Honored Contributor
Honored ContributorHi Frank,
--- Quote Start --- The third point is the critical one, I think. It effectively ends up in emulating FT245 on the USB side, or using a FTDI chip and a respective configuration that's recognized by the USB Blaster driver, too. I didn't clearly hear from Dave's posts if this is the case with the new HS FTDI chips. Presently I'm under the impression that a solution like the mentioned Cypress USB Blaster emulation devices promise a better functionality. --- Quote End --- A UM232H FT232H operating in asynchronous FIFO mode can transfer data at 7.1MB/s PC-to-FPGA (140ns per byte) and 10MB/s FPGA-to-PC (100ns per byte) (SignalTap II traces at 100MHz clock). A UM245R FT245R operating in asynchronous FIFO mode transfers data at between 1MB/s and 2MB/s. If you program an FT232H with the VID/PID of an USB-Blaster, then Quartus recognizes it as such. I'm just working on the USB-Blaster logic now. If that works, then the FT232H solution should be a few times faster than the FT245-based designs. The maximum JTAG speed is limited by the JTAG clock, eg., a Cyclone IV can have up to 25MHz (40ns) period, so a maximum data rate of 25Mbps, or 3.125MB/s over the FTDI FIFO interface. The FT245 cannot max out the JTAG rate, but the FT232H could. After I get the USB-Blaster logic working, I'll test the synchronous FIFO mode. I'm interested in that mode for communications. Cheers, Dave
