http://www.eevblog.com/forum/reviews/ftdi-driver-kills-fake-ftdi-ft232/msg535378/#msg535378 http://www.eevblog.com/forum/reviews/ftdi-driver-kills-fake-... mar

http://www.eevblog.com/forum/reviews/ftdi-driver-kills-fake-ftdi-ft232/msg535378/#msg535378 http://www.eevblog.com/forum/reviews/ftdi-driver-kills-fake-... marcan: "In case anyone was still wondering if this is intentional and malicious... Straight out of their driver. Function/variable naming and comments mine. https://marcan.st/transf/ftdi_evil.png https://marcan.st/transf/ftdi_evil.png I figured out what's going on with the real chips: turns out their EEPROM is written in 32bit units. Writing to even addresses is ignored; the value is buffered and the address discarded. Writing to odd addresses writes the entire 32bits, using whatever value was last buffered for the other half. So both the PID write and the checksum write are ignored on real FTDI chips, as they are both written to even addresses. I still don't know why it works on clone chips though, since the checksum is written to the wrong place (it should normally be on an odd address); presumably they don't check it." Basically driver is fuzzing 'chips claiming to be FTDI' with illegal instructions. Want to play clone games? better emulate me completely, otherwise tough titties. I like it. Might not work to well for FTDI in the end due to PR nightmare, but from engineering standpoint its quite brilliant.