Stepper Motor Spinning Slow

Btw, code in post #20 has to be changed to make proper direction changes in all step phases.

Current code has a step sequence discontinuity / hick-up when changing direction in lines 36 and 43.

After issuing a stop, there is also a small issue: if stopping in an 'instable' step phase - where two magnetic fields 'fight' for the rotor and move the rotor between the fighting poles - it may come to rest in either pole position - back or forward after digitalWrite of 0b000 / taking the power off. To compensate for that when continuing, power with the same last step phase has to be applied before moving on... - of course for the proper amount of time. Implementation depends on whether the setInterval(...) invokes the function the first time at beginning or end of the first interval, which I do not know.

Simplest resolution is to remove the stop() in the direction change, change the stop, and - most important - change the sequence in the backward steps sequence and adjust the step adjustment in direction change.

This are the 4 changed lines:

16.var stBW = [0b1001,0b0001,0b0011,0b0010,0b0110,0b0100,0b1100,0b1000];

36.} else { if (stT) { st = Math.abs(st - 7); } if (!stI) { st--; } setI((stT = t),stFW," FW"); }

43.} else { if (stT) { st = Math.abs(st - 7); } if (!stI) { st--; } setI(-(stT = t),stBW," BW"); }

49.if (stI) { stI = clearInterval(stI); stI = null; }

Resulting code:

// stPs stepper pins
// st   step 0..8
// stT  step Time in milliseconds [ms]
// stI  step Interval (from setInterval() and for clearInterval()
// sts  steps 0001,0011,0010,... pin signals
// stBW sts - steps Backwards
// stFW sts - steps Forward
// dmy  ...because of (cond) ? exprT : exprF needs something to assign to
var run = false;
var st = 0;
var stT = 0;
var stI = null;
var sts = null;
var stSt =  0b0000;
var stFW = [0b1000,0b1100,0b0100,0b0110,0b0010,0b0011,0b0001,0b1001];
var stBW = [0b1001,0b0001,0b0011,0b0010,0b0110,0b01­00,0b1100,0b1000];
var stPs = [C6,C7,C8,C9];

// setI setInterval(i,stsC) i in [ms] with (optionl) step Change (if not null), 
// and direction info (string)
var setI = function(t,stsN,d) {
  console.log("t = ",t, d); 
  if (stI) clearInterval(stI);
  if (stsN) sts = stsN;
  run = true;
  stI = setInterval(stp,t);
};

// stp step
var stp = function() { digitalWrite(stPs, sts[st = ++st % 8]); };

// _sFW step ForWard
var _sFW = function(t) {
  console.log("FW w/ " + t);
  if (stT > 0) { setI((stT = t),null," ~F");
  } else { if (stT) { st = Math.abs(st - 7); } if (!stI) { st--; } setI((stT = t),stFW," FW"); }
};

// _sBW step BackWards
var _sBW = function(t) {
  console.log("BW w/ " + t);
  if (stT < 0) { setI(-(stT = t),null," ~B"); 
  } else { if (stT) { st = Math.abs(st - 7); } if (!stI) { st--; } setI(-(stT = t),stBW," BW"); }
};

// stop
var stop = function() {
  console.log("stop");
  if (stI) { stI = clearInterval(stI); stI = null; }
  console.log(stI);
  run = false;
  digitalWrite(stPs, stSt);
};


// run function - t is stepping interval in [ms]
var r = function(t) {  
  if (typeof t === "undefined" ) {
    if (stT) {
      console.log((stT > 0) ? "F>B" : "B>F");
      r(-stT);
    } else {
      console.log("What ?");
    }
  } else { 
    dmy = (t) ? (t>0) ? _sFW(t) : _sBW(t) : stop(); 
  }
};