main.c

lpc2200 i2c 代码分析,希望大家指导

/******************************************************************************
 *
 * A simple program which sends a greeting to UART0, then echos
 * characters on UART0 and blinks an LED every 1/2 second.
 * from: Bill Knight, R O SoftWare <[e-mail]>
 * ----------------------------------------------------------------------------
 *
 * - Adapted to the Olimex LPC-P2106 demo-board (Philips LPC2106).
 * - Sends message if button/switch on demo-board is hit.
 * - Slightly modified and extended as WinARM demo-application.
 * by Martin THOMAS <[e-mail]>
 *
 * $RCSfile: $
 * $Revision: $
 *
 *****************************************************************************/
#include "types.h"
#include "LPC210x.h"
#include "config.h"
#include "armVIC.h"
#include "sysTime.h"
#include "uart.h"

/******************************************************************************
 *
 * Function Name: lowInit()
 *
 * Description:
 *    This function starts up the PLL then sets up the GPIO pins before
 *    waiting for the PLL to lock.  It finally engages the PLL and
 *    returns
 *
 * Calling Sequence: 
 *    void
 *
 * Returns:
 *    void
 *
 *****************************************************************************/
static void lowInit(void)
{
  // set PLL multiplier & divisor.
  // values computed from config.h
  PLLCFG = PLLCFG_MSEL | PLLCFG_PSEL;

  // enable PLL
  PLLCON = PLLCON_PLLE;
  PLLFEED = 0xAA;                       // Make it happen.  These two updates
  PLLFEED = 0x55;                       // MUST occur in sequence.

  // setup the parallel port pin
  IOCLR = PIO_ZERO_BITS;                // clear the ZEROs output
  IOSET = PIO_ONE_BITS;                 // set the ONEs output
  IODIR = PIO_OUTPUT_BITS;              // set the output bit direction

  // wait for PLL lock
  while (!(PLLSTAT & PLLSTAT_LOCK))
    continue;

  // enable & connect PLL
  PLLCON = PLLCON_PLLE | PLLCON_PLLC;
  PLLFEED = 0xAA;                       // Make it happen.  These two updates
  PLLFEED = 0x55;                       // MUST occur in sequence.

  // setup & enable the MAM
  MAMTIM = MAMTIM_CYCLES;
  MAMCR = MAMCR_FULL;

  // set the peripheral bus speed
  // value computed from config.h
  VPBDIV = VPBDIV_VALUE;                // set the peripheral bus clock speed
}

/******************************************************************************
 *
 * Function Name: sysInit()
 *
 * Description:
 *    This function is responsible for initializing the program
 *    specific hardware
 *
 * Calling Sequence: 
 *    void
 *
 * Returns:
 *    void
 *
 *****************************************************************************/
static void sysInit(void)
{
  lowInit();                            // setup clocks and processor port pins

  // set the interrupt controller defaults
#if defined(RAM_RUN)
  MEMMAP = MEMMAP_SRAM;                 // map interrupt vectors space into SRAM
#elif defined(ROM_RUN)
  MEMMAP = MEMMAP_FLASH;                // map interrupt vectors space into FLASH
#else
#error RUN_MODE not defined!
#endif
  VICIntEnClear = 0xFFFFFFFF;           // clear all interrupts
  VICIntSelect = 0x00000000;            // clear all FIQ selections
  VICDefVectAddr = (uint32_t)reset;     // point unvectored IRQs to reset()

//  wdtInit();                            // initialize the watchdog timer
  initSysTime();                        // initialize the system timer
  uart0Init(UART_BAUD(HOST_BAUD), UART_8N1, UART_FIFO_8); // setup the UART
}

/******************************************************************************
 *
 * Function Name: button_state()
 *
 * Description:
 *    This function checks if a key has been pressed. Assumes
 *    key to be "active low" (PIN-Bit==0 -> pressed). Does
 *    debouncing for given debounce time-difference
 *
 * Calling Sequence: 
 *    GPIO-Initialisation for Inputs
 *
 * Returns:
 *    -1 : key changed or bouncing
 *     0 : key released
 *     1 : key pressed
 *
 *****************************************************************************/
#define KEY_DEBOUNCE FIFTY_MS
static int button_state(void)
{
	static uint32_t lastchangetime;
	static boolean  laststate=FALSE;
	boolean actstate;
	
	actstate = (IOPIN & SW1_BIT) ? FALSE : TRUE; // TRUE if pressed (active low)
	
	if (laststate != actstate) {
		lastchangetime = getSysTICs();
		laststate = actstate;
	}
	else {
		if (getElapsedSysTICs(lastchangetime) > KEY_DEBOUNCE) {
			if (actstate) return 1;
			else return 0;
		}
	}
	return -1; // changed or bouncing
}

/******************************************************************************
 *
 * Function Name: main()
 *
 * Description:
 *    This function is the program entry point.  After initializing the
 *    system, it sends a greeting out UART0 then enters an endless loop
 *    echoing chracters on the UART and blinking an LED every half
 *    second.
 *
 * Calling Sequence: 
 *    void
 *
 * Returns:
 *    void
 *
 *****************************************************************************/
int main(void)
{
  uint32_t startTime;
  boolean lock=FALSE;
  
  sysInit();
#if defined(UART0_TX_INT_MODE) || defined(UART0_RX_INT_MODE)
  enableIRQ();
#endif
  startTime = getSysTICs();
  
  uart0Puts("\r\nHello World!\r\n");
  uart0Puts("(a WinARM Demo-Application based on code from R O Software)\r\n\r\n");

  for (;;)
    {
    do
      {
      int ch;

      if ((ch = uart0Getch()) >= 0) {
	    uart0Puts("the <");
        uart0Putch(ch);
		uart0Puts("> key has been pressed\r\n");
	  }
	
	  // send button-pressed string only once if hit
	  if (button_state()==0) lock=FALSE; // release lock if button is released
	  if ((button_state()==1) && !lock)  
		{
		uart0Puts("\r\nButton Pressed!\r\n");
		lock=TRUE;
		}
      }
    while (getElapsedSysTICs(startTime) < HALF_SEC);

	if (IOPIN & LED1_BIT) IOCLR = LED1_BIT;
	else IOSET = LED1_BIT; 

    startTime += HALF_SEC;
    }

  return 0;
  
}