/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private variables ---------------------------------------------------------*/
TIM_HandleTypeDef htim2;

volatile uint32_t last_capture = 0;
volatile uint32_t pulse_period = 0;
volatile uint8_t speed = 0; // Speed in km/h

// 7-seg digits segments lookup table for common cathode display
const uint8_t SEGMENT_CODES[10] = {
  0x3F, // 0
  0x06, // 1
  0x5B, // 2
  0x4F, // 3
  0x66, // 4
  0x6D, // 5
  0x7D, // 6
  0x07, // 7
  0x7F, // 8
  0x6F  // 9
};

#define WHEEL_CIRCUMFERENCE 2.1f  // meters (example value)
#define DISPLAY_DIGITS 4

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM2_Init(void);
void Display_Speed(uint8_t speed);
void Display_Digit(uint8_t digit, uint8_t position);

/* USER CODE BEGIN 0 */
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
  if(htim->Channel == HAL_TIM_ACTIVE_CHANNEL_1)
  {
    uint32_t capture = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1);
    if(capture > last_capture) // Basic handle rollover if needed
      pulse_period = capture - last_capture;
    else
      pulse_period = (0xFFFF - last_capture) + capture;

    last_capture = capture;

    if(pulse_period != 0)
    {
      // Timer frequency depends on APB1 timer clock and prescaler
      float timer_freq = HAL_RCC_GetPCLK1Freq() * 2; // TIM2 clock freq (APB1 x2)
      float freq = timer_freq / (float)pulse_period;  
      float speed_mps = freq * WHEEL_CIRCUMFERENCE;
      speed = (uint8_t)(speed_mps * 3.6f); // m/s to km/h
    }
    else
    {
      speed = 0;
    }
  }
}
/* USER CODE END 0 */

int main(void)
{
  /* MCU Configuration--------------------------------------------------------*/
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_TIM2_Init();

  /* Start input capture in interrupt mode */
  HAL_TIM_IC_Start_IT(&htim2, TIM_CHANNEL_1);

  while (1)
  {
    Display_Speed(speed);
    HAL_Delay(5);
  }
}

void Display_Speed(uint8_t speed)
{
  uint8_t digits[DISPLAY_DIGITS];
  digits[0] = speed / 1000;
  digits[1] = (speed / 100) % 10;
  digits[2] = (speed / 10) % 10;
  digits[3] = speed % 10;

  for(uint8_t i=0; i<DISPLAY_DIGITS; i++)
  {
    Display_Digit(digits[i], i);
    HAL_Delay(2);
  }
}

void Display_Digit(uint8_t digit, uint8_t position)
{
  // GPIO code to enable digit (position) and display segments for digit
  // Customize pins based on your hardware wiring here

  // Example:
  // Set segments pins (PORTx->ODR = SEGMENT_CODES[digit])
  // Enable digit select line for 'position'
}

/* TIM2 init function */
static void MX_TIM2_Init(void)
{
  TIM_IC_InitTypeDef sConfigIC = {0};

  htim2.Instance = TIM2;
  htim2.Init.Prescaler = 1799;  // Assuming APB1 clock = 36 MHz, gives timer freq = 20 kHz
  htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim2.Init.Period = 0xFFFF;
  htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;

  if (HAL_TIM_IC_Init(&htim2) != HAL_OK)
  {
    Error_Handler();
  }

  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
  sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
  sConfigIC.ICFilter = 0;

  if (HAL_TIM_IC_ConfigChannel(&htim2, &sConfigIC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
}

/* GPIO init function */
static void MX_GPIO_Init(void)
{
  /* Configure GPIO pins for 7-seg display segments and digit control */
  /* Example for GPIO ports and pins you define for your hardware */
}

/* System Clock Configuration */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  // Configure PLL and clocks as per your hardware
}

/* Error Handler */
void Error_Handler(void)
{
  while(1) {}
}