rusefi.com

maybe we will use USB bus?
USB can connect 127 devices in 1 bus .
stm32f4 support usb-OTG .

still have a cheap chip usb hubs, such http://web.comhem.se/mulle1/GL850.pdf

80211 usb modules also cheaper, for example http://www.realtek.com.tw/products/productsView.aspx?Langid=1&PFid=48&Level=5&Conn=4&ProdID=228

+ Can connect usb flash memory card

USB is just a... bus. Why do you think we need a bus? Between what and what?

Let's stay real and implement features from simple to complex. We still have so many trivial things in the queue that it seems like it's not yet time for a USB flash drive.

Then why we use usb devices in live , if not different devices can work via another bus?
implement features can do many people , but only some people can do it correct without example

For conver UART(RS232) >< USB
iam use FT232RL (have on any pc-atx mainboard)