Content originally posted in LPCWare by Lobisomem on Thu Feb 27 12:13:37 MST 2014
Hi all !!
Please, take a look at the following code:
void DMA_IRQHandler(void)
{
__asm volatile("nop"::);
}
//-----------------------------------------------------------------------------
void spi_init()
{
//---------------------------
//- P1.20 -> shift CLK -
//---------------------------
// Put pin as third alternate func
PINSEL3 |= (0x03 << 8);
// Put the pull up resistor
PINMODE3 &= ~(0x03 << 8);
//---------------------------
//- P1.23 -> MISO -
//---------------------------
// Put pin as third alternate func
PINSEL3 |= (0x03 << 14);
// Put the pull up resistor
PINMODE3 &= ~(0x03 << 14);
//---------------------------
//- P1.24 -> MOSI -
//---------------------------
// Put pin as third alternate func
PINSEL3 |= (0x03 << 16);
// Put the pull up resistor
PINMODE3 &= ~(0x03 << 16);
// ----------------------------------
// -------- SSP0 -----------
// ----------------------------------
// Turn on the SSP0 clock
PCONP |= (1 << 21);
// Select the peripheral clock
// Put SSP0 feed clock = (System clock / 1)
PCLKSEL1 &= ~(0x03 << 10);
PCLKSEL1 |= (0x01 << 10);
// Put 16 bits data transfer
// Pre-scaler = 0
LPC_SSP0->CR0 = 0x00Cf;
// Enable the controller
LPC_SSP0->CR1 |= (1 << 1);
// Set the pre scaler
LPC_SSP0->CPSR = 8;
// Enable the RX FIFO to generate DMA request
LPC_SSP0->DMACR = 0x1;
}
//-----------------------------------------------------------------------------
void dma_init(void)
{
// Turn DMA on
PCONP |= (1 << 29);
// Enable the DMA
LPC_GPDMA->DMACConfig = 1;
while ( !(LPC_GPDMA->DMACConfig & 0x01) );
// Clear any pending interrupt
LPC_GPDMA->DMACIntTCClear = 1;
// Enable the interrupt on NVIC
NVIC_EnableIRQ(DMA_IRQn);
// Set source address
LPC_GPDMACH0->DMACCSrcAddr = (uint32_t)&LPC_SSP0->DR;
// Set the destination address
LPC_GPDMACH0->DMACCDestAddr = (uint32_t)dmaBuffer;
// No linked list
LPC_GPDMACH0->DMACCLLI = 0;
// Set the length of the transfer
// Make destination auto increment
// Enable the terminal count interrupt
LPC_GPDMACH0->DMACCControl = 1 | (1<<27) | (1<<31);
// Select SSP0 RX DMA request
LPC_GPDMACH0->DMACCConfig = (1<<1);
// Peripheral to memory transfer
LPC_GPDMACH0->DMACCConfig |= (2<<11);
// Set error interrupt
LPC_GPDMACH0->DMACCConfig |= (1<<14);
// Set terminal count interrupt
LPC_GPDMACH0->DMACCConfig |= (1<<15);
// Turn Channel 0 on
LPC_GPDMACH0->DMACCConfig |= 1;
}
//-----------------------------------------------------------------------------
int main(void)
{
//system_setSysTicTimerTo1ms();
spi_init();
dma_init();
// Write to data reg to generate clock
LPC_SSP0->DR = 0x00;
while(1) {
}
return 0 ;
}
Well, as one may observ, I am trying to get a byte from an off-chip ADC conected to the SSP0. And I am trying to make the transfer tho memory by DMA. The thing is ... it is not working ! The DMA never generates the interrupt. Can you help me and show me what I am doing wrong ?
Best regards
