Using stock power button to turn on printer with RAMPS

#1

Gutted my machine, using rasp pi and RAMPS type board instead. Want to use stock power button to turn on/off how would I hook it up?

#2

I don’t know the full interworkings of the power button, but it should be pretty easy to determine with a multimeter by probing the 5 pins with reference to GND. See the schematic here: https://github.com/Zeepro/zimboard/blob/master/Zim_Boardv6.pdf

Not sure what kind of input a RAMPS board needs or if it even has a soft power switch type of input looks like there is no soft on/off power switch, but the raspberry pi can just be left plugged in all of the time so it’s ready to transfer files to. You also won’t have to wait a couple minutes for it to boot then each time you turn it on.

The Zimboard is basically an arduino mega and ramps board combined. The power switch is hooked to an has a RS latch made of discrete transistors that controls a P-channel MOSFET that switches the 12V to the zimboard. So they effectively added the soft on/off power circuitry to a ramps/arduino circuit. You could build something like that from the zimboard schematic, or maybe even just buy a small breakout board.

Or you could use the PS_ON input on an ATX supply if that’s what you are using… and short it to GND. I’m not sure what the RAMPS wiki is suggesting here:

If you want to use PS_ON to turn on your power supply then don’t use diode D1, you need your Arduino to be powered from 5Vsb otherwise when no USB is connected the PS_ON pin floats (and your power supply pulses on and off).

But that RS Latch circuit seems like it could be hooked directly to the PS_ON input of the ATX supply. Push it once to SET the RS latch (output LOW), push again the RESET the RS latch (output HIGH 12V or 5V depending on what you are powering your RS latch with). Honestly you’ll need to do some digging here to know for sure, but start with 5V… if it works, you’re done and you haven’t damaged anything. PS_ON might be a 5V input, I’m not sure.

#3

I have a 2 channel relay board, just got it on amazon. Would this work to turn it on with the button?

#4

would something like this work instead of a relay? http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=253089681743&category=4666&pm=1&ds=0&t=1507839737000&ver=0