added 2 more activities

docs/maker.md

@@ -21,6 +21,20 @@ These six activities require the LEGO® MINDSTORMS® Education EV3 Core Set (455
   "url":"/maker/sound-of-color",
   "cardType": "example",
   "imageUrl": "/static/maker/sound-of-color.png"
+},
+{
+  "name": "Security Gadget",
+  "description": "Raise the alarm when your brick is lifted!",
+  "url":"/maker/security-gadget",
+  "cardType": "example",
+  "imageUrl": "/static/maker/security-gadget.png"
+},
+{
+  "name": "Intruder Detector",
+  "description": "Raise the alarm when an intruder sneaks in",
+  "url":"/maker/intruder-detector",
+  "cardType": "example",
+  "imageUrl": "/static/maker/intruder-detector.png"
 }
 ]
 ```

docs/maker/intruder-detector.md

@@ -0,0 +1,11 @@
+# Intruder Detector
+
+This program will activate an alarm when an object moves in front of the Ultrasonic Sensor.
+
+TODO support for event when value changes
+
+```blocks
+input.ultrasonic4.onObjectNear(function () {
+    music.playSoundUntilDone(music.sounds(Sounds.PowerUp))
+})
+```

docs/maker/security-gadget.md

@@ -0,0 +1,9 @@
+# Security Gadget
+
+This program will activate an alarm when an object is lifted from the Touch Sensor.
+
+```blocks
+input.touchSensor1.onEvent(TouchSensorEvent.Released, function () {
+    music.playSoundUntilDone(music.sounds(Sounds.PowerUp))
+})
+```

libs/core/ultrasonic.ts

@@ -43,7 +43,7 @@ namespace input {
         //% blockNamespace=input
         //% weight=100 blockGap=8
         //% group="Ultrasonic Sensor"
-        onObjectNear(distance: number, handler: () => void) {
+        onObjectNear(handler: () => void) {
             control.onEvent(this._id, PromixityEvent.ObjectNear, handler);
             if (this.distance() == PromixityEvent.ObjectNear)
                 control.runInBackground(handler);