We're planning a new universal boot loader for a family of ST processors. The uP would host the loader in a bit of local flash and read an outboard serial flash to get the specific application code and one or more FPGA configurations.
So, how many config bits might there be for a modern mid-range FPGA doing a moderately complex application?
I think we could enable compression too.
Please consider this a PHB type question. I don't do FPGA development myself, past whiteboarding.
Am 08.11.19 um 20:08 schrieb John Larkin:
The size of the programming file is in the data sheet. It is constant and does not depend on the implemented circuitry.
Newer FPGAs may allow to program only some sectors of the chip.
regards, Gerhard
Anyone know what a "PHB type question" is?
The uncompressed FPGA configuration file size does not change with the device utilization. You need to look at the data sheet for the particular device. Obviously the compressed file size will be variable - with anything from
0% to near 100% compression ratio dependent on content and compression algorithm.
There's a general trend of about 60-80 bits per LUT input (can go higher).
4LUT has ~4-6 inputs, 6LUT or ALM 6-8 inputs. Count the number of LUTs in the part and multiply. Some go as high as 400M+ configuration bits.Jim Brakefield
Yeah, someone explained in the other group. A bit obscure, methinks.
From Lattice ECP5 sysCONFIG Usage Guide FPGA-TN-02039.
LFE5-45 - 8.86Mb
From Xilinx UG470 Xilinx Artix 35T and 50T need the same 17.536 Mb
MK
Why complicate things with memory soooo cheap ??? Just store raw data...
Compression could save bootup time. The Artix7 that I'm using now is only 17 mbits, but some of the Vertix chips are approaching a gigabit. Luckily, I can't afford them.
Probably lots of config bits.
My PHB answer would be 32 Mbit.
However, "mid-range" FPGA is a very broad definition. These days I would call mid-range something like the Spartan 7 family, but probably someone could argue that it is already low-range. So you could choose 32 Mbit (which is the maximum bitstream size required for the Spartan-7 and for a mid-range Artix 7) or go a little further to accomodate also the mid-range Kintex-7. See table 1-1:
Nah. I get suspicious of any engineer who doesn't know the term PHB!
It's like not understanding the term SEP.
I had to think a bit to come up with PHB, but I got it. I've no idea what SEP is.
But then I'm acronymn dumb (and too lazy to try and google it right now.)
(I've got a feeling a "whoosh" at my expense is incoming...)
--Mark
"Somebody else's problem". It's a term from Douglas Adams:
""" An SEP is something we can't see, or don't see, or our brain doesn't let us see, because we think that it's somebody else's problem. That?s what SEP means. Somebody Else?s Problem. The brain just edits it out, it's like a blind spot. """
You need to swat up on your TLA's :-)
"swot" up, rather - and I need to work on my spelling!
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