Thank you for taking the time to explain all of this. It's really helpful and now I understand it a bit more.
currently my motor is 1 pulse per rotation for testing, it's just a thick band of tape on the shaft and 50% of it is painted silver and the other 50% of it is black so the optical ir reflective sensor can read it I hope that the resolution is not too low. I've been playing with the PID tuning settings for a while and it seems that most of my issues are leading back to the way it's getting the rpm.
the reason I didn't post all of my code it because it's messed up and I'm embarrassed.. but here it is, it might be broken in it's current state.
/******************************************************************
* PID Simple Example (Augmented with Processing.org Communication)
* Version 0.3
* by Brett Beauregard
* License: Creative-Commons Attribution Share-Alike
* April 2011
******************************************************************/
#include <PID_v1.h>
//Define Variables we'll be connecting to
double Setpoint, Input, Output;
int setpointPin=0, inputPin=1, outputPin=13;
//Specify the links and initial tuning parameters
PID myPID(&Input, &Output, &Setpoint,10,40,0, DIRECT);
volatile byte rpmcount;
unsigned int rpm;
unsigned long timeold;
unsigned long serialTime; //this will help us know when to talk with processing
void setup()
{
//initialize the serial link with processing
Serial.begin(9600);
attachInterrupt(0, rpm_fun, RISING);
rpmcount = 0;
rpm = 0;
timeold = 0;
//initialize the variables we're linked to
Input = (rpm);
Setpoint = analogRead(setpointPin);
//turn the PID on
myPID.SetMode(AUTOMATIC);
}
void loop()
{
//send-receive with processing if it's time
if(millis()>serialTime)
{
SerialReceive();
SerialSend();
serialTime+=500;
}
if (rpmcount >= 20) {
//Update RPM every 20 counts, increase this for better RPM resolution,
//decrease for faster update
rpm = 30*1000/(millis() - timeold)*rpmcount;
timeold = millis();
rpmcount = 0;
//pid-related code
Setpoint = analogRead(setpointPin);
myPID.Compute();
analogWrite(outputPin,Output);
}
}
void rpm_fun()
{
rpmcount++;
//Each rotation, this interrupt function is run twice
}
/********************************************
* Serial Communication functions / helpers
********************************************/
union { // This Data structure lets
byte asBytes[24]; // us take the byte array
float asFloat[6]; // sent from processing and
} // easily convert it to a
foo; // float array
// getting float values from processing into the arduino
// was no small task. the way this program does it is
// as follows:
// * a float takes up 4 bytes. in processing, convert
// the array of floats we want to send, into an array
// of bytes.
// * send the bytes to the arduino
// * use a data structure known as a union to convert
// the array of bytes back into an array of floats
// the bytes coming from the arduino follow the following
// format:
// 0: 0=Manual, 1=Auto, else = ? error ?
// 1: 0=Direct, 1=Reverse, else = ? error ?
// 2-5: float setpoint
// 6-9: float input
// 10-13: float output
// 14-17: float P_Param
// 18-21: float I_Param
// 22-245: float D_Param
void SerialReceive()
{
// read the bytes sent from Processing
int index=0;
byte Auto_Man = -1;
byte Direct_Reverse = -1;
while(Serial.available()&&index<26)
{
if(index==0) Auto_Man = Serial.read();
else if(index==1) Direct_Reverse = Serial.read();
else foo.asBytes[index-2] = Serial.read();
index++;
}
// if the information we got was in the correct format,
// read it into the system
if(index==26 && (Auto_Man==0 || Auto_Man==1)&& (Direct_Reverse==0 || Direct_Reverse==1))
{
Setpoint=double(foo.asFloat[0]);
//Input=double(foo.asFloat[1]); // * the user has the ability to send the
// value of "Input" in most cases (as
// in this one) this is not needed.
if(Auto_Man==0) // * only change the output if we are in
{ // manual mode. otherwise we'll get an
Output=double(foo.asFloat[2]); // output blip, then the controller will
} // overwrite.
double p, i, d; // * read in and set the controller tunings
p = double(foo.asFloat[3]); //
i = double(foo.asFloat[4]); //
d = double(foo.asFloat[5]); //
myPID.SetTunings(p, i, d); //
if(Auto_Man==0) myPID.SetMode(MANUAL);// * set the controller mode
else myPID.SetMode(AUTOMATIC); //
if(Direct_Reverse==0) myPID.SetControllerDirection(DIRECT);// * set the controller Direction
else myPID.SetControllerDirection(REVERSE); //
}
Serial.flush(); // * clear any random data from the serial buffer
}
// unlike our tiny microprocessor, the processing ap
// has no problem converting strings into floats, so
// we can just send strings. much easier than getting
// floats from processing to here no?
void SerialSend()
{
Serial.print("PID ");
Serial.print(Setpoint);
Serial.print(" ");
Serial.print(Input);
Serial.print(" ");
Serial.print(Output);
Serial.print(" ");
Serial.print(myPID.GetKp());
Serial.print(" ");
Serial.print(myPID.GetKi());
Serial.print(" ");
Serial.print(myPID.GetKd());
Serial.print(" ");
if(myPID.GetMode()==AUTOMATIC) Serial.print("Automatic");
else Serial.print("Manual");
Serial.print(" ");
if(myPID.GetDirection()==DIRECT) Serial.println("Direct");
else Serial.println("Reverse");
}
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. For starters, you're never updating Input within loop().