add smooth blinky example

1_Basic_GPIO/digitalOut.md

@@ -233,6 +233,8 @@ Code to turn the fan on and off with a 2 second delay:
 
 ```
 
+---
+
 ## Binary LED Counter
 
 This example again uses 5 LEDS to visualize a 5 bit binary counter. Mask commands are used to set the LEDS simultaneously.
@@ -257,6 +259,34 @@ if counter is `11001`, `counter<<11` will be `1100100000000000`.
 
 ---
 
+## SmoothBlinky
+
+This example demonstrates how brightness of an LED can be controlled by modulating the output using the time delay
+
+```c
+const uint LEDPin = 14;
+gpio_init(LEDPin);
+gpio_set_dir(LEDPin, GPIO_OUT);
+gpio_set_drive_strength(LEDPin, GPIO_DRIVE_STRENGTH_2MA);
+int onDelay=0;
+int totalDelay=10;
+while (true)
+{
+    for (int i = 0; i < 50; i++)
+    {
+        gpio_put(LEDPin, true);
+        sleep_ms(onDelay);
+        gpio_put(LEDPin, false);
+        sleep_ms(totalDelay - onDelay);
+    }
+onDelay = (onDelay+1) % totalDelay;
+}
+```
+
+`onDelay` is maintained such that total time for each iteration remains constant, equal to `totalDelay`. This above code will make the LED look like the brightness changes.
+
+---
+
 ## Summary
 
 Below are the API calls used in this document:
@@ -282,3 +312,5 @@ Below are the API calls used in this document:
 | - | - | - |
 | `sleep_ms` | TIME | Pauses the program for given number of milli-seconds when called |
 | `stdio_init_all` | -- | Initializes stuff |
+
+add fading led example by changing the amount of times the led blinks in a given cycle.