The Xena Research Project Part 1

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The Xena Research Project Part 1



http://amigaonthelake.com/blog/

This is a superb initiative from someone that appears to have done their homework. The XMOS chip has been around long enough now, and it is about time someone payed some interest in it.

May I suggest you either don your flame-proof jacket, or ignore the negative comments that will inevitably ensue from this.

Either way, please do not be put off by the doom-mongers and nay-sayers in the various fora. Despite their repeated attempts to discredit such an initiative, just carry on and ignore the bad.

It really is something worth pursuing, despite what others might say.

Simon

edit: typo

@apsturk

Nice article.. enjoyed reading it..

looking forward to the next.. for I think it could be fun playing around with the xmos chips

@apsturk

"The presence of the Xena chip and Xorro expansion slot on the AmigaONE X5000 opens the door to many possible commercial and user-created expansion options. The Xena may simply be used as a co-processor to the main CPU, or via the Xorro slot as a high performance controller of external hardware. The possibilities are limited only by the imagination of the user."

A few things spring to mind (I have no idea if these are feasible):

Emulation of Classic hardware (e.g., Alice)
Provide Altivec to otherwise Altivec-less P5020
A USB 3 controller

@apsturk
Quote:

This great initiative is highly appreciated!
Finally some reliable infos on the XENA stuff!

The Blog states:
"It should be noted that in every other case (that I am aware of) the XMOS chips are programmed externally via a JTAG port, where as with the X5000 the JTAG interface is already connected to the CPU, allowing the Xena chip (and any further XMOS chips connected via the Xorro slot) to be programmed *from* the native AmigaOS4 Operating System.".

Wouldn't a "native AmigaOS4" version of the XMOS tool chain be required to program XMOS chips "*from* the native AmigaOS4 Operating System"? Hadn't there been talk ahead of the A1X1k-release about porting the XMOS tools to OS4? What's the state of that?

Really looking forward towards the next parts!

@apsturk

+1

@apsturk

Thanks for the thorough and informative article!

I am very interested in learning how to program the XMOS on my AmigaOne, so this blog is highly appreciated.

Most of the stuff so far was discuss on AW.net (years ago) when details of Xena/Xorro were first announced... The Xena chip has approximately the same CPU power as a 68060 (Wikipedia states 110 Mips at 75 MHz, so that equates to about one of Xena's 4 hardware threads).

@daveyw Quote:
I don't understand why people keep suggesting that Xena is used for emulation. Our PPC processors are far more powerful (than an 060 equivalent), and have access to far far more RAM.

Quote:
I'm a bit doubtful (I don't know enough to be completely sure). Xena would need direct access to the motherboard's RAM, but I don't think it has any such access?

Quote:
While this might be technically possible, it would seem quicker & cheaper to use an existing USB 3 card, rather than making your own Xorro card with the right connections for USB 3. And using an existing USB 3 card would mean re-implementing less of the USB 3 spec yourself. And you probably wouldn't get USB 3 speeds with Xena, as I doubt it can communicate with the PPC fast enough.


IMHO, Xena/Xorro are best suited for I/O (so USB 3 would be a candidate) where there are not cheap off-the-shelf solutions (so unlike USB 3). It also needs to be something where Xena can do reasonable (but not heavy) processing to reduce the amount of data down to a small amount, such this can be (stored in it's small RAM and then) communicated to the PPC chip (at whatever speed it can - I don't think it's super fast?). An oscilloscope might fit all those criteria.

IMHO the biggest problem with Xena/Xorro is the risk of blowing-up your expensive X1000/X5000 motherboard, if you wire Xorro up wrongly (or program Xena's I/O ports wrongly), during development. Far less risky to use a cheap 'disposable' USB2/3 card with an XMOS chip on it. Alternatively, we need a Xorro card that has it's own Xena chip on it, and then we program that instead of the on-board Xena - this should be possible (and potentially quick) using the "xConnect" bus.

@ChrisH

Quote:


Almost every discussion about Xena contains something similar to the above.
Please, please. Stop warning people with scare tactics about BLOWING-UP their EXPENSIVE motherboards.
People that have little or no knowledge of electronics should not be tinkering with any motherboards. However, if these same folks wish to learn then do not discourage them, it's their property after all, no matter the cost. Education can be expensive, and only a fool would attempt tinkering with something like a X1000/X5000 without at least knowing the basics of what they are doing. The foolish..........will not be stopped.

You are correct about needing a Xorro card. The one available is crap.

@ChrisH
Quote:

Wouldn't it be a logical step then to have a kind of 'protection circuit board' first, where you can connect your Xorro boards to, without having the risk of blowing-up the mobo?

