#include <stdint.h>
#include <stdio.h>
#include "stm32f30x_conf.h"
#include "usart.h"

#define MAX_DATA 4
unsigned char rxData[MAX_DATA+1];
uint8_t rxDataCount = 0;

static USART_InitTypeDef USART_InitStructure;
static GPIO_InitTypeDef GPIO_InitStructure;
static NVIC_InitTypeDef NVIC_InitStructure;

void USART2_Init(uint32_t speed)
{
    /*!< At this stage the microcontroller clock setting is already configured,
               this is done through SystemInit() function which is called from startup
               file (startup_stm32f37x.s) before to branch to application main.
               To reconfigure the default setting of SystemInit() function, refer to
               system_stm32f37x.c file
     */
    /* USARTx configured as follow:
                - BaudRate = 115200 baud
                - Word Length = 8 Bits
                - One Stop Bit
                - No parity
                - Hardware flow control disabled (RTS and CTS signals)
                - Receive and transmit enabled
     */
    USART_InitStructure.USART_BaudRate = speed;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

    /* Enable GPIO clock */
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

    /* Enable USART clock */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    /* Connect PXx to USARTx_Tx */
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_7);

    /* Connect PXx to USARTx_Rx */
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_7);

    /* Configure USART Tx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* Configure USART Rx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* USART configuration */
    USART_Init(USART2, &USART_InitStructure);

    /* Here the USART2 receive interrupt is enabled
     * and the interrupt controller is configured
     * to jump to the USART2_IRQHandler() function
     * if the USART2 receive interrupt occurs
     */
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE); // enable the USART2 receive interrupt

    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;        // we want to configure the USART2 interrupts
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;// this sets the priority group of the USART2 interrupts
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;       // this sets the subpriority inside the group
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;          // the USART2 interrupts are globally enabled
    NVIC_Init(&NVIC_InitStructure);                          // the properties are passed to the NVIC_Init function which takes care of the low level stuff

    /* Enable USART */
    USART_Cmd(USART2, ENABLE);
}

// this is the interrupt request handler (IRQ) for ALL USART2 interrupts
void USART2_IRQHandler(void){

    // check if the USART2 receive interrupt flag was set
    if( USART_GetITStatus(USART2, USART_IT_RXNE) != RESET ){
        rxData[rxDataCount++] = USART_ReceiveData(USART2) & 0x7F;
        if (rxDataCount >= MAX_DATA) rxDataCount = 0;
    } else if(USART_GetITStatus(USART2, USART_IT_ORE) != RESET ){
        USART_ClearFlag(USART2, USART_FLAG_ORE);
    } else if(USART_GetITStatus(USART2, USART_IT_NE) != RESET ){
        USART_ClearFlag(USART2, USART_FLAG_NE);
    } else if(USART_GetITStatus(USART2, USART_IT_FE) != RESET ){
        USART_ClearFlag(USART2, USART_FLAG_FE);
    } else if(USART_GetITStatus(USART2, USART_IT_PE) != RESET ){
        USART_ClearFlag(USART2, USART_FLAG_PE);
    }
}

/**
 * @brief  Retargets the C library printf function to the USART.
 *          Overwrite __io_putchar function used by printf
 * @param  None
 * @retval None
 */
PUTCHAR_PROTOTYPE
{
    /* Put character on the serial line */
    USART2->TDR = (ch & (uint16_t)0x01FF);

    /* Loop until transmit data register is empty */
    while ((USART2->ISR & USART_FLAG_TXE) == (uint16_t) RESET);

    return ch;
}