Add doxygen documentation for low_pass_filter.c functions

Author: taisirhassan

common/low_pass_filter.c

@@ -4,7 +4,17 @@
 #include "common.h"
 #include "low_pass_filter.h"
 
-// Initialize the low-pass filter
+/**
+ * @brief Initializes the low-pass filter by calculating and storing the alpha value
+ *
+ * This function calculates the alpha value based on the given response time and stores
+ * it in the provided pointer. The alpha value is used in subsequent filter updates.
+ *
+ * @param alpha Pointer to store the calculated alpha value
+ * @param response_time Response time constant in milliseconds (must be > 0)
+ * @return w_status_t Returns W_SUCCESS on success, W_INVALID_PARAM if alpha is NULL or
+ * response_time is invalid
+ */
 w_status_t low_pass_filter_init(double *alpha, double response_time) {
 	if (alpha == NULL || response_time <= 0) {
 		return W_INVALID_PARAM; // Return specific error for invalid parameters
@@ -14,7 +24,19 @@ w_status_t low_pass_filter_init(double *alpha, double response_time) {
 	return W_SUCCESS; // Return success after initialization
 }
 
-// Update the low-pass filter with a new value
+/**
+ * @brief Updates the low-pass filter with a new value and returns the operation status
+ *
+ * This function applies the low-pass filter algorithm to the new input value using the
+ * provided alpha value. The filtered result is stored in low_pass_value and updated
+ * in-place for the next iteration.
+ *
+ * @param alpha Alpha value (0.0 to 1.0) for the low-pass filter
+ * @param new_input_value New input value to filter
+ * @param low_pass_value Pointer to the current filtered value (updated in-place)
+ * @return w_status_t Returns W_SUCCESS on success, W_INVALID_PARAM if low_pass_value is
+ * NULL or alpha is out of valid range (0.0 to 1.0)
+ */
 w_status_t update_low_pass(double alpha, uint16_t new_input_value, double *low_pass_value) {
 	// Check if low_pass_value pointer is NULL
 	if (low_pass_value == NULL) {