I'm working on this problem as well and would like to share results with others.

I didn't get very far... we ended up using blocking SPI. I am still interested though and would like to hear about progress you may have made.

volatile uint8_t data;

//interrupt handler
extern "C" void SPI_IRQHandler()
{
	uint32_t status_reg=0;

	//clear interrupt flag
	LPC_SPI->SPINT = 1<<0;

	status_reg = LPC_SPI->SPSR;

	if((status_reg & (1<<7)) == 1<<7)
		data = LPC_SPI->SPDR;
}



//SPI init call
void spi0_init(void)
{
    LPC_SC->PCONP |= (1<<8);                                //power up SPI
    LPC_SC->PCLKSEL0 |= (1<<16);                            //run SPI0 at 96MHz (prescale 1)
    
    //configure PIN-outs
    LPC_PINCON->PINSEL0 |= (0xC0000000);	            //SCK
    LPC_PINCON->PINSEL1 |= (3<<4) | (3<<2) | (3<<0);        //MISO, MOSI, SSEL
    LPC_PINCON->PINMODE0 |= (0x80000000);                   //no pull-up or down on SCK
    LPC_PINCON->PINMODE1 |= (2<<4) | (2<<2) | (2<<0);       //no pull-up or down on MISO, MOSI, SSEL

    //clock counter/prescaler setup
    LPC_SPI->SPCCR = 12;                                    //run SPI clock at 8MHz
    
    //interrupt enabled, MSB first, slave mode, SCK active high, first clock sampled, 8 bits per transfer
    LPC_SPI->SPCR = (8<<8) | (1<<7) | (0<<6) | (0<<5) | (0<<4) | (0<<3) | (0<<2) | (0<<0);   //(CPOL=0, CPHA=0)

    //enable interrupt
    NVIC_SetPriority(SPI_IRQn);
    NVIC_EnableIRQ(SPI_IRQn);
}

try this out, SPI on P0.15, P0.16, P0.17, P0.18 (check your mbed schematics for the corresponding board pins) <<code>> volatile uint8_t data; //interrupt handler extern "C" void SPI_IRQHandler() { uint32_t status_reg=0; //clear interrupt flag LPC_SPI->SPINT = 1<<0; status_reg = LPC_SPI->SPSR; if((status_reg & (1<<7)) == 1<<7) data = LPC_SPI->SPDR; } //SPI init call void spi0_init(void) { LPC_SC->PCONP |= (1<<8); //power up SPI LPC_SC->PCLKSEL0 |= (1<<16); //run SPI0 at 96MHz (prescale 1) //configure PIN-outs LPC_PINCON->PINSEL0 |= (0xC0000000); //SCK LPC_PINCON->PINSEL1 |= (3<<4) | (3<<2) | (3<<0); //MISO, MOSI, SSEL LPC_PINCON->PINMODE0 |= (0x80000000); //no pull-up or down on SCK LPC_PINCON->PINMODE1 |= (2<<4) | (2<<2) | (2<<0); //no pull-up or down on MISO, MOSI, SSEL //clock counter/prescaler setup LPC_SPI->SPCCR = 12; //run SPI clock at 8MHz //interrupt enabled, MSB first, slave mode, SCK active high, first clock sampled, 8 bits per transfer LPC_SPI->SPCR = (8<<8) | (1<<7) | (0<<6) | (0<<5) | (0<<4) | (0<<3) | (0<<2) | (0<<0); //(CPOL=0, CPHA=0) //enable interrupt NVIC_SetPriority(SPI_IRQn); NVIC_EnableIRQ(SPI_IRQn); } <</code>> in your main loop, catch the SPI data byte by flagging a variable in the interrupt handler. also, you might want to pull-up your slave select line from the master SPI this assuming you are running your mbed at 96MHz

@Joshua: You might want to follow my new topic: http://mbed.org/forum/mbed/topic/3369/