AVR JTAGICE Clone: JTAGICE With USB Interface

Sun Ge

Image avr-jtagice1
The picture shows that JTAGICE is debuging a butterfly.

Project Origin

This AVR JTAGICE clone is based on Evertool's schematic and bootloader, Evertool is a JTAGICE compatible programmer/debuger. With it's bootloader, This JTAGICE clone can programe itself using avrprog.exe which is contained in AVRSTUDIO.

I just add a USB-to-Serial interface to the existing hardware, it cannot speed up the debuging.

You are recommended to visit:
http://www.siwawi.arubi.uni-kl.de/avr_projects/evertool/
From this Evertool's original site, you can get schematics, bootloader, and other sources.

Hardware

Please visit Evertool's original website, I built this JTAGICE clone according to "Evertool Light", and a FT232BM substitute the MAX232, in order to use USB interface.

The schematic of FT232BM circuit is simply a copy from FT232BM Designers Guide (VERSION 1.1), on page 2, "Figure 1.0  FT232BM - 5 volt Bus Powered Example Schematic (232-5VB)". You can find this Designers Guide from:
http://www.ftdichip.com (Now it's updated to VERSION 2.0)

Firmware Downloading

You should following these steps to download the firware to AVR JTAGICE clone.

Everything You Need

Of course you need a programmer (i.e. STK500), but for those Linux users, you must prepare the following items:
  1. avrprog.exe, a part of AVRSTUDIO
  2. Upgrade.ebn, a part of AVRSTUDIO
  3. A true windows system, which can run avrprog.exe correctly. If you use WINE, avrprog.exe will fail with message "target board not found" or something like that.

Procedure

  1. make sure all your hardware can work correctly.
  2. Write bootloader (evertool.hex) to ATmega16.
  3. Write fuse and lock-bits of ATmega16:
    low fuse: 0xff (in order to use 7.3728MHz crystal)
    high fuse: 0xd8 (in order to set boot size to 1024 words, disable OCD, disable JTAG and enable SPI.)
    lock-bits: 0x2f (SPM instruction is not allowed for boot sector)
  4. Pull down PC6 of ATmega16 to GND.
  5. Connect your JTAGICE to PC, through serial port or USB-to-Serial interface.
  6. In your microsoft windows system, run avrprog.exe, it will detect ATmega16's bootloader, then you can select the file "Upgrade.ebn" - it's in a encrypt format that only avrprog.exe can decode - and program it to ATmega16.
  7. Open PC6 of ATmega16.
Now you have a ready-to-use AVR JTAGICE.

How to Use

I think this JTAG debuger can work well in AVRSTUDIO, but for Linux users, we may use two GNU tools: avarice and avr-gdb.

When you installed avarice and avr-gdb, connected JTAGICE to PC's serial port($SERIAL-PORT) and target microcontroller($PART), power on the target board, then run: 

$avarice -P $PART -j $SERIAL-PORT: $TCP-PORT

avarice will open a TCP port($TCP-PORT, usually 4242) for listening to GDB's connection.

Next we can run avr-gdb to begin debug, the following is a example: 

$avr-gdb
...
file example.elf
target remote localhost:4242
load
break main
continue
...


sun ge 2007-10-26