. Analog to Digital Converter ............................................................. 44 4.2.2. Digital to Analog Convert ................................................................ 48 4.2.3. Clocking .......................................................................................... 51 ii 4.3. Digital Signal Processor ........................................................................ 52 4.3.1. Clocking for Processor .................................................................... 52 4.3.2. Memory ........................................................................................... 55 4.3.3. Power On and Boot Sequence ....................................................... 56 4.3.4. Software .......................................................................................... 57 4.4. User Interface ........................................................................................ 59 4.4.1. Hardware Interface ......................................................................... 59 4.4.2. Software Interface ........................................................................... 61 4.4.2.1. Coding ......................................................................................... 62 4.4.2.2. Communication ............................................................................ 63 4.5. Printed Circuit Board Design ................................................................. 64 4.5.1. Printed Circuit Board Requirements ................................................ 65 4.5.2. Analog Board .................................................................................. 65 4.5.3. Digital Board ................................................................................... 65 4.5.3.1. Hardware configuration of the TMS320C6657 ............................. 66 4.5.3.2. Filtered Voltage Supplies ............................................................. 67 4.5.3.3. DDR3 Routing ............................................................................. 69 4.5.4. Bulk Power Supply Board ............................................................... 69 4.6. Power Supply Design ............................................................................ 70 4.6.1. Digital Sub System .......................................................................... 72 4.6.1.1. Power On and Off Sequencing .................................................... 75 4.6.2. User Interface Sub System ............................................................. 75 4.6.3.