Friday, August 26, 2011

Playing with Fritzing

So I've been looking at various chips to use for memory, and they all seem to be pretty much the same, so I decided to take one and start designing for it. I started playing around in Fritzing, making a simple schematic with just the micro and the SRAM to see how the software works.

Here's my schematic, autorouted by Fritzing. If I try and autoroute with that last R/W- CE line, it will crash the software. Maybe I can send that in...

This is just the 6802 Microprocessor and an Alliance Memory AS6C6264A 8Kx8Bit SRAM. Not all necessary lines are connected, the CS line goes through a decoder chip which isn't on here yet, and the power/grounds aren't wired up either.

This worked out pretty well, but I was really interested in trying out the PCB designer part, because I've tried a few before, and while they're interesting, they all have their quirks. Fritzing is no different, but there are a few little things that help. One in particular is the shift-click on bendpoints on traces.. It lines the trace bendpoint up in an intuitive way, though it does require a bit of getting used to in order to make things work the way you want. The autorouter leaves much to be desired, but it's still an alpha piece of software, so I decided to route by hand to see what I could do. Here's the result:

It's not too bad, yeah, I might not be able to fit a 16 mil trace between those pads, but I was getting a little impatient after things kept crashing and I wanted to get this blog post up. I just did a quick bit of hand-routing to make this work, which it seems to quite decently. Vias work, the way they should after you figure them out, and it's something I've been able to quickly pick up and run with.

One lesson I've come back to: Save often!

I'm going to keep going in Fritzing I think, laying out the schematic mainly and building parts I need, then I'll work on getting the traces all worked out on the schematic. I'm going to keep posting progress pictures, though this weekend will be a bit busy, going to see what I can get done.

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