I only looked at U44 as it had CS on it. But I don't see how all the delays add up, as when AS goes high, the address bus will all be pulled high, so U44 wouldn't have a valid address so CS would go high as well. Depending on the speed of thee GAL that should happen within like 25ns.
The only way I can see U44 taking 100+ ns to set CS high, aside from some other pin on U44 screwing it up, is the adress bus is taking to long to all go high. But then we back to bus pullups again
But can you monitor a couple address line on U44 with CS and AS to at least prove the address isn't "hanging around" for some time keeping CS low for longer than it should ..
DFB1r4 design discussion thread
Re: DFB1r4 design discussion thread
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: DFB1r4 design discussion thread
I think you've misunderstood something. There's no 100ns delay.
A 10ns delay on CS compared to stock is enough for it to fail.
BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
You mention 125ns delay here https://www.exxosforum.co.uk/forum/viewt ... 150#p73224
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: DFB1r4 design discussion thread
Ah, right. That's a completely different test case.exxos wrote: ↑Wed Nov 17, 2021 5:36 pm You mention 125ns delay here https://www.exxosforum.co.uk/forum/viewt ... 150#p73224
That's a delay in assertion caused by round-trip logic propagation meaning it misses a clock cycle. It's only a 62ns delay -- compare it to the first trace here (https://www.exxosforum.co.uk/forum/viewt ... 140#p73085), which is the same test on stock.
The delay I've identified as causing trouble is the deassertion of CS (DSP latches on LO-HI CS transition). The experiment I rigged simply deasserts on the next positive clock edge after assertion, but in reality I don't have access to that line.
How to stimulate that behaviour with only the lines I have available is the next task.
I think something like: if AS and DSP then on negedge of XDTACK assert DSACK0 and deassert XAS. Reset on AS goes high.
Which will probably not now fit in the CPLD!
BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
So close, but no cigar.
With one amendment to the above (which is I only do the short termination on writes), DMA2DSP runs happily for quite some time (I've had it going for 20 minutes without a red line so far), but alas, FRAC.DSP, my go-to hard nut program, only works intermittently. It's gets a quarter, sometimes half through.
This is *almost* ok, now, but there must be something not quite right with the timing still. I'm getting sorely tempted to just do a bloody daughterboard for the GAL and control that chip select myself!
Thinking cap back on.
BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
I was thinking to try to build some pullup 'hats' for my card over the weekend.
Am I right in thinking it's both (address and data) busses that benefit, or should it just be data?
All the lines currently have 10k on them, so I was thinking to add 3.3k to each line to bring the total down to 2.4k. Reasonable?
Cheers,
BW.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
It's worth trying. Only takes one bit or ringing or noise in one line at the wrong time and all goes to hell. As to if it will help with your problem or not is anyone's guess..
Do both and have done with it.
Possibly, though it's something I never tried on a Falcon. Maybe aim for about 3.3K - 4.7K. There becomes a point where things will get worse. On a ST it's around 1K, but that's getting a bit *too* low anyway.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: DFB1r4 design discussion thread
Yep, but (hopefully!) can't hurt.
It's *so* close to working now. I was getting a fail on the DSP program probably one time in 20 with the current set of hacks, so I'm looking for that final piece of the jigsaw. That said I thought I'd nailed it before and then the next moring it was gone again.
Yeah, fair enough. The upper address lines are occupied ATM, so that requires a bit more work is all.
Adding 6.8k would give about 4k in total. I'll give that a crack, then.Possibly, though its something I never tried on a Falcon. Maybe aim for about 3.3K - 4.7K. There becomes a point where things will get worse. On a ST its around 1K, but thats getting a bit *to* low anyway.
Cheers,
BW.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
Haha. Well f**k it!
Just spent the evening fine-tuning some pure DSACK0 simulation logic, as this seemed to be far more stable than responding to the GALs. Finally passed all my tests. Was working great. Super!
Put in a different crystal to test the reset problem...
...aaaand the DSP fails at first test.
There's not even an oscillator dependency in the bloody logic I'm testing!
Anyway, I've ordered some new veroboard to let me go to go to town on the pull-ups & and investigate bypassing the GAL for DSP access.
Enough for now!
BW.
Just spent the evening fine-tuning some pure DSACK0 simulation logic, as this seemed to be far more stable than responding to the GALs. Finally passed all my tests. Was working great. Super!
Put in a different crystal to test the reset problem...
...aaaand the DSP fails at first test.
There's not even an oscillator dependency in the bloody logic I'm testing!
Anyway, I've ordered some new veroboard to let me go to go to town on the pull-ups & and investigate bypassing the GAL for DSP access.
Enough for now!
BW.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Re: DFB1r4 design discussion thread
So it ain't pretty, but I've added 6k8 pull ups to all the motherboard data lines to bring the whole pull-up resistance down to about 4k.
Also, I found a 5k pull-up on the reset line solved that oscillating reset problem at 50MHz.
The system as a whole is now running very nicely. Touch wood, I haven't seen any memory issues yet.
However it's not helped with the DSP at all. I haven't faced doing the same sticky-out resistor trick on the 22 address lines yet, but I ought to do that for completeness.
The DSP just seems so temperamental. Going back to the 40MHz oscillator didn't restore functionality either. It's very strange indeed.
Steve mentioned the additional DMA clock pull-down -- I'm not sure there's any cross pollination with the tests I'm doing, but it perhaps would be worth looking at anyway.
BW
Also, I found a 5k pull-up on the reset line solved that oscillating reset problem at 50MHz.
The system as a whole is now running very nicely. Touch wood, I haven't seen any memory issues yet.
However it's not helped with the DSP at all. I haven't faced doing the same sticky-out resistor trick on the 22 address lines yet, but I ought to do that for completeness.
The DSP just seems so temperamental. Going back to the 40MHz oscillator didn't restore functionality either. It's very strange indeed.
Steve mentioned the additional DMA clock pull-down -- I'm not sure there's any cross pollination with the tests I'm doing, but it perhaps would be worth looking at anyway.
BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark