OT: Re: [avr-gcc-list] Programming Atmel FPGAs from AVR?

[Clemens Koller]

Hello, Todd!

TODD BATZLER schrieb:
> Although I'm most familiar with Altera, Lattice and Xilinx FPGA's, they 
> all have
> one thing in common and that's the serial flash device that they 
> configure from
> on power up.

That's not true anymore.

Therefore I mentioned the Actel Flash Based FPGAs (I use ProAsic3 here)
where you can use a small on chip "user Flash memory" to let an
AVR IPCore fetch it's code...
There is no external eeprom needed. The FPGA comes up "Live at Power-Up"

There are similar Lattice FPGA's which have a internal FLASH -> SRAM -> FPGA 
Fabric
structure which also don't need external components. However, I don't
know if the Flash is accessible from an AVR.

>  I'll assume without checking that the Atmel is the same.

Atmel's std. FPGA parts need an off chip serial configuration memory.
Whereas the FPSLIC devices have that thingy on chip!

> I would think you could certainly come up with a method to
> program the serial flash part from the on-board Atmel.  I do a similar thing
> with a mux between the programming connector, FPGA and serial flash to
> allow re-programming of the serial flash while the FPGA is in operation. 
> Using the serial config flash means that for changes to take affect, the
> easiest way is through a power down/up forcing a re-configuration of the
> FPGA.  There's probably a way to force that to happen 'on the fly' as 
> well, but
> I don't have experience here.  I'm controlling multi-kilowatt power 
> conversion and
> pre-regulation stages and interrupting the gate-drive async is 'bad'.

The learning curve there sounds like a lot of fun :-)

> I'd be willing to share a hardware snippet in Eagle showing how I've done
> the multiplexing.

It would be nice to see how you did that multiplexing?
(Can you send me some pdf (no eagle here, yet) of that part? (But please off 
this list.))
I thought about feeding an ATmega168 and an FPGA thru some JTAG which
can also come from two sources.

Thanks,
--
Clemens Koller
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