Kinetis MicrocontrollersのトピックRe: Troubleshooting with SPI0 using MK10

Troubleshooting with SPI0 using MK10

michael_k — Mon, 11 Jul 2016 14:28:21 GMT

Hello,

at the moment I'm facing a problem with SPI0. I want to establish a connection to a pressure sensor at this interface. The clock initialization looks like:

SIM_SCGC5 = 0x00

| SIM_SCGC5_PORTE_MASK

| SIM_SCGC5_PORTD_MASK

| SIM_SCGC5_PORTC_MASK

| SIM_SCGC5_PORTB_MASK

| SIM_SCGC5_PORTA_MASK;

SIM_SCGC6 = 0x00

| SIM_SCGC6_PIT_MASK

| SIM_SCGC6_SPI0_MASK;

After that, I initialized the SPI module, using the following code:

/* Function to initialize the SPI 0 interface at a frequency of 2.4MHz */

void init_spi_0(void)

{

/* Use alternative 2 on pin 0 of PORTD (CS) */

PORTD_PCR0 = 0x00

| PORT_PCR_MUX(0x02);

/* Use alternative 2 on pin 1 of PORTD (CLK) */

PORTD_PCR1 = 0x00

| PORT_PCR_MUX(0x02);

/* Use alternative 2 on pin 2 of PORTD (MOSI) */

PORTD_PCR2 = 0x00

| PORT_PCR_MUX(0x02);

/* Use alternative 2 on pin 3 of PORTD (MISO) */

PORTD_PCR3 = 0x00

| PORT_PCR_MUX(0x02)

| PORT_PCR_PE_MASK

| PORT_PCR_PS_MASK;

/* Use SPI0 as master, CS0 is low-active, clear TX FIFO and clear RX FIFO */

SPI0_MCR = 0x00

| SPI_MCR_MSTR_MASK

| SPI_MCR_PCSIS(0x01)

| SPI_MCR_DIS_TXF_MASK

| SPI_MCR_DIS_RXF_MASK;

/* Use in every frame 8 bits (0x08), baud rate prescaler is 3 (0x01) and the

baud rate scaler is 2 (0x00) creating a SPI frequency of 8.33MHz */

SPI0_CTAR0 = 0x00

| SPI_CTAR_FMSZ(0x08)

| SPI_CTAR_CPOL_MASK

| SPI_CTAR_PBR(0x1)

| SPI_CTAR_BR(0x00);

}

To write or read data I use the code:

/* Function to send or read a byte */

uint8_t write_read_spi_0(int8_t data, uint32_t continuous)

{

switch (continuous){

case 0:

/* Use a continuous chip select, assert PCS0 and write the byte to the register */

SPI0_PUSHR = 0x00

| SPI_PUSHR_CONT_MASK

| SPI_PUSHR_CTAS(0x00)

| SPI_PUSHR_PCS(0x01)

| SPI_PUSHR_TXDATA(data);

break;

case 1:

/* Assert PCS0 and write the byte to the register */

SPI0_PUSHR = 0x00

| SPI_PUSHR_CTAS(0x00)

| SPI_PUSHR_PCS(0x01)

| SPI_PUSHR_TXDATA(data);

break;

}

/* Wait for the byte to be sent */

while(!(SPI0_SR & SPI_SR_TCF_MASK));

/* Read the received byte */

data = SPI0_POPR;

/* Clear the flag (not self-clearing) */

SPI0_SR |= SPI_SR_TCF_MASK;

/* Return value */

return (data);

}

I checked the signals with a scope and the signal CLK and MOSI are as expected. Only MISO remains low all the time.

The next step I made was connecting MISO to the power supply. If I use MISO as a GPIO I'm able to read in the right logic levels. If I switch back to SPI the results are wrong again. I recognized that 0x01FF is shifted through registers SPI0_RXFR0 till SPI0_RXFR3 (I need four write/read cyles) and if it reached register SPI0_RXFR3 it is written into SPI0_POPR.

Does anyone know what I'm doing wrong? I thought I had switched of the FIFO registers.

Thank you for your help.

Regards,

Michael

Re: Troubleshooting with SPI0 using MK10

Hui_Ma — Tue, 12 Jul 2016 06:47:07 GMT

I would recommend to refer SPI demo of Kinetis V2 product example software, which using SPI module read data from external SPI Flash.

Wish it helps.

Have a great day,
Ma Hui
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Re: Troubleshooting with SPI0 using MK10

michael_k — Tue, 12 Jul 2016 09:00:22 GMT

thank you for your reply. I tried the example and I solved the problem with the FIFOs. The only problem I still have is that the POPR register is always filled with 0x01FF regardless of setting MISO high or low. Do yo may have a suggestion what that can be?

Have a great day too,

Michael

Re: Troubleshooting with SPI0 using MK10

Hui_Ma — Wed, 13 Jul 2016 03:18:07 GMT

Hi Michael,

The MISO pin is SPI master input pin.

From your code, the SPI0_CTAR0 register [FMSZ] bits with value 8, which means transfer 9 bits data frame during SPI communication.

That's why you will get 0x1FF at SPI0_POPR register.

SPI0_CTAR0 = 0x00

| SPI_CTAR_FMSZ(0x08)

| SPI_CTAR_CPOL_MASK

| SPI_CTAR_PBR(0x1)

| SPI_CTAR_BR(0x00);

Wish it helps.