fixed typo and added comment before main

boards/stm32l432kc/src/bin/levitation.rs

@@ -32,6 +32,15 @@ const GAIN_CURRENT: PidGain = PidGain{
 };
 
 
+/*
+For the lev control, we need to chain 2 PIDs together and output a PWM signal. The first one takes in a height and 
+outputs a current, the second one takes in a current and outputs a voltage, which we the use to calculate duty cycle of
+the PWM signal. Outside the loop, we initialise the pids and the board pins for PWM. We also need max_duty to represent
+our voltage output as a fraction of the max duty cycle. In the loop, there is a timer which measures the time between 
+the signal being set and us taking readings from the sensors as part of the PID calculations. The PID calculations are 
+then performed, and the duty cycle is set, and timer restarted.
+*/
+
 #[embassy_executor::main] 
 async fn main(_spawner: Spawner) {
 
@@ -43,21 +52,22 @@ async fn main(_spawner: Spawner) {
     let green_light = PwmPin::new_ch2(p.PB3, OutputType::PushPull); // TODOLater change to actual pin (this is just for testing)
 
     let mut pwm = SimplePwm::new(p.TIM2, None, Some(green_light), None, None, hz(2000), CountingMode::EdgeAlignedUp); // TODOLater change to actual pin (this is just for testing)
-    pwm.enable(Channel::Ch2);
-
+
     let max_duty = pwm.get_max_duty() as f32;
+
+    pwm.enable(Channel::Ch2);
 
     let mut time_start = Instant::now().as_micros() as f32;
 
     loop {
 
         let actual_height = 0.7; // TODOLater we'll get that from a sensor
-
-        let dt = (Instant::now().as_micros() as f32) - time_start; // this gets the timeframe between the last change in the pwm signal for the PID
 
-        let target_curent = (pid_height.update(TARGET_HEIGHT, actual_height, dt)).min(MAX_CURRENT); // takes in height -> outputs current target (within boundaries)
+        let actual_current = 1.0; // TODOLater we'll get that from a sensor        
+
+        let dt = (Instant::now().as_micros() as f32) - time_start; // this gets the timeframe between the last change in the pwm signal for the PID
 
-        let actual_current = 1.0; // TODOLater we'll get that from a sensor
+        let target_current = (pid_height.update(TARGET_HEIGHT, actual_height, dt)).min(MAX_CURRENT); // takes in height -> outputs current target (within boundaries)
 
         let required_voltage = (pid_current.update(target_current, actual_current, dt)).min(MAX_VOLTAGE); // takes in current -> outputs voltage (within boundaries)