topic Re: Continuous Transfer LPSPI S32K14x in S32K

Continuous Transfer LPSPI S32K14x

Khaledag — Mon, 18 Mar 2024 09:40:34 GMT

I am wondering how exactly a code for the Continuous Transfer looks like.

void receiveBytes(uint8_t address, uint8_t *buffer, uint8_t numBytes)

{

uint8_t i;

address = address|0x40; // multibyte enabled

address = address|0x80; // write enabled

while((LPSPI0->SR & LPSPI_SR_TDF_MASK)>>LPSPI_SR_TDF_SHIFT==0) {}

LPSPI0->TDR = LPSPI_TDR_DATA(address) ;

LPSPI0->SR |= LPSPI_SR_TDF_MASK; /* Clear TDF flag */

while((LPSPI0->SR & LPSPI_SR_RDF_MASK)>>LPSPI_SR_RDF_SHIFT==0){}

LPSPI0->RDR ;

LPSPI0->SR |= LPSPI_SR_RDF_MASK; /* Clear RDF flag */

for (i = 0 ; i < numBytes; ++i) {

while ((LPSPI0->SR & LPSPI_SR_TDF_MASK) >> LPSPI_SR_TDF_SHIFT == 0) {}

LPSPI0->TDR = LPSPI_TDR_DATA(0x00);

while ((LPSPI0->SR & LPSPI_SR_RDF_MASK) >> LPSPI_SR_RDF_SHIFT == 0) {}

*buffer++ = LPSPI0->RDR;

}

LPSPI0->SR |= LPSPI_SR_RDF_MASK; /* Clear RDF flag */

}

I have this code here, and I would like to receive the bytes after one another with the CS staying low all the time.
I tried controlling the CS pin but the clock was then always working as seen on the scope even if the CS pin was high.
And if I wanna use the Continuous Transfer mode, do I also need to add a few SPI settings or just add the lines iin the transfer and receive functions?

Thanks in advance!

Re: Continuous Transfer LPSPI S32K14x

PetrS — Mon, 18 Mar 2024 11:09:19 GMT

Hi,

this one would work for continuous selection

#define TCR_COMMAND LPSPI_TCR_CPOL_MASK|LPSPI_TCR_CPHA_MASK|LPSPI_TCR_PRESCALE(2)|LPSPI_TCR_PCS(1)|LPSPI_TCR_FRAMESZ(7)

void LPSPI1_receive(uint8_t address, uint8_t *rxBuf, uint8_t nbytes)

{

uint8_t i=1;

LPSPI1->TCR = TCR_COMMAND | LPSPI_TCR_CONT(1);

while((LPSPI1->SR & LPSPI_SR_TDF_MASK)>>LPSPI_SR_TDF_SHIFT==0){};

LPSPI1->TDR = 0xC0|address;

while((LPSPI1->SR & LPSPI_SR_TDF_MASK)>>LPSPI_SR_TDF_SHIFT==0){};

LPSPI1->TDR = i++; // write dummy byte

while((LPSPI1->SR & LPSPI_SR_RDF_MASK)>>LPSPI_SR_RDF_SHIFT==0){};

(void)LPSPI1->RDR;

while(i <= nbytes)

{

while((LPSPI1->SR & LPSPI_SR_TDF_MASK)>>LPSPI_SR_TDF_SHIFT==0);

LPSPI1->TDR = i++; // write dummy byte

while((LPSPI1->SR & LPSPI_SR_RDF_MASK)>>LPSPI_SR_RDF_SHIFT==0);

*rxBuf++ = LPSPI1->RDR;

};

LPSPI1->TCR = TCR_COMMAND | LPSPI_TCR_CONT(0);

while((LPSPI1->SR & LPSPI_SR_RDF_MASK)>>LPSPI_SR_RDF_SHIFT==0);

*rxBuf++ = LPSPI1->RDR;

}

BR, Petr

Re: Continuous Transfer LPSPI S32K14x

Khaledag — Mon, 18 Mar 2024 12:16:43 GMT

Thank you very much