ssp.c

[詳解]

/*****************************************************************************
 *   ssp.c:  SSP C file for NXP LPC13xx Family Microprocessors
 *
 *   Copyright(C) 2008, NXP Semiconductor
 *   All rights reserved.
 *
 *   History
 *   2008.07.20  ver 1.00    Preliminary version, first Release
 *
*****************************************************************************/
#include "LPC13xx.h"                    /* LPC13xx Peripheral Registers */
#include "ssp.h"

/* statistics of all the interrupts */
volatile uint32_t interruptRxStat = 0;
volatile uint32_t interruptOverRunStat = 0;
volatile uint32_t interruptRxTimeoutStat = 0;

/*****************************************************************************
** Function name:               SSP_IRQHandler
**
** Descriptions:                SSP port is used for SPI communication.
**                                              SSP interrupt handler
**                                              The algorithm is, if RXFIFO is at least half full,
**                                              start receive until it's empty; if TXFIFO is at least
**                                              half empty, start transmit until it's full.
**                                              This will maximize the use of both FIFOs and performance.
**
** parameters:                  None
** Returned value:              None
**
*****************************************************************************/
void SSP_IRQHandler(void)
{
  uint32_t regValue;

  regValue = LPC_SSP->MIS;
  if ( regValue & SSPMIS_RORMIS )       /* Receive overrun interrupt */
  {
        interruptOverRunStat++;
        LPC_SSP->ICR = SSPICR_RORIC;            /* clear interrupt */
  }
  if ( regValue & SSPMIS_RTMIS )        /* Receive timeout interrupt */
  {
        interruptRxTimeoutStat++;
        LPC_SSP->ICR = SSPICR_RTIC;             /* clear interrupt */
  }

  /* please be aware that, in main and ISR, CurrentRxIndex and CurrentTxIndex
  are shared as global variables. It may create some race condition that main
  and ISR manipulate these variables at the same time. SSPSR_BSY checking (polling)
  in both main and ISR could prevent this kind of race condition */
  if ( regValue & SSPMIS_RXMIS )        /* Rx at least half full */
  {
        interruptRxStat++;              /* receive until it's empty */
  }
  return;
}

/*****************************************************************************
** Function name:               SSPInit
**
** Descriptions:                SSP port initialization routine
**
** parameters:                  None
** Returned value:              None
**
*****************************************************************************/
void SSPInit( void )
{
     uint8_t i, Dummy=Dummy;

      LPC_SYSCON->PRESETCTRL |= (0x1<<0);
      LPC_SYSCON->SYSAHBCLKCTRL |= (1<<11);
      LPC_SYSCON->SSPCLKDIV = 0x0f;                 /* Divided by 2 */
      LPC_IOCON->PIO0_8           &= ~0x07; /*  SSP I/O config */
      LPC_IOCON->PIO0_8           |= 0x01;          /* SSP MISO */
      LPC_IOCON->PIO0_9           &= ~0x07;
      LPC_IOCON->PIO0_9           |= 0x01;          /* SSP MOSI */
    #ifdef __JTAG_DISABLED
      LPC_IOCON->SCKLOC = 0x00;
      LPC_IOCON->JTAG_TCK_PIO0_10 &= ~0x07;
      LPC_IOCON->JTAG_TCK_PIO0_10 |= 0x02;          /* SSP CLK */
    #endif

    #if 0
      /* On HummingBird 1(HB1), SSP CLK can be routed to different pins,
      other than JTAG TCK, it's either P2.11 func. 1 or P0.6 func. 2. */
      LPC_IOCON->SCKLOC = 0x01;
      LPC_IOCON->PIO2_11 = 0x01;/* P2.11 function 1 is SSP clock, need to combined
                                                            with IOCONSCKLOC register setting */
    #else
      LPC_IOCON->SCKLOC = 0x02;
      LPC_IOCON->PIO0_6 = 0x02;     /* P0.6 function 2 is SSP clock, need to combined
                                                            with IOCONSCKLOC register setting */
    #endif

    #if USE_CS
      LPC_IOCON->PIO0_2 &= ~0x07;
      LPC_IOCON->PIO0_2 |= 0x01;            /* SSP SSEL */
    #else
      LPC_IOCON->PIO0_2 &= ~0x07;           /* SSP SSEL is a GPIO pin */
      /* port0, bit 2 is set to GPIO output and high */
      LPC_GPIO0->DIR  |= (0x1<<2);     //Data Direction(1 output , 0 input)
      LPC_GPIO0->DATA |= (0x1<<2);

    #endif

      /* Set DSS data to 8-bit, Frame format SPI, CPOL = 0, CPHA = 0, and SCR is 15 */
      LPC_SSP->CR0 = 0x0707;
      //CPOL 6bit
      //LPC_SSP->CR0 |= (0x1<<6);
      //CPHA 7bit
      //LPC_SSP->CR0 &= ~(0x1<<7);


