Digital Homebrewing. Bob Okas W3CD. Copyright 2004 Robert P. Okas

Transcription

1 Digital Homebrewing Bob Okas W3CD Copyright 2004 Robert P. Okas 1

2 Introduction Digital Homebrewing is a broad topic that encompasses: Hardware Logic Design Software design Combinations of both: Embedded Systems 2

3 Introduction Pure hardware design uses only logic to get the job done. For example a CMOS keyer 1. Pure software design assumes a general purpose platform and an operating system, such as a PC running Windows or Linux. Keyboards and mice let you know you re using a computer. 3

4 Introduction PC software can be considered digital homebrewing. WD6CNF s CW decoder program. 2 Digipan, MixW, etc. are all homebrewed. Software Defined Radio uses a PC platform for many functions. 3 4

5 Introduction Embedded systems are usually task-specific and you don t interact with the processor like you would with a PC. Examples of embedded systems are NorCal keyer 4, Small Wonder Labs Freq-Mite 5, PIC-EL 6 or the microcontroller in modern rigs. Today, we ll focus is on homebrewing embedded systems. 5

6 Hardware Let s start with the hardware. Embedded systems obviously require some sort of platform. The application dictates the size and method of construction. 6

7 Hardware There are several approaches to digital hardware: Wire Wrap Dead Bug PC Board Cadsoft 7 Manhattan Style visit K7QO s Website 8 No-Brew 7

8 Hardware Wire-wrapped S-100 Single Board Computer Front 8

9 Hardware Wire-wrapped S-100 Single Board Computer Back 9

10 Hardware Printed Circuit / Dead Bug Video Display Prototype Top 10

11 Hardware Printed Circuit / Dead Bug Video Display Prototype Bottom 11

12 Hardware Homebrew Printed Circuit 12

13 Hardware AA0ZZ s Manhattan PIC-EL Prototype 9 13

14 Hardware No-brew Hardware options: PIC-EL board 10 Micro 908 Board 11 Atmel Butterfly 12 Evaluation boards from Analog Devices, TI, Freescale and others 14

15 Hardware PIC-EL Board Unfortunately, no longer available Full hardware documentation on the Web 10 Elmer 160 Course is an excellent tutorial on PIC programming 15

16 Hardware Micro-908 Powerful, self-contained processor Adapts easily to your base board Excellent support by AmQRP 11 16

17 Hardware AmQRP Micro

18 Hardware Atmel Butterfly Low Cost - $20 at DigiKey 13 Self-contained Battery powered Numerous Enthusiasts 14 KD1JV Melt Solder projects15, 16 18

19 Hardware Atmel Butterfly 19

20 Hardware Homebrewing From Scratch What if No-Brew doesn t satisfy needs? 20

21 Hardware Homebrewing From Scratch 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 21

22 Hardware Homebrewing From Scratch 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 22

23 Hardware Homebrewing From Scratch 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! 23

24 Hardware Homebrewing From Scratch 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/D converters & Timers Free Development Software 17 24

25 Hardware Homebrewing From Scratch 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 Software 18 25

26 Software Once the processor is selected, it s time to start writing code. 26

27 Software There are two basic options: Assembly Language High Level Language - C 27

28 Software Assembly Language Most chip vendors provide free tools Integrated development environments provide: Context-sensitive editors Assemblers & linkers Simulators 28

29 Software Assembly Language MPLAB M P L A B 29

30 Software Assembly Language 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 30

31 Software Assembly Language 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. 31

32 Software Assembly Language Simulators provide: A way to test your program without using actual hardware A way to simulate hardware inputs 32

33 Software C Why use a High Level Language? It allows you to be efficient. A few lines of C replace several lines of assembly. You don t lose control of the hardware. You can easily port your program to another processor. 33

34 Pros and Cons: Embedded Systems Software C It s easy to port programs between chips C is not supported on some processors. Commercial development packages cost $$$$. Development suites offer similar features as assembly language: Editors Program Build tools Simulators / Debuggers 34

35 Software C There are alternatives to commercial packages. Just as homebrew software enthusiasts developed Linux, there are folks who develop microcontroller development tools. The good news is they re free! WinAVR 19 is one example 35

36 Software C WinAVR Development Environment 36

37 Chip Programming Several options exist for programming the processor Commercial programmers: $150 - $200 Microchip ICD 2 Quick Writer JTAG Homebrew Self-programming processors 37

38 Chip Programming JTAG can be used for programming and debugging Commercial units are expensive The Web has plenty of homebrew designs 38

39 Chip Programming Homebrew Designs PIC-EL board KB0P s programmer 20 Numerous other designs can be found on the Web 39

40 Chip Programming Self-programming processors come with built-in loader software A serial cable is all that s usually required AmQRP HC-908 Atmel Butterfly Use the supplied software to download the code and store it in the chip 40

41 Summary Powerful, highly integrated microcontrollers don t require support logic. Hardware options are numerous: Homebrew construction using various techniques Club Kits Low cost evaluation modules There are numerous no-cost software development packages available: Chip vendors provide free assembly language tools Free C language development tools. 41

42 Summary 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 software 21 Many low cost device programmers are available 42

43 References Google MPLAB IDE for latest version