pwm

src/blinky/pwm.md

@@ -4,46 +4,17 @@ PWM stands for **Pulse Width Modulation**. It is a technique used to control the
 
 In PWM, a digital signal switches between **on** and **off** states. The **duty cycle** of the signal determines how long it stays on compared to how long it stays off. 
 
-- **Duty Cycle**: The percentage of time the signal is on during one cycle. 
+- **Duty Cycle**: 
+The percentage of time the signal is on during one cycle. 
+<img style="display: block; margin: auto;" alt="pico2" src="../images/pwm-duty-cycle.png" />
+<span style="text-align: center;display: block; margin: auto;  font-size: 12px;">Image Credit: Wikipedia</span>
   - For example:
     - 100% duty cycle means the signal is always on.
     - 50% duty cycle means the signal is on half the time and off half the time.
     - 0% duty cycle means the signal is always off.
 
-For LED brightness, PWM works by rapidly turning the LED on and off. If this happens fast enough, our eyes perceive a steady light, and the brightness increases with a higher duty cycle.
-
 Refer the 1073th page of the [RP2350](https://datasheets.raspberrypi.com/rp2350/rp2350-datasheet.pdf) Datasheet for more information.
 
-In the previous example code, we use PWM to fade an LED.
-
-### Fading Up
-The code below gradually increases the LED brightness by adjusting the duty cycle from 0 to 25,000, with a small delay between each step:
-```rust
-for i in LOW..=HIGH {
-  delay.delay_us(8);
-  let _ = channel.set_duty_cycle(i);
-}
-```
-The delay ensures the LED brightens gradually. Without it, the brightness would change too quickly for the eye to notice, making the LED appear to jump from dim to bright. The delay allows for a smooth, noticeable "fading up" effect.  Dont' believe me! Adjust the delay to 0 and observe. You can increase the delay (eg: 25) and observe the fading effect.
-
-Note: `set_duty_cycle` function under the hood writes the given value into CC register(Count compare value). 
-
-### Fading Down
-The following code decreases the LED brightness by reducing the duty cycle from 25,000 to 0.
-```rust
-// Here rev is to reverse the iteration. so it goes from 25_000 to 0
-for i in (LOW..=HIGH).rev() {  
-    delay.delay_us(8);
-    let _ = channel.set_duty_cycle(i);
-}
-```
-
-### Pause
-After fading up and down, the program pauses for 500 milliseconds before repeating the cycle, allowing the LED to rest briefly.
-
-Play around by adjusting the `delay` and observe. You can even comment out one of the for loop and observe the effect. 
-
-
 ## PWM Peripheral in RP2350
 The PWM peripheral is responsible for generating PWM signals. The Pico 2 features 12 PWM generators, known as slices, with each slice having two channels(A/B). This configuration results in a total of 24 PWM output channels available for use.
 
@@ -73,3 +44,40 @@ Get a mutable reference to channel B of PWM4 and direct its output to GPIO pin 2
 let channel = &mut pwm.channel_b;
 channel.output_to(pins.gpio25);
 ```
+
+## Fading Effect
+
+For LED brightness, PWM works by rapidly turning the LED on and off. If this happens fast enough, our eyes perceive a steady light, and the brightness increases with a higher duty cycle.
+
+
+In the previous example code, we use PWM to fade an LED.
+
+### Fading Up
+The code below gradually increases the LED brightness by adjusting the duty cycle from 0 to 25,000, with a small delay between each step:
+```rust
+for i in LOW..=HIGH {
+  delay.delay_us(8);
+  let _ = channel.set_duty_cycle(i);
+}
+```
+The delay ensures the LED brightens gradually. Without it, the brightness would change too quickly for the eye to notice, making the LED appear to jump from dim to bright. The delay allows for a smooth, noticeable "fading up" effect.  
+
+Dont' believe me! Adjust the delay to 0 and observe. You can increase the delay (eg: 25) and observe the fading effect.
+
+Note: `set_duty_cycle` function under the hood writes the given value into CC register(Count compare value). 
+
+### Fading Down
+The following code decreases the LED brightness by reducing the duty cycle from 25,000 to 0.
+```rust
+// Here rev is to reverse the iteration. so it goes from 25_000 to 0
+for i in (LOW..=HIGH).rev() {  
+    delay.delay_us(8);
+    let _ = channel.set_duty_cycle(i);
+}
+```
+
+### Pause
+After fading up and down, the program pauses for 500 milliseconds before repeating the cycle, allowing the LED to rest briefly.
+
+Play around by adjusting the `delay` and observe. You can even comment out one of the for loop and observe the effect. 
+