Servo Motor

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This library allows you to control RC (hobby) servo motors. Servos have integrated gears and a shaft that can be precisely controlled. Standard servos allow the shaft to be positioned at various angles, usually between 0 and 180 degrees. Continuous rotation servos allow the rotation of the shaft to be set to various speeds. To use, specify #include <servo.h>. You will need to create Servo myservo or a similar instance.

attach

Description

Initializes and attaches the Servo output to a pin.

Syntax

servo.attach(int pin)servo.attach(int pin, int min, int max)

Parameters

pin: The number of the pin to which the servo is attached
min: The pulse width, in microseconds, corresponding to the minimum (0-degree) angle on the servo (defaults to 544)
max: The pulse width, in microseconds, corresponding to the maximum (180-degree) angle on the servo (defaults to 2400).

Returns

None

write

Description

Writes a value to the servo to set the shaft angle, controlling the shaft accordingly. The pulse for moving the shaft to that orientation is output from the pin specified in attach.

Syntax

servo.write(int angle)

Parameters

angle: The value of the angle to write to the servo, from 0 to 180

Returns

None

writeMicroseconds

Description

Writes a value in microseconds (uS) to the servo, controlling the shaft accordingly. On a standard servo, this will set the angle of the shaft. On standard servos a parameter value of 1000 is fully counter-clockwise, 2000 is fully clockwise, and 1500 is in the middle.

Syntax

servo.writeMicroseconds(int us)

Parameters

us: The value of the pulse width in microseconds.

Returns

None

read

Description

Read the current angle of the servo.

Syntax

int servo.read()

Parameters

None

Returns

pulse width [us]

attached

Description

Check whether the servo variable is attached to a pin.

Syntax

bool servo.attached()

Parameters

None

Returns

True if the servo is attached to pin; false otherwise.

detach

Description

Detach the servo variable from its pin. This stops the pulse width output from the specified pin.

Syntax

servo.detach()

Parameters

None

Returns

None

This sample uses pin 9 as the servo motor output pin, enabling the motor to be run by pushing a switch on the GR-PEACH board.

#include <Arduino.h>
#include <servo.h> 
 
#define INTERVAL 50
char g_inc = 10;
unsigned char g_pos = 0;
Servo servo0;
 
void setup() 
{ 
    pinMode(PIN_SW, INPUT);
    servo0.attach(9);
    servo0.write(g_pos);
} 
 
void loop() {
    if(digitalRead(PIN_SW) == LOW){
        g_pos = g_pos + g_inc;
        servo0.write(g_pos);
        if(g_pos == 180 | g_pos == 0){
            g_inc = g_inc * -1;
        }
     
    }
    delay(INTERVAL);
}