_NXP LPC1000_ /* This function resets some microcontroller peripherals to reset

   hardware configuration to ensure that the USB In-System Programming module

   will work properly. It is normally called from reset and assumes some reset

   configuration settings for the MCU.

   Some of the peripheral configurations may be redundant in your specific

   project.

*/

void ReinvokeISP(void)

{

      /* make sure USB clock is turned on before calling ISP */

      LPC_SYSCON->SYSAHBCLKCTRL |= 0x04000;

      /* make sure 32-bit Timer 1 is turned on before calling ISP */

      LPC_SYSCON->SYSAHBCLKCTRL |= 0x00400;

      /* make sure GPIO clock is turned on before calling ISP */

      LPC_SYSCON->SYSAHBCLKCTRL |= 0x00040;

      /* make sure IO configuration clock is turned on before calling ISP */

      LPC_SYSCON->SYSAHBCLKCTRL |= 0x10000;

      /* make sure AHB clock divider is 1:1 */

      LPC_SYSCON->SYSAHBCLKDIV = 1;

      

      /* Send Reinvoke ISP command to ISP entry point*/

      command[0] = 57;

      

      /* Set stack pointer to ROM value (reset default) This must be the last

       piece of code executed before calling ISP, because most C expressions

       and function returns will fail after the stack pointer is changed. */

      __set_MSP(*((uint32_t *)0x1FFF0000)); /* inline asm function */

      

      /* Enter ISP. We call "iap_entry" to enter ISP because the ISP entry is done

       through the same command interface as IAP. */

      iap_entry(command, result);

      // Not supposed to come back!

}



/* Bit access of uint32 */

unsigned char GetUInt32BitValue(unsigned int source, unsigned char bitIndex)

{

      unsigned char value;

      //value = (unsigned char)((source >> bitIndex) & 0x00000001); this take more spaces than below

      source = source >> bitIndex;

      value = (unsigned char)(source & 0x00000001);

      return value;

}



/* When connect to a PC, wait until user presses the boot buttons */

void BootloaderRequest(void)

{

      unsigned int key;

      key = GetUInt32BitValue(LPC_GPIO0->DATA, 3);

      // key = 1, then the device connects to PC

      if(key == 1)

      {

            //key = GetUInt32BitValue(LPC_GPIO0->DATA, 1);

            key = GetUInt32BitValue(LPC_GPIO2->DATA, 11);

            // key = 0, then the boot key has been pressed

            if(key == 0)

            {

                  GPIOSetValue( 0, 2, 1); // turn on LED5



                  /* Disable SYSTICK timer and interrupt before calling into ISP */

                  SysTick->CTRL &= ~(SYSTICK_ENABLE | SYSTICK_TICKINT);



                  /* Start ISP */

                  ReinvokeISP();

            }

      }

}



int main (void)

{

      /* for delay loop */

      volatile int n;

      

      SystemInit();



      /* Initialize input port pins */

      LPC_IOCON->;PIO0_2 = 0x10;           //LED5, Pull-up resistor enabled

      GPIOSetDir( 0, 2, 1);

      /* Init */

      LPC_IOCON->;PIO0_1 &= ~0x1F;               //Inactive (no pull-down/pull-up resistor enabled)    PIO0_1 -> DTH0033 boot button

      LPC_IOCON->;PIO0_3 &= ~0x1F;             //Inactive (no pull-down/pull-up resistor enabled)  PIO0_3 -> DTH0033 USB_VBUS

      LPC_IOCON->;PIO2_11 &= ~0x1F;        //Inactive (no pull-down/pull-up resistor enabled)      PIO2_11 -> DTH0033 SW3 button



      GPIOSetValue( 0, 2, 0);         //LED5 is off at the beginning until user press SW3 button (PIO2_11)

      

      while (1)

      {

            /* Check SW3 button has been pressed? */

            BootloaderRequest();

      }

}