Freenove Ultimate Starter Kit, Руководство пользователя

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163 Chapter 15 Servo █ www.freenove.com
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Code
In this project, we make the servo rotate from 0 degrees to 180 degrees, and then from 180 degrees to 0
degrees.
C Code 15.1.1 Sweep
First observe the project result, and then analyze the code.
1.
Use cd command to enter 15.1.1_Sweep directory of C code.
cd ~/Freenove_Ultimate_Starter_Kit_for_Raspberry_Pi/Code/C_Code/15.1.1_Sweep
2. Use following command to compile "Sweep.c" and generate executable file "Sweep".
gcc Sweep.c -o Sweep -lwiringPi
3. Run the generated file "Sweep".
sudo ./Sweep
After the program is executed, the servo will rotate from 0 degrees to 180 degrees, and then from 180 degrees
to 0 degrees, circularly.
The following is the program code:
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#include <wiringPi.h>
#include <softPwm.h>
#include <stdio.h>
#define OFFSET_MS 3 //Define the unit of servo pulse offset: 0.1ms
#define SERVO_MIN_MS 5+OFFSET_MS //define the pulse duration for minimum angle of
servo
#define SERVO_MAX_MS 25+OFFSET_MS //define the pulse duration for maximum angle of
servo
#define servoPin 1 //define the GPIO number connected to servo
long map ( long value , long fromLow , long fromHigh , long toLow , long toHigh ){
return ( toHigh - toLow )*( value - fromLow ) / ( fromHigh - fromLow ) + toLow ;
}
void servoInit ( int pin ){ //initialization function for servo PWM pin
softPwmCreate ( pin , 0 , 200 );
}
void servoWrite ( int pin , int angle ){ //Specif a certain rotation angle (0-180) for the
servo
if ( angle > 180 )
angle = 180 ;
if ( angle < 0 )
angle = 0 ;
softPwmWrite ( pin , map ( angle , 0 , 180 , SERVO_MIN_MS , SERVO_MAX_MS ));
}
void servoWriteMS ( int pin , int ms ){ //specific the unit for pulse(5-25ms) with
specific duration output by servo pin: 0.1ms
if ( ms > SERVO_MAX_MS )
ms = SERVO_MAX_MS ;