Re: RAMPS for Due!

On servos, I did some research before and it appears most servos will accept a PWM voltage of 3-5V, so that should be ok, although I didn't find an official standard, it seems that 3.3V compatibility is quite common.

However, even small hobby servos might take 500mA, which is already getting to the limit of the 5V supply from the Arduino. I did make a mistake on the V1 board by providing the servo power from the main 5V rail. RAMPS has a separate 5V rail for the servos, which I didn't appreciate. Bigger servos run off higher voltages and use several amps, so you couldn't run those off a shield anyway, an extension board is a good idea.

In RAMPS-FD v2 the 5V can be supplied externally. On both versions 5V is only used on board for the endstops and is provided for external connectors (e.g. SD card etc).

On V1, there are a couple of options:

1. Cut the track to the Arduino 5V on the bottom side of the board between JP101 and the shield OR cut the 5V pin off!
Then provide external 5V power on one of the connectors AU3 or AUX4.
You can then plug straight in to servo headers.
Remember that without 5V power the endstops won't work properly.

2. Connect the servo to PWM signal and ground on the RAMPS-FD header, and provide power separately to the servos.