Stand-alone AVR JTAG Programmer

I needed this device myself and thought others may find it useful.

This device allows you to load a HEX file onto a micro SD card, change the name to 'firmware.hex', plug it into the board, hook up your target board, press the program button, and the programmer will transfer the program to the target. This programmer is setup to work with 5V targets only.

This software is based on the work of Nick Gammon. I have removed some of the routines (like the Crossroads code) and added a function to change the target fuse settings. More information can be found in Nick's Github site: https://github.com/nickgammon/arduino_sketches/

The green LED lights up when the device is ready to program. If there is a problem with reading the file, the device will flash the red LED based on the issue (the error codes are on the back of the PCB). If during programming there is an error, the red LED will come on and the yellow will flash based on the issue. If all goes well, the green LED will flash 3 times (10 cycles of 3 flashes).

To change the fuse settings, add a line to the beginning of the HEX file for each fuse with the following format:

FXhh

• where F tells the software that this line changes a Fuse
• X is the fuse to change (L = low, H = high, E = extended, B = Lock Byte)
• hh is the hex value to change the fuse to.

Ex: FL7F will change the Low fuse to 7F

Be careful because I haven't put any checks on fuse settings in software

The power jumper allows you to supply 5V to the target through the JTAG connection. If the target is self powered, you can remove this jumper to prevent connecting the two supplies together.

The kit is supplied with the PCB and all of the components to make the programmer. It requires just through-hole soldering. It also includes a 9V battery connector to be able to power the programmer without access to a 5V USB source. A micro SD card is NOT included.

Kit contents:

• Bare PCB
• programmed 5V Arduino Nano board
• micro SD card board
• Power connector
• Program switch
• LEDs (R/Y/G)
• resistors (3x 1k)
• 9V power adapter
• JTAG programming cable
• headers and jumper required for parts and connections (JTAG and TGT PWR jumper)

The SD card board has 90 degree headers already attached. You can mount the board as is, but it will stick up vertical from the board. The other option is to remove the 90 degree header and install a straight header. I include a header for this option. To remove the existing header, I recommend gently working off the black plastic standoff. Then, the header pins can be removed one by one. Clean the holes and it is ready for the straight headers.

Assembly is straight forward. Note that the LEDs anode (positive - long lead) is toward the resistors. There is an unpopulated pad labeled '8Mhz out' on the board. Some chips require an 8Mhz clock for programming but this is pretty rare. If needed, a single header or wire could be soldered into this pad for use.