I would also encourage everyone to chime in here.  These decisions are vital to the success of the product and as I said, they are not easily changed.  Further it's not just the Neuros' success that's at stake.  If we have success with this type of open development, you can bet that other manufacturers will ultimately follow suit, and that's going to result in more open products for all of you to hack.  So if you have opinions or thoughts, don't be shy.
-----Original Message-----
From: neuros442linux-main-admin@lists.sourceforge.net [mailto:neuros442linux-main-admin@lists.sourceforge.net] On Behalf Of Bob Faskos
Sent: Thursday, September 29, 2005 9:36 PM
To: Daniel Stenberg
Cc: neuros442linux-main@lists.sourceforge.net
Subject: Re: [Neuros 442 Linux Main] USB and Audio Codec


You raise good points, as always.
Please see below.


Daniel Stenberg wrote:
On Wed, 28 Sep 2005, Bob Faskos wrote:

The main reason we chose the NET2272 route is to enable other than direct-to-disk applications in high speed. Such applications include Janus (MTP), Ethernet-over-USB (RNDIS), fast serial as well as mass storage.

Correct, if you want your box to be able to fly to the moon and make coffee automatically every morning (over USB), you'll need these features! ;-)

In my view, this looks like you get an awful lot of work and trouble for some very blue-sky dreams of the future. And again your choices and dreams for the 442 spill over and make N3 development harder.

But that's me.
Bob: Why is this "an awful lot of work"? The drivers for the NET2272 have been present in the standard uCLinux distribution for a long time. There is usb Gadget support and everything right off the distribution. Why do you think that the effort of enabluing these features is not worth the prize of having all sorts of possibilities open?

I think that Janus or any other DRM scheme is of secondary importance - I *H*A*T*E* any DRM schemes.
But I think that you can't dismiss the possibility of implementing it.

But that is me. To me there are much more important uses to this bus-driven USB.
For example I can see a scenario where someone wants to develop application code to run on the N3. Since there is no Ethernet adapter on the N3, one good way of setting up the environment would be to use the high speed USB interface to connect to your Linux PC host using NFS, and do a NFS root mount on the N3. This is such a flexible development environment that I would jump through hoops to be able to enable.

Let me know if I conviced you or if you still swayed to the other side.

The architecture of the chip is such that only the DSP has access to the ADC and DAC, but there will be interfaces from the ARM side available that just pass the PCM samples back and forth.

Right. But then you can't power off the DSP part to save power (if that is even possible - this little MCU is as usual not possible to read up any details on so how can we tell?).

Bob: Sadly, you are right. You can't power off the DSP without losing control of the audio port.
However, the DSP can be sleeping when it is not needed, and come out of IDLE whenever there is audio to be processed. This consumes next to nothing in power. Actually, when you consider the big picture the DSP side of the chip is more economical than the ARM side. Unfortunately you cannot completelly shut down either side.
I don't think we've seen any good use for the DSP yet in the N3. Or am I wrong?

Then there are the advanced decoders. These can work on the ARM and pass 24-bit samples to the DSP at up to 96 KHz SR. The MIPS are available.


Bob: The MIPS - Millions of Instructions Per Second. The ARM is powerful enough to implement prettymuch any audio decoder or encoder that somehow never got implemented on the DSP. Also, the ARM can be used to decode audio and leasve the entire DSP available to decode video. This achieves much higher performance due to load balancing.

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