External power Arduino+D1 diode+SD (M1)

[MAF]

I've just installed a SD card in Mosaic (RAMPS 1.4) and it works fine.

Now, I want powering the arduino board to remove the USB wire (once you have selected the file from the sd and given the "start printing order" ) and keep printing without PC.

Question is about powering Arduino: If I solder D1 diode in my Ramps, will it be enough to power the arduino board without any risk? 

Can I disconnect the USB wire and continue printing from the SD card without any problem? Does arduino reset itself or keep working normally?

Thanks in advance, :) 

[Triffid Hunter]

On Mon, Dec 3, 2012 at 11:20 AM, MAF <astr...@gmail.com> wrote:

Question is about powering Arduino: If I solder D1 diode in my Ramps, will it be enough to power the arduino board without any risk? 

Can I disconnect the USB wire and continue printing from the SD card without any problem? Does arduino reset itself or keep working normally?

installing D1 is the way to go as long as your power supply is 12v. If your supply is more than 15v or so, you risk burning the 5v regulator on the arduino. In that case, use an external regulator (78xx, LM2596, etc) to feed 8-12v into the DC barrel jack on the mega.

Alternatively, use your regulator to feed 5v directly into RAMPS via some of the spare pin headers such as the PS_ON connector near the polyfuses, or unused endstop connectors. This will bypass the small 5v regulator on the mega completely.

This will allow your printer to continue uninterrupted from SD when you disconnect USB. Note however that reconnecting USB will reset your printer unless you disable the auto-reset by cutting a pcb trace on the mega. See http://arduino.cc for specifics on that operation.

[MAF]

A very good answer. Thanks. :)