add lab resources

res/lab_2/SimplisticRampStepper Mac.c

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+// Simplistic Ramp Stepper program with millis function adapted for MacOS
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <windows.h>
+#include <math.h>
+#include <time.h>
+
+/* Only needed in Windows program to maintain compatibility with Arduino version of C/C++ */
+typedef enum { false, true } bool; 
+#define true 1
+#define false 0
+const bool FWDS = true;
+const bool BWDS = false;
+
+const long ticksPerSec = 1000; // ms on PC
+// on Arduino it is 1E6 for micros (for s/w) or 1.6E7 for 62.5 ns ticks (for h/w)
+
+void moveOneStep();
+void computeNewSpeed();
+long computeStepsToGo();
+void goToPosition(long newPosition);
+long millis(void);
+
+/* Note: we are using global variables ONLY to preserve compatibility with the Arduino program structure.
+   They should not normally be used in C or C++ programs as they make for a poor software design. */
+/* 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 */
+float maxSpeed;            /* Maximum speed in present movement (not nec. max permitted) */
+bool direction;             /* Direction of present movement: FWDS or BWDS */
+
+/* Global variables used in simplistic and Leib Ramp algorithms */
+volatile float p;   /* Step interval in clock ticks or microseconds */
+float ps;       /* Maximum step periods */
+float deltaP;      /* You'll be able to get rid of this later */
+
+/* Global variable used for noting previous time of a step in timed loop and for calculating speed and accel */
+long prevStepTime=0;
+long millisAtStart;
+float prevSpeed=0.0;
+
+/* Define permissible parameters for motor */
+// For testing on PC only, not for use in Arduino program: try movements in order of 50-100 steps
+float accelSteps=20; /* leave this as a variable as we may over-write it */
+const float minSpeed = 1.0;  // in steps/s
+const float maxPermissSpeed = 20.0;   // in steps/s
+const float maxAccel = 10.0;     // in steps/s^2
+
+int main()
+{
+    unsigned long currentMillis = millis();
+    prevStepTime = 0;
+    long positionToMoveTo;
+    while(true)
+    {
+        printf("Enter position to move to in profile (or 999 to terminate)\n");
+        scanf("%ld", &positionToMoveTo);
+        if (positionToMoveTo==999) break;
+        printf("        Time (s),  Speed (steps/s), Accel (steps/s^2),  Posit'n (steps), Step time (ticks)\n");
+
+        goToPosition(positionToMoveTo);
+
+        /* -------------------------------------------------------------- */
+        /* Start of pre-computation code - only executed once per profile */
+        
+        float maxInterval = ((float)ticksPerSec) / minSpeed;
+        ps = ((float)ticksPerSec) / maxPermissSpeed;
+        deltaP = (maxInterval - ps) / accelSteps;
+        stepsToGo = computeStepsToGo();
+        maxSpeed = maxPermissSpeed;
+        if (2 * accelSteps > stepsToGo)
+        {
+            accelSteps = (long)(stepsToGo / 2);
+        }
+
+        p = maxInterval;
+        
+        ps = ((float)ticksPerSec) / maxSpeed;
+        /* End of pre-computation code                                    */
+        /* -------------------------------------------------------------- */
+        millisAtStart = millis(); /* Needed only to tabulate speed vs. time */
+
+        /* Timed loop for stepping */
+        while(stepsToGo > 0)
+        {
+            currentMillis = millis();
+            if (currentMillis - prevStepTime >= p)
+            {
+               moveOneStep();
+               prevStepTime = currentMillis;
+               computeNewSpeed();
+            }
+        }
+    }
+    return 0;
+}
+
+/* Only needed for compatibility with Arduino program because millis() is not a native MacOS function */
+long millis(void)
+{
+    struct timespec _t; 
+    clock_gettime(CLOCK_REALTIME, &_t); 
+    return _t.tv_sec*1000 + lround(_t.tv_nsec/1e6); 
+}
+
+/* Move a single step.  If this were running on the Arduino we would holding pulse high for delayMicroSeconds */
+void moveOneStep()
+{
+  if (p != 0) /* p=0 is code for "don't make steps" */
+  {
+    // Print to screen instead of making a step
+    if (direction == FWDS)
+    {
+      currentPosition++;
+    }
+    else
+    {
+      currentPosition--;
+    }
+    
+    /* Instead of actually making step, print out parameters for current step */
+    float speed = (float)(ticksPerSec)/p;
+    float accel = (float)(ticksPerSec)*(speed-prevSpeed)/p;
+    printf("%16.3f, %16.3f,  %16.3f, %16ld, %16.3f\n", 0.001*(millis()-millisAtStart), speed, accel, currentPosition, p);
+    prevSpeed = speed;
+  }
+}
+
+/* Calcuate new value of step interval p based on constants defined in timed loop */
+void computeNewSpeed()
+{
+  stepsToGo = computeStepsToGo();
+
+  /* Start of on-the-fly step calculation code, executed once per step */
+  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) // Changed to make ramps even length
+  /* Speeding up */
+  {
+    p -= deltaP;
+  }
+  else if (stepsToGo <= accelSteps)
+  /* Slowing down */
+  {
+    p += deltaP;
+  }
+  /* else p is unchanged: running at constant speed */
+
+  /* End of on-the-fly step calculation code */
+}
+
+/* Work out how far the stepper motor still needs to move */
+long computeStepsToGo()
+{
+  if (direction == FWDS)
+  {
+    return targetPosition - currentPosition;
+  }
+  else
+  {
+    return currentPosition - targetPosition;
+  }
+}
+
+/* Set the target position and determine direction of intended movement */
+void goToPosition(long newPosition)
+{
+  targetPosition = newPosition;
+  if (targetPosition - currentPosition > 0)
+  {
+    direction = FWDS;
+  }
+  else
+  {
+    direction = BWDS;
+  }
+}
+