added Moving Arrow Compass

apps/arrow/README.md

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+# Moving Arrow Compass
+
+A variation of jeffmer's Navigation Compass.  The compass points
+North and shows the current heading.
+
+This is a tilt and roll compensated compass with a linear
+display. The compass will display the same direction that it shows
+when flat as when it is tilted (rotation around the W-S axis) or
+rolled (rotation around the N-S) axis. *Even with compensation, it
+would be beyond foolish to rely solely on this app for any serious
+navigational purpose.*
+
+![](screenshot.jpg)
+
+## Calibration
+
+Correct operation of this app depends critically on calibration. When
+first run on a Bangle, the app will request calibration. This lasts
+for 30 seconds during which you should move the watch slowly through
+figures of 8. It is important that during calibration the watch is
+fully rotated around each of it axes. If the app does give the
+correct direction heading or is not stable with respect to tilt and
+roll - redo the calibration by pressing *BTN3*. Calibration data is
+recorded in a storage file named `magnav.json`.
+
+It is also worth noting that the presence of the magnetic charging
+clamps will require the compass to be recalibrated after every
+charge.
+
+## Controls
+
+*BTN1* - switches to your selected clock app.
+
+*BTN2* - switches to the app launcher.
+
+*BTN3* - invokes calibration ( can be cancelled if pressed accidentally)
+

