Mini Maestro 18-Channel USB Servo Controller from Raspberry Pi and Python

I’m attempting to control two servos on a Raspberry Pi using Python but cannot get python to communicate with the Mini Maestro.

I have the Maestro connected to the pi using a USB cable. I installed the requirements listed in the from the Pololu Linux tar download, copied the 99-pololu.rules to /etc/udev/rules.d (I then reboot the pi), and modified the permissions on the USB device /dev/ttyACM0.

I can move both servos using the Linux MaestroControlCenter, but when I run the sample Python script I found on GitHub (, the python script hangs. Here is a slightly modified version of the sample GitHub python script that I’m running.

import Maestro.maestro as maestro
servo = maestro.Controller("/dev/ttyACM0")
servo.setAccel(0,10) #set servo 0 acceleration to 4
print(“After setAccel”)
servo.setTarget(0,6000) #set servo to move to center position
print(“After setTarget”)
servo.setSpeed(1,10) #set speed of servo 1
print(“After setSpeed”)
x = servo.getPosition(0) #get the current position of servo 1
print("servo 1 position "+str(x))

Here is the output:

After setAccel
After setTarget
After setSpeed

(Neither servo moves. The script hangs waiting for the getPosition to return.)

When I run the script, the green light blinks once rapidly. The yellow light continually blinks twice quickly, then pauses, and then blinks twice again.

I’m also attempting to communicate using a Linux serial port program but have yet to be able to make a connection with the Maestro. I’ve gone through the serial parameter setup validation and I think the settings are correct. I wanted to at least validate the connection, but the terminal hangs.

Any ideas?

Thanks in advance.


Did you set the Maestro’s Serial Mode to be “USB Dual Port”? The “USB Dual Port” serial mode tells the Maestro to listen for serial commands coming to its Command Port. By default, the Maestro’s Serial Mode is set to “UART, detect baud rate”, which won’t work with the code you are using. You can configure the Serial Mode setting in the Maestro Control Center under the “Serial Settings” tab.

- Amanda

The USB dual port works like a charm. I misread the documentation. Sigh…