// STM32 Nucleo-L031K6 HAL Blink + printf() example
// Simulation: https://wokwi.com/projects/367244067477216257

// TODO: Have three LEDs (RGB) and have a way to turn on one of 8 color combinations

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stm32l0xx_hal.h>

// ST Nucleo Green user LED (PB3)
#define LED_PORT                GPIOB
#define LED_PIN_1                 GPIO_PIN_1
#define LED_PIN_2                 GPIO_PIN_5
#define LED_PIN_3                 GPIO_PIN_4
#define LED_PORT_CLK_ENABLE     __HAL_RCC_GPIOB_CLK_ENABLE
#define VCP_TX_Pin GPIO_PIN_2
#define VCP_RX_Pin GPIO_PIN_15

UART_HandleTypeDef huart2;
TIM_HandleTypeDef htim2;

void SystemClock_Config(void);
static void MX_USART2_UART_Init(void);

void initGPIO()
{
  GPIO_InitTypeDef GPIO_Config;

  GPIO_Config.Mode = GPIO_MODE_AF_PP;
  GPIO_Config.Pull = GPIO_NOPULL;
  GPIO_Config.Speed = GPIO_SPEED_FREQ_HIGH;
  GPIO_Config.Alternate = GPIO_AF2_TIM2;

  LED_PORT_CLK_ENABLE();

  GPIO_Config.Pin = LED_PIN_1;
  GPIO_Config.Pin = LED_PIN_2;
  GPIO_Config.Pin = LED_PIN_3;

  HAL_GPIO_Init(LED_PORT, &GPIO_Config);
}

volatile uint32_t color = 0;

volatile uint32_t redBrightness = 0;
volatile uint32_t greenBrightness = 0;
volatile uint32_t blueBrightness = 0;

volatile uint8_t usePWM = 0;

void nextColor()
{
  usePWM = 0;
  color++;

  WriteToPins();
  
  if (color == 7) color = -1;
}

void changeColor(uint32_t newColor)
{
  color = newColor;

  WriteToPins();
  
  if (color == 7) color = 0;
}

void changeColorHEX(
  uint8_t newRedBrightness, uint8_t newGreenBrightness, uint8_t newBlueBrightness)
{
  /*
  color = ((newRedBrightness > 0) << 2)
          | ((newGreenBrightness > 0) << 1)
          | (newBlueBrightness > 0); */

  redBrightness = newRedBrightness;
  greenBrightness = newGreenBrightness;
  blueBrightness = newBlueBrightness;
}

void WriteToPins()
{
  HAL_GPIO_WritePin(LED_PORT, LED_PIN_1, color & 4 ? GPIO_PIN_SET : GPIO_PIN_RESET);
  HAL_GPIO_WritePin(LED_PORT, LED_PIN_2, color & 2 ? GPIO_PIN_SET : GPIO_PIN_RESET);
  HAL_GPIO_WritePin(LED_PORT, LED_PIN_3, color & 1 ? GPIO_PIN_SET : GPIO_PIN_RESET);
}

void runPWM()
{
    for (uint8_t dutyCycle = 0; dutyCycle < 255; dutyCycle++)
    {
        color = ((redBrightness > dutyCycle) << 2) |
                ((greenBrightness > dutyCycle) << 1) |
                (blueBrightness > dutyCycle);

        WriteToPins();

        delay(0.1);
    }
}

static void MX_TIM2_Init(void)
{
  TIM_OC_InitTypeDef sConfigOC = {0};

  __HAL_RCC_TIM2_CLK_ENABLE();

  htim2.Instance = TIM2;
  htim2.Init.Prescaler = (uint32_t)(SystemCoreClock / 1000000) - 1;
  htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim2.Init.Period = 255;
  htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
  {
    Error_Handler();
  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 0;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

  if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_4) != HAL_OK)
  {
    Error_Handler();
  }
}

void setup()
{
  HAL_Init();
  SystemClock_Config();

  initGPIO();
  MX_USART2_UART_Init();

  pinMode(2, INPUT_PULLUP);

  //noInterrupts();
  attachInterrupt(digitalPinToInterrupt(2), nextColor, RISING);

  Serial.begin(9600);
  Serial.println("Enter R, G or B to toggle LEDs. Enter color name to change color.");
}

void loop()
{  
  if (Serial.available() > 0)
  {
    String input = Serial.readStringUntil('\n');
    input.trim();
    input.toUpperCase();

    usePWM = false;

    if (input == "R")
    {
      changeColor(color^4);
    }
    else if (input == "G")
    {
      changeColor(color^2);
    }
    else if (input == "B")
    {
      changeColor(color^1);
    }
    else if (input == "BLUE")
    {
      changeColor(1);
    }
    else if (input == "GREEN")
    {
      changeColor(2);
    }
    else if (input == "CYAN")
    {
      changeColor(3);
    }
    else if (input == "RED")
    {
      changeColor(4);
    }
    else if (input == "MAGENTA")
    {
      changeColor(5);
    }
    else if (input == "YELLOW")
    {
      changeColor(6);
    }
    else if (input == "WHITE")
    {
      changeColor(7);
    }
    else if (input == "BLACK")
    {
      changeColor(8);
    }
    else
    {
       if (input.charAt(0) == '#')
       {
        input.remove(0, 1);
    }
    if (input.length() == 6)
    {
      uint32_t value = strtol(input.c_str(), NULL, 16);

    uint32_t inputRedBrightness = (value >> 16) & 0xFF;
    uint32_t inputGreenBrightness = (value >> 8) & 0xFF;
    uint32_t inputBlueBrightness = value & 0xFF;

    Serial.print("Red brightness: ");
    Serial.println(inputRedBrightness);
    Serial.print("Green brightness: ");
    Serial.println(inputGreenBrightness);
    Serial.print("Blue brightness: ");
    Serial.println(inputBlueBrightness);

    changeColorHEX(inputRedBrightness, inputGreenBrightness, inputBlueBrightness);
    usePWM = true;
    }
    else
    {
      Serial.println("Invalid input");
    }
    }
  }
  
  if (usePWM)
  {
    runPWM();
  }
  else
  {
    delay(1000);
  }
}

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

  /** Configure the main internal regulator output voltage
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** Initializes the RCC Oscillators according to the specified parameters
    in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLLMUL_4;
  RCC_OscInitStruct.PLL.PLLDIV = RCC_PLLDIV_2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
                                | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART2;
  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}


/**
    @brief USART2 Initialization Function
    @param None
    @retval None
*/
static void MX_USART2_UART_Init(void)
{
  __HAL_RCC_GPIOA_CLK_ENABLE();
  /**USART2 GPIO Configuration
    PA2     ------> USART2_TX
    PA15     ------> USART2_RX
  */
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  GPIO_InitStruct.Pin = VCP_TX_Pin | VCP_RX_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF4_USART2;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }

  __HAL_RCC_USART2_CLK_ENABLE();
}

// The following makes printf() write to USART2:

#define STDOUT_FILENO   1
#define STDERR_FILENO   2

int _write(int file, uint8_t *ptr, int len)
{
  switch (file)
  {
    case STDOUT_FILENO:
      HAL_UART_Transmit(&huart2, ptr, len, HAL_MAX_DELAY);
      break;

    case STDERR_FILENO:
      HAL_UART_Transmit(&huart2, ptr, len, HAL_MAX_DELAY);
      break;

    default:
      return -1;
  }

  return len;
}