servo

src/SUMMARY.md

@@ -24,5 +24,6 @@
     - [Intro](./servo/servo.md)
     - [More on PWM](./servo/pwm.md)
     - [Servo and Pico](./servo/servo-pico.md)
+    - [Action](./servo/action.md)
 
 - [Resources](./resources.md)

src/servo/action.md

@@ -0,0 +1,139 @@
+## Action
+
+Setting Up the PWM and Servo Control
+```rust
+const PWM_DIV_INT: u8 = 64;
+const PWM_TOP: u16 = 46_874;
+
+const TOP: u16 = PWM_TOP + 1;
+const MIN_DUTY: u16 = (TOP as f64 * (2.5 / 100.)) as u16;
+const HALF_DUTY: u16 = (TOP as f64 * (7.5 / 100.)) as u16;
+const MAX_DUTY: u16 = (TOP as f64 * (12. / 100.)) as u16;
+```
+
+
+#### 1. Set Up the PWM Slice and Channel
+
+First, initialize the PWM slice and channel. You should have already done similar in the previous blinky section.
+
+```rust
+let mut pwm_slices = hal::pwm::Slices::new(pac.PWM, &mut pac.RESETS);
+let pwm = &mut pwm_slices.pwm4;
+```
+
+### 2. Adjust for 50HZ frequency
+Now, set the divisor and the top value to achieve a PWM frequency of 50Hz.
+
+```rust
+pwm.set_div_int(PWM_DIV_INT);
+pwm.set_div_frac(0);
+
+pwm.set_top(PWM_TOP);
+pwm.enable();
+```
+
+### 3. Set Output Pin
+Next, specify the GPIO pin where the PWM signal will be sent. We will use GPIO pin 9.
+
+```rust
+    let servo = &mut pwm.channel_b;
+    servo.output_to(pins.gpio9);
+
+```
+### 4. Set Servo Position in a Loop
+Finally, in the loop, we adjust the duty cycle which will control the servo's position. We will move the servo to different positions (0°, 90°, and 180°) using the MIN_DUTY, HALF_DUTY, and MAX_DUTY values calculated earlier.
+
+```rust
+loop {
+    servo.set_duty_cycle(MIN_DUTY).unwrap(); // 0 degrees
+    timer.delay_ms(1000);
+
+    servo.set_duty_cycle(HALF_DUTY).unwrap(); // 90 degrees
+    timer.delay_ms(1000);
+
+    servo.set_duty_cycle(MAX_DUTY).unwrap(); // 180 degrees
+    timer.delay_ms(1000);
+}
+
+```
+
+### Full Code snippet
+```rust
+const PWM_DIV_INT: u8 = 64;
+const PWM_TOP: u16 = 46_874;
+
+const TOP: u16 = PWM_TOP + 1;
+const MIN_DUTY: u16 = (TOP as f64 * (2.5 / 100.)) as u16;
+const HALF_DUTY: u16 = (TOP as f64 * (7.5 / 100.)) as u16;
+const MAX_DUTY: u16 = (TOP as f64 * (12. / 100.)) as u16;
+
+#[hal::entry]
+fn main() -> ! {
+    // Grab our singleton objects
+    let mut pac = hal::pac::Peripherals::take().unwrap();
+
+    // Set up the watchdog driver - needed by the clock setup code
+    let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
+
+    // Configure the clocks
+    // The default is to generate a 125 MHz system clock
+    let clocks = hal::clocks::init_clocks_and_plls(
+        XTAL_FREQ_HZ,
+        pac.XOSC,
+        pac.CLOCKS,
+        pac.PLL_SYS,
+        pac.PLL_USB,
+        &mut pac.RESETS,
+        &mut watchdog,
+    )
+    .ok()
+    .unwrap();
+
+    // The single-cycle I/O block controls our GPIO pins
+    let sio = hal::Sio::new(pac.SIO);
+
+    // Set the pins up according to their function on this particular board
+    let pins = hal::gpio::Pins::new(
+        pac.IO_BANK0,
+        pac.PADS_BANK0,
+        sio.gpio_bank0,
+        &mut pac.RESETS,
+    );
+
+    // The delay object lets us wait for specified amounts of time (in
+    // milliseconds)
+    let mut timer = hal::Timer::new_timer0(pac.TIMER0, &mut pac.RESETS, &clocks);
+
+    // Init PWMs
+    let mut pwm_slices = hal::pwm::Slices::new(pac.PWM, &mut pac.RESETS);
+
+    // Configure PWM4
+    let pwm = &mut pwm_slices.pwm4;
+
+    pwm.set_div_int(PWM_DIV_INT);
+    pwm.set_div_frac(0);
+
+    pwm.set_top(PWM_TOP);
+    pwm.enable();
+
+    let servo = &mut pwm.channel_b;
+    servo.output_to(pins.gpio9);
+
+    loop {
+        servo.set_duty_cycle(MIN_DUTY).unwrap();
+        timer.delay_ms(1000);
+        servo.set_duty_cycle(HALF_DUTY).unwrap();
+        timer.delay_ms(1000);
+        servo.set_duty_cycle(MAX_DUTY).unwrap();
+        timer.delay_ms(1000);
+    }
+}
+```
+
+## Clone the existing project
+You can clone (or refer) project I created and navigate to the `servo` folder.
+
+```sh
+git clone https://github.com/ImplFerris/pico2-projects
+cd pico2-projects/servo
+```

src/servo/servo-pico.md

@@ -24,3 +24,20 @@ After performing the calculation, we find that the top value is `46,874`.
 You can experiment with different div_int and corresponding top values. Just ensure that div_int stays within the u8 range, top fits within the u16 range, and the formula yields a 50Hz frequency.
 
 (In case you are wondering, we are not setting the `div_frac` which is 0 by default. That's why it is not included in the calculation.)
+
+
+### Position calculation based on top
+To calculate the duty cycle that corresponds to specific positions (0, 90, and 180 degrees), we use the following formula based on the top value:
+
+```rust
+const PWM_DIV_INT: u8 = 64;
+const PWM_TOP: u16 = 46_874;
+
+const TOP: u16 = PWM_TOP + 1;
+const MIN_DUTY: u16 = (TOP as f64 * (2.5 / 100.)) as u16;
+const HALF_DUTY: u16 = (TOP as f64 * (7.5 / 100.)) as u16;
+const MAX_DUTY: u16 = (TOP as f64 * (12. / 100.)) as u16;
+```
+
+We multiply the TOP value by a duty cycle percentage to determine the appropriate pulse width for each position of the servo.
+