File content as of revision 0:ae90ac40c518:

#include "mbed.h"

DigitalOut myled(LED1);

Serial pc(p9, p10);

void initStartLogic (unsigned int p0, unsigned int p1) {
    LPC_SYSCON->SYSAHBCLKCTRL |= (1<<24);
    LPC_GPIO_GROUP_INT1->PORT_POL[0] = 0;
    LPC_GPIO_GROUP_INT1->PORT_POL[1] = 0;
    LPC_GPIO_GROUP_INT1->PORT_ENA[0] = p0;
    LPC_GPIO_GROUP_INT1->PORT_ENA[1] = p1;
    LPC_GPIO_GROUP_INT1->CTRL = 0; // Edge, OR, INT

    LPC_SYSCON->PDAWAKECFG = LPC_SYSCON->PDRUNCFG;

    LPC_SYSCON->STARTERP1 = (1<<21); // start logic GROUP1
    NVIC_ClearPendingIRQ(GINT1_IRQn);
    NVIC_EnableIRQ(GINT1_IRQn);
}

unsigned int setSystemMainClock(unsigned short S) {
    
    if ((S & 0x03) == 3) {
        LPC_SYSCON->PDRUNCFG     &= ~(1 << 5);          /* Power-up System Osc      */
        for (int i = 0; i < 200; i++) __NOP();
    }
    
    LPC_SYSCON->MAINCLKSEL    = S;     /* Select PLL Clock Output  */
    LPC_SYSCON->MAINCLKUEN    = 0x01;               /* Update MCLK Clock Source */
    LPC_SYSCON->MAINCLKUEN    = 0x00;               /* Toggle Update Register   */
    LPC_SYSCON->MAINCLKUEN    = 0x01;
    while (!(LPC_SYSCON->MAINCLKUEN & 0x01));       /* Wait Until Updated       */

    if ((S & 0x03) == 0) {
        LPC_SYSCON->PDRUNCFG     |= (1 << 5);          /* Power-down System Osc      */
    }

    SystemCoreClockUpdate();
    return SystemCoreClock;
}

unsigned int setSystemFrequency(unsigned short M, unsigned short P) {
    LPC_SYSCON->SYSPLLCTRL = ((P & 0x03)<<5) | (M & 0x1f);
    while (!(LPC_SYSCON->SYSPLLSTAT & 0x01)); // Wait Until PLL Locked
    SystemCoreClockUpdate();
    return SystemCoreClock;
}

void DeepSleep () {
    SCB->SCR |= (1<<2);
    __WFI();
}

void Sleep () {
    __WFI();
}

extern "C"
void GINT1_IRQHandler(void) {
    LPC_GPIO_GROUP_INT1->CTRL |= (1<<0);
    NVIC_ClearPendingIRQ(GINT0_IRQn);
}

int main() {
    int i;

//    setSystemFrequency(3, 1); // M, P, 48MHz

    pc.baud(9600);
    pc.printf("low power\r\n");

    for (i = 0; i < 6; i ++) {
        myled = !myled;
        wait(0.5);
    }

    initStartLogic((1<<8), 0);

loop:
    pc.printf("enter sleep\r\n");
    wait_ms(10);
    setSystemMainClock(0);

    DeepSleep();

    setSystemMainClock(3);

    pc.printf("wake up\r\n");
    for (i = 0; i < 6; i ++) {
        myled = !myled;
        wait(0.5);
    }

    goto loop;

}