basic servo simulation (#297)

libs/core/pins.cpp

@@ -201,6 +201,7 @@ namespace pins {
      */
     //% help=pins/servo-write-pin weight=20
     //% blockId=device_set_servo_pin block="servo write|pin %name|to %value" blockGap=8
+    //% parts=microservo trackArgs=0
     void servoWritePin(AnalogPin name, int value) { 
         PINOP(setServoValue(value));
     }

libs/core/pxtparts.json

@@ -29,6 +29,37 @@
             {"pinIndices": [2, 3]}
         ]
     },
+    "microservo": {
+        "simulationBehavior": "microservo",
+        "visual": {
+            "builtIn": "microservo",
+            "width": 74.85,
+            "height": 200,
+            "pinDistance": 10,
+            "pinLocations": [
+                {"x": 30, "y": 5},
+                {"x": 37, "y": 5},
+                {"x": 45, "y": 5}
+            ]
+        },
+        "numberOfPins": 3,
+        "pinDefinitions": [
+            {"target": {"pinInstantiationIdx": 0}, "style": "croc", "orientation": "+Z"},
+            {"target": "threeVolt", "style": "croc", "orientation": "+Z"},
+            {"target": "ground", "style": "croc", "orientation": "+Z"}
+        ],
+        "instantiation": {
+            "kind": "function",
+            "fullyQualifiedName": "pins.servoWritePin",
+            "argumentRoles": [
+                {"pinInstantiationIdx": 0, "partParameter": "name"}
+            ]
+        },
+        "assembly": [
+            {"part": true, "pinIndices": [2]},
+            {"pinIndices": [0, 1]}
+        ]
+    },
     "neopixel": {
         "simulationBehavior": "neopixel",
         "visual": {

libs/core/shims.d.ts

@@ -585,7 +585,8 @@ declare namespace pins {
      * @param value angle or rotation speed, eg:180,90,0
      */
     //% help=pins/servo-write-pin weight=20
-    //% blockId=device_set_servo_pin block="servo write|pin %name|to %value" blockGap=8 shim=pins::servoWritePin
+    //% blockId=device_set_servo_pin block="servo write|pin %name|to %value" blockGap=8
+    //% parts=microservo trackArgs=0 shim=pins::servoWritePin
     function servoWritePin(name: AnalogPin, value: number): void;
 
     /**