X12: initial cut at support for the X12.17 driver.

SwitecX12.cpp

@@ -0,0 +1,156 @@
+/*
+ *  SwitecX12 Arduino Library
+ *  Guy Carpenter, Clearwater Software - 2017
+ *
+ *  Licensed under the BSD2 license, see license.txt for details.
+ *
+ *  All text above must be included in any redistribution.
+ */
+
+#include <Arduino.h>
+#include "SwitecX12.h"
+
+// This table defines the acceleration curve.
+// 1st value is the speed step, 2nd value is delay in microseconds
+// 1st value in each row must be > 1st value in subsequent row
+// 1st value in last row should be == maxVel, must be <= maxVel
+static unsigned short defaultAccelTable[][2] = {
+  {   20, 800},
+  {   50, 400},
+  {  100, 200},
+  {  150, 150},
+  {  300, 90}
+};
+
+const int stepPulseMicrosec = 1;
+const int resetStepMicrosec = 300;
+#define DEFAULT_ACCEL_TABLE_SIZE (sizeof(defaultAccelTable)/sizeof(*defaultAccelTable))
+
+SwitecX12::SwitecX12(unsigned int steps, unsigned char pinStep, unsigned char pinDir)
+{
+  this->steps = steps;
+  this->pinStep = pinStep;
+  this->pinDir = pinDir;
+  pinMode(pinStep, OUTPUT);
+  pinMode(pinDir, OUTPUT);
+  digitalWrite(pinStep, LOW);
+  digitalWrite(pinDir, LOW);
+  pinMode(13, OUTPUT);
+
+  dir = 0;
+  vel = 0;
+  stopped = true;
+  currentStep = 0;
+  targetStep = 0;
+
+  accelTable = defaultAccelTable;
+  maxVel = defaultAccelTable[DEFAULT_ACCEL_TABLE_SIZE-1][0]; // last value in table.
+}
+
+void SwitecX12::step(int dir)
+{
+  digitalWrite(pinDir, dir > 0 ? LOW : HIGH);
+  digitalWrite(13, vel == maxVel ? HIGH : LOW);
+  digitalWrite(pinStep, HIGH);
+  delayMicroseconds(stepPulseMicrosec);
+  digitalWrite(pinStep, LOW);
+  currentStep += dir;
+}
+
+void SwitecX12::stepTo(int position)
+{
+  int count;
+  int dir;
+  if (position > currentStep) {
+    dir = 1;
+    count = position - currentStep;
+  } else {
+    dir = -1;
+    count = currentStep - position;
+  }
+  for (int i=0;i<count;i++) {
+    step(dir);
+    delayMicroseconds(resetStepMicrosec);
+  }
+}
+
+void SwitecX12::zero()
+{
+  currentStep = steps - 1;
+  stepTo(0);
+  targetStep = 0;
+  vel = 0;
+  dir = 0;
+}
+
+void SwitecX12::advance()
+{
+  // detect stopped state
+  if (currentStep==targetStep && vel==0) {
+    stopped = true;
+    dir = 0;
+    time0 = micros();
+    return;
+  }
+
+  // if stopped, determine direction
+  if (vel==0) {
+    dir = currentStep<targetStep ? 1 : -1;
+    // do not set to 0 or it could go negative in case 2 below
+    vel = 1;
+  }
+
+  step(dir);
+
+  // determine delta, number of steps in current direction to target.
+  // may be negative if we are headed away from target
+  int delta = dir>0 ? targetStep-currentStep : currentStep-targetStep;
+
+  if (delta>0) {
+    // case 1 : moving towards target (maybe under accel or decel)
+    if (delta < vel) {
+      // time to declerate
+      vel--;
+    } else if (vel < maxVel) {
+      // accelerating
+      vel++;
+    } else {
+      // at full speed - stay there
+    }
+  } else {
+    // case 2 : at or moving away from target (slow down!)
+    vel--;
+  }
+
+  // vel now defines delay
+  unsigned char i = 0;
+  // this is why vel must not be greater than the last vel in the table.
+  while (accelTable[i][0]<vel) {
+    i++;
+  }
+  microDelay = accelTable[i][1];
+  time0 = micros();
+}
+
+void SwitecX12::setPosition(unsigned int pos)
+{
+  // pos is unsigned so don't need to check for <0
+  if (pos >= steps) pos = steps-1;
+  targetStep = pos;
+  if (stopped) {
+    // reset the timer to avoid possible time overflow giving spurious deltas
+    stopped = false;
+    time0 = micros();
+    microDelay = 0;
+  }
+}
+
+void SwitecX12::update()
+{
+  if (!stopped) {
+    unsigned long delta = micros() - time0;
+    if (delta >= microDelay) {
+      advance();
+    }
+  }
+}

SwitecX12.h

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+#ifndef SwitecX12_h
+#define SwitecX12_h
+#include <Arduino.h>
+
+class SwitecX12 {
+  public:
+    unsigned char pinStep;
+    unsigned char pinDir;
+    unsigned int currentStep;      // step we are currently at
+    unsigned int targetStep;       // target we are moving to
+    unsigned int steps;            // total steps available
+    unsigned long time0;           // time when we entered this state
+    unsigned int microDelay;       // microsecs until next state
+    unsigned short (*accelTable)[2]; // accel table can be modified.
+    unsigned int maxVel;           // fastest vel allowed
+    unsigned int vel;              // steps travelled under acceleration
+    char dir;                      // direction -1,0,1
+    boolean stopped;               // true if stopped
+    SwitecX12(unsigned int steps, unsigned char pinStep, unsigned char pinDir);
+
+    //void stepUp();
+    void step(int dir);
+    void zero();
+    void stepTo(int position);
+    void advance();
+    void update();
+    void setPosition(unsigned int pos);
+};
+
+#endif