Read ADC values using DMA in FRDM k64

oliviachristyva — Mon, 20 Mar 2017 07:29:38 GMT

Hi guys,

I am using FRDM K64 in MQX to read 32 values from ADC and find the avaerage of it using DMA.But i am not getting any reading at the buffer. when read from DMA.

This is my DMA setting.

void Set_Dma(void)
{
// setup the DMA channels ( CH0 = playback and CH1 = buffer transfer )
DMA_CR = 0
| DMA_CR_EDBG_MASK // Stall DMA transfers when debugger is halted (avoid noise)
; // no minor loop mapping

DMA_DCHPRI15 = 0; // just not to have same priorities
DMA_DCHPRI0 = 15; // cannot be pre-empeted, can pre-empt, highest priority

// fill the TCD area
DMA_TCD0_SADDR = (uint32_t)&ADC0_RA ;
DMA_TCD0_SOFF = 0; // 2 byte offset
DMA_TCD0_ATTR = DMA_ATTR_SMOD(0) | DMA_ATTR_SSIZE(1) | DMA_ATTR_DMOD(0) | DMA_ATTR_DSIZE(1); // no circular addressing S&D, 16 bit S&D
DMA_TCD0_NBYTES_MLNO = 2; // one 16bit sample every minor loop
DMA_TCD0_SLAST = 0;//-(DMA_BUF_SIZE*2); // source address will always be newly written before each new start DMA_TCD0_DADDR
DMA_TCD0_DADDR = (uint32_t) &BufferSource_A[0]; // the FTM Channel 0 duty value
DMA_TCD0_DOFF = 2;
DMA_TCD0_CITER_ELINKNO = DMA_BUF_SIZE; // total samples ( 32 )
DMA_TCD0_DLASTSGA = -64;
DMA_TCD0_CSR = DMA_CSR_INTMAJOR_MASK ; // interrupt when done
DMA_TCD0_BITER_ELINKNO = DMA_BUF_SIZE;

// configure DMA_MUX to trigger DMA channel 0 with FTM2 CH1
Set_Dma_Mux();

// now enable chan0 for HW triggers
DMA_ERQ = DMA_ERQ_ERQ0_MASK ;
// Install DMA0 Major loop complete IRQ
_int_install_isr(INT_DMA0, dma_ch0_isr, NULL);
//_cortex_int_init(INT_DMA0, 3, TRUE);
_nvic_int_init(INT_DMA0, 3, TRUE);

}

Can anyone tell me what is wrong in this??

Tanks and Regards,

Olivia

Re: Read ADC values using DMA in FRDM k64

danielchen — Wed, 26 Apr 2017 08:16:09 GMT

Hi Olivia:

I would suggest you dump the adc and dma register value to check this issue. Have you enabled the DMA in ADC module? please check ADC0_SC2->DMAEN.

In fact, MQX ADC driver doesn't include the DMA integration , but you can easily move a bare metal project into your MQX project to handle it.

The below link might be help to use DMA and ADC

PIT- ADC- DMA Example for FRDM-KL25z, FRDM-K64F, TWR-K60D100 and TWR-K70

Regards

Danniel

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Read ADC values using DMA in FRDM k64

Re: Read ADC values using DMA in FRDM k64