apps/arrow/app.js

@@ -0,0 +1,180 @@
+var pal1color = new Uint16Array([0x0000,0xFFC0],0,1);
+var pal2color = new Uint16Array([0x0000,0xffff],0,1);
+var buf1 = Graphics.createArrayBuffer(160,160,1,{msb:true});
+var buf2 = Graphics.createArrayBuffer(80,40,1,{msb:true});
+
+var bearing=0; // always point north
+var heading = 0;
+var candraw = false;
+var CALIBDATA = require("Storage").readJSON("magnav.json",1)||null;
+
+Bangle.setLCDTimeout(30);
+
+function flip1(x,y) {
+ g.drawImage({width:160,height:160,bpp:1,buffer:buf1.buffer, palette:pal1color},x,y);
+ buf1.clear();
+}
+
+function flip2(x,y) {
+ g.drawImage({width:80,height:40,bpp:1,buffer:buf2.buffer, palette:pal2color},x,y);
+ buf2.clear();
+}
+
+function radians(d) {
+  return (d*Math.PI) / 180;
+}
+
+function drawCompass(course) {
+  if(!candraw) return;
+
+  var img = require("heatshrink").decompress(atob("lEowIPMjAEDngEDvwED/4DCgP/wAEBgf/4AEBg//8AEBh//+AEBj///AEBn///gEBv///wmCAAImCAAIoBFggE/AkaaEABo="));
+
+  buf1.setColor(1);
+  buf1.fillCircle(80,80,79,79);
+  buf1.setColor(0);
+  buf1.fillCircle(80,80,69,69);
+  buf1.setColor(1);
+  buf1.drawImage(img, 80, 80, {scale:3,  rotate:radians(course)} );
+  flip1(40, 30);
+}
+
+function newHeading(m,h){ 
+    var s = Math.abs(m - h);
+    var delta = (m>h)?1:-1;
+    if (s>=180){s=360-s; delta = -delta;} 
+    if (s<2) return h;
+    var hd = h + delta*(1 + Math.round(s/5));
+    if (hd<0) hd+=360;
+    if (hd>360)hd-= 360;
+    return hd;
+}
+
+function tiltfixread(O,S){
+  var start = Date.now();
+  var m = Bangle.getCompass();
+  var g = Bangle.getAccel();
+  m.dx =(m.x-O.x)*S.x; m.dy=(m.y-O.y)*S.y; m.dz=(m.z-O.z)*S.z;
+  var d = Math.atan2(-m.dx,m.dy)*180/Math.PI;
+  if (d<0) d+=360;
+  var phi = Math.atan(-g.x/-g.z);
+  var cosphi = Math.cos(phi), sinphi = Math.sin(phi);
+  var theta = Math.atan(-g.y/(-g.x*sinphi-g.z*cosphi));
+  var costheta = Math.cos(theta), sintheta = Math.sin(theta);
+  var xh = m.dy*costheta + m.dx*sinphi*sintheta + m.dz*cosphi*sintheta;
+  var yh = m.dz*sinphi - m.dx*cosphi;
+  var psi = Math.atan2(yh,xh)*180/Math.PI;
+  if (psi<0) psi+=360;
+  return psi;
+}
+
+// Note actual mag is 360-m, error in firmware
+function reading() {
+  var d = tiltfixread(CALIBDATA.offset,CALIBDATA.scale);
+  heading = newHeading(d,heading);
+  var dir = bearing - heading;
+  if (dir < 0) dir += 360;
+  if (dir > 360) dir -= 360;
+  drawCompass(dir);  // we want compass to show us where to go
+  buf2.setColor(1);
+  buf2.setFontAlign(-1,-1);
+  buf2.setFont("Vector",38);
+  var course = Math.round(heading);
+  var cs = course.toString();
+  cs = course<10?"00"+cs : course<100 ?"0"+cs : cs;
+  buf2.drawString(cs,0,0);
+  flip2(90, 200);
+}
+
+function calibrate(){
+  var max={x:-32000, y:-32000, z:-32000},
+      min={x:32000, y:32000, z:32000};
+  var ref = setInterval(()=>{
+      var m = Bangle.getCompass();
+      max.x = m.x>max.x?m.x:max.x;
+      max.y = m.y>max.y?m.y:max.y;
+      max.z = m.z>max.z?m.z:max.z;
+      min.x = m.x<min.x?m.x:min.x;
+      min.y = m.y<min.y?m.y:min.y;
+      min.z = m.z<min.z?m.z:min.z;
+  }, 100);
+  return new Promise((resolve) => {
+     setTimeout(()=>{
+       if(ref) clearInterval(ref);
+       var offset = {x:(max.x+min.x)/2,y:(max.y+min.y)/2,z:(max.z+min.z)/2};
+       var delta  = {x:(max.x-min.x)/2,y:(max.y-min.y)/2,z:(max.z-min.z)/2};
+       var avg = (delta.x+delta.y+delta.z)/3;
+       var scale = {x:avg/delta.x, y:avg/delta.y, z:avg/delta.z};
+       resolve({offset:offset,scale:scale});
+     },30000);
+  });
+}
+
+function docalibrate(e,first){
+  const title = "Calibrate";
+  const msg = "takes 30 seconds";
+  function action(b){
+    if (b) {
+      buf1.setColor(1);
+      buf1.setFont("Vector", 30);
+      buf1.setFontAlign(0,-1);
+      buf1.drawString("Figure 8s",80, 40);
+      buf1.drawString("to",80, 80);
+      buf1.drawString("Calibrate",80, 120);
+      flip1(40,40);
+
+      calibrate().then((r)=>{
+        require("Storage").write("magnav.json",r);
+        Bangle.buzz();
+        CALIBDATA = r;
+        startdraw();
+        setButtons();
+      });
+    } else {
+      startdraw();
+      setTimeout(setButtons,1000);
+    }
+  }   
+  if (first===undefined) first=false;
+  stopdraw();
+  clearWatch();
+  if (first) 
+    E.showAlert(msg,title).then(action.bind(null,true));
+  else 
+    E.showPrompt(msg,{title:title,buttons:{"Start":true,"Cancel":false}}).then(action);
+}
+
+var intervalRef;
+
+function startdraw(){
+  g.clear();
+  g.setColor(1,1,1);
+  Bangle.drawWidgets();
+  candraw = true;
+  intervalRef = setInterval(reading,200);
+}
+
+function stopdraw() {
+  candraw=false;
+  if(intervalRef) {clearInterval(intervalRef);}
+}
+
+function setButtons(){
+  setWatch(()=>{load();}, BTN1, {repeat:false,edge:"falling"});
+  setWatch(Bangle.showLauncher, BTN2, {repeat:false,edge:"falling"});
+  setWatch(docalibrate, BTN3, {repeat:false,edge:"falling"});
+}
+ 
+Bangle.on('lcdPower',function(on) {
+  if (on) {
+    startdraw();
+  } else {
+    stopdraw();
+  }
+});
+
+Bangle.on('kill',()=>{Bangle.setCompassPower(0);});
+
+Bangle.loadWidgets();
+Bangle.setCompassPower(1);
+startdraw();
+setButtons();

apps/arrow/icon.js

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+require("heatshrink").decompress(atob("mUywIebg/4AocP//AAoUf//+BYgMDh/+j/8Dol/wEAgYFBg/wgEBFIV+AQIVCh4fBnwFBgISBj8AhgJCh+Ag4BB4ED8ED+ASCAYJDBnkAvkAIYIWBjw8B/EB8AcBn//gF4DwJdBAQMA/EP738FYM8g/nz+A+EPgHx8YKBgfAjF4sAKBHIItBBQJMBFoJEBHII1BIQIDCvAUCAYYUBHIIDBMIXACgQpBRAIUBMIIrBDAIWCVYaiBTYQJCn4FBQgIIBEYKrDQ4MBVYUf8CQCCoP/w6DBAAKIBAocHAoIwBBgb5DDoYAZA="))