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In my opinion, 500 ohm series resistance isn't too high for slow and medium speed signals. Another option for 5 to 3.3V conversion not yet mentioned is a simple resistive divider.
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I was originally going to do a resistive divider on a solderless board. But then the practicality of it hit me, 16 * 2 = 32. That's a lot of resistors, and when I sat down, it's just a big pain in the butt. I looked for alternative package of resistors, and I didn't find one that would work the way I need it. Also don't know if the resistive dividers would just naturally support the series termination requirement of AN447.
Using those little boards at NKC (that contain the LCX245) would be more convenient, handle 8 connections at a time, in on one side, out on the other. Most of those solderless boards won't do two sets of ICs SIDE BY SIDE(40-pin on left, say, and the boards on right), which, for wiring purposes is the most ideal.
I've wanted to do a PCB forever, and this might be a good excuse.
I'd prefer soldering the connector, the two LCX245 boards, and then even 16 through-hole resistors(for termination) that have consistent lead lengths to cut, and so on. Much cleaner and permanent solution. If I get some PCB schematic capture/layout experience for a more complicated project later, then so be it!
I'm pretty green with this stuff.
Thanks
Keith
Honored Contributor
