Pololu Maestro User Manual
Page 11
Mini Maestro 12 power pins.
Mini Maestro 18 power pins.
Mini Maestro 24 power pins.
The processor and the servos can have separate power supplies.
Processor power must come either from USB or from an external
5–16V power supply connected to the VIN and GND inputs on the
left side of the board. It is safe to have an external power supply
connected at the same time that USB is connected; in that case the
processor will be powered from the external supply. Note that if the
external supply falls below 5 V, correct operation is not guaranteed,
even if USB is also connected.
Servo power connections are provided in the lower right corner of
the Mini Maestro board. On the Mini Maestro 18 and 24, you can
make servo power connections via a 2-pin terminal block or a 2-pin
0.1″ header; the Mini Maestro 12 only has a 2-pin 0.1″ header for
connecting servo power. Servo power is passed directly to the
servos without going through a regulator, so the only restrictions on
your servo power supply are that it must be within the operating
range of your servos and provide enough current for your
application. Please consult the datasheets for your servos to
determine an appropriate servo power source, and note that a
ballpark figure for the current draw of an average straining servo is
1 A.
You can power the Maestro’s processor and servos from a single
power supply by connecting the positive power line to both VIN and
the servo power ports (only one ground connection is needed
because all ground pins on the board are connected). The
recommended way to do this is to connect your power supply to the
dedicated servo power pins in the corner of the board and use the
included blue shorting block to connect the pins labeled
“VSRV=VIN”.
The 5V (out) power output allows you to power your own 5V
devices from the 150mA on-board regulator or directly from USB.
The on-board regulator is used whenever VIN is powered; in this
case, since the Maestro requires 50 mA, there is about 50 mA
available to power other devices.
The signal lines (0, 1, 2, …) are used for sending pulses to servos,
controlling digital outputs, and measuring voltages. The total
current limit (in or out) for these pins is 150 mA, but when using the
on-board regulator the current out is limited to 50 mA (see above.)
The RX line is used to receive non-inverted TTL (0–5 V) serial bytes, such as those from microcontroller UARTs.
These bytes can either be serial commands for the Maestro, arbitrary bytes to send back to the computer via the USB
connection, or both. For more information about the Maestro’s serial interface, see
. Note that the Maestro
will probably be able to receive 3.3V TTL serial bytes, but it is not guaranteed to read 3.3V as high on the RX pin, so
you should boost 3.3V TTL serial signals to above 4V if you want to ensure reliable operation.
The TX line transmits non-inverted TTL (0–5 V) serial bytes. These bytes are either generated by the Mini Maestro
itself (as responses to serial commands or arbitrary bytes sent from the computer via the USB connection), or they
come from the TXIN line.
Pololu Maestro Servo Controller User's Guide
© 2001–2014 Pololu Corporation
1. Overview
Page 11 of 73