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8/12/2006 microcontrollers_cres_arc.ppt 1

Microcontroller Talk CRES-ARC

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Topics To Touch On

History of microcontrollers

What are microcontrollers

How you can work with microcontrollers

Overview of the W8ZPF Voter IDproject

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History Of Microcontrollers Microprocessors came before Microcontrollers

November 1971

Intel introduced the world's first single chip microprocessor, the Intel4004

April of 1972 First 8-bit microprocessor appeared on the market under a name 8008

April of 1974 8080 became available

Addressed 64Kb of memory, had 75 instructions, and cost $360

MOS Technology - WESCON exhibit ( 1975) a pivotal event in the history of microprocessors Announced the 6501 and 6502 at $25 each

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What Are Microcontrollers? Microprocessor Microcontroller what's the diff?

Microprocessors can not stand alone

instruction decoder, ALU, address/data/ctl. busses, timing logic, (CPU)

Has no capability to interact with the outside world

memory, I/O ports, UARTS, etc. must be added to make it useful

Microcontrollers are small computing systems on a single chip

Central Processing Unit (CPU)

Program memory

Random Access Memory (RAM)

EEPROM - Electrically Erasable Programmable Read Only Memory

A variety of peripheral devices

USARTs, Timer/Counters, ADC, DAC, I/O Ports, CANs, SPIs, etc., etc.

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What Are Microcontrollers?So, whats all the excitement about?

They are inexpensive- even in single pieces You can design complex functionality in a small

package Microcontrollers can be viewed as a universal building

block There are a lot offree tools to work with

Microcontrollers

And The thing I like the best - Next Slide!

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What Are Microcontrollers?

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Microchip 16F88 DIP Package

$3.90 each single unit price

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16F88 INTERNAL VIEW


(Harvard Architecture)

Has 35 instructionsDatasheet 214 pages

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ATMEL ATmega8 DIP Package

$4.50 Each single unit price

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Atmega8 INTERNAL VIEW(Harvard Architecture)


Has 130 instructionsDatasheet 302 pages

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So whats the catch?

If you are new to software development

You need to think in a new paradigm

Start small and learn the basics first

You can work with microcontrollers on a

couple of levels Walk before you attempt to run

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Ok So What Do Microcontrollers Do?

Well out of the box it does nothing!

But you can make it do fantastic things

Just add software

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How To Get Started

Select a controller family

Based on your goals

Availability of free stuff

set-up a development environment

Not a trivial task for the beginner

You need a way to load programs

Then are you ready to start!

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The W8ZPF Voter ControllerA real project

What are we trying to accomplish

Interface to the repeater system

Microcontroller Selection

Development Environment

Software Design

The Final Board (observations)

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The W8ZPF Voter ControllerWhat are we trying to accomplish?

Identify how each receiver participated inrelaying signals to the main transmitterduring a key down session

Accommodate up to 3 receivers in thedesign

Use existing repeater interfaces/signals

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The W8ZPF Voter ControllerSimplified Interface Diagram

Current VoterCard

New VoterMicrocontroller

Current RepeaterController

CORE (H)

RX1(H)

RX2 (H)

RX3 (H)

RX1 Voted (^)

RX2 Voted (^)

RX3 Voted (^)

RX1 Dominant (^)

RX1 Dominant (^)

RX1 Dominant (^)

=>90% of the timeHigh Pitch CW ID (M/R)(VOTED)**

< 90% of the timeLow Pitch CW ID (M/R)**

(DOMINANT)

Inputs, Outputs, & Transformation

CD ID (M/R)

*Controller remembers last transition

** ACTUALLY 88.8 %

*

Sample every 100ms

When CORE is active

Calculate output whenCORE goes inactive

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The W8ZPF Voter ControllerINTERFACE FOR THE VOTER CONTROLLER PROJECT

RX1 RX3 output lines (active high)

CORE LINE

1 or 0 Output lines retain previous datauntil core goes active again

All output lines are clearedafter core goes active fordebounce time.

