I would like some help understanding a program I am using. I got this code from an instructable for little arm robotic arm. The code works really well using the littlearm app. I am fairly new to Arduino and code so I'm having trouble understanding how this program works. I understand how the servos are attached and working but I am totally lost on how the app is telling the Arduino how to move the servos. Could someone please explain how this code works and what is going. For example I get how a potentiometer controls a servo and the code used for controlling servos shows that( val = map(val, 0, 1023, 0, 179); ). But in the code in question does not have a clear path from the bluetooth to the arduino. So does send numbers or letters to tell the servos where to move or what??? thank you in advance
Here is the CODE
#include <Servo.h> //arduino library
#include <math.h> //standard c library
#define PI 3.141
Servo baseServo;
Servo shoulderServo;
Servo elbowServo;
Servo gripperServo;
int command;
struct jointAngle{
int base;
int shoulder;
int elbow;
};
int desiredGrip;
int gripperPos;
int desiredDelay;
int servoSpeed = 15;
int ready = 0;
struct jointAngle desiredAngle; //desired angles of the servos
//+++++++++++++++FUNCTION DECLARATIONS+++++++++++++++++++++++++++
int servoParallelControl (int thePos, Servo theServo );
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
void setup()
{
Serial.begin(9600);
baseServo.attach(9); // attaches the servo on pin 9 to the servo object
shoulderServo.attach(10);
elbowServo.attach(11);
gripperServo.attach(6);
Serial.setTimeout(50); //ensures the the arduino does not read serial for too long
Serial.println("started");
baseServo.write(90); //intial positions of servos111wASZ
shoulderServo.write(150);
elbowServo.write(110);
ready = 0;
}
//primary arduino loop
void loop()
{
if (Serial.available()){
ready = 1;
desiredAngle.base = Serial.parseInt();
desiredAngle.shoulder = Serial.parseInt();
desiredAngle.elbow = Serial.parseInt();
desiredGrip = Serial.parseInt();
desiredDelay = Serial.parseInt();
if(Serial.read() == '\n'){ // if the last byte is 'd' then stop reading and execute command 'd' stands for 'done'
Serial.flush(); //clear all other commands piled in the buffer
//send completion of the command
Serial.print('d');
}
}
int status1 = 0;
int status2 = 0;
int status3 = 0;
int status4 = 0;
int done = 0 ;
while(done == 0 && ready == 1){
//move the servo to the desired position
status1 = servoParallelControl(desiredAngle.base, baseServo, desiredDelay);
status2 = servoParallelControl(desiredAngle.shoulder, shoulderServo, desiredDelay);
status3 = servoParallelControl(desiredAngle.elbow, elbowServo, desiredDelay);
status4 = servoParallelControl(desiredGrip, gripperServo, desiredDelay);
if (status1 == 1 & status2 == 1 & status3 == 1 & status4 == 1){
done = 1;
}
}// end of while
}
//++++++++++++++++++++++++++++++FUNCTION DEFITNITIONS++++++++++++++++++++++++++++++++++++++++++
int servoParallelControl (int thePos, Servo theServo, int theSpeed ){
int startPos = theServo.read(); //read the current pos
int newPos = startPos;
//int theSpeed = speed;
//define where the pos is with respect to the command
// if the current position is less that the actual move up
if (startPos < (thePos-5)){
newPos = newPos + 1;
theServo.write(newPos);
delay(theSpeed);
return 0;
}
else if (newPos > (thePos + 5)){
newPos = newPos - 1;
theServo.write(newPos);
delay(theSpeed);
return 0;
}
else {
return 1;
}
}