> I need some clarification on
Bluetooth-to-USB transmission.
> As you know, some Bluetooth
modules now have an on-chip
> USB interface, used for device
firmware upgrade and as HCI
> transport. Future
Bluetooth firmware upgrades will also allow
> you to change the USB
descriptors in the module so you can
> receive data over USB and
transmit it over the air.
> However, I was told that
this will not allow me to layer additional
> firmware over the embedded Bluetooth stack to do an exact
> USB cable replacement using a
USB-to-Bluetooth adapter/dongle
> device, because:
> (1) USB has strict timings
which would be violated if the adapter/
> dongle had to transmit the
request over the air and wait for a
> response.
Correct, though
this can be overcome with a "smart" device.
> (2) The Bluetooth module
is not capable of being a USB master,
> (3) The code doesn't fit on
chip - USB is "normally" for PC apps
> where you have ample resources
on the host.
These are really
part of the same issue. USB has a master/slave concept. The
logic/code to be a slave is relatively small compared to that required to be
a master.
> As there are already a lot of
USB-to-Bluetooth adapters/dongles
> available in the market, I was just
wondering how these devices
> use USB for their applications. Can anybody shed some
light
> on this?
They are devices
and can be used, as you mentioned, for firmware upload, the connecting bus
to the PC, ...
But in general,
they are devices (slaves) not hosts (masters).
Marc
Reinig
System
Solutions