1. USB-to-UART bridge (UART mode)
(1) Setup
- Host: Linux PC, Ubuntu 14.04, ftdi_sio driver.
- Target: FTDI FT232H.
- Baud rate: 12 M.
(2) Loopback test result:
- round-trip time of 128 bytes: 1.48 ms —> 0.173 Mbaud (= 1.38 Mbits/sec)
2. USB-to-FIFO bridge (asynchronous FIFO mode)
(1) Setup
- Host: Linux PC, Ubuntu 14.04, libftdi 1.2 user-space driver.
- Target: FTDI FT2232H + Xilinx FPGA.
- Baud rate: 8 M.
(2) Loopback test results :
- round-trip time of 128 bytes with 25 MHz FPGA clock: 0.13 ms —> 1.97 Mbaud (= 15.8 Mbits/sec)
- round-trip time of 1530 bytes with 25 Mhz FPGA clock: 0.79ms —> 3.87 Mbaud (= 31.0 Mbits/sec)
- round-trip time of 1530 bytes with 50 MHz FPGA clock: 0.48ms —> 6.38 Mbaud (= 51.0 Mbits/sec)