Hey guys,
I did not find a problem similar to mine on the forum, so here goes.
My polargraph works nicely and draws nice pictures, but when i want to draw pictures that need the pen to be lifted from the paper, the polargraph stops. The program shows BUSY: C14, END and never moves on from there, however it did actually lift the pen off the paper with the servo. The pen lift and pen drop functions all work fine.
When drawing without a servo connected, the pen lift option is not available and thus the drawing finishes.
Can anybody tell me what is going wrong?
Thanks in advance!

Hey!
Thanks for the response!

I was thinking about power supply issues, but making the motors run on another (external) supply doesn't seem to solve the problem. If i go too high on the voltage and/or amperage with the wall supplies i have around the motors do not work as expected. They shake (move back and forth quick), it's a 12V 1A supply and i would think that would work better than the 6V 500mA supply i was using before.
The arduino is powered via USB and i'm using what seems like an adafruit motorshield v1 clone of the brand Funduino. The motorshield should be able to handle this i think. I replaced one of the l293d chips once already because i probably used a too high voltage supply (not the 12V supply).
The servo motor i'm using is a small one and not rated for a lot of torque and so i expect not a lot of current draw. I will try with another small servo. (Will have to make a new connector because these connectors are apparently not standard)

When the robot stops drawing i usually reconnect via the serial port to get it starting again, but then the drawing does not start where it left off. The pen lift command keeps being busy, so i cannot execute any other commands.
The pen lift commands (buttons in controller) do work when it is not drawing

Should i power the arduino also via the external power supply or only power the motors with this supply?

When sending:
C13,END
C14,END
C13,90,END
C14,180,END
Everything seems to work fine. It drops and lifts the pen just as expected.
The pen lift and pen drop functions in the polargraphcontroller program work.

This is what i get on startup:

POLARGRAPH ON!
Bad format for hardware version - defaulting to ATMEGA328 (Uno)
incoming: Hardware: 1
incoming: MC_UNO
incoming: Loaded width:370
incoming: Loaded height:700
incoming: Loaded mmPerRev:20.00
incoming: Loaded steps per rev:400
incoming: Loaded step multiplier:1
incoming: Loaded down pos:143
incoming: Loaded up pos:23
incoming: Recalc mmPerStep (0.05), stepsPerMM (20.00)
incoming: Recalc pageWidth in steps (7400)
incoming: Recalc pageHeight in steps (14000)

But i found in the arduino code i uploaded to the arduino that the version is 1.2.1

Right now when drawing a simple image with white areas (so that the pen needs to be lifted) it will lift the pen and drop it for a quarter of the image drawn, but then get stuck at a pen lift/ pen drop command (C14,END or C13,END), i tried to reconnect and then place the pen where it was before and start the drawing from there, but at the next pen drop/lift it would stop again.

Hum! Not sure I was really much help there, but glad you got it working!