Hello Daryl,
On Tuesday, 23. June 2009 19:11:16 Daryl Lee wrote:
> I'm doing my first libftdi app, and I don't quite understand "chunk size"
> and latency. I'm sending 32-byte messages to my device and getting
> 32-byte messages back. I need to do this at 1 millisecond intervals. I
> find experimentally that setting chunk size to 32 doesn't work very well.
> Setting it to 64 works better, but the time to write the message out is
> usually too long. This is a port from Windows software using FTDI's own
> drivers, so there's a lot of new stuff for me to figure out. I'm going
> to give async a try, but I wonder if there is some good explanation of
> latency and chunk sizing somewhere?
What happens when you set the chunk size to 32?
The latency setting is used by a hardware timer on the chip
to wait for more data if there's not a full buffer yet.
They've done this to reduce the traffic on the USB bus.
Thomas
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