Re: [casper] Weird FFT block problem
Ah, I would guess what happens is that you have delay stages being implemented in bram where the stage delay is fewer clock cycles than the bram latency, causing an initialization implosion. I suspect if you changed the "minimum delay implemented in bram" (or whatever it's called) parameter to be a bit higher you might not get this error. But as you say, >10 is very excessive, and I'd be surprised if it makes any difference to your timing. I think if you open your mapped design in planahead/fpga editor you'll find that almost all that latency is being wrapped up in a single slice as a shift register. But hey, if it works it works :) Jack On Tue, 6 Oct 2015 at 16:42 Michael D'Cruze < michael.dcr...@postgrad.manchester.ac.uk> wrote: > Hi Jack, > > > > After cycling through the settings I think I’ve isolated the issue. I was > a bit quick to declare a solution….i was able to repeat the problem. The > problem occurs when the BRAM latency is set to >10. I appreciate this may > seem excessive in any case however as you know I’m messing with settings to > get a 2^17 point FFT block to compile at 256 MHz… > > > > When the problem first arose I grabbed the latest casper-astro-soak-test > commit, which didn’t solve the immediate issue. > > > > Perhaps someone could confirm that bram latencies >10 causes this issue? > It’s a 2^17 point FFT with fanout 1. > > > > BW > Michael > > > > *From:* Jack Hickish [mailto:jackhick...@gmail.com] > *Sent:* 06 October 2015 15:50 > *To:* Michael D'Cruze; casper@lists.berkeley.edu > *Subject:* Re: [casper] Weird FFT block problem > > > > Hi Michael, > > > > If the initialisation script fails half way through drawing then often > you'll be left with a bunch of blocks half connected, so I think that's > (probably) a symptom rather than a cause of the issue. Are you using the > latest casper-astro branch? Do you remember what FFT parameters you were > using? Was it a block fresh from the library of one you had previously > configured? If the latter, do you remember how it was configured? > > Gonna be tricky to track this down if it can't be recreated... > > > > Cheers, > > Jack > > > > On Tue, 6 Oct 2015 at 15:25 Michael D'Cruze < > michael.dcr...@postgrad.manchester.ac.uk> wrote: > > Hi all, > > > > I had an odd problem while messing about with the FFT block today – on > setting a new combination of parameters and attempting a new compile, an > error came up which I’ve never seen before. Something along the lines of an > initialisation error in the FFT. On inspection, the component blocks within > the FFT were in pieces and not linked up correctly. In the biplex core > itself there was nothing except the in/out ports. This is very strange and > I can’t find anything similar on the mailing list. I’ve solved it by > erasing and re-cloning the CASPER libraries, however wondered if anyone had > a clue why this would happen? FYI update_blocks didn’t help. > > > > Thanks > > Michael > >
Re: [casper] Weird FFT block problem
Hi Jack, After cycling through the settings I think I’ve isolated the issue. I was a bit quick to declare a solution….i was able to repeat the problem. The problem occurs when the BRAM latency is set to >10. I appreciate this may seem excessive in any case however as you know I’m messing with settings to get a 2^17 point FFT block to compile at 256 MHz… When the problem first arose I grabbed the latest casper-astro-soak-test commit, which didn’t solve the immediate issue. Perhaps someone could confirm that bram latencies >10 causes this issue? It’s a 2^17 point FFT with fanout 1. BW Michael From: Jack Hickish [mailto:jackhick...@gmail.com] Sent: 06 October 2015 15:50 To: Michael D'Cruze; casper@lists.berkeley.edu Subject: Re: [casper] Weird FFT block problem Hi Michael, If the initialisation script fails half way through drawing then often you'll be left with a bunch of blocks half connected, so I think that's (probably) a symptom rather than a cause of the issue. Are you using the latest casper-astro branch? Do you remember what FFT parameters you were using? Was it a block fresh from the library of one you had previously configured? If the latter, do you remember how it was configured? Gonna be tricky to track this down if it can't be recreated... Cheers, Jack On Tue, 6 Oct 2015 at 15:25 Michael D'Cruze mailto:michael.dcr...@postgrad.manchester.ac.uk>> wrote: Hi all, I had an odd problem while messing about with the FFT block today – on setting a new combination of parameters and attempting a new compile, an error came up which I’ve never seen before. Something along the lines of an initialisation error in the FFT. On inspection, the component blocks within the FFT were in pieces and not linked up correctly. In the biplex core itself there was nothing except the in/out ports. This is very strange and I can’t find anything similar on the mailing list. I’ve solved it by erasing and re-cloning the CASPER libraries, however wondered if anyone had a clue why this would happen? FYI update_blocks didn’t help. Thanks Michael
Re: [casper] Weird FFT block problem
Hi Michael, If the initialisation script fails half way through drawing then often you'll be left with a bunch of blocks half connected, so I think that's (probably) a symptom rather than a cause of the issue. Are you using the latest casper-astro branch? Do you remember what FFT parameters you were using? Was it a block fresh from the library of one you had previously configured? If the latter, do you remember how it was configured? Gonna be tricky to track this down if it can't be recreated... Cheers, Jack On Tue, 6 Oct 2015 at 15:25 Michael D'Cruze < michael.dcr...@postgrad.manchester.ac.uk> wrote: > Hi all, > > > > I had an odd problem while messing about with the FFT block today – on > setting a new combination of parameters and attempting a new compile, an > error came up which I’ve never seen before. Something along the lines of an > initialisation error in the FFT. On inspection, the component blocks within > the FFT were in pieces and not linked up correctly. In the biplex core > itself there was nothing except the in/out ports. This is very strange and > I can’t find anything similar on the mailing list. I’ve solved it by > erasing and re-cloning the CASPER libraries, however wondered if anyone had > a clue why this would happen? FYI update_blocks didn’t help. > > > > Thanks > > Michael >
[casper] Weird FFT block problem
Hi all, I had an odd problem while messing about with the FFT block today - on setting a new combination of parameters and attempting a new compile, an error came up which I've never seen before. Something along the lines of an initialisation error in the FFT. On inspection, the component blocks within the FFT were in pieces and not linked up correctly. In the biplex core itself there was nothing except the in/out ports. This is very strange and I can't find anything similar on the mailing list. I've solved it by erasing and re-cloning the CASPER libraries, however wondered if anyone had a clue why this would happen? FYI update_blocks didn't help. Thanks Michael