Hi all, I have some experience with the FTDI USB controllers and I thought I'd share what I know.
FTDI's USB-to-RS232 controller is quite simple to use: It looks and works like a regular serial port from both sides. No surprises there. (Ok, one big surprise, there's a Windows driver bug to watch out for., but it's another discussion.) The major difference however, is the long latency: 1 to 10ms, or more, depending on system load. Flow control is necessary, and the data must be packetized if you want any kind of performance. I have not used it myself, but parallel transfer is potentially even simpler than serial, as it uses a basic FIFO interface. It looks like this: D0-D7 (inout): Data bus. TXE# (output): When low, data can be written to the FIFO. RXF# (output): When low, data can be read from the FIFO. WR# (input): Writes data to the FIFO on negedge. RD# (input): New data byte can be read on D0-D7 after negedge. Data output enabled while low. Pin descriptions and timing diagrams are on page 10 and 11, here: http://www.ftdichip.com/Documents/DataSheets/DS_FT245R_v105.pdf Finally, someone asked if it is possible to target a specific USB device. The answer is yes: You assign a serial number that is stored in the USB IC. The driver enumerates all attached FTDI USB devices so the application can pick the right one from the list. I hope that clears some things up. Cheers, Andreas
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