Terriblefire Accelerators

Help & news on accelerators from TF, Amiga, Atari, CD32 etc

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terriblefire
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Re: Terriblefire Accelerators

Post by terriblefire »

Stimpy wrote: Mon Nov 12, 2018 8:46 pm ICs best routed direct to power and ground plane with as short as possible tracks, ideally via right next to pad. Then place caps in small package as possible, again with vias to decouple the plane. Place vias to side of caps for smallest inductance loop, imagine viewing the board if it was sliced along the layers. Choose highest value within your budget with a decent dielectric and spec the voltage 2x or 3x the DC bias. Then more larger ceramics for bulk. This is perhaps overkill but if you ever need to do high speed designs and pass EM testing, that will get it through. Also a tip on switch mode power supplies, get your inductors round the right way!
Absolutely...

Pretty much exactly what i have here.
Capture.JPG
Capture.JPG (161.21 KiB) Viewed 5388 times
I'm probably 1 cap short if you go by the rules of thumb.
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Re: Terriblefire Accelerators

Post by exxos »

Fine by me :thumbup:

Just caught up with your previous stream... You have fun routing boards! I was like that once, now its more, shoot me now... :lol:
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terriblefire
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Re: Terriblefire Accelerators

Post by terriblefire »

exxos wrote: Mon Nov 12, 2018 9:01 pm Fine by me :thumbup:

Just caught up with your previous stream... You have fun routing boards! I was like that once, now its more, shoot me now... :lol:
I dont do it for a day job though. I sit coding all day.
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Re: Terriblefire Accelerators

Post by rpineau »

This is all very interesting.
On our 68020board I did put 100nF on all power pins as close as possible to them (1206 packages). This does make things harder to route (both for me and the auto router). I might have to reconsider the number of caps and their placement to lower the count and do a you did above and place them center of the component and change them for 1uF instead.
This is a hobby for me so I never tried to hard, but if I can lower the component count and get a more stable board I'm all for it :)
Thanks guys
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Re: Terriblefire Accelerators

Post by AEV80 »

The last few post's was excellent info guys, helpful for noobs like me.
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Re: Terriblefire Accelerators

Post by terriblefire »

AEV80 wrote: Tue Nov 13, 2018 3:22 am The last few post's was excellent info guys, helpful for noobs like me.
Generally I do more than just use rules of thumb. I spice model my clock lines and capacitances before I ship a board. I chat stuff over with guys like Chris & Jamie.

Doesn’t mean I don’t screw up but that’s why I test.

Speaking of screwing up I’ve not wired up the Halt line to the onboard CPU. The 030s is wired to my CPLD. I was planning to switch off the onboard CPU with BG/BR anyways. So not sure it matters. Nothing is wired to halt on the CD32
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Re: Terriblefire Accelerators

Post by Stimpy »

terriblefire wrote: Mon Nov 12, 2018 8:56 pm
Stimpy wrote: Mon Nov 12, 2018 8:46 pm ICs best routed direct to power and ground plane with as short as possible tracks, ideally via right next to pad. Then place caps in small package as possible, again with vias to decouple the plane. Place vias to side of caps for smallest inductance loop, imagine viewing the board if it was sliced along the layers. Choose highest value within your budget with a decent dielectric and spec the voltage 2x or 3x the DC bias. Then more larger ceramics for bulk. This is perhaps overkill but if you ever need to do high speed designs and pass EM testing, that will get it through. Also a tip on switch mode power supplies, get your inductors round the right way!
Absolutely...

Pretty much exactly what i have here.

Capture.JPG

I'm probably 1 cap short if you go by the rules of thumb.

Not quite what I meant, done a image as its perhaps easier to show it.

mod.png
mod.png (783.17 KiB) Viewed 5324 times
terriblefire
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Re: Terriblefire Accelerators

Post by terriblefire »

I see. Better to get the caps onto the power planes with as short tracks as possible. Agree.

Will apply this to my toolkit from now on.
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8 Bit Dreams
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Re: Terriblefire Accelerators

Post by 8 Bit Dreams »

last few pages was very interesting to read - excellent info guide about caps and methods to use them correctly for noobs like me. Thank You very much
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Re: Terriblefire Accelerators

Post by alenppc »

I understand the worry about being overwhelmed with support requests. Unfortunately the more complex a card is, the more difficult it is to get it working (for people building them at home), and the complexity is increasing with every card you make so... there is no escaping that part :)

For end users who end up buying prebuilt boards, it's usually the people who build them that offer support, which is why I stopped mass-building and selling the 530s because I was finding it too overwhelming.

As far as the firmwares are concerned, the 328 is good and done, the 530 is looking that way too for the moment, and the 534 is close to it as well. I really love the 534 so far (especially with the NO-INT2 trick), so I vote for releasing it but your call obviously. (It also makes the 530 mostly obsolete).
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