exxos's DFB1 trials

[exxos]

One thing I just remembered to add is the buffers for the CPU & FPU.

They may or may not help. Basically it is an experiment. But the PLD can drive the clocks as normal. Or jumper to the buffer. The buffer is driven off 5V we should give a higher clock drive to the chips which may or may not help. It will however add a 4ns delay to the signal. So while the high-voltage drive (5V from the buffer as opposed to 3V from the PLD) may ultimately help, the extra delay may be detrimental.. Only one way to find out...

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[Badwolf]

@Badwolf The LCSC part numbers you have, are they part numbers directly from LCSC site, or the LCSC part numbers from JLCPCB ?

I ask because sometimes the numbers do not always tally up or get discontinued on one site but not the other etc

Ah, I half-heartedly started a BOM and put some different companies' part numbers in there, but didn't get very far to be honest.

I can't remember how I got them. Probably from JLCPCB, but I would not trust them to any great degree. I've never done a proper BOM for manufacture, so it's likely all nonsense.

BW

[exxos]

Ended up with a strange power rail problem again :roll:

Every time I connect power to the buffer it literally shorts out VCC and GND with the entire power plane :roll:

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[exxos]

I flipped the power around and I think the problem is gone now.

So I have a huge distrust of these symbols because there does not seem to be anything to differentiate between positive and ground ?!

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[Badwolf]

Ended up with a strange power rail problem again :roll:

Every time I connect power to the buffer it literally shorts out VCC and GND with the entire power plane :roll:

Check the pins.

Is it possible you've rotated (180 degrees) the symbol, rather than flipped it (in Y axis), meaning GND should be on the top and VCC at the bottom?

BW

EDIT: OK, I see that's exactly what you've done.

[exxos]

EDIT: OK, I see that's exactly what you've done.

Probably :roll:

Is there there no way of knowing which is ground or not because it clearly does not say in the symbol which is which :(

Also have you any idea why I cannot get the PLCC68 SMD package to 3D render (and some others) I think the 3-D model is missing but I have imported the entire 3-D library and cannot see them in there :(

[Badwolf]

EDIT: OK, I see that's exactly what you've done.

Probably :roll:

Is there there no way of knowing which is ground or not because it clearly does not say in the symbol which is which :(

I'm not familiar with the symbol, but it obviously knows as connecting it up backwards shorted everything out.

Is the pin number not visible before you connect the labels?

Also have you any idea why I cannot get the PLCC68 SMD package to 3D render (and some others) I think the 3-D model is missing but I have imported the entire 3-D library and cannot see them in there :(

I presume there simply isn't a 3d model associated with that part.

BW

[exxos]

Is the pin number not visible before you connect the labels?

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[Badwolf]

Is the pin number not visible before you connect the labels?

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Yeah, that's a bit unhelpful. I presume it normally faces the other other way and has VCC at the top and GND at the bottom.

You can rotate parts (R) which will cause the issue here and flip them (Y) which won't.

BW

[exxos]

Another oddity in the DRC. This reminds me of the crazy stuff eagle does.

The red track is actually on the top layer, and the pads for the jumpers are on the bottom layer. There is nothing for it to be too close to :stars:

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