add lab resources

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/* Stepper motor demonstration program written by Arthur Jones,
4 November 2018. Implements a simplistic and ineffective ramping
algorithm but provides framework for implementation of LeibRamp
algorithm described by Aryeh Eiderman, http://hwml.com/LeibRamp.pdf
Makes use of background work and some aspects of code developed
by Choaran Wang, 2017-18. This in turn incorporates some ideas
used in the AccelStepper library:
https://www.airspayce.com/mikem/arduino/AccelStepper/
Serial input aspects are based closely upon:
http://forum.arduino.cc/index.php?topic=396450
Example 4 - Receive a number as text and convert it to an int
Modified to read a long */
// #define USEINTERRUPTS
const int stepPin = 13;
const int dirPin = 9;
const bool FWDS = true;
const bool BWDS = false;
#ifdef USEINTERRUPTS
const long ticksPerSec = 16000000; // Clock speed of Arduino
#else
const long ticksPerSec = 1000000; // microseconds in this case
#endif
/* Define permissible parameters for motor */
// For testing by watching LED: try movements in order of 100 steps
//float accelSteps=20; /* leave this as a variable as we may over-write it */
//const float minSpeed = 2.0;
//const float maxPermissSpeed = 20.0;
//const float maxAccel = 10.0;
//const long stepLengthMus = 10000;
// For lab testing with real motor: try movements in the order of 3000 steps
float accelSteps=1000; /* leave this as a variable as we may over-write it */
const float minSpeed=10.0;
const float maxPermissSpeed=1000.0;
const float maxAccel=500.0;
const long stepLengthMus=100;
/* Intervals in milliseconds for user-defined timed loops */
const long printInterval = 1000;
/* Global variables used for loop timing */
unsigned long prevMillisPrint = 0; /* stores last time values were printed */
/* Global variables used in serial input */
enum {numChars = 32};
char receivedChars[numChars]; /* an array to store the received data */
long dataNumber = 0; /* Value read from serial monitor input */
boolean newData = false;
/* Global variables relating to stepper motor position counting etc. */
long stepsToGo; /* Number of steps left to make in present movement */
long targetPosition; /* Intended destination of motor for given movement */
volatile long currentPosition = 0; /* Position in steps of motor relative to startup position */
double maxSpeed; /* Maximum speed in present movement (not nec. max permitted) */
bool direction; /* Direction of present movement: FWDS or BWDS */
volatile float p; /* Step interval in clock ticks or microseconds */
float p1, ps; /* Minimum and maximum step periods */
double deltaP; /* You'll be able to get rid of this later */
double R; /* Multiplying constant used in Eiderman's algorithm */
/* Global variable used for noting previous time of a step in timed loop */
long prevStepTime;
void setup()
{
long stepsToGo = 0;
currentPosition = 0;
goToPosition(dataNumber);
pinMode(stepPin, OUTPUT);
pinMode(dirPin, OUTPUT);
Serial.begin(9600);
Serial.println("Enter target position in number of steps and hit return");
// If USEINTERRUPTS is defined at the start of the program this section will be used
#ifdef USEINTERRUPTS
cli();
TCCR1A = 0; // No output compare
TCCR1B = 0;
TCCR1B |= (1 << WGM12); //CTC mode
OCR1A = 0; // Set to zero for the present time: catch this to switch interrupt off
TCCR1B |= (1 << CS12); // 256 prescaler: overwritten in ISR
TIMSK1 |= (1 << OCIE1A); //enable timer compare interrupt
sei();
#else //
// Use built-in Arduino function micros() to get the time in microseconds since the program started running.
// Documentation: https://www.arduino.cc/reference/en/language/functions/time/micros/
prevStepTime = micros(); // This is a built-in Arduino function.
