ADC_HandleTypeDef hadc1;

void SystemClock_Config(void) // This function is declared WEAK in the stm32duino code,
                              // we can redefine it here and it will be used instead in init.
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  HAL_PWREx_ControlVoltageScaling(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.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

extern "C" void HAL_ADC_MspInit(ADC_HandleTypeDef* hadc)    // This function is called from within
                                                            // MX_ADC1_Init
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(hadc->Instance==ADC1)
  {
    /* Peripheral clock enable */
    __HAL_RCC_ADC_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**ADC1 GPIO Configuration
    PA1     ------> ADC1_IN1
    */
    GPIO_InitStruct.Pin = GPIO_PIN_1;
    GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  }
}

/**
  * @brief ADC1 Initialization Function
  * @param None
  * @retval None
  */
static void MX_ADC1_Init(void)
{
  ADC_ChannelConfTypeDef sConfig = {0};

  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
  */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.LowPowerAutoPowerOff = DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.DMAContinuousRequests = ENABLE;
  hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
  hadc1.Init.SamplingTimeCommon1 = ADC_SAMPLETIME_1CYCLE_5;     // Highest possible sampling speed
  hadc1.Init.SamplingTimeCommon2 = ADC_SAMPLETIME_1CYCLE_5;     // Ensures data is updated on every main loop
  hadc1.Init.OversamplingMode = DISABLE;
  hadc1.Init.TriggerFrequencyMode = ADC_TRIGGER_FREQ_HIGH;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }

  /** Configure Regular Channel
  */
  sConfig.Channel = ADC_CHANNEL_1;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLINGTIME_COMMON_1;
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
}

#define VOLTAGE_REFERENCE 3300
#define MAX_ANALOG_READ   4096
#define VOLTAGE_COEFFICIENT (int)(1000*((float)VOLTAGE_REFERENCE/MAX_ANALOG_READ))

unsigned int time_since_start = 0;
unsigned int value = 0;


void setup() {
  pinMode (D12, OUTPUT);            // initialize D12 (PB_4) as an output.  
                                    // ADC pin initialization happens in init code.

  analogWriteFrequency(1000);       // PWM freq
  analogWrite(D12, 128);            // Duty cycle = 128/256 = 50%
  
  MX_ADC1_Init();                   // Initialize ADC1

    /* Run the ADC calibration */
  if (HAL_ADCEx_Calibration_Start(&hadc1) != HAL_OK) {
    /* Calibration Error */
    Error_Handler();
  }


  Serial.begin(2000000);            
  Serial.print("$$TSTM32DUINO");    // Intro message 

  HAL_ADC_Start(&hadc1);            // Start contiunous sampling
}

void loop() {
  value = HAL_ADC_GetValue(&hadc1)*VOLTAGE_COEFFICIENT;
  time_since_start = micros();
  
  Serial.write("$$Puu4", 6);
  Serial.write((unsigned char *)&time_since_start, 4);
  Serial.write("uu4", 3);
  Serial.write(((unsigned char*)&value), 4);
  Serial.write(";", 1);
}