#define HSE_VALUE ((uint32_t)8000000) /* STM32 discovery uses a 8Mhz external crystal */

#include "stm32f4xx_conf.h"
#include "stm32f4xx.h"
#include "stm32f4xx_gpio.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_exti.h"
#include "stm32f4xx_usart.h"
#include "usbd_cdc_core.h"
#include "usbd_usr.h"
#include "usbd_desc.h"
#include "usbd_cdc_vcp.h"
#include "usb_dcd_int.h"
#include "misc.h"

volatile uint32_t ticker, downTicker;

/*
 * The USB data must be 4 byte aligned if DMA is enabled. This macro handles
 * the alignment, if necessary (it's actually magic, but don't tell anyone).
 */
__ALIGN_BEGIN USB_OTG_CORE_HANDLE  USB_OTG_dev __ALIGN_END;


void init();
void ColorfulRingOfDeath(void);

/*
 * Define prototypes for interrupt handlers here. The conditional "extern"
 * ensures the weak declarations from startup_stm32f4xx.c are overridden.
 */
#ifdef __cplusplus
 extern "C" {
#endif

void SysTick_Handler(void);
void NMI_Handler(void);
void HardFault_Handler(void);
void MemManage_Handler(void);
void BusFault_Handler(void);
void UsageFault_Handler(void);
void SVC_Handler(void);
void DebugMon_Handler(void);
void PendSV_Handler(void);
void OTG_FS_IRQHandler(void);
void OTG_FS_WKUP_IRQHandler(void);






int main(void)
{
    SystemInit(); //Set up the system clocks
    init(); //Initialize USB, IO, SysTick

    //RCC
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); //Enable GPIO clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); //Enable UART clock



    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    //Tx
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource2,GPIO_AF_USART2);
    GPIO_InitStructure.GPIO_OType=GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
    GPIO_Init(GPIOA,&GPIO_InitStructure);

    //Rx
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource3,GPIO_AF_USART2);
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_3;
    GPIO_Init(GPIOA,&GPIO_InitStructure);

    //USART2
    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_Init(USART2, &USART_InitStructure);
    USART_Cmd(USART2, ENABLE); // Enable USART

    //NVIC
    NVIC_InitTypeDef NVIC_InitStructure;
    USART_ITConfig(USART2,USART_IT_RXNE,ENABLE);
    NVIC_InitStructure.NVIC_IRQChannel=USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority=0;
    NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    NVIC_EnableIRQ(USART2_IRQn);

    while (1)
        {
            if (500 == ticker)
            {
                GPIOD->BSRRH = GPIO_Pin_13;
            }
            else if (1000 == ticker)
            {
                ticker = 0;
                GPIOD->BSRRL = GPIO_Pin_13;
            }

            uint8_t theByte;
            if (VCP_get_char(&theByte))
            {
                while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);

                USART_SendData(USART2, theByte);

                while(USART_GetFlagStatus(USART2,USART_FLAG_TC)==RESET);

                GPIOD->BSRRL = GPIO_Pin_12;
                downTicker = 10;
            }
            if (0 == downTicker)
            {
                GPIOD->BSRRH = GPIO_Pin_12;
            }
        }
    return 0;
}


void init()
{

    GPIO_InitTypeDef LED_Config;
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    LED_Config.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13| GPIO_Pin_14| GPIO_Pin_15;
    LED_Config.GPIO_Mode = GPIO_Mode_OUT;
    LED_Config.GPIO_OType = GPIO_OType_PP;
    LED_Config.GPIO_Speed = GPIO_Speed_25MHz;
    LED_Config.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOD, &LED_Config);

    if (SysTick_Config(SystemCoreClock / 1000))
    {
        ColorfulRingOfDeath();
    }

    USBD_Init(&USB_OTG_dev,
                USB_OTG_FS_CORE_ID,
                &USR_desc,
                &USBD_CDC_cb,
                &USR_cb);
    return;
}

void ColorfulRingOfDeath(void)
{
    uint16_t ring = 1;
    while (1)
    {
        uint32_t count = 0;
        while (count++ < 500000);

        GPIOD->BSRRH = (ring << 12);
        ring = ring << 1;
        if (ring >= 1<<4)
        {
            ring = 1;
        }
        GPIOD->BSRRL = (ring << 12);
    }
}

void SysTick_Handler(void)
{
    ticker++;
    if (downTicker > 0)
    {
        downTicker--;
    }
}

void NMI_Handler(void)       {}
void HardFault_Handler(void) { ColorfulRingOfDeath(); }
void MemManage_Handler(void) { ColorfulRingOfDeath(); }
void BusFault_Handler(void)  { ColorfulRingOfDeath(); }
void UsageFault_Handler(void){ ColorfulRingOfDeath(); }
void SVC_Handler(void)       {}
void DebugMon_Handler(void)  {}
void PendSV_Handler(void)    {}

void OTG_FS_IRQHandler(void)
{
  USBD_OTG_ISR_Handler (&USB_OTG_dev);
}

void OTG_FS_WKUP_IRQHandler(void)
{
  if(USB_OTG_dev.cfg.low_power)
  {
    *(uint32_t *)(0xE000ED10) &= 0xFFFFFFF9 ;
    SystemInit();
    USB_OTG_UngateClock(&USB_OTG_dev);
  }
  EXTI_ClearITPendingBit(EXTI_Line18);
}

uint8_t usartGetChar(void)
{
while(USART_GetFlagStatus(USART2,USART_FLAG_RXNE)==RESET);
return USART_ReceiveData(USART2);
}

void USART2_IRQHandler(void)
{
    if(USART_GetITStatus(USART2,USART_IT_RXNE)!=RESET)
    {
        usartGetChar();
        VCP_put_char(USART2->DR);
    }
}