Using FT2232H in Sync FIFO mode for streaming out data

[chensx2012]

I want to use FT2232H in fifo mode for streaming out data. The external altera FPGA reads the FT2232H at a fixed rate of 48kb/s. On my PC side, what I need to do is to continuously check the number of bytes in the transmit queue. If the bytes falls below 32, the program will feed 256 bytes using FT_write. But when I use FT_GetStatus(ftHandle,@RxBytes,@TxBytes,@EventDWord), TxBytes always return 0 (unlike RxBytes which can truthfully indicate the number of bytes in the receive buffer). Any ideas? Thanks in advance!

 

[KlausST]

Hi,

Sending out via pc has several bufferd.
Pc software buffer ... FTDI driver buffer ... FTDI transmit FIFO ... FTDI receive FIFO.

I think you read pc software buffer status. (Or FTDI drver buffer)
So as soon as you write data it is immediately in the next buffer. Mind your FTDI is a high speed USB chip with large size fifo.

Klaus