What is an AVR?
An AVR is a relatively inexpensive user-programmable microprocessor that can be integrated into just about any project that needs a brain. Unlike most computer/electronics terms, decoding the AVR acronym is tricky. While some Atmel AVR devotees will claim that it doesn't have a definition others will state with a straight face that it isn't even an acronym. Some microcontroller programmers think that AVR is derived from the initials of the engineers who designed the AVR--Alf & Vegard + RISC. After extensive research, however, the most believable definition could be: AVR = Advanced Virtual RISC.
Enter the AVR Dragon
Whether it's a marketing lapse or a brilliant design configuration feature, beginners should be aware that Atmel Corporation does not include several vital pieces of equipment in the AVR Dragon box.
Yes, the AVR Dragon is USB-powered and yes, there is a free programming application that can be used with the AVR Dragon; but, you will need to provide your own USB cable and you will have to download the latest version of AVR Studio from the Atmel Web site.
Furthermore, you will be required to solder several components to the AVR Dragon to enable it to work with the widest variety of 8-bit AVR products. These components enable the budding AVR user to program and emulate many of the products in the AVR device family. A properly configured AVR Dragon offers these programming interfaces:
- In-System Programming
- High Voltage Serial Programming
- Parallel Programming
- JTAG Programming
Step 1: How to Prepare the AVR Dragon for AVR Programming
- AVR Dragon (Digi-Key; ATAVRDRAGON-ND $49)
- (1) AMP 6-Position, 2-Row, .100 Connector Housing (Digi-Key; A3032-ND $1.30)
- (32) AMP 1-Position, .100 Connector Housing (Digi-Key; A26962-ND $11.12)
- (38) AMP 15 Au, Crimp 27-32 AWG, Connector Socket (Digi-Key; A25955-ND $25.02)
- (1) IDC Multi-Color 20-Position Ribbon Cable with 20-Position, 2-Row Socket (Digi-Key; M1AXA-2036R-ND $4.39)
- (1) AMP 20-Position, 2-Row .100 Straight Breakaway Header Connector (Digi-Key; A26525-10-ND $1.21)
- (1) AMP 40-Position, 2-Row, .100 Straight Breakaway Header Connector (Digi-Key; A26525-20-ND $1.61)
- (1) ARES 40-Pin ZIF Socket (Digi-Key; A306-ND $12.02)
Step 2: It's in There, Somewhere
Atmel does include a brief mention about configuring the AVR Dragon inside its online help with AVR Studio 4. Unfortunately, they don't offer any help for determining the best components for obtaining this flexible configuration capability.
In order to review Atmel's AVR Dragon hardware configuration information, select AVR Tools User Guide under the Help menu. Inside the chapter AVR Dragon Prototype Area and under the section Using the Onboard Prototype Area near the bottom of this section there is a brief mention of adding a 20-pin header, a 40-pin header, and a 40-pin zero insertion force socket (ZIF) for making the AVR Dragon "even more flexible."
Step 3: Headers and ZIF and Solder, Oh My
From a beginner's perspective, the thought of having to "scratch build" your commercial programmer might seem a little daunting. Actually, the hardest part of this DIY venture is complete--once you purchase the headers and ZIF. The actual soldering is tedious, but straightforward.
Step 4: Follow the Device Connection Sheet
All of the connection information for setting up the programming and emulation interfaces for a specific AVR device is listed on a Device Connection Sheet. A handful of these sheets are available in the online AVR Tools User Guide. Consult the appropriate microcontroller's Device Connection Sheet for determining how many jumpers you will need to fabricate.
Step 5: Long and Winding Ribbon Cable
Making the various header connections depicted on an AVR Device Connection Sheet is best accomplished with a fistful of jumper wires. A 20-position socket with ribbon cable can reduce the drudgery of soldering 1-position socket receptacles to both ends of 20 jumpers. Using ribbon cable is optional. If you elect to use ribbon cable, cut the cable to a length of approximately 7 inches.
Regardless of your choice, you will need to make one jumper for each header/ZIF connection that is cited on the applicable AVR Device Connection Sheet.
Step 6: If I Only Had a Brain
Drop your target AVR DIP into the ZIF, connect the USB cable to the AVR Dragon, fire up AVR Studio 4, and you are ready to burn your first microcontroller. Consider yourself armed and very dangerous. Now no LED is safe.