Digital Home Brewing

8/9/2019 Digital Home Brewing

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DigitalHomebrewingBob Okas W3CD

Copyright 2004 Robert P. Okas


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Introduction

Digital Homebrewing is a broad topic thatencompasses:

Hardware Logic Design Software design

Combinations of both: Embedded Systems


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Introduction

Pure hardware design uses only logic to get thejob done. For example a CMOS keyer1.

Pure software design assumes a generalpurpose platform and an operating system, suchas a PC running Windows or Linux. Keyboards

and mice let you know youre using a computer.


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Introduction

PC software can be considered digitalhomebrewing.

WD6CNFs CW decoder program.2

Digipan, MixW, etc. are all homebrewed.

Software Defined Radio uses a PC platform formany functions.3


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Introduction

Embedded systems are usually task-specific and you

dont interact with the processor like you would with aPC.

Examples of embedded systems are NorCal keyer4,Small Wonder Labs Freq-Mite5 , PIC-EL6 or themicrocontroller in modern rigs.

Today, well focus is on homebrewing embeddedsystems.


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Embedded Systems

Hardware

Lets start with the hardware.

Embedded systems obviously require some sort

of platform.

The application dictates the size and method of

construction.


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Embedded Systems

Hardware

There are several approaches to digitalhardware:

Wire Wrap

Dead BugPC Board Cadsoft7

Manhattan Style visit K7QOs Website8

No-Brew


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Embedded Systems

HardwareWire-wrapped S-100 Single Board ComputerFront


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Embedded Systems

HardwareWire-wrapped S-100 Single Board ComputerBack


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Embedded Systems

HardwarePrinted Circuit / Dead Bug Video Display PrototypeTop


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Embedded Systems

HardwarePrinted Circuit / Dead Bug Video Display PrototypeBottom


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Embedded Systems

HardwareHomebrew Printed Circuit


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Embedded Systems

HardwareAA0ZZs Manhattan PIC-EL Prototype9


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Embedded Systems

Hardware

No-brew Hardware options:

PIC-EL board10

Micro 908 Board11 Atmel Butterfly12

Evaluation boards from Analog Devices, TI,

Freescale and others


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Embedded Systems

Hardware

PIC-EL Board

Unfortunately, no longer available

Full hardware documentation on the Web10 Elmer 160 Course is an excellent tutorial on PIC

programming


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Embedded Systems

Hardware

Micro-908

Powerful, self-contained processor

Adapts easily to your base board Excellent support by AmQRP11


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Embedded Systems

HardwareAmQRP Micro-908


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Embedded Systems

Hardware

Atmel Butterfly

Low Cost - $20 at DigiKey13

Self-contained

Battery powered

Numerous Enthusiasts14

KD1JV Melt Solder projects15, 16


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Embedded Systems

HardwareAtmel Butterfly


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Embedded Systems

HardwareHomebrewing From Scratch

What if No-Brew doesnt satisfy needs?


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Embedded Systems


Time for a homebrew project!

1 Identify requirements

2 Evaluate suitable processors

3 Evaluate software development tools

4 Repeat steps 1, 2 & 3 until satisfied


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Embedded Systems


Choosing a Processor

Many Factors determine the best choice:

Cost

Package

Processing Speed

Memory Type and Size

Power Consumption

I/O pins & Features

Software Development Environment


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Embedded Systems


Cost less that $10

Package DIP or Surface Mount

Speed Fast enough to do the job Memory Flash for the program, RAM for the variables

Power Consumption The lower, the better

I/O pins & Features Depends on application

Software Development Environment Free is best!


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Embedded Systems


Consider the Microchip PIC processors:

Inexpensive

Available in DIP package

Various clock speeds Various Flash memory sizes, limited RAM

RISC Architecture yields high processing speed

Current Consumption as low as 13 uA

Limited I/O pins, but numerous features like USARTs, A/Dconverters & Timers

Free Development Software17


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Embedded Systems


Consider the Atmel processors:

Inexpensive

Available in DIP package

Various clock speeds Large program Flash memory and RAM

RISC Architecture yields high processing speed

Low power consumption

Numerous features like USARTs, A/D converters & Timers Free Development Software18


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Embedded SystemsSoftware

Once the processor is selected, its time to startwriting code.


