I’m running bCNC on a Raspberry Pi which is connected to the Smoothieboard via a short USB cable. I’d like to install a 5V regulator (Murata has a 5V/2A, (model 78SR-5/2C) but I saw on the schematic that both Vbus and 5Vreg are fed into the LM1117-3.3V regulator (IC10).
Isn’t that going to cause a problem if I use both?
Imported from wikidot
Nope, there are diodes that make sure that’s fine.
Thanks, I see that now. Sorry, but I’m an Altium user and for some reason Eagle files are confusing to me. It appears that the only header which would connect to this regulator’s output is at the endstops and to bring 5V to pin 1 of the header I would need to place a solder jumper on SJ2, is that correct?
If so then I think trying to power a Raspberry Pie from that header is not good since SJ2 pads are small. I think it would be better to attach wires directly to the output of the regulator, would you agree?
You don’t need to use any solder jumpers, those are just to select if the endstop outputs are 3.3v or 5V
You just feed 5V by :
Or any combination of those, and it will just work.
And yes don’t prower a full raspi off an endstop pin, just get that 5V off the vreg directly ( or off the Serial port 5V pin, that would work )
Yes, I understand about the 5V power, thank you. I think maybe Altium did not import the PCB correctly. It is showing the jumpers on the top layer (red is top, blue is bottom) and it shows a trace between the middle pad of SJ1 (and SJ2) but it’s on the bottom layer without any via.
I can’t post an image yet in this forum but a screen shot of what I’m talking about yet so when I can I’ll insert it here
I see a 10mil trace going between the pads of the serial header so if the RPi really pulls 2A it’s probably not a good idea to use this and better to solder wires onto the regulator.