      /* SSPCPSR clock prescale register, master mode, minimum divisor is 0x02 */
      LPC_SSP->CPSR = 0x2;

      for ( i = 0; i < FIFOSIZE; i++ )
      {
            Dummy = LPC_SSP->DR;            /* clear the RxFIFO */
      }

      /* Enable the SSP Interrupt */
      NVIC_EnableIRQ(SSP_IRQn);

      /* Device select as master, SSP Enabled */
    #if LOOPBACK_MODE
      LPC_SSP->CR1 = SSPCR1_LBM | SSPCR1_SSE;
    #else
    #if SSP_SLAVE
      /* Slave mode */
      if ( LPC_SSP->CR1 & SSPCR1_SSE )
      {
            /* The slave bit can't be set until SSE bit is zero. */
            LPC_SSP->CR1 &= ~SSPCR1_SSE;
      }
      LPC_SSP->CR1 = SSPCR1_MS;             /* Enable slave bit first */
      LPC_SSP->CR1 |= SSPCR1_SSE;   /* Enable SSP */
    #else
      /* Master mode */
      LPC_SSP->CR1 = SSPCR1_SSE;
    #endif
    #endif
      /* Set SSPINMS registers to enable interrupts */
      /* enable all error related interrupts */
      LPC_SSP->IMSC = SSPIMSC_RORIM | SSPIMSC_RTIM;
      return;
}

/*****************************************************************************
** Function name:               SSPSend
**
** Descriptions:                Send a block of data to the SSP port, the
**                                              first parameter is the buffer pointer, the 2nd
**                                              parameter is the block length.
**
** parameters:                  buffer pointer, and the block length
** Returned value:              None
**
*****************************************************************************/
void SSPSend( uint8_t *buf, uint32_t Length )
{
  uint32_t i;
  uint8_t Dummy = Dummy;

  for ( i = 0; i < Length; i++ )
  {
        /* Move on only if NOT busy and TX FIFO not full. */
        while ( (LPC_SSP->SR & (SSPSR_TNF|SSPSR_BSY)) != SSPSR_TNF );
        LPC_SSP->DR = *buf;
        buf++;
#if !LOOPBACK_MODE
        while ( (LPC_SSP->SR & (SSPSR_BSY|SSPSR_RNE)) != SSPSR_RNE );
        /* Whenever a byte is written, MISO FIFO counter increments, Clear FIFO
        on MISO. Otherwise, when SSP0Receive() is called, previous data byte
        is left in the FIFO. */
        Dummy = LPC_SSP->DR;
#else
        /* Wait until the Busy bit is cleared. */
        while ( LPC_SSP->SR & SSPSR_BSY );
#endif
  }
  return; 
}

/*****************************************************************************
** Function name:               SSPReceive
** Descriptions:                the module will receive a block of data from
**                                              the SSP, the 2nd parameter is the block
**                                              length.
** parameters:                  buffer pointer, and block length
** Returned value:              None
**
*****************************************************************************/
void SSPReceive( uint8_t *buf, uint32_t Length )
{
  uint32_t i;

  for ( i = 0; i < Length; i++ )
  {
        /* As long as Receive FIFO is not empty, I can always receive. */
        /* If it's a loopback test, clock is shared for both TX and RX,
        no need to write dummy byte to get clock to get the data */
        /* if it's a peer-to-peer communication, SSPDR needs to be written
        before a read can take place. */
#if !LOOPBACK_MODE
#if SSP_SLAVE
        while ( !(LPC_SSP->SR & SSPSR_RNE) );
#else
        LPC_SSP->DR = 0xFF;
        /* Wait until the Busy bit is cleared */
        while ( (LPC_SSP->SR & (SSPSR_BSY|SSPSR_RNE)) != SSPSR_RNE );
#endif
#else
        while ( !(LPC_SSP->SR & SSPSR_RNE) );
#endif
        *buf = LPC_SSP->DR;
        buf++;

  }
  return; 
}


#ifdef debug
void readWhoAmI()
{
    uint8_t send_data[2];
    uint8_t receive_data[10];
    send_data[0] = 0x8f;
    send_data[1] = 0x8f;

    receive_data[0] = 0;

    LPC_GPIO0->DATA &= ~(0x1<<2);

    SSPSend( &send_data[0], 1 );
    SSPReceive( &receive_data[0], 2 );

    LPC_GPIO0->DATA |= (0x1<<2);

    myPrintfUSB("whoAmI %d %d %d \n",receive_data[0],receive_data[1],receive_data[2] );
}
#endif

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