K10 Spi read buffer bit inverted

nicola90 — Thu, 20 Feb 2014 08:39:17 GMT

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

Re: K10 Spi read buffer bit inverted

jeremyzhou — Mon, 24 Feb 2014 07:30:52 GMT

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

topic K10 Spi read buffer bit inverted in Kinetis Microcontrollers

K10 Spi read buffer bit inverted

Re: K10 Spi read buffer bit inverted