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Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Mon Jul 16, 2018 6:00 pm
by PhilC
troed wrote:
Mon Jul 16, 2018 1:43 pm
(The next update will be from Chris swearing over hard to find connections between pins ;))
LMAO, was thinking along the same lines.

Solder sucker anyone?

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Mon Jul 16, 2018 7:55 pm
by exxos
So this one worked first time.. see how it goes.. got the new firmware in it...

It it seems OK, will sell it cheaper for someone to beta test it ;) Will have a second one when I get more bits..

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Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 10:35 am
by exxos
So today I found a odd issue.. I have seen it before, but I put it down to the previous problems but this seems to be a new problem, it is difficult to tell if there is still a bad connection or not.. I'm not sure if the board I was testing yesterday and this issue or not, but I will retest later today to make sure.

At some random point generally over half an hour, GB6 locks up without bombs.. HALT on the CPU is going crazy I am not sure why.. :shrug:

I swapped out the 40MHz oscillator for a 38.4MHz one, and this did not change anything. So it is not like speed itself issue here, I think not anyway.

I don't think it is ROM related, as it does just the same if accessing ROM at 8MHz.

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EDIT:
OK so it died pretty quick that time, I will try disabling the blitter to see if that helps..
I remember having some odd issues while ago where there was a couple of blitters which did not play nice with the booster, I don't know why, but out of 100s tested which worked fine, I just put it down to some bad blitter chips.. I also have had contact problems with the blitter causing issues in the past.. So I will investigate...

EDIT2:
One suspect thing is that BR has a heck of a lot of noise on it.. I guess it could be possible the CPU is seeing a bus request when there actually isn't one..

Or could be possible the slow rise time could falsely be triggering another BR on the CPU.. The CPU is running at around 25ns cycles, if we took a rough figure of BR is still below 1V around 50ns.. then likely as possible random points timings could just trip the CPU into another bus request..
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.. and on x10..
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EDIT3:

Added 1K onto BR..
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Faster rise times, but also lot of oscilations on the low part..

It ran for about 90mins with blitter off, no issues, before with blitter on, was getting lockups after 10-20mins. So think I am looking in the right places here..

Now I am trying with blitter on and the 1K pull up on BR to see how long it runs for this time.. possible may need small pF capacitor to help with noise... but will see how it goes...

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 3:56 pm
by exxos
The 1K resistor pull-up did not seem to change anything. So I added a 100pF across it and so far so good.. Fast approaching loop 50 in GB6. It wasn't getting past around 10-20 before. So seems the oscillation on the low part of BR is causing the issue somehow. Not really sure how or why..

I will leave it running for another hour and then I will try diode clamp on the pin instead. If I can clamp the huge negative undershoot then maybe the oscillation will be a lot less anyway. Then I can leave the 1K pull-up to get a faster rise time without it being counteracted by the capacitor is currently in place..

Nothing like waiting endless hours for something to maybe crash or not :ball:

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 4:18 pm
by rubber_jonnie
exxos wrote:
Mon Jul 16, 2018 7:55 pm
So this one worked first time.. see how it goes.. got the new firmware in it...

It it seems OK, will sell it cheaper for someone to beta test it ;) Will have a second one when I get more bits..
As usual, I would be very interested in beta testing. :)

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 4:43 pm
by exxos
rubber_jonnie wrote:
Tue Jul 17, 2018 4:18 pm
As usual, I would be very interested in beta testing. :)
There will be much angular velocity involving a sledgehammer if it locks up again :lol:

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 4:55 pm
by rpineau
:stickwhack: :chairsmack: :smackbum: :mad:

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 6:16 pm
by exxos
At some point the ROM CS wire had snapped off :roll: I soldered it back on and now just getting rows of bombs pretty soon after GB6 starts. Removing the wire and it did not bomb. So this seems yet another problem which has only just started to show up :roll:

So I have tweaked the code and added in a wait state onto the ROM CS line. I have also put back the 40MHz OSC.

Now to leave it running again... oh it died on ROM access test :roll: ... So now 2WS on ROM.. so now ROM speed is just 267% (normally 309% or 368%) .. See how long it runs for this time... oh nope, second loop.. So god knows why its started acting up really odd all of a sudden.

It also looks like my monitor is developing the fault :cry: it looks like there is some noise and odd scaling issues for some reason. Has been fine for years and always gave a really sharp image. I guess the heat and constant use lately has pushed it over the edge :cry: so at some point how have to take it apart start changing the capacitors I guess :roll:

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 6:21 pm
by Stimpy
Sometimes a slow slew rate can causes issues, stronger pullup as you tried. Depends on the logic family. Also that signal is not monotonic, likely caused by reflections. Especially nasty if it happens between the logic thresholds as it looks like it does. More modern faster logic is more sensitive to this. How do you measure the signal? Your ground is clipped close to the receiver or driver and not on the ground ring around the motherboard?

Re: STE V1.5 32MHz BOOSTER - STATUS

Posted: Tue Jul 17, 2018 6:28 pm
by exxos
Stimpy wrote:
Tue Jul 17, 2018 6:21 pm
Sometimes a slow slew rate can causes issues, stronger pullup as you tried. Depends on the logic family. Also that signal is not monotonic, likely caused by reflections. Especially nasty if it happens between the logic thresholds as it looks like it does. More modern faster logic is more sensitive to this. How do you measure the signal? Your ground is clipped close to the receiver or driver and not on the ground ring around the motherboard?
The scope is on the outring gnd, but all other signals look really good, just BR is all over the place. The gnd oscillation is a lot less now.. probably spikes up to 0.3V.. so should be ok at that, but still having some odd issues with something else.

I've put back the 38MHz osc.. see if things look to improve.. I'm starting to wonder if the CPU's simply can't run at these speeds at all. I seem to be getting a lot of screwy problems with no real apparent causes :roll:

Even more annoying as it has gone back to the odd fault now where won't reset, that always seem to be bad soldering somewhere.. But this board has been fine two days :roll:

EDIT:
..and that is odd as it boots without the ROM_CS line connected.. Bizarre..