Datasheet

provided by the USB controller that is input to the FPGA. In asynchronous mode data transfer is happening on
transitions of read and write control signals. The USB controller emulates a FIFO memory, providing status signals about
the availability of data to be read or free space for data to be written. The FPGA controls data transfer by read, write and
output enable signals.
Signal Direction
(FPGA)
Description
D[7:0] I/O Data bus.
RXF# Input When low, data is available for reading from the FIFO.
TXE# Input When low, data can be written to the FIFO.
RD# Output A low-pulse triggers data to be read out from the FIFO.
WR# Output A low-pulse triggers data to be written to the FIFO.
SIWU# Input Send immediate or Wake-up function. In normal mode a low pulse triggers sending a data
packet with the data currently in the FIFO, even if below the normal packet size. In
suspend mode a low pulse can wake up the Host PC.
OE# Output When low, the data bus is driven by the USB controller (read transfer). When high, the bus
is driven by the FPGA (write transfer).
CLKO Input 60 MHz clock used in synchronous mode. Data is launched and can be captured on the
rising edge.
Table 6. DPTI signal description.
For more information, see the
FT2232H datasheet
[http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT2232H.pdf].
10.2. Serial Peripheral Interface (DSPI)
An industry-standard SPI interface can also be used for transferring data. It uses only four signals for serial full-duplex
communication. The USB controller acts as a SPI master, with the FPGA taking the slave role. The USB controller
initiates a transaction after API function calls and transfers data in both directions simultaneously.
Signal Direction (FPGA) Description
SCK Input Data bus.
MOSI Output When low, data is available for reading from the FIFO.
MISO Input When low, data can be written to the FIFO.
SS Input A low-pulse triggers data to be read out from the FIFO.
Table 7. DSPI signal description.
For more information, see the
FT2232H datasheet
[http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT2232H.pdf].