app: stethoscope

apps.json

@@ -264,6 +264,18 @@
       {"name":"*hrm","url":"heartrate-icon.js","evaluate":true}
     ]
   },
+  { "id": "stetho",
+    "name": "Stethoscope",
+    "icon": "stetho.png",
+    "version":"0.0198",
+    "description": "Hear your heart rate",
+    "tags": "health",
+    "storage": [
+      {"name":"+stetho","url":"stetho.json"},
+      {"name":"-stetho","url":"stetho.js"},
+      {"name":"*stetho","url":"stetho-icon.js","evaluate":true}
+    ]
+  },
   { "id": "swatch",
     "name": "Stopwatch",
     "icon": "stopwatch.png",

apps/stetho/stetho.js

@@ -0,0 +1,82 @@
+// a variation on the hrm app
+Bangle.setLCDPower(1);
+Bangle.setLCDTimeout(0);
+Bangle.ioWr(0x80,0)
+x=0;
+var min=0,max=0;
+var wasHigh = 0, wasLow = 0;
+var lastHigh = getTime();
+var hrmList = [];
+var hrm;
+var SPEAKER_PIN = D18;
+
+function freq(f) {
+ console.log("frequency: ", f);
+ if (f===0) digitalWrite(SPEAKER_PIN, 0);
+  else analogWrite(SPEAKER_PIN, 0.5, {freq: f});
+}
+
+function readHRM() {
+  var a = analogRead(D29);
+  var h = getTime();
+  min=Math.min(min*0.97+a*0.03,a);
+  max=Math.max(max*0.97+a*0.03,a);
+  y = E.clip(170 - (a*960*4),100,230);
+  if (x==0) {
+    g.clearRect(0,100,239,239);
+    g.moveTo(-100,0);
+  }
+  let frequency = parseFloat((170 - (a*960*4)) + 500);
+  if(frequency > 0) freq(frequency);
+
+  g.setColor(1,1,1);
+  g.lineTo(x,y);
+  if ((max-min)>0.005) {
+    if (4*a > (min+3*max)) { // high
+      g.setColor(1,0,0);
+      g.fillRect(x,230,x,239);
+      g.setColor(1,1,1);
+      if (!wasHigh && wasLow) {
+        var currentHrm = 60/(h-lastHigh);
+        lastHigh = h;
+        if (currentHrm<250) {
+          while (hrmList.length>12) hrmList.shift();
+          hrmList.push(currentHrm);
+          // median filter
+          var t = hrmList.slice(); // copy
+          t.sort();
+          // average the middle 3
+          var mid = t.length>>1;
+          if (mid+2<t.length)
+            hrm = (t[mid]+t[mid+1]+t[mid+2])/3;
+          else if (mid<t.length)
+            hrm = t[mid];
+          else
+            hrm = 0;
+          g.setFontVector(40);
+          g.setFontAlign(0,0);
+          g.clearRect(0,0,239,100);
+          var str = hrm ? Math.round(hrm) : "?";
+          var px = 120;
+          g.drawString(str,px,40);
+          px += g.stringWidth(str)/2;
+          g.setFont("6x8");
+          g.drawString("BPM",px+20,60);
+        }
+      }
+      wasLow = 0;
+      wasHigh = 1;
+    } else if (4*a < (max+3*min)) { // low
+      wasLow = 1;
+    } else { // middle
+      g.setColor(0.5,0,0);
+      g.fillRect(x,230,x,239);
+      g.setColor(1,1,1);
+      wasHigh = 0;
+    }
+  }
+  x++;
+  if (x>239)x=0;
+}
+
+setInterval(readHRM,50);

apps/stetho/stetho.json

@@ -0,0 +1,5 @@
+{
+  "name":"Stethoscope","type":"app",
+  "icon":"*stetho",
+  "src":"-stetho"
+}