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I want to connect FPGA to PC with usb device, but most applications access devices by serial (COM port).
Is that possible let usb device appear as an additional COM port?
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Yes, there are USB-to-serial converters and USB-to-FIFO converters that appear to the PC as a serial port. If you have ever used a USB-to-serial adapter cable, the ICs inside those cables are what you want.
FTDI have a range of parts that work well. They have pre-made modules and cables that you can use to interface to an existing FPGA board, eg.,
UM245R and UM232H
http://www.digikey.com/scripts/dksearch/dksus.dll?vendor=0&keywords=um245r http://www.digikey.com/product-detail/en/um232h/768-1103-nd/2614628 and cables with breakout headers
http://www.digikey.com/product-detail/en/c232hm-ddhsl-0/768-1106-nd/2714139 http://www.digikey.com/product-detail/en/c232hd-ddhsp-0/768-1011-nd/2767783 If you need high performance, then the USB-to-FIFO mode devices are pretty good
http://www.ovro.caltech.edu/~dwh/correlator/pdf/ftdi.pdf Cheers,
Dave
Honored Contributor
