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RE: [bluetooth-dev] Test Control Interface & HCI

Hello Mr.Gordon..

Hope this info will complement what Mr.Ben has said on HCI..

Presented here is 'One interesting info on HCI..' 

Is the HCI Layer Optional?

Original Post: Questions - Link Manager Protocol and Base Band (SIG Forum )
Date: 2000-06-16 
Although the HCI (Host Controller Interface ) directly instructs the
Baseband to do these inquiry/paging instructions, there exist device ,such
as cordless phone, which are envisaged to function without the use of the
HCI layer. As far as I know HCI is not necessary.
This is because the HC layer is actually not absolutely necessary. It
provides a typical standard command interface to the baseband controller and
link manager, and access to hardware status and control registers. Knowing
this it would be up to the developer , and application/profile setup, to
decide whether to implement it. The Cordless Telephony Profile doesn't use
many of the lower features (such as hold, sniff) so it makes sense for it to
not implement the HCI interface, and so reducing complexity & cost. 


-----Original Message-----
From: Ben Walter [mailto:bwalter@xxxxxxx.com]
Sent: Wednesday, November 22, 2000 9:28 AM
To: Gordon McNutt; bluetooth-dev@xxxxxxx.com
Subject: Re: [bluetooth-dev] Test Control Interface & HCI

Hi Gordon,

> While browsing the spec I noticed the chapter on the Test Control
> Interface (TCI). Something in there puzzles me. It says that the TCI
> will be used to test L2CAP. And it will be used to test HCI if the
> manufacturer claims to support HCI.
> How could you implement L2CAP without HCI? Am I missing something?

In an embedded application it doesn't necessarily make sense to use an HCI
layer.  Take, for example, the forthcoming BIC2301 from BrightStar that
implements an entire Bluetooth LAN Access Point on a single chip.  It
doesn't need to implement an HCI interface because the upper and lower
levels of the stack are running on the same silicon.  In this case the L2CAP
layer can interact directly the Link Manager.



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