Electronics > FPGA

Mixing DDR3 data lines between bytes

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asmi:
The best test of memory interface is a successful boot up of Lunux. Build a quick petalinux image and see if it reliably boots. Also remember that things tend to change with temperature,  so make sure to run a long term test.

Berni:
Nice, congrats.

And yeah i also find that booting linux is a very good test due to how varied the access is, so it also exposes issues with address lines, power delivery, crosstalk..etc

Indeed also try doing tests at different temperatures, i seen RAM work fine, but stop working when things get hot.

TomS_:
I find something that helps with reviewing my own schematics is to step away for a couple of days, maybe work on another project for a bit. Basically you just need to forget about it for a little bit and then come back to review it again with a fresher perspective.

Yes it slows things down when you really just want to hit the order button and get it moving, but you also have an increased chance of finding errors.

A couple of months ago I built my most complex board yet, it had 6 layers and a bunch of parts I'd never worked with before. After reviewing on and off for a couple of weeks I found a couple of errors that would have absolutely ended up requiring a respin to fix.

And after all that I made a last minute addition which ended up shorting all of the internal power planes together due to a KiCad quirk. I was able to drill out the offending vias and rescue the board which worked perfectly otherwise.

I guess long story short, it pays to slow things down a bit. If you're working intensely on something you'll fatigue yourself, and that will lead to mistakes.

Boscoe:

--- Quote from: TomS_ on October 06, 2023, 11:04:22 pm ---I find something that helps with reviewing my own schematics is to step away for a couple of days, maybe work on another project for a bit. Basically you just need to forget about it for a little bit and then come back to review it again with a fresher perspective.

Yes it slows things down when you really just want to hit the order button and get it moving, but you also have an increased chance of finding errors.

A couple of months ago I built my most complex board yet, it had 6 layers and a bunch of parts I'd never worked with before. After reviewing on and off for a couple of weeks I found a couple of errors that would have absolutely ended up requiring a respin to fix.

And after all that I made a last minute addition which ended up shorting all of the internal power planes together due to a KiCad quirk. I was able to drill out the offending vias and rescue the board which worked perfectly otherwise.

I guess long story short, it pays to slow things down a bit. If you're working intensely on something you'll fatigue yourself, and that will lead to mistakes.

--- End quote ---

Hi Tom, thank you for sharing this great piece of wisdom! This is something I already practice and did with this design finding many mistakes before commuting - long are the days I order from pure excitement! Although that is difficult not to do. I made this mistake having reviewed it multiple times because it was simply a gap in my knowledge. It’s completely obvious to me now but I didn’t think this was a problem before I coincidently read about it while my PCBs were getting fabbed.

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