Pololu Maestro - Manual (Page 12)

The RST pin can be driven low to reset the Maestro’s microcontroller, but this should not be necessary for typical
applications. The line is internally pulled high, so it is safe to leave this pin unconnected. Driving RST low is roughly
equivalent to powering off the Maestro; it will not reset any of the configuration parameters stored in non-volatile
memory. To reset the configuration parameters, select Device > Reset to default settings… in the Maestro Control
Center.
The ERR line is an output that is tied to the red error/user LED. It is driven high when the red LED is on, and it is a
pulled low through the red LED when the red LED is off. The red LED turns on when an error occurs, turns off when
the error flags have been cleared, and can also be controlled by the user script. Since the ERR line is never driven low,
it is safe to connect the ERR line of multiple Mini Maestros together. Please note, however, that doing this will cause
the red LEDs of all connected Mini Maestros to turn on whenever one of the Mini Maestros turns on its red LED. For
more information on the possible error conditions and response options, please see
Section 4.b .
The TXIN line is a serial input line that makes it easy to chain together multiple Mini Maestros. Any serial bytes
received on this line will be buffered through an AND gate and transmitted on the TX line. See
Section 5.g for more
information about daisy chaining.
Bottom view with dimensions (in inches) of Pololu Micro and Mini Maestro
servo controllers.
The dimensions of the Mini Maestro PCBs are shown in the picture above, along with the Micro Maestro for
comparison. The mounting holes have a diameter of 0.086″and are intended for #2 or M2 screws. The vertical and
horizontal distances between the two mounting holes are as follows: 1.2″ and 0.5″ for the Mini Maestro 12, 1.58″ and
0.5″ for the Mini Maestro 18, and 1.5″ and 0.5″ for the Mini Maestro 24.
1.c. Indicator LEDs
The Maestro has three indicator LEDs:
• The green USB LED indicates the USB status of the device. When the Maestro is not connected to a
computer via the USB cable, the green LED will be off. When you connect the Maestro to USB, the green
LED will start blinking slowly. The blinking continues until the Maestro receives a particular message from the
computer indicating that the Maestro’s USB drivers are installed correctly. After the Maestro gets this message,
the green LED will be on, but it will flicker briefly when there is USB activity. The control center application
constantly streams data from the Maestro, so when the control center is running and connected to the Maestro,
the green LED will flicker constantly.
• The red error/user LED usually indicates an error. The red LED turns on when an error occurs, and turns off
when the error flags have been cleared. See Section 4.b for more information about errors. The red LED can also
Pololu Maestro Servo Controller User's Guide © 2001–2014 Pololu Corporation
1. Overview Page 12 of 73