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 -- libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]
