Servos to Rambo 1.2 d

Hi everyone

How can I connect small RC 5V servo to Rambo 1.2d board? I can't find any detail description of connectors. Can I use motors ext connectors?

just put the orange signal wire from the servo on pin 6 of the EXT1 header.
Pin 1 is +5V
Pin 2 is ground.

in the pins.h file, you need to define the pin, under the 301 motherboard section.
#define SERVO0_PIN 4 // RAMBO ext1 pin 6, verified to work
this is 1x6 straight pin header, right above the Mega processor, when looking at the board with green connectors at the top.
Pin 1 is the left pin, with a small 1 indicating it.
if you put the voltage backwards, the servo is dead, in my experience. plus it heats up quickly.

change the number of servos to 1 in config.h.

use M280 p0 s45 to rotate it to 45 degrees. you can also use pulse widths to determine the farthest ends.
m280 p0 s550 or 535 or 540 or whatever.

you can time the servo to the correct 0 and 180 degree extents, in the servo.h file.
generally, the 550 range signal is close to the zero point.
the 2500 is close to the full extent.
these are pulse widths to drive an angle. you need to play around and set those so there is no chatter at either endpoint.
if you hear the servo chatter at the extent, it might be trying to rotate beyond its physical limit.
This can cause overheating, so you need to tune tune the pulse width so it stops near the limit, and no chatter.


#define MIN_PULSE_WIDTH 535 // the shortest pulse sent to a servo
#define MAX_PULSE_WIDTH 2390 // the longest pulse sent to a servo
#define DEFAULT_PULSE_WIDTH 1465 // default pulse width when servo is attached
#define REFRESH_INTERVAL 20000 // minimum time to refresh servos in microseconds

Edited 2 time(s). Last edit at 03/17/2014 11:01AM by davew_tx.

Hello davew_tx,
i'm interseted too but my english is not so perfect (I'm french ... lol). Can you confirme the plug drawed on the picture of my board (Model 1.1b but it's about the same) ?
It will be great. Thanks a lot.

Edited 1 time(s). Last edit at 03/24/2014 04:30PM by Steph ane.

Perfect !!!
Work on my Rambo 1.1b.
I add only a picture if it can help somebody.

Thanks a lot for your post.

Edited 1 time(s). Last edit at 04/04/2014 04:48PM by Steph ane.

I've connected my servos instructed above, but I get a lot of jitter, and just moving the servo in pronterface cause the printer to crash, can anyone help me out with this at all? I'm also using a Rambo 1.1b

In my case I haven't jitter problem.
But since I use a bigger servo and need a direct alimentation from my power supply. The jitter can come from bad china servo ...
Davew_tx has post a solution on this topic with a resistor for stop them : [forums.reprap.org]
Do you use big servo ?
You said that the machine crash ? What it mean ? What do you do after ?
In my case I use Repetier Host but I think it's not the problem
I can send my firmware (for Delta) if you want test .

I connected the servor just like you did, and I also have Rambo V.1.1b. However, when I powered it up it kept "moving". For Instance, when the printer powered up it would move by 10 degrees or so, then it would randomly move on it's own. Sometimes retracting to 90 degrees, some times just a few, but I could always hear it moving. The machine crashed several times after using M280 to move the servo, re-flashing the firmware fixed it, but the jitter still remained. Looking around it seems that I may have to try applying Resistor to the circuit, What servo are you using? I'm using a HS-55 I picked up from a hobby shop, and I'm wondering if it is drawing too much current?

In my case the servo move a little bit the machine connect to the pc after no.
I use this servo : Turnigy 620DMGplusHS High Torque Digital Servo
I have forgot but I have change the logic fuse of 5A for on of 10A, I had problem when I have upgrade with dual extruder. Perhaps it will help you.
If you have a 5volt on your power supply (with commun ground between the rambo board (servo gound pin) and power supply 5volt ground) try to plug your servo on this output.
I'm not an expert ... I explain you only what I have do and try to understand the difference between our machine setting ...