I was just wondering if the Sam FPGA could be configured as a SIMD unit. I assume that you couldn't just make it compatible with the Altivec instruction set and have code work. but there would have to make Sam specific code instead.

The main question is whether or not it it would be fast enough to make it worthwhile, although there may be other technical reasons why it wouldn't work.

Last edited by Rob on 06-Dec-2011 at 10:10 PM.

@Rob

Good question. I wonder if anyone has even thought about using the FPGA on the SAM for anything while running OS4. It would be interesting to hear from any developers that are working on anything that uses the FPGA.

That would give me some hope that the Amiga community was still alive, if there were still some really innovative developers working on Amiga programs that were unique and exciting. OS4 developers trying to use the SAM's FPGA to do things that normal computers don't or can't do, or X1000 owner/developers trying to use the XMOS chip and Xena bus to do something different and exciting, that would be a great thing to see happen.

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@amigadave

As I've understood it, the FPGA on the SAM can not be reconfigured on-the-fly. Instead you need to flash an updated FPGA image and reboot the computer. Not exactly user/developer friendly. I assume the SAM has an FPGA simply to allow "bugfixing" the hardware without having to replace any chips.

Should be nice to have the possibility to flash the Kickstart on it for very quick start up

@ilbarbax

The FPGA is not a flash memory. A CF card or something is better suited for quick booting. But the slowness in the boot process is the eternal time it takes for UBoot to scan through the hardware and convince itself it is really ready to boot (most BIOSes takes half a century doing this). Then using the ancient PIO-0 mode to read the boot media - this is where boot speed can really be gained.

And since the FPGA is used to control some part of the board, it cannot be flashed in runtime, but has to be taken offline and flashed using another computer if I understood it correctly. That makes it unpractical.

It would have been cooler if it was a RAM based FPGA that was completely idle and free and could be used for anything from a user/programmer's perspective.

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@AmiDog

Quote:

As I've understood it, the FPGA on the SAM can not be reconfigured on-the-fly. Instead you need to flash an updated FPGA image and reboot the computer. Not exactly user/developer friendly. I assume the SAM has an FPGA simply to allow "bugfixing" the hardware without having to replace any chips.

Actually, the FPGA can be reconfigured on the fly and you don't need to reboot the computer

Past summer I was porting a little utility from LatticeSemi which allows you to reconfigure the FPGA with a new bitstream using 4 GPIO pins, all from within AmigaOS4.1.
It takes around 13-17 secs to reprogram the FPGA on a Sam440ep.
Unfortunally my "main" work takes me too busy now and I don't have time to finalize it, but I hope to be able to release it in the next months.

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@m3x
Great to hear a confirmation on this since I will be using the FPGA on the 460. You gave us access to the GPIO pins which is enough to try my ideas out. Great work guys. The 460 is really a great machine even outside the Amiga community. ;)
Ps. Tell Enrico to answer mail a little bit quicker.
Ds.

@m3x

Quote:

Actually, the FPGA can be reconfigured on the fly and you don't need to reboot the computer Past summer I was porting a little utility from LatticeSemi which allows you to reconfigure the FPGA with a new bitstream using 4 GPIO pins, all from within AmigaOS4.1.

Oh cool!
I got the impression the FPGA had an important role in bus management or whatever on the Sam that it couldn't be disabled at runtime. Thought it had to be programmed externally by JTag or something. Glad I was wrong

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@m3x
that's great surplus value! Is it available also on linux? Do you have sources?

And again... is this utility also capable to drive LatticeXP2 on Sam460ex?

*Nello*

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@Rob

Depends on the capacity of the FPGA present and how it's connected to the system. I'm not sure the FPGA on the SAM is suitable in either of these two details to become an Altivec (or other SIMD) unit.

I've pondered the idea of an FPGA implementation of Altivec for Sam and such, in an FPGA on a PCI card. It's possible, certainly.

I think that you'd trap the altivec instructions, and direct them to the PCI FPGA card. The Altivec registers would be inside the FPGA, so any loads to or stores from Altivec will go to and from the FPGA over PCI. Other instructions, such as math, shifts, logics, etc. will be trapped on the CPU and send commands to the FPGA to appropriately do things using the in-FPGA Altivec registers.

