In SX Microcontrollers, SX/B Compiler and SX-Key Tool, maxwin wrote:

Hello all,

I have attached my first ever pcb design, based on the earlier schematic! Yippee!

Any feedback would be great. In particular, my earlier concerns which in short are:

1. I have added a ground plane/copper pour on the bottom layer, connecting all the VSS points. Is it sensible to do the same on the top layer? Or alternatively just put in a pour on the top which is not connected to ground? Does it make a difference?

2. The break in the ground plane around the analog section... is it worth it, a waste of time, likely to cause more problems than it solves... ?

3. I have not done so yet, but as I have read commented, is it really worth to remove the ground plane from under the resonator - or is that just myth/not relevant for the SX?

4. Is it sensible to "tie" the vehicle ground and 5v gnd together (as I have done). I have tried to isolate noise coming from the ignition sense (opto device), by giving that its own earth connection (Vgnd#2), but for the ADC circuit I figured I would rely on the vehicle ground being in my circuit anyhow, so by connecting the 2 together at the DCDC converter, I figured I may be saving myself some ground loop trouble.

5. Any other obvious clangers ?


Thanks for looking, Max.


[u]Admission:[/u] I appreciate I have mounted a couple of components "the wrong way round" according to the others on the pcb, but overall pcb size and short track length were my prime concerns here, rather than ensuring no placement errors are made in mass-production. I am sure given more time I can rework the jigsaw and find a completely consistent way, but this will serve the purpose for my first effort. Actually really enjoying putting these together - beats crosswords!

[u]Notes:[/u] The markings on the side of the SX-Key socket next to the resonator are just to tell me which way round to plug in the key! The headers connecting to the unused pins on the SX are just in case I want to add something later. I figured I can just pull the pins high until I need them later.

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