general midi explorer instructor and uga presentation, and demo professor sandip kundu fall 2014 ece...

General MIDI ExplorerInstructor and UGA Presentation,

and DemoProfessor Sandip Kundu

Fall 2014

ECE 353 Lab D

ECE353: 2 Computer Systems Lab 1 Kundu

Lab DGeneral MIDI Explorer with Record/Playback

Getting Started


Where Are We?

Lab A Cache Simulator in C• C programming, data structures• Cache architecture and analysis

Lab B MIDI Receiver• Hardware design • Proper Verilog Coding• Functional Simulation, GoLogic, MIDI-Ox

Lab C Pipelined Machine• C programming, data structures• Pipeline architecture and analysis

Lab D General MIDI Explorer with Record/Playback• Microcontroller programming

• C and Assembly (optional for 10% extra credit)


Perspective

• As an engineer you often have multiple choices for implementation

• What you do will depend on performance and cost requirements

• Use a CPLD, FPGA, ASIC/microprocessor, or microcontroller

• Write it in Verilog (CPLD, FPGA, ASIC) => Lab B• Write it in C or ASM => Lab D


When to use: PLDs, FPGAs, ASICs, Structured ASICs• Programmable logic devices (PLDs) provide low/medium density

logic.

• Field-programmable gate arrays (FPGAs) provide more logic and multi-level logic. Advanced peripheral support.

• Application-specific integrated circuits (ASICs) are manufactured for a single purpose. Typically built with standard cells implementing gates. Higher performance vs. FPGAs.

• Structured ASICs are in between FPGAs and ASIC in density & performance. Typically wire together cells that are pre-built and exist in island configurations.


Differences between microcontrollers, microprocessors and FPGA systems for running software

FPGA systems often contain CPUs in softcore (synthesized) or hardcore (part of die) format but can also contain logic blocks for other hardware, e.g., state machines, etc

• 45-65 nm FPGAs (Virtex 5-7) can achieve high performance.

Microcontrollers are more limited in functionality and often do not include support for virtual memory and caches

• Up to 50MHz

Microprocessors are higher performance capable and have typically virtual memory support

• From 50MHz to GHz

TxTx

RxRx

DiscreteDiscretePHYPHY

DiscreteDiscretePHYPHY

TxTx

RxRx

Soft coreSoft core

Hard core with built-in

Transceivers

Hard core with built-in

Transceivers


Lab D Objectives

• Exposure to microcontroller programming vs. design of hardware• Compiled Language (C)

• Data Structure in Memory• Talking to UART, Timer

• Assembly Language (ASM) - optional• Talking to A/D converter, Timer, UART

• Continuation of MIDI theme• Serial communication• Notes and instruments

• Complete system with MIDI – FUN! with input, output, storage


Lab D Requirements

• Part 1: C Program• Send & Receive MIDI Messages• Play and Recording Modes• Store and Replay MIDI Messages

• Part 2: ASM Program (optional for extra credit)• Vary speed of messages via hex switch• Instrument / Note / Velocity via photo cells• Change channels between Percussion & Instrument


AVR Components Used

• In Part 1 (C Program)• Data EEPROM (Storage)• USART (Communication)• Timer1 (Counter)

• In Part 2 (ASM Program) • Timer1 (Counter)• USART (Communication)• ADC (Analog to Digital Converter)• Will manipulate these components using AVR assembly.


ATmega32 AVR

• 16MHz CMOS 8-bit microcontroller with AVR RISC instruction set

• 32 general purpose registers

• 32KB of Flash

• 2Kb internal SRAM

• 1KB E2PROM – 100,000 erase cycles

• 8 and 16 bit counters

• USART

• 8-bit ADC

• JTAG

• ….


Board Demonstration


Wired Board


Part 1 – C Program

• Develop, program AVR through JTAG, for:

• Getting MIDI messages through the Midi OX from the PC serially

• Similar to Lab B but using AVR Studio and AVR gcc compiler – to receive

To PC

Play Switch

Record Switch

Transmit

Input

Input

AT

Me

ga3

2C Program Block Diagram

From PC Receive

EEPROM DATA

USART


Part 1 – C Program contd.

• Once received in AVR, store in E2PROM if switch set to Record

• Compress/decompress before/after storing - you can use any algorithm you find suitable

• Record timing also so that you can replay exactly the same way

• If switch set to Playback, play back

• Incoming signal optically isolated from PC

To PC

Play Switch

Record Switch

Transmit

Input

Input

AT

Me

ga3

2

C Program Block DiagramFrom PC Receive

EEPROM DATA

USART


Compression

• Why compress?• Store more data in same persistent memory• Persistent data limited in # of erase cycles• Save on bandwidth when communicating in some apps

• Lossless compression (LZ, Huffman, RLE):• Decompress and get the same data, bit - for - bit

• Lossy compression (JPEG,…):• Decompress and get something *similar*.• Any amount of compression is possible.

• Tradeoff between quality and compression.

• Domain specific • You may understand the pattern, e.g., in the case of MIDI

messages there is a repetition that could be exploited.


Example: Run Length Encoding (RLE)

• Very simple lossless encoding of repeating patterns

• Example: Imagine a stream of bits with many 0s and 1s • Source: 000000000111111110001111111• RLE Version: 9Zeros8Ones3Zeros7Ones

• Can be transformed into a sequence of 1s and 0s but we often limit the encoding of the maximum sequence value to avoid too much overhead for very random sequences.

