Do you know which is the most popular connector, which is frequently being used in the electronic industry? Yeah, the answer is USB and it’s compatible with most of the PC peripherals, such as AVR programmers, printers, scanners and so on.
All you have to do is doing a little modification on an old serial AVR In-System_Programmer (ISP) to work with USB connection. Or, it’s also mean that you’re use a USB serial adaptor to connect the AVR ISP with your PC! This will be the solution, but it has to cost you more money than a single FT232BM chip.
If you want to cut down the cost, the finest solution is to replace the two transistors, where is used to adapt the RS-232 voltage levels to TTL voltage levels, with a USB to RS-232 chip (such as FT-232BM).
For the firmware, you should prefer the Klaus Leidinger’s, as it’s a little bit better and faster than others are. However, you still need to do some modification with the source code, for enables it to work with 11.0592 MHz crystal instead of 7.3724 MHz. This programmer is working perfectly with AVRprog.