@Dandy

I feel a lot safer if there was bored with Optokobler to connect between




The risk of overloading or short circuit something is dramatically reduced, you might even hot plug things out and in, this nice instead of powering down the system.

@daveyw

“Provide Altivec to otherwise Altivec-less P5020”

Don’t think that’s possible, Xena CPU is separate to PowerPC CPU chip, how will the Xena chip know the program counter of register inside PowerPC chip? Code on PowerPC is executed on instruction cache inside the CPU, the address lines on the outside of CPU wont reflect the program counter.

You probably make a advanced floppy controller, or even migrate a few chipsets from UAE into XZorro card, but that’s about it.

@LiveForIt
Quote:

Well, the Xorro thingie might also be useful for things like e.g. robot controls.
"...making it ideal for ultra-low latency data sampling applications and extremely easy to turn into control hardware for... well, virtually anything.", as A-Eon put it.

I envision 'robotics' as a broadly defined field of application. Small to medium-scale flexible production cells spring to my mind, or 3d scanning/printing, or controlling model railways, or drones, or..., or "virtually anything".

Back in the old days my clique and I loved e.g. to make a pcb from a schematic in some tech mag and make it work (e.g. a sound digitiser for A500). Or I went to some small electronics store and bought assembly sets for amplifiers, mixing desk, clavilux, loudspeaker boxes or to tinker with electronic Leslie systems for sound effects.

Today I'm missing such inspirations for do-it-yourselfers - handiwork and tech tinkering seem to be out of fashion. Obviously the majority of not-only-youngsters today prefers scrawling, playing games or 'social networking' on their mobile devices (even when crossing roads) over tech tinkering.

So I think while the Xorro thingie is inspiring for me, it might not appeal to todays target audiences. The problem seems to be getting them interested in something going beyond their mobile devices...

@LiveForIt
Quote:

No matter if the risk of overloading or short-circuiting something is real or not - connecting all Xorro cards via such a protection circuit (reasonably priced) will comfort cautious users.

I don't mean one protection circuit for each connected Xorro card, but making the (unprotected) onboard XORRO slot protected by plugging in the protection circuit, which provides the protected slot.

@Dandy

Opto couplers are ideal for connection to Xena. There are several other schemes that should work just as well. I believe LyleHaze has looked into this and found some interesting alternatives.

There are also some development boards that can be used for tinkering. then coupled to the on-board Xorro/Xena.


Perhaps a short height card with protection for Xorro with a standard PCI connector for plug-in cards.

http://www.futurlec.com/Protoboards.shtml (Bottom of page)

https://www.digikey.ca/en/product-highlight/x/xmos/startkit

EDIT:
P.S.
With all Xena signals isolated whatever is on the proto board could be powered separately even by a wall wart with regulation on the board. The isolators powered by the motherboard.

That way the card could be on without any interaction with Xena until the isolators are activated by turning on the motherboard and if the card is off no signals would be supplied to Xena.

EDIT 2:

For those interested, a Xmos chip is not required to write programs and test input/output.

Their Xtimecomposer has what is needed for design and testing programs. Unfortunately it only runs on x86.
The get-going curve is a little steep but the user pdf is very good.

@mechanic

Since most of us aren't going to risk putting garage-built boards in our $2000+ Amigas, why not take it a step further and make a USB enabled XMOS based board and USB driver for OS4?

@xenic

Once a board is designed, if enough people want one, then they could be produced,tested, and distributed by Amigakit. That was the original thought by A-eon.

What you are talking about is one of these from my last post. https://www.digikey.ca/en/product-highlight/x/xmos/startkit

@mechanic Quote:
Really? That's news to me. But if it's often repeated, maybe it's because it's true?

Quote:
I'm not "warning" anyone about anything. I'm merely expressing a reason why I (or someone else) might think twice before doing so. IMHO it is a valid concern.

ALSO, I proposed a possible solution, which would still allow using the X1000 for development. I suppose I shouldn't mention that either?

@Dandy Quote:
Yes, that was (pretty much) what I proposed... although others here have suggested alternative ways of achieving the same thing (with different pros/cons - mine basically used an extra Xena chip as a giant fuse, but that's not perfect).

What surprises me most is that during the X1000's 5 year life, neither A-Eon nor AmigaKit created or sold such a card.

@ChrisH

Fear leads to the Dark Side.

@all

An application I would love to see with the Xena would be a multi channel digital mixer. It should give us 8 inputs with digital controls and CPU based filters could be applied based on a cheap peice of HW.

I would use this at AmiWest to manage all the audio channels. Maybe pull the master out and stream it directly via Shoutcast or Icecast.

Hopeing we get a Xorro card at some point!

Cheers,
Bill "tekmage' Borsari