REV 3 - The beginning

All about the TF536 port to the ST.
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exxos
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Re: REV 3 - The beginning

Post by exxos » Tue Apr 06, 2021 10:50 pm

terriblefire wrote:
Tue Apr 06, 2021 10:46 pm
is your ram clock set to 100Mhz, 50mhz or CPU clock speed...
CPU CLK50M, RAM ~CLK100M
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Re: REV 3 - The beginning

Post by exxos » Tue Apr 06, 2021 10:51 pm

Current scores...

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Re: REV 3 - The beginning

Post by terriblefire » Tue Apr 06, 2021 10:58 pm

exxos wrote:
Tue Apr 06, 2021 10:50 pm
terriblefire wrote:
Tue Apr 06, 2021 10:46 pm
is your ram clock set to 100Mhz, 50mhz or CPU clock speed...
CPU CLK50M, RAM ~CLK100M
Hmmm. Yeah leave it like that if its working then... i think later boards i have CPU and RAM at same clock rate.
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indicates how much hurting you shall receive."

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Re: REV 3 - The beginning

Post by exxos » Tue Apr 06, 2021 11:04 pm

terriblefire wrote:
Tue Apr 06, 2021 10:58 pm
Hmmm. Yeah leave it like that if its working then... i think later boards i have CPU and RAM at same clock rate.
Looks like 847% is the "proper" speed anyway... Mine must have been running too fast for some reason to get 903% originally.

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Re: REV 3 - The beginning

Post by Badwolf » Wed Apr 07, 2021 10:48 am

exxos wrote:
Tue Apr 06, 2021 10:04 pm
Finally looking how things are supposed to be :thumbup:

When high it is either accessing ROM or TTRAM... If it is pulsing low, it is accessing the ST bus.. which is not all that often now :)
Yes! That's *got* to be the tipping point.

Should not have been seeing all those AS30s on the ST side.

:dualthumbup:

BW

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Re: REV 3 - The beginning

Post by exxos » Wed Apr 07, 2021 1:02 pm

Badwolf wrote:
Wed Apr 07, 2021 10:48 am
Yes! That's *got* to be the tipping point.
It seems TTRAM access for some reason happens too fast. When it's not working, TTRAM hits 903%, not 847%. So I think STERM is ever so slightly too fast. Inverting the 100mhz clock does the trick. What I may try is clocking STERM via a FF to delay it 10ns to see what happens. I assume worst case the score would drop. But if inverting the clock is enough to fix / break stuff, something is very borderline.

So what's next... 60mhz ... :lol: :hide:
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Re: REV 3 - The beginning

Post by Badwolf » Wed Apr 07, 2021 5:11 pm

exxos wrote:
Wed Apr 07, 2021 1:02 pm
Badwolf wrote:
Wed Apr 07, 2021 10:48 am
Yes! That's *got* to be the tipping point.
It seems TTRAM access for some reason happens too fast. When it's not working, TTRAM hits 903%, not 847%. So I think STERM is ever so slightly too fast. Inverting the 100mhz clock does the trick. What I may try is clocking STERM via a FF to delay it 10ns to see what happens. I assume worst case the score would drop. But if inverting the clock is enough to fix / break stuff, something is very borderline.

So what's next... 60mhz ... :lol: :hide:
Bear in mind the SDRAM is synchronous on the positive edge and the 030 on the negative. Inverted is probably the optimum, therefore as the data should be valid between the falling edge 1.5 cycles after CAS is latched and the falling edge 2.5 cycles after CAS is latched.

But AIUI your SDRAM is running at twice the CPU's frequency, so you're on your own!

BW

PS: my ceramic 030 (purchased just six months ago from your very boutique!) can't get beyond about 55MHz and I can barely keep the SDRAM in sync at 50!

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Re: REV 3 - The beginning

Post by exxos » Wed Apr 07, 2021 6:23 pm

Badwolf wrote:
Wed Apr 07, 2021 5:11 pm
But AIUI your SDRAM is running at twice the CPU's frequency, so you're on your own!

PS: my ceramic 030 (purchased just six months ago from your very boutique!) can't get beyond about 55MHz and I can barely keep the SDRAM in sync at 50!
Challenge accepted! ;)
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Re: REV 3 - The beginning

Post by PhilC » Wed Apr 07, 2021 6:47 pm

Meanwhile,

Somewhere in the UK @exxos has just pressed the reset button on his 60mhz 030.

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Re: REV 3 - The beginning

Post by terriblefire » Wed Apr 07, 2021 7:25 pm

For the avoidance of doubt.. the SDRAM controller sends for 2 reads when it runs at x2 cpu speed. It’s done this way because the required delays are in clocks not ns.
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indicates how much hurting you shall receive."

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