VOGONS


First post, by bimole

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Hi,

I need an advice from FPGA experts 😀

I plan to build a vintage DAW from the early 2000.
What was financialy out of my reach at these times, is now cheaper than a Voodoo1... Yes, if you are looking for vintage ProTools hardware, you can find absolute bargains !!
This kind of hardware is still very capable compared to actual crappy USB audio interfaces. The counterpart is that you have to deal with PCI, FireWire, Win2K/XP...

I've just found an RME Multiface at a very decent price. This is an external audio interface linked to motherboard with a dedicated PCI card. It uses a FireWire cable but RME developped its own communication protocol between the external box and the PCI card. So it is NOT FireWire.
An ExpressCard 34mm went with the interface to use the Multiface with a laptop computer, as well as an ExpressCard to PCIe adapter card to use the Multiface with more modern motherboards.
This is the great strenght of RME : the Multiface is about 25 years old but you can still use it on Windows 11.

But I've got a problem.
The ExpressCard as well as the PCIe adapter are working well on laptop and desktop computers, but I want to use the PCI card on a vintage motherboard.
The problem is that when this PCI card is inserted in a slot, it prevents the PC to POST. I made the test on different PCI slots and on 4 different motherboard (from Super Socket 7 to LGA1150), without any success. It's a very tiny board with an EEPROM, a Xilinx CPLD, a Xilinx FPGA (XC2S100), two LDOs, a driver and a receiver for the "FireWire-like" link (I can provide picts if needed).
When switching ON, an 5V to 3.3V LDO gets quickly very hot as well as the FPGA. This LDO provides the VCC0 voltage for the FPGA
After measuring the output voltage of this LDO on the PCB, I read 1.2V instead of 3.3V and when measuring the resistance between this LDO output (i.e. FPGA VCC0) and GND, I get about 1 ohm which is way to low and can explain the burning-skin FPGA temperature.
Normally, the quiescent current of this FPGA is at max 100mA (according to the datasheet), so I think the FPGA is toast.
I desoldered the LDO and I still get the 1 ohm resistance between VCC0 and GND...

My question :
I don't know well FPGA black magic but in my old memories, you have to program it to set it up the way you want.
If I replace the toast one by a brand new out-of-the-box one, would it work without any "factory re-flashing" ?
Keep in mind that there is an EEPROM on the board so I think the firmware may be loaded every time you turn it on, but I'm not sure...

Your help is very appreciated!

Cheers,
JB

Reply 1 of 4, by Tiido

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The FPGA uses external configuration memory (that EEPROM is likely that memory) so if that one is still intact, you can get things to live again by replacing the FPGA with another of the same kind, assuming there are no other faults.
Why it died may be due to 5V related factors. The FPGA seems to have limited 5V tolerance and I am unsure how it is set up on the board. The photos suggest 3.3V keying so it is quite likely the card will self destruct in any slot that does 5V signalling but that shouldn't be a concern in most cases, except 486 and some Pentium1 boards.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 2 of 4, by bimole

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Thank you for your answer it seems to confirms what I sensed...
By "5V related factors", you mean, for instance, 5V signals from the PCI slot directly applied on the I/O pins of the FPGA (even if the 3.3V is guaranteed by the LDO) ?
There is no Zeners nor level shifting circuitry on the board to guarantee 3.3V I/O signals.

Reply 3 of 4, by Tiido

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The FPGA has 5V tolerance but not on all the pins, and I don't know if any of those non-tolerant pins are being wired to the PCI slot. On early enough PCI chipsets the signals are 5V and will fry those inputs that are not 5V tolerant, but if this is what happened here I don't actually know but it is definitely a way of getting similar damage you have at hand. But your 2000+ range machine is gonna be 3.3V on the PCI slot so it shouldn't be an issue to you when the FPGA has been replaced with a new one.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 4 of 4, by bimole

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OK thanks, let's find a "cheap" Xilinx XC2S100 TQFP144... 😁