How can I control external accessories?

Hello,

I have a RAMbo 1.4 board with dual endstop firmware. I would like to toggle accessories using GCODE. For example toggle a vacuum. I need a +5V output.

I suppose I can use the M42 command, but it’s not clear to me which pin I can use on the RAMbo.

Thank you,
Julien

I think most of us repurpose the fan pins for this to switch relays. I think there’s 3 fans broken out on the rambo, could be wrong.

This isn’t cheap, but it is versatile and can manage AC voltages without much risk.

https://www.amazon.com/Iot-Relay-Enclosed-High-Power-Raspberry/dp/B00WV7GMA2

The endstops S pins should be fine to use for M42 commands.

3 Likes

I went the simple way and got one of those green power bars that detects load. They also sell them for shop dust collectors. The better ones have a pot to adjust what load triggers the outlet… once the tool comes on, the vacuum comes on automatically.

This document shows the rambo pins… but as mentioned a fan connector should work.
https://reprap.org/wiki/Rambo_development

I use the same lot relay that Jeffeb3 linked to. All I did was wired it up to the first fan pins, and use the M106 and M107 commands to turn it on at the beginning and off at the end. I have both my vacuum and my spindle plugged into it, so they both come on before the cut, and shut off after the job is finished.

Thank you guys, I will consider using fan pins, they are easy to locate and map I guess.

Because I want to understand, how do you identify S pins ? I had a look at Rambo development - RepRap and the board diagrams, but I still can’t relate any endstop S pin to an arduino pin number. What’s the method ?

You could look at the schematics, but easier is just to look at the pins_rambo.h file in Marlin.

I can’t use the fans because they are 12V PWM and I need 5V to control my PID.

I tried with Digital pin 45 (PWM) which is 5V PWM. When I look at it on an oscilloscope the low voltage is inconsistent. Do I need to add a pulldown resistor ? Where should I connect GND ?

Thanks,
Julien

Hmmm looking at the schema there is a GND on MX2-2 and MX2-5 (pin 45) already has a pulldown resistor. I will test this tomorrow. Hopefully it will solve my problem.