The biggest problem with this is the overhead. The trap in the CPU takes time to determine the right thing to do. It takes time to tell the FPGA to do that or to send data to/from it. It takes time for the FPGA to execute the command, as it will probably be running at a slower clock rate than the CPU is. (See the FPGA for dummies thread at amiga.org for some information as to why an FPGA is slower than a custom chip like a CPU or ASIC) I'm not sure if it's possible to calculate performance of this idea before doing it and measuring it. There is some possibility that a pure software emulation of Altivec would perform faster than a distant FPGA harware implementation, as the software emulation would be closer to the processor. (inside it and in memory, and memory bus is probably faster than PCI)

I think it'd be cool if someone does this. They'll need to know VHDL or Verilog as well as computer architecture design. (Implementing Altivec is a computer architecture topic) I'm taking a VHDL course this spring semester, and plan to take a couple computer architecture courses next year. But I already have way too many project ideas that I don't have time to work on, I doubt I'll ever do anything for this.

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@AmiDog

Quote:

As I've understood it, the FPGA on the SAM can not be reconfigured on-the-fly. Instead you need to flash an updated FPGA image and reboot the computer. Not exactly user/developer friendly.

I don't think he said anything about reconfiguration. Even if it can't be, it can still become something useful, if it's connected to the system in a way to allow useful things. I asked once, I forget the reponse, but for me it really put an end to thinking about using it for accelerators, minimig, or peripherals I'd find interesting to have.

Quote:

I assume the SAM has an FPGA simply to allow "bugfixing" the hardware without having to replace any chips.

I doubt that. I doubt it would be worth the PCB connections of that purpose in this sort of board. They released an FPGA resource library for AmigaOS recently, I think it looked like you can use the FPGA's pin header connectors as general purpose IO (GPIO), if I understood that correctly. Industrial and embedded customers can put something a little more interesting in there to interface with machinery, sensors, control panels and simple displays (on/off LEDs, 7segments), or some special-purpose embedded computers.

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@ppc_addon

Quote:

@m3x that's great surplus value! Is it available also on linux? Do you have sources? And again... is this utility also capable to drive LatticeXP2 on Sam460ex? *Nello*

Yes, sources will be released, and it should be very easy to adapt it to run on Linux, and more: it could drive any LatticeSemi FPGA devices (basically it's a JTAG "emulation")

We'll even release the source code to recreate the original bitstream under GPL license too.

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@m3x



The future is looking good.

@Rob

Anyone done anything with those extra DSP instructions? Let's first use those.


other than that, great to hear that FPGA can be programmed on board.
Perhaps SAM460 owners could now get SATA controller out of the FPGA ... or serial port to use old Amiga midi adapters ... or multiple joystick ports ... or xlink to "xena" ... or MPEG stream processor .... etc..

My old ideas thread:
http://amigaworld.net/modules/newbb/viewtopic.php?topic_id=27379&forum=33

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@KimmoK

Quote:

Perhaps SAM460 owners could now get SATA controller out of the FPGA ... or serial port to use old Amiga midi adapters

Instead of that, it would be WAY more useful to concentrate on modern USB midi interfaces, or even (PC) gameport MIDI.

Remember that you cannot even connect many (especially cheap) so-called "midi keyboards" directly to classic Amiga midi adapters (as they have midi only over usb).

For more "traditional" use, just buy a cheap single in/out USB adaptor cable (around 7 euros), or a bigger external USB midi box with as many input & output channels than you need (I got my 6 input & 6 output box for 50 euros)

NOTE: I have absolutely NO idea about the state of Midi on OS4, just pointing out I cannot see any sensible reason to use those ancient midi boxes on anything but classic amigas.

@Jupp3

Ok, ok. The use of old midi adapter would be futile.


Does anyone know (yet) if SAM FPGA would be able to handle SATA or PATA?
I think it would be usefull for SAM460 owners, they would then have extra PCI/PCIe slot free.

Last edited by KimmoK on 10-Dec-2011 at 02:56 PM.

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@KimmoK

Quote:

Does anyone know (yet) if SAM FPGA would be able to handle SATA or PATA?

Yes, definitely (if you can get the pins wired there somehow)

However, the REAL question is if it can handle that in any meaningful way (nowadays people, even Amiga users expect things like speed, DMA and low CPU use), and I'm pretty sure that the answer to that is pretty much "No".

Last edited by Jupp3 on 11-Dec-2011 at 01:20 AM.

@Jupp3

IIRC, the fpga is on 16bit 66mhz bus, so the bus should not limit the speed. But perhaps there are other more limiting factors.

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// For freedom, for honor, for AMIGA
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@all

please may anyone explain, what this could mean for an Amiga User who do not have any programming background?

what will I be able to do in the future with the FPGA on a SAM460?

Just some possible examples, please...

Thank you.

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@Birbo

If they realese an upgrade of the Lattice XP2 up to 40k size, you can quite do on AmigaOne 500 Natami like things. With the actual FPGA size you can do some trick to speed up certain operations.

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