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README.md
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README.md

AVR JTAG ICE v2.0

The firmware can be uploaded to AVR JTAG ICE usb stick with no dismantling or soldering just by a simple upload tool.

Currently AVR JTAG ICE can be bought from various sources, one of them: Aliexpress

 +----------+          +---------------------+                           +--------------------+
 | PC       |          | AVR JTAG ICE  VTref +(4)--------->--------------+ Vcc                |
 | avrdude  |          |                     |      +----------+         |                    |
 |          |          |               nSRST +(6)---+   4k7    +---------+ UPDI               |
 |      USB +----------+ USB                 |      +----------+         |                    |
 |          |          |                     |                           |       Target       |
 |          |          |                     |                           |                    |
 |          |          |                     |                           |                    |
 |          |          |                 GND +(2)-+                   +--+ GND                |
 +----------+          +---------------------+    |                   |  +--------------------+
             JTAGICE MkII                        +-+     UPDI        +-+
             Protocol                            GND     Protocol    GND

Just remember VTref will supply the target MCU chip with 5V from the AVR JTAG ICE ! For using with different own MCU board potential (e.g. 3.3V or 1.8V) leave VTref unconnected. Also you can step down the voltage using a regulator (e.g. 3.3V) from VTref if target mcu supports lower voltage only.

Building the firmware

Uncomment lines below to enable AVR JTAG ICE support and then run makefile to compile the firmware.

  • For windows build edit make.bat remove remarks from two lines:
...
rem
rem select AVRJTAGICE v2.0 as target (override upper)
rem
set TARGETMCU=atmega16
set DEFINES=-DNDEBUG -DUPDI_BAUD=120000U -DF_CPU=7372800 ...
...
  • For linux build edit make.sh uncomment two of the lines:
...
##
## select AVRJTAGICE v2.0 as target (override upper)
##
TARGETMCU=atmega16
DEFINES="-DNDEBUG -DUPDI_BAUD=120000U -DF_CPU=7372800 ...
...

Flashing the firmware

To burn the USB module, use avr-aosp.py uploader tool (as superuser) plug in USB module and while the LED blinks fast red-blue (5 seconds window at statup) run these steps:

  1. Erase content of module:
python3 avr-aosp.py -op erase

INFO

  S = AVRBOOT 	#programmer id
  V = 10 	#software version
  v = ? 	#hardware version
  p = S 	#programmer type
  a = Y 	#autoincrement support
  b = ? 	#block mode support
  t = [7400] 	#supported device code
  s = 02941e 	#signature
  N = ? 	#high fuse bits
  F = ? 	#low fuse bits
  r = ? 	#lock bits
  Q = ? 	#extended fuse bits

ERASE program memory
  1. Upload the firmware:
python3 avr-aosp.py -op write -file ../../build/JTAG2UPDI.hex

INFO

  S = AVRBOOT 	#programmer id
  V = 10 	#software version
  v = ? 	#hardware version
  p = S 	#programmer type
  a = Y 	#autoincrement support
  b = ? 	#block mode support
  t = [7400] 	#supported device code
  s = 02941e 	#signature
  N = ? 	#high fuse bits
  F = ? 	#low fuse bits
  r = ? 	#lock bits
  Q = ? 	#extended fuse bits

WRITE program memory [../../build/JTAG2UPDI.hex] #2378 bytes
0...10...20...30...40...50...60...70...80...90...100 - done.

  1. Unplug and then replug the USB stick, red-blue blinking stops with permanent red LED turned on.

  2. With red LED turned on firmware is active and can be used with avrdude, see provided wiring to target MCU.