libftdi Archives

Subject: Re: FT245R transfer rates

From: Xiaofan Chen <xiaofanc@xxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Mon, 22 Feb 2010 22:16:46 +0800
On Mon, Feb 22, 2010 at 10:08 PM, Jan Wilmans <janwilmans@xxxxxxxxx> wrote:

> But what I think you mean is: data is being read from the FT245
> simulatiously,
> so whilest packets arrive, the receive buffer is being read and more then 4
> packets (up to 19 is the hardware reads fast enough) can be send in 1 ms?
> Greetings,

I do not know how the internal of FT245R works. But for USB bulk transfer
multiple (up to 19) packets (each packer is 64Bytes max for full speed bulk
endpoint) can be done in one transfer (1 frame, 1ms).

I can imagine the following.
The receive buffer can hold two 64bytes packets, each frame (1ms)
 they can receive up to 19 USB packets of 64bytes (9 x full
128 byets full buffer plus one 64 bytes partial buffer) in theory.
In reality, maybe it is less. And there are some overhead involved.


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