Posted on April 10, 2015 at 13:46Hi all! I study the maximum transfer speed possible for USB HS host in STM32F407.
Using code from ST-examples for USB High Speed host, I managed to transmit no more than 4 bulk packets of 512 bytes per microframe (125 us);
Receiving data, I managed 5 bulk packets of 512 bytes per microframe. It seems to be suspiciously slow.
Can it be just a software limitation, or there are such limitations in USB hardware core? What are officially possible maximum data rates for STM USB HS host?
If somebody managed to get higher speeds with USB, it would be great to know about the fact, or maybe look at some useful source codes.
Theoretical limit is supposed to be 13 such packets (according to USB2.0 specification).
Device connected to our host is fast enough to operate with higher speeds (for example, MSWindows USB host allows 9 OUT and 11 IN packets per microframe with this device), there are no NAKs or other delays from its side. Also there are no other transactions on the bus from other host channels; channel tested have full bus bandwidht. OUT and IN operations are made one after another, not simultaneously at the same microframe.
