Usefull combination: AT90USB646 + AVR Dragon?

Thread Starter


Joined Mar 20, 2010
I am very new to microprocessors, but I want to construct a device, that needs to have some small display and some buttons. Most times it is connected to a PC (USB preferably), but it needs also some limited logic on its own, for the times, it is not connected.
After some web search, I came up with the above mentioned combination of microprocessor and development board. According to the Atmel list of supported devices the AT90USB646 is supported by the Dragon. What I am unsure is:

a) according to the product specification page at the shop, the AT90USB646 is a SMD device. Can I really put that onto the Dragon for programming it? Or do I first have it wired on another board (breadboards, you're calling them, right?) and wired it with dozens of connections to create a ISP or JTAG port, before I can program it?

b) How hard is it, to program the USB interface to act like a USB-Serial device (so, that it looks like a COM port on the PC)?

c) do I need anything else to get started with this chip?

thanks a lot for you help. This whole stuff is quite hard, if you're just starting.


Joined Oct 12, 2009
First of all you need a board with AT90USB646 on it or something like adapter to connect MCU to breadboard, because selected MCU is SMD. I'm not sure in the difficulty of programming, but for your task I'd rather use FTDI chips (or their analogs).

For the c) - this depends on your final task.

Also I would suggest to trying with demo-boards like Atmel Butterfly. After some experiments you can add FTDI chip and use Butterfly for your initial task.

With kind regards, Kirill.
Last edited:


Joined Sep 7, 2009
You might not even need the dragon. From a quick look at the datasheet it has a bootloader so you should be able to hook it straight up to the USB port to program it. I've got no experience with this but it might be worth looking into.