USB stack is open-source assembler software, by Bradley A. Minch. I have modified it so that it accepts uppercase/lowercase charracters, servicing <shift> bit in USB packet.

MCU keeps all generated passwords in internal Flash memory. Each time the new password is generated, the old one is lost (no undo).

Password creation routine guaranties at least one lowercase, one uppercase and one number in the password string.

Source file is in Microchip's MPLAB or MPLABx format. At the beginning of .ASM file there is the processor definition for PIC18F2550. It should be modified if PIC18F2455 is used.