hello,my friends!

I want to design a token with at91sam7s256;
it must have only usb port to communication.

I want to use only it's usb port ,for programming my code on it, so I must choose "programming with sam-ba via usb port" and I need to load sam_ba on chip .
thus I must active erase and TST,a0,a,a2 in known order,to load sam_ba and then I can connect the module directly to usb port of computer and program it with sam_ba or sam_prog softwares.

I must do this without any switch on module to active tst and erase,

does anybody have an idea???
thanks a lot for your attention & helps!!!!