for issue 93 in t2-docs

issue.md

@@ -0,0 +1,48 @@
+### Usage
+```js
+// Invoke this method to set the pull mode.
+// pullType can be - pullup, pulldown or none.
+pin.pull(pullType, callback);
+```
+
+
+Example of the `pin.pull(mode)` command using a pushbutton. The code example given below turns on the Blue LED of the Tessel module when the pushbutton is pressed and turns off the Blue LED when the pushbutton is not pressed.
+
+```js
+var tessel= require('tessel'); // Import Tessel
+
+var pin = tessel.port.A.pin[2]; // Select pin 2 on port A
+
+var pullType = "pullup"; // Set the mode of `pin.pull to pullup`
+
+var led = tessel.led[3]; // Blue LED of Tessel
+
+pin.pull(pullType,(error, buffer) => { // Pin 2 pulled high
+
+  if (error){
+    throw error;
+  }
+});
+
+setInterval({
+  pin.read(function(error, number){
+
+      if (error) {
+        throw error;
+      }
+
+      // Pin 2 reads high when the pushbutton is not pressed since it is pulled up
+      console.log(number);
+      if (number == 1){
+        led.off();
+      }
+
+      // Pin 2 reads low when the pushbutton is pressed since its connection with ground gets complete
+      else{
+        led.on();
+      }
+
+  });
+
+}, 500);
+```