> 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
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