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ANALOG VERSUS DIGITAL SERVOS 257

Figure 23- 7 A standard male header,
versus one that uses long pins on both ends.
You want the long- pin version to connect
Standard header Long header your RC servos to a solderless breadboard.

ward. These polarized connectors are fairly expensive, and most folks instead use 0.100″
“snap- off” pin headers, common in electronics. You can buy these things at any local or
online electronic parts outlet, and they’re pennies a piece.
For a servo, snap off three pins, then solder them to your circuit board. Since these header
pins lack any kind of polarization, it’s possible to plug servos in backward. You’ll want to mark
how the servo connector should attach to the header, to help prevent this.
Fortunately, reversing the connector probably won’t cause any damage to either the servo
or the electronics, since reversing the connector merely exchanges the signal and ground
wires. This is not true of the “old- style” Airtronics connector: if you reverse this connector,
the signal and DC power (+V) lines are swapped. In this case, both servo and control electron-
ics can be irreparably damaged.

Damage can and will occur if you wire up the pin headers wrong. Mix up the Ground and +V
pins, and within seconds your servo will be permanently ruined— perhaps even die a violent
death. I’ve seen the bottoms of servos blown out when they have been connected backward in a
circuit.

You can also use headers with solderless breadboards to easily and quickly connect servo
motors to the rest of your robot electronics, but it works best if you use the kind of header
where the pins are long on both ends (Figure 23- 7).

Analog versus Digital Servos

The most common, and most affordable, R/C servos are analog, meaning their control elec-
tronics uses traditional circuitry for controlling the motor. Digital servos use onboard micro-
controllers to enhance their operation.
Among the added features of digital servos include higher- power and programmable
behavior. With the proper external programmer (available separately, and at extra cost) it’s
possible to control the maximum speed of the servo, for example, or make the servo always
start from power- up in a specific position.
Except for higher torques, from an applications standpoint there is little difference between
analog and digital servos. You control both the same way. However the higher torque of a

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