• Say we limit to maximum 16 repetition of 1s or 0s: represent with 4 bits

• 1001(0)1000(1)0011(0)0111(1) for the above sequence

• Best we get is minimum 5 bits needed for a sequence of length 16, or a compression ratio of 16/5

• 111111111111111 => 1111(1)• Worst we get an overhead of how much?

• To avoid, change algorithm to have a first bit encode WHEN RLE is used

• RLE can be applied at various granularities


Example of lossy compression - JPEG compression

Very high quality: compression = 2.33Photoshop Image

Very low quality: compression = 115Produced by MATLABwith Quality = 0


For Part 1 you need to figure out how to

• Initialize the USART• Set baud rate for midi

• Enable the receiver and transmitter

• Initialize to 8 data bits, 1 stop, and 1 stop bit

• Create functions for receive, transmit, and flush USART• Create functions to read and write E2PROM• Work with timers and interrupts

• Use 16-bit counter and generate interrupts for overflows; need to setup ISR (interrupt service routine)

• Main function• Use LEDs to debug, try something simple first• All information is in AVR datasheet; sample codes


Part 2 – AVR ASM Program

• Develop, program AVR through JTAG

• Use the three optical sensors that are connected to three ADC inputs on AVR to generate instrument, note, and velocity MIDI bytes

• Use the internal AVR counter to synchronize when sending back MIDI messages to PC

• Sets 1 bit into register, your code will be polling

• Speed-dial hex switch on board

• Use GPIO connected switch

• To program channel select (percussion, instrument)

• Note that you will see 2 byte message for program channel selection and the typical 3 bytes for the message that contains note and velocity

ADC

TransmitTo PC

Input

Input

Hex Switch

Instrument Switch

AT

Meg

a32

ASM Program Block Diagram

Analog Signal (Photocells)

Timer1

USART

ADC Converter


Build Process

Board Assembly C & Assembly Programming

• AVR Studio (IDE)• Olimex JTAG Programmer

Testing• MIDI-OX• GoLogic Logic Analyzer• Oscilloscope


Board Assembly Reuse parts of Lab B

• MIDI input (Opto-isolator)

Plan for both programs if you decide to do both C and ASM versions

• Layout should be compatible with both

Use resistors as indicated in schematic

• Otherwise photo-senors may not work correctly


AVR Studio

Atmel IDE Tool chains for building C and assembly code Programmer Debug

Easier to use than Quartus!


AVR Studio Demonstration

• Open up a new instance of AVR Studio 4• When the welcome screen pops up, click New Project



• Select AVR GCC for the project type• Type in project title and choose project directory if necessary• Click next and choose the debugging platform used to program

the MCU as well as the MCU that you are using

• Now go to Project --> Configurations and choose the MCUs clock frequency.



• Start Coding!• When finished, 1.build your project and then 2.connect to the

MCU.



• Once you connect to your MCU, erase the device and then load up the .hex file created in your project directory on to the Flash Memory.



• Click on program to load your .hex file on to the board.• Now open up MIDI OX and set it up like you did in Lab B.• Start sending notes to your board!


Testing

Familiar tools• MIDI-OX• GoLogic Logic Analyzer

• Analyzer individual MIDI frames• Oscilloscope

• Demonstrate frequency of sent MIDI messages


General Advice

Consult the Atmega32 datasheet• Pin layouts• Code examples in C and assembly• All the info you need to manipulate the microcontroller

for this project is here!

Use the AVR studio debugger• Check the value of pins and registers• Single step through code to find source of problems

Use internet resources• avrfreaks.net is a good resource for examples


DEMO


Backup


AVR AssemblyCommands similar to MIPS

ldi, breq, andi, lsr, rsr, etc.‘in’/’out’ used when working with I/O portsCan ‘rjmp’ using tags (no offsets to worry about)

There are some differences though…sbic, neg, cbi, etc.


Setup Example (AVR)

Setup Example.include "m32def.inc“ (Include system file).def Temp=R16 (Define R16 register)

.org 0x0000 (Where to begin) rjmp RESET (Jump to RESET)RESET:…


Stack PointerYou must initialize the stack pointer if you wish to

return from jumps…Set stack pointer

ldi Temp, 0x65

out SPL, Temp


Setup Example (C)

Setup Example#include <avr/io.h> (Include system file)int main() {

int data;DDRA = 0xFF; (PORTA output)DDRB = 0x00; (PORTB input)PORTA = 0x55; (Output 0x55 or

0b01010101)data = PINB; (Store input values)

}…


Timer1Timer1 is the 16-bit counter on the AVR

Will count overflows of Timer1 in order to gauge transmission time.

Good to set counter prescalar to 1024Choose 1024 prescalar for Timer1

ldi Temp, 0x05out TCCR1B, Temp


USARTMust initialize with desired baud rate and frame

formatMust be initialized in both C and ASM

MIDI Baud rate : 31.25 kbpsWant start/stop bits and 8 data bitsRead data sheet

general midi explorer instructor and uga presentation, and demo professor sandip kundu fall 2014 ece...

Documents

lab d ece353

lab bwrite

softwarefpga systems

midi messagesplay

midi fun

storage ece353

extra credit ece353

replay midi messagespart