Hi,
I posted this code when I had a do..while loop problem, which is now solved.
Now the real enigma...
The defaul timing loop for my stepper driver should give 21.3 Hz (this gives correct rate for telescope to track stars), but I've found in practice you have to be able to trim this rate slightly. So I've set up some control with a pot on analog pin A0 to trim +/- 10% when the pot is away from its mid point (with +/- 500 'deadzone').
I have checked the pot output and the maths:
//trimming control
trim = analogRead(A0);
if (trim<400){ra = raset-((raset0.1)((-0.0025trim)+1)); //raset-((raset0.1)((-0.0025trim)+1))
}
if (trim>600){ra = raset+((raset0.1)((0.002364trim)-1.4151)); //raset+((raset0.1)((0.0023585trim)-1.4151))
}
if (trim<=600 && trim >=400){ra=raset;}
The timer pulse should give between 19 and 23 Hz with a default of 21.4 Hz
What I get is: 70Hz default !!why??!!
And when pot read = 0, 103Hz; and when pot read = 1023, 371Hz !!
This is crazy. Is there something obviously wrong with my timing loops and the delayMicroseconds ?? Why do I get 70Hz when 1/0.046900 = 21.3 ??? How can the loop run faster than the programmed delay?
Thanks for any help.
Theo
P.S. I know the control program still has problems, but my concern here is why the timing is off.
Here's the whole thing:
//scope
int trim = 0; //1024 = 5v
long ra = 46895;
long raset =46895;
float acc = 1;
float dacc = 1;
int pulselength = 5;
float accrate = 0.05;
int npin = 4;
int spin = 5;
int epin = 6;
int wpin = 7;
//int gnpin = 4;
//int gspin = 5;
//int gepin = 6;
//int gwpin = 7;
int rastep = 8;
int radir = 9;
int decstep = 10;
int decdir = 11;
int raenable = 12;
int decenable = 13;
//tracking rate = 21.317hz = 0.0469 sec
// with 5us pulse 1x RA = 46895us
void setup() {
//Serial.begin(9600);
//N
//pinMode(0,INPUT); //will be used for guide inputs when not on serial
//S
//pinMode(1,INPUT);
//E
//pinMode(2,INPUT);
//W
//pinMode(3,INPUT);
// guide N
pinMode(4,INPUT);
//S
pinMode(5,INPUT);
//E
pinMode(6,INPUT);
//W
pinMode(7,INPUT);
//step RA
pinMode(8,OUTPUT);
//dir RA
pinMode(9,OUTPUT);
//step dec
pinMode(10,OUTPUT);
//dir dec
pinMode(11,OUTPUT);
//enable ra
pinMode(12,OUTPUT);
//enable dec
pinMode(13,OUTPUT);
digitalWrite(radir, HIGH); //set fwd on RA
digitalWrite(raenable, HIGH); //enable ra
digitalWrite(decenable, HIGH); //enable dec
}
//timing loop
void loop() {
//Serial.print(trim);
//Serial.println();
//Serial.print(" ; ");
//Serial.print(ra);
//Serial.print(" ; ");
//Serial.print(acc);
//Serial.print(" ; ");
//Serial.print(1/(ra/acc * 1E-06));
//Serial.print(digitalRead(wpin));
//Serial.print(digitalRead(epin));
//Serial.print(digitalRead(spin));
//Serial.print(digitalRead(npin));
// Serial.println();
debug print
//trimming control
trim = analogRead(A0);
if (trim<400){ra = raset-((raset*0.1)*((-0.0025*trim)+1)); //raset-((raset*0.1)*((-0.0025*trim)+1))
}
if (trim>600){ra = raset+((raset*0.1)*((0.002364*trim)-1.4151)); //raset+((raset*0.1)*((0.0023585*trim)-1.4151))
}
if (trim<=600 && trim >=400){ra=raset;}
while (digitalRead(wpin)==HIGH)
{
read pot on pin A0 and trim 'ra' value +/- 10%
// RA slew w
acc = acc + accrate;
if (acc > 500) {acc = 500;}
digitalWrite(radir, HIGH);
digitalWrite(rastep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(rastep, LOW);
delayMicroseconds(ra / acc);
}
while (digitalRead(epin)==HIGH)
{
// RA slew e
acc = acc + accrate;
if (acc > 500) {acc = 500;}
digitalWrite(radir, LOW); //reverse direction
digitalWrite(rastep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(rastep, LOW);
delayMicroseconds(ra / acc);
}
while (digitalRead(npin)==HIGH)
{
//dec slew n
dacc = dacc + accrate;
if (dacc > 500) {dacc = 500;}
digitalWrite(decdir, HIGH);
digitalWrite(decstep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(decstep, LOW);
delayMicroseconds(ra / dacc);
}
while (digitalRead(spin)==HIGH)
{
//dec slew s
dacc = dacc + accrate;
if (dacc > 500) {dacc = 500;}
digitalWrite(decdir, LOW);
digitalWrite(decstep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(decstep, LOW);
delayMicroseconds(ra / dacc);
}
if telescope slew buttons pressed then move scope with accelerating speed up to 500x 'raset'
//dec pulse if dacc>1
if (dacc > 1) {dacc=dacc-(dacc/100);
digital Write(decstep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(decstep, LOW);
delayMicroseconds(ra / dacc); //range of dacc=1 to 500
}
else
{dacc = 1;
if (acc > 1) //bring down slew rate if nothing pressed
{acc = acc -(acc/100); }
else
{acc=1; }
if buttons not pressed, decelerate to normal speed
// RA pulse when no other inputs
digitalWrite(rastep, HIGH);
delayMicroseconds(pulselength);
digitalWrite(rastep, LOW);
delayMicroseconds(ra / acc); //range of acc=1 to 500
}//end ra else
} //end loop
normal speed stepping when nothing pressed, should be 21.3 hz but actually gives 70hz?