Version 1.0 - wje

There are 6 output lines3 -> rx1 - rx3 voted3-> rx1 - rx3 dominant

Active Idle

AccumulateData (100ms)Ignore RX inputs

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The W8ZPF Voter ControllerMicrocontroller Selection

Looked at 2 controllers For This Project Microchip 16F88

Atmel Atmega8 Basic software structure was implemented using both

Either would have done the job So how did I choose?

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The W8ZPF Voter ControllerThe development environment

16F88 Microchip microcontroller (initial choice)

MPLAB

Free environment for assembly language Create, Edit, Assemble, Link, Load, & emulate programs

I use it on Windows 2K

I have used it for several projects works well

No limitations on usage

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ATmega8 microcontroller (final choice) Open Software Foundation tool-set

GNU C compiler, assembler, linker

Make utility

Avrdude program loader

Runs on Linux (Unix) & Windows

Wanted experience with this environment Atmega8 is more compiler friendly

Generally faster to develop SW using a compiler However, a not significant issue for this project

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ATmega8Development board(Spark Fun)

LINUX environment(FC3 FC5)

Serial port(program flash memory)

This is what it physically looks like

Final board

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The W8ZPF Voter ControllerVoter ID Board Schematic

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The W8ZPF Voter ControllerThe Microcontroller Board

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The W8ZPF Voter ControllerThe Software Design

This is where it gets a bit philosophical

I think of it in these terms

Software is a solution to a problem

Must understand the problem first

Then think about strategies to solve it

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The W8ZPF Voter ControllerThe Software Design How does one start?

VARIOUS SOFTWARE STRATEGIES

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The W8ZPF Voter ControllerThe Software Design (STATE MACHINE)

BackgroundProcessing

ForegroundProcessing

Background Responsibilities- Debounce inputs- Watch core line- Determine when new

state exists- Maintain count for each Rx

Foreground Responsibilities- HW initialization- Call action routines on

state changes- Processes RX data onkey-up

- Signals main controllerregarding RX usage(sets output lines)

New state

Call routineTo handle theState change

Go to sleep

100 MS interrupt

Return from interruptWakes-up foreground

HW

Run Backgroundprocess

States are:STARTUPIDLECOUNTING

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Source File Statistics

main.c 155 lines

main.h 17 lines

init_timer1.c 30 lines

init_io.c 103 lines

interrupt.c 118 lines Makefile 328 lines

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More Statistics (Decimal)

RESOURCE USED/AVAILABLE

Text size 1462/8K Bytes (program instructions/tables, etc)

Data size 37/512 Bytes (variables)

TOTAL 1499 Bytes (5DBh) Used

512 Bytes of EEPROM none used

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The W8ZPF Voter Controllermain.h file variable declarations

#ifdef LOCAL #define LOCAL#define EXTERN #include main.h#else#define EXTERN extern

#endif

enum { NO, YES };

enum { STARTUP, COUNTING, IDLE };

EXTERN unsigned char state;EXTERN unsigned char new_state;EXTERN int16_t rx1_count;EXTERN int16_t rx2_count;EXTERN int16_t rx3_count;

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The W8ZPF Voter ControllerThis is the main loop (part of it anyway) of the foreground state machine code

while(1){if(new_state == YES ){new_state = NO;cli();switch(state){

case COUNTING:// clear out old receiver counts on this state changerx1_count = 0;rx2_count = 0;rx3_count = 0;

//clear all "voted" output lines to the repeaterPORTB &= ~(_BV(PB0));

PORTB &= ~(_BV(PB1));PORTB &= ~(_BV(PB2));

//clear all "dominant" output lines to the repeaterPORTD &= ~(_BV(PD5));PORTD &= ~(_BV(PD6));PORTD &= ~(_BV(PD7));break;

case IDLE:/*

Calculate results, set outputlines accordingly**** This is long & will not show details here ****/break;

case STARTUP:// Do initialization herebreak;

}sei();}sleep_mode();}

Fragment of code from main.c

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8/12/2006 microcontrollers cres arc ppt 31

The W8ZPF Voter Controller

THE END !!

2006 08 N9CX Uproc Talk

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