#endif
}
void loop()
{
unsigned long currentMillis = millis();
unsigned long currentMicros;
recvWithEndMarker();
stepsToGo = computeStepsToGo();
if (convertNewNumber())
{
/* Only get to this stage if there was new data to convert */
if (stepsToGo <= 0)
{
/* Only get to this stage if not busy, otherwise will have thrown away input */
goToPosition(dataNumber);
/* Delete these and replace with Leib Ramp formulae */
double maxInterval = ((double)ticksPerSec) / minSpeed;
ps = ((double)ticksPerSec) / maxPermissSpeed;
deltaP = (maxInterval - ps) / accelSteps;
/* End of section requiring redefinitions */
stepsToGo = computeStepsToGo();
maxSpeed = maxPermissSpeed;
if (2 * accelSteps > stepsToGo)
{
/* Definiiton of S where ther is no constant speed period - check it is still applicable */
accelSteps = (long)(stepsToGo / 2);
/* Need to redefine maxSpeed here as we never fully accelerate */
}
/* Will need to over-write these with correct initial value of p and p1, along with R */
p = maxInterval;
p1 = (double)ticksPerSec/minSpeed;
/* End of section requiring redefinitions */
ps = ((double)ticksPerSec) / maxSpeed; /* Eq 7 in paper: this is OK */
#ifdef USEINTERRUPTS
if (p != 0)
{
// Re-enable interrupts if non-zero steps
TIMSK1 |= (1 << OCIE1A);
}
#endif
}
}
#ifndef USEINTERRUPTS
/* Timed loop for stepping, and associated coding */
currentMicros = micros();
if (currentMicros - prevStepTime >= p)
{
moveOneStep();
prevStepTime = currentMicros;
computeNewSpeed();
}
#endif
/* Timed loop for printing */
if (currentMillis - prevMillisPrint >= printInterval)
{
/* Save the last time output was printed */
prevMillisPrint = currentMillis;
printLoop();
}
}
void moveOneStep()
/* Move a single step, holding pulse high for delayMicroSeconds */
{
if (p != 0) /* p=0 is code for "don't make steps" */
{
digitalWrite(stepPin, HIGH);
if (direction == FWDS)
{
/* Is something missing here? */
currentPosition++;
}
else
{
/* Is something missing here? */
currentPosition--;
}
delayMicroseconds(stepLengthMus);
digitalWrite(stepPin, LOW);
}
}
void computeNewSpeed()
/* Calcuate new value of step interval p based on constants defined in loop() */
{
/* You may need to declare some temporary variables for this function... */
stepsToGo = computeStepsToGo();
if (stepsToGo == 0)
{
p = 0; // Not actually a zero step interval, used to switch stepping off
return;
}
else if (stepsToGo > accelSteps && (long)p > long(ps))
/* Speeding up */
{
/* Delete this simplistic change to p and replace with something else */
p -= deltaP;
}
else if (stepsToGo <= accelSteps)
/* Slowing down */
{
/* Delete this simplistic change to p and replace with something else */
p += deltaP;
}
else
/* Running at constant speed */
{
/* For simpplistic approach, p=p so do nothing to it.
But you will need to put something here for Leib ramp ... */
}
/* Update to step interval based on Leib ramp algorithm, using temporary variables */
/* Need to ensure rounding error does not cause drift outside acceptable interval range:
replace p with relevant bound if it strays outside - so need to write some code here */
}
long computeStepsToGo()
/* Work out how far the stepper motor still needs to move */
{
if (direction == FWDS)
{
return targetPosition - currentPosition;
}
else
{
return currentPosition - targetPosition;
}
}
void goToPosition(long newPosition)
/* Set the target position and determine direction of intended movement */
{
targetPosition = newPosition;
if (targetPosition - currentPosition > 0)
{
direction = FWDS;
}
else
{
direction = BWDS;
}
}
void recvWithEndMarker()
/* Receive data from serial port finishing with "newline" character.
Based on http://forum.arduino.cc/index.php?topic=396450 Example 4 */
{
static byte ndx = 0;
char endMarker = '\n';
char rc;
if (Serial.available() > 0)
{
rc = Serial.read();
if (rc != endMarker)
{
receivedChars[ndx] = rc;
ndx++;
if (ndx >= numChars)
{
ndx = numChars - 1;
}
}
else
{
receivedChars[ndx] = '\0'; // terminate the string
ndx = 0;
newData = true;
}
}
}
bool convertNewNumber()
/* Converts character string to long integer only if there are new
data to convert, otherwise returns false */
{
if (newData)
{
dataNumber = 0.0; // new for this version
dataNumber = atol(receivedChars); // new for this version
newData = false;
return true;
}
else
{
return false;
}
}
void printLoop()
/* Print current position of stepper using timed loop */
{
/* Sample all counters one after the other to avoid delay-related offsets */
Serial.print("Current position = ");
Serial.print(currentPosition);
Serial.print("\r\n");
}
#ifdef USEINTERRUPTS
ISR(TIMER1_COMPA_vect)
/* Interrupt service routine which essentially just calls moveOneStep and computeNewSpeed.
However, it also changes the prescale value on-the-fly so that the full range of possible
step rates can be exploited, from around 0.25 Hz upwards, limited by step pulse width. */
{
if (p == 0)
{
// Disable interrupt to avoid endless calling of interrupt if not needed
TIMSK1 &= !(1 << OCIE1A);
}
moveOneStep();
/* Adapt prescaler to keep OCR1A as large as possible within acceptable range */
if (p < 65536)
{
// Prescaler 1
OCR1A = (long)p - 1;
TCCR1B = (TCCR1B & 0xF8) | 0x01;
}
else if (p < 524288)
{
// Prescaler 8
OCR1A = ((long)p >> 3) - 1;
TCCR1B = (TCCR1B & 0xF8) | 0x02;
}
else if (p < 4194304)
{
// Prescaler 64
OCR1A = ((long)p >> 6) - 1;
TCCR1B = (TCCR1B & 0xF8) | 0x03;
}
else if (p < 16777216)
{
// Prescaler 256
OCR1A = ((long)p >> 8) - 1;
TCCR1B = (TCCR1B & 0xF8) | 0x04;
}
else
{
// Prescaler 1024
OCR1A = ((long)p >> 10) - 1;
TCCR1B = (TCCR1B & 0xF8) | 0x05;
}
computeNewSpeed();
}
#endif