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Embedded SystemsSoftware

There are two basic options:

Assembly Language

High Level Language - C


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Embedded Systems

SoftwareAssembly Language

Most chip vendors provide free tools

Integrated development environments provide:

Context-sensitive editors

Assemblers & linkers

Simulators


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Embedded Systems


MP

LAB

MPLAB

E b dd d S


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Embedded Systems


Context-sensitive editors:

Provide a convenient way to type in your program

Highlight labels, variables, instructions and comments

using various colors

Help you avoid common mistakes

E b dd d S t


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Embedded Systems


Assemblers: Convert your source program into opcodes the

processor understands. They work on individual

source files.

Linkers: Combine the outputs from the assembler and resolve

references to labels (jump and call instruction targets)and any library functions.

Produce the final binary program for the processor.

E b dd d S t


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Embedded Systems


Simulators provide:

A way to test your program without using actualhardware

A way to simulate hardware inputs

E b dd d S t


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Embedded Systems

SoftwareC

Why use a High Level Language? It allows you to be efficient. A few lines of C replace

several lines of assembly.

You dont lose control of the hardware. You can easily port your program to another

processor.

E b dd d S t


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Embedded Systems

SoftwareC

Pros and Cons: Its easy to port programs between chips C is not supported on some processors.

Commercial development packages cost $$$$.

Development suites offer similar features as assemblylanguage: Editors

Program Build tools

Simulators / Debuggers

E b dd d S t


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Embedded Systems

SoftwareC

There are alternatives to commercial packages. Just as homebrew software enthusiasts developed

Linux, there are folks who develop microcontrollerdevelopment tools.

The good news is theyre free! WinAVR19 is one example

Embedded Systems


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Embedded Systems

SoftwareCWinAVR Development Environment


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Embedded SystemsChip Programming

Several options exist for programming the processor Commercial programmers: $150 - $200

Microchip ICD 2

Quick Writer JTAG

Homebrew

Self-programming processors


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JTAG can be used for programming and debugging

Commercial units are expensive

The Web has plenty of homebrew designs


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Homebrew Designs

PIC-EL board

KB0Ps programmer20

Numerous other designs can be found on the Web


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Self-programming processors come with built-inloader software

A serial cable is all thats usually required AmQRP HC-908

Atmel Butterfly

Use the supplied software to download the code andstore it in the chip


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Embedded SystemsSummary

Powerful, highly integrated microcontrollers dont requiresupport logic.

Hardware options are numerous:

Homebrew construction using various techniques

Club Kits Low cost evaluation modules

There are numerous no-cost software development packagesavailable:

Chip vendors provide free assembly language tools Free C language development tools.


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Embedded SystemsSummary

Hardware design is easy Only a few chips at most are required

Many examples of projects on the Web

Copy or adapt existing an existing design

Use your favorite construction method

Software development is easy

Online tutorials like Elmer160 help you get started

Copy or adapt existing software21

Many low cost device programmers are available


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References 1 http://www.io.com/~n5fc/keyer.html

2 http://www.amqrp.org/projects/cwdecod/cwdecod.htm

3 http://www.sdrforum.org/

4 http://www.amqrp.org/kits/NCKeyer/ 5 http://smallwonderlabs.com/swl_frq.htm

6 http://www.amqrp.org/elmer160/board/index.html

7 http://www.cadsoft.de/

8 http://www.qsl.net/k7qo/manhattan.pdf

9 http://home.comcast.net/~aa0zz/

10 http://www.amqrp.org/elmer160/board/index.html

11 http://www.njqrp.org/hc908/index.html 12 http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3146

13 http://dkc3.digikey.com/PDF/T043/0300.pdf

14 http://www.avrfreaks.net/

15 http://www.qsl.net/kd1jv/bfydds.HTM

16 http://www.qsl.net/kd1jv/digiswr.HTM

17 Google MPLAB IDE for latest version

18 http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2725 19 http://winavr.sourceforge.net/

20 http://www.qsl.net/kb0p/pic.html

21 http://home.earthlink.net/~vintage2

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Digital Home Brewing