K10 Spi read buffer bit inverted

[nicola90]

Hi, I'm using a K10 as SPI master. I've some problem with rx buffer.

I'm trying to read data from MAX31855: data are storage, but MSB  has been saved in bit 0 of rx_buffer. Do someone explain me why?

My code is the following:

/* Initialization SPI */

SIM_SCGC6 |= SIM_SCGC6_SPI0_MASK;

SPI_MCR_REG(regmap) = SPI_MCR_MSTR_MASK | SPI_MCR_CONT_SCKE_MASK | SPI_MCR_PCSIS(0xF) | SPI_MCR_HALT_MASK; 

SPI_CTAR_REG(regmap,0) = SPI_CTAR_FMSZ(0x7) | SPI_CTAR_BR(0x05) | SPI_CTAR_CPHA_MASK | ~SPI_CTAR_CPOL_MASK;

SPI_CTAR_REG(regmap,1) = SPI_CTAR_FMSZ(0x7) | SPI_CTAR_BR(0x05) | SPI_CTAR_CPHA_MASK | ~SPI_CTAR_CPOL_MASK;

/* Main */

while((SPI_SR_REG(regmap)  & SPI_SR_TFFF_MASK) != 0x2000000U);

  // Transmit Byte on SPI

SPI_MCR_REG(regmap) &= ~SPI_MCR_HALT_MASK;

SPI_PUSHR_REG(regmap) |= 0xFFFF;

//--> Wait till transmit complete

while (((SPI_SR_REG(regmap) & SPI_SR_TCF_MASK)) != SPI_SR_TCF_MASK);

//--> Clear Transmit Flag.

SPI_SR_REG(regmap) |= SPI_SR_TFFF_MASK;

data = SPI_POPR_RXDATA(regmap);

Another problem that I have is that I want to send a 8bit per time, but it send and receive 16bit per time. Why? I have setted SPI_CTAR_FMSZ(0x7), but when I stop in debug mode, I read 0xF in FMSZ!

Can you help me?

Nicola

[jeremyzhou]

Hi Nicola,

I've had a brief through your code and I think your cod is not very right.

For instance, your code didn't select the CTAR0 or CTAR1 for clock and transfer attribute if use SPI_PUSHR_REG(regmap) |= 0xFFFF;
You also can't send a 8bit per time prorperly with this code.

So I've like to suggest a demo code about K60 connect with a exteranl flash chip through SPI interface.

I think it should be useful for reference and I've attached the file with the reply. Please refer to it for details.

Wish it help.

Best regards,

Ping