Posted on July 23, 2015 at 10:28Hi, all!
Didn't found any mention about transmission of data for Low speed devices, connected to USB host via Full speed Hub. Is it really possible to use STM32F405 USB controller in host mode for such a sittuation?
Details: suppose we have old USB hub, supporting just Full speed on its upstream port. We use STM-controller as a USB host, connect it to hub. Then we connect Low speed device to Hub (mouse, for example). According to USB2.0 (and USB1.0) standard host should add special preamble before every OUT packet, sended to Low speed device. This preamble contains pid PRE. This preamble is sent in Full speed, and data packet then is sent in Low speed.
As far as I know, the most of this operations are implemented in PHY controller - the host should just select XcvrSelect in PHY to value 3 (look for example to USB3300 PHY controller). The problem is that I failed to find any information about working in this mode in controller documentation. Is it really possible in STM microcontrollers?
