libftdi Archives

Subject: Re: potential libftdi data loss issue

From: derRolf@xxxxxxxxxxxxxx
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Mon, 16 Jan 2012 18:03:03 +0100
>>>>> Rolf <derRolf@xxxxxxxxxxxxxx> writes:
    Rolf> Hello, my name is Rolf and I am new to this list. I think I may
    Rolf> have found and issue with libftdi (I am using the latest git at
    Rolf> time of writing).
 
    Rolf>  We have some hardware that has a FPGA connected to an FT245BL. We
    Rolf> have been using that on Windows with D2XX for some time
    Rolf> (years). The data rate is quite high, to operate the device we
    Rolf> need to transfer around 500 KB/s (that means KBytes).
 
>For high data rates, think about a streaming solution like in libftdi-1.0
>ftdi_stream.c for the sychronous fifo modus. We quite reliable achiev around
>16 MB/s rate on modern usb chipsets.

Uwe, thanks for this suggestion. However, I am not too much worried about 
reaching the highest possible data rate. Also, the FT245BL dies not support 
BITMODE_SYNCFF as far as I know, so I might not be able to use ftdi_stream.

My problem is that the current implementation of ftdi_read_data seems to loose 
data (flow control not working), whereas on the same machine (MacBook Air) the 
D2XX FTDI lib on Windows in VirtualBox works without any data loss.

How could I find out if this is a bug in libftdi-1.0 or in libusb-1.0?

Thanks,
Rolf
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