uart.c

[詳解]

/*****************************************************************************
 *   uart.c:  UART API file for NXP LPC13xx Family Microprocessors
 *
 *   Copyright(C) 2008, NXP Semiconductor
 *   All rights reserved.
 *
 *   History
 *   2008.08.21  ver 1.00    Preliminary version, first Release
 *
******************************************************************************/
#include "LPC13xx.h"
#include "uart.h"


// CodeRed - change for CMSIS 1.3
#define SystemFrequency SystemCoreClock

volatile uint32_t UARTStatus;
volatile uint8_t  UARTTxEmpty = 1;
volatile uint8_t  UARTBuffer[BUFSIZE];
volatile uint32_t UARTCount = 0;

/*****************************************************************************
** Function name:       UART_IRQHandler
**
** Descriptions:        UART interrupt handler
**
** parameters:          None
** Returned value:      None
** 
*****************************************************************************/
void UART_IRQHandler(void)
{
  uint8_t IIRValue, LSRValue;
  uint8_t Dummy = Dummy;

  IIRValue = LPC_UART->IIR;
    
  IIRValue >>= 1;           /* skip pending bit in IIR */
  IIRValue &= 0x07;         /* check bit 1~3, interrupt identification */
  if (IIRValue == IIR_RLS)      /* Receive Line Status */
  {
    LSRValue = LPC_UART->LSR;
    /* Receive Line Status */
    if (LSRValue & (LSR_OE | LSR_PE | LSR_FE | LSR_RXFE | LSR_BI))
    {
      /* There are errors or break interrupt */
      /* Read LSR will clear the interrupt */
      UARTStatus = LSRValue;
      Dummy = LPC_UART->RBR;    /* Dummy read on RX to clear 
                                interrupt, then bail out */
      return;
    }
    if (LSRValue & LSR_RDR) /* Receive Data Ready */            
    {
      /* If no error on RLS, normal ready, save into the data buffer. */
      /* Note: read RBR will clear the interrupt */
      UARTBuffer[UARTCount++] = LPC_UART->RBR;
      if (UARTCount == BUFSIZE)
      {
        UARTCount = 0;      /* buffer overflow */
      } 
    }
  }
  else if (IIRValue == IIR_RDA) /* Receive Data Available */
  {
    /* Receive Data Available */
    UARTBuffer[UARTCount++] = LPC_UART->RBR;
    if (UARTCount == BUFSIZE)
    {
      UARTCount = 0;        /* buffer overflow */
    }
  }
  else if (IIRValue == IIR_CTI) /* Character timeout indicator */
  {
    /* Character Time-out indicator */
    UARTStatus |= 0x100;        /* Bit 9 as the CTI error */
  }
  else if (IIRValue == IIR_THRE)    /* THRE, transmit holding register empty */
  {
    /* THRE interrupt */
    LSRValue = LPC_UART->LSR;       /* Check status in the LSR to see if
                                valid data in U0THR or not */
    if (LSRValue & LSR_THRE)
    {
      UARTTxEmpty = 1;
    }
    else
    {
      UARTTxEmpty = 0;
    }
  }
  return;
}

/*****************************************************************************
** Function name:       UARTInit
**
** Descriptions:        Initialize UART0 port, setup pin select,
**              clock, parity, stop bits, FIFO, etc.
**
** parameters:          UART baudrate
** Returned value:      None
** 
*****************************************************************************/
void UARTInit(uint32_t baudrate)
{
  uint32_t Fdiv;
  uint32_t regVal;

  UARTTxEmpty = 1;
  UARTCount = 0;
  
  NVIC_DisableIRQ(UART_IRQn);

  LPC_IOCON->PIO1_6 &= ~0x07;    /*  UART I/O config */
  LPC_IOCON->PIO1_6 |= 0x01;     /* UART RXD */
  LPC_IOCON->PIO1_7 &= ~0x07;   
  LPC_IOCON->PIO1_7 |= 0x01;     /* UART TXD */
  /* Enable UART clock */
  LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
  LPC_SYSCON->UARTCLKDIV = 0x1;     /* divided by 1 */

  LPC_UART->LCR = 0x83;             /* 8 bits, no Parity, 1 Stop bit */
  regVal = LPC_SYSCON->UARTCLKDIV;
  Fdiv = (((SystemFrequency/LPC_SYSCON->SYSAHBCLKDIV)/regVal)/16)/baudrate ;    /*baud rate */

  LPC_UART->DLM = Fdiv / 256;                           
  LPC_UART->DLL = Fdiv % 256;
  LPC_UART->LCR = 0x03;     /* DLAB = 0 */
  LPC_UART->FCR = 0x07;     /* Enable and reset TX and RX FIFO. */

  /* Read to clear the line status. */
  regVal = LPC_UART->LSR;

  /* Ensure a clean start, no data in either TX or RX FIFO. */
// CodeRed - added parentheses around comparison in operand of &
  while (( LPC_UART->LSR & (LSR_THRE|LSR_TEMT)) != (LSR_THRE|LSR_TEMT) );
  while ( LPC_UART->LSR & LSR_RDR )
  {
    regVal = LPC_UART->RBR; /* Dump data from RX FIFO */
  }
 
  /* Enable the UART Interrupt */
  NVIC_EnableIRQ(UART_IRQn);

#if TX_INTERRUPT
  LPC_UART->IER = IER_RBR | IER_THRE | IER_RLS; /* Enable UART interrupt */
#else
  LPC_UART->IER = IER_RBR | IER_RLS;    /* Enable UART interrupt */
#endif
  return;
}

/*****************************************************************************
** Function name:       UARTSend
**
** Descriptions:        Send a block of data to the UART 0 port based
**              on the data length
**
** parameters:      buffer pointer, and data length
** Returned value:  None
** 
*****************************************************************************/
void UARTSend(uint8_t *BufferPtr, uint32_t Length)
{
  LPC_UART->IER = IER_THRE | IER_RLS;               // Disable RBR

  while ( Length != 0 )
  {
      /* THRE status, contain valid data */
#if !TX_INTERRUPT
      while ( !(LPC_UART->LSR & LSR_THRE) );
      LPC_UART->THR = *BufferPtr;
#else
      /* Below flag is set inside the interrupt handler when THRE occurs. */
      while ( !(UARTTxEmpty & 0x01) );
      LPC_UART->THR = *BufferPtr;
      UARTTxEmpty = 0;  /* not empty in the THR until it shifts out */
#endif
      BufferPtr++;
      Length--;
  }

  LPC_UART->IER = IER_THRE | IER_RLS | IER_RBR; // Re-enable RBR
  return;
}


/******************************************************************************
**                            End Of File
******************************************************************************/