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Servo Motor

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Servo Motor

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 a 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

Sample Program

This sample uses pin 9 as the servo motor output pin, enabling the motor to be run by pushing a switch on the GR-LYCHEE 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_SW0, INPUT);
    servo0.attach(9);
    servo0.write(g_pos);
}
    
void loop() {
    if(digitalRead(PIN_SW0) == 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);
}