Keyestudio ARDUINO maker learning kit, Manual

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Project 28: 9g servo control
Introduction
Servomotor is a position control rotary actuator. It mainly consists of housing, circuit board,
core-less motor, gear and position sensor. The receiver or MCU outputs a signal to the servomotor.
The motor has a built-in reference circuit that gives out reference signal, cycle of 20ms and width
of 1.5ms. The motor compares the acquired DC bias voltage to the voltage of the potentiometer
and outputs a voltage difference. The IC on the circuit board will decide the rotate direction
accordingly and drive the core-less motor. The gear then pass the force to the shaft. The sensor
will determine if it has reached the commanded position according to the feedback signal.
Servomotors are used in control systems that requires to have and maintain different angles. When
the motor speed is definite, the gear will cause the potentiometer to rotate. When the voltage
difference reduces to zero, the motor stops. Normally, the rotation angle range is among 0-180
degrees.
Servomotor comes with many specifications. But all of them have three connection wires,
distinguished by brown, red, orange colors(different brand may have different color). Brown one
is for GND, red one for power positive, orange one for signal
line.