flashing brand new atmega 8u2

hello, I'd like to embed arduino in a project.
I want to build my own board with smd components, but I'm not sure about the way to go for the usb to serial chip
I'd like to use the atmega8u2 used by arduino uno, but I don't know if it's possible to upload the firmware into a brand new atmega8u2.
I think I'll need an AVR ISP, where can I find the firmware for this purpose?
or do you think is better to go for the good old FTDI chip?

here are the instructions for upgrading the 8u2, including a link for the v.001 firmware, so it should be possible if you
have a programmer, and incorporate the necessary connections in your design.


One advantage of the "good old FTRI chip" is that it allows for Bit-banging a bootloader using it's DCD, DSR, CTS, and RI pins (see the X3 connector on the Deumilanove schematic) and connecting them via jumpers to the ICSP pins. (MISO, MOSI, SCK, Reset)


I think both can be difficult to solder.
What else are you putting on the board?

AVR ISP programmers are not very much $, good tool to have also.
I have been using this one very successfully with '1284 chips with these 2 lines added to programmers.txt:



do you think this one could be ok?
the atmega 328 and atmega 8u2 are not shown in the supported device list, maybe they forgot to add it?
It's a bit expensive related to others, but I like it because it has an enclosure to protect it, my environment is not always so clean


then I downloaded atmel FLIP and then went here

here I can choose to download
1 - arduino usb dfu
2 - arduino usb-serial
3 - both combined

I downloaded the last one, since my ATmega 8u2 is empty

Now when I try to load the hex file with FLIP it returns this error message: invalid HEX file syntax
Am I missing something?

Thnks for helping a novice like me!
The board I want to make is an arduino with some relay onboard, i want to have them made by a manufacturer in a small number (20 or so), just to serve my definitive applications.


I couldn't find many good resources on reprogramming the 8U2, so after attempting it successfully, I blogged about it. You can find it here:


Hopefully that will help you out!