User Manual

Mini SSC offset: This parameter determines which servo numbers the device will respond to in the

Mini SSC protocol (see Section 5.e).

Timeout: This parameter specifies the duration before which a Serial timeout error will occur. This

error can be used as a safety measure to ensure that your servos and digital outputs go back to their

default states whenever the software sending commands to the Maestro stops working. The serial

timeout error will occur whenever no valid serial commands (or qualifying native USB commands)

are received within the specified timeout period. A timeout period of 0.00 disables the serial timeout

error. The resolution of this parameter is 0.01 s and the maximum value available is 655.35 s. The

native USB commands that qualify correspond to the following methods in the Usc class: setTarget ,

setSpeed , setAcceleration , setPwm , disablePWM , and clearErrors . Running the Maestro Control

Center will not prevent the serial timeout error from occurring, but setting targets in the Status tab or

playing a sequence will.

Never sleep (ignore USB suspend): By default, the Maestro’s processor will go to sleep and stop all

of its operations whenever it detects that it is only powered by USB (no VIN supply) and that the USB

has entered the Suspend State. However, this behavior can be disabled by checking the Never sleep

checkbox.

5.b. TTL Serial

The Maestro’s serial receive line, RX, can receive bytes when connected to a logic-level (0 to 4.0–5 V,

or “TTL”), non-inverted serial signal. The bytes sent to the Maestro on RX can be commands to the

Maestro or an arbitrary stream of data that the Maestro passes on to a computer via the USB port,

depending on which serial mode the Maestro is in (Section 5.a). The voltage on the RX pin should not

go below 0 V and should not exceed 5 V.

The Maestro provides logic-level (0 to 5 V) serial output on its serial transmit line, TX. The bytes sent

by the Maestro on TX can be responses to commands that request information or an arbitrary stream

of data that the Maestro is receiving from a computer via the USB port and passing on, depending

on which Serial Mode the Maestro is in. If you aren’t interested in receiving TTL serial bytes from the

Maestro, you can leave the TX line disconnected.

The serial interface is asynchronous, meaning that the sender and receiver each independently time

the serial bits. Asynchronous TTL serial is available as hardware modules called “UARTs” on many

microcontrollers. Asynchronous serial output can also be “bit-banged” by a standard digital output line

under software control.

The data format is 8 data bits, one stop bit, with no parity, which is often expressed as 8-N-1. The

diagram below depicts a typical asynchronous, non-inverted TTL serial byte:

5. Serial Interface Page 49 of 102