Hi
I'm trying to create my own SPI baremetal driver. But I was expecting a clock after the init because I set the continious clock register.
Why am I not seeing a clock on my oscilloscope?
[code]
int frdm_spi_init(SPI_Type *spi, struct frdm_spi_mode *mode, uint32_t hz) {
if(mode->frame < FRDM_SPI_MIN_FRAME_SIZE) {
return -1;
}
// Enable clock
SIM_SCGC6 |= SIM_SCGC6_SPI0(FRDM_ENABLE);
// For debug purpose
SPI_MCR_REG(spi) &= ~SPI_MCR_CONT_SCKE_MASK;
SPI_MCR_REG(spi) |= (FRDM_ENABLE<<SPI_MCR_CLR_RXF_SHIFT);
// Master/slave
SPI_MCR_REG(spi) &= ~SPI_MCR_MSTR_MASK;
SPI_MCR_REG(spi) |= (mode->mode<<SPI_MCR_MSTR_SHIFT);
if(mode->mode == FRDM_SPI_MASTER) {
//Frame size
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_FMSZ_MASK;
SPI_CTAR_REG(spi,0) |= (((mode->frame-1) & 0x0F)<<SPI_CTAR_FMSZ_SHIFT);
// Spi mode
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_CPOL_MASK;
SPI_CTAR_REG(spi,0) |= (mode->CPOL)<<SPI_CTAR_CPOL_SHIFT;
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_CPHA_MASK;
SPI_CTAR_REG(spi,0) |= (mode->CPHA)<<SPI_CTAR_CPHA_SHIFT;
//Always in msb mode
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_LSBFE_MASK;
} else if(mode->mode == FRDM_SPI_SLAVE) {
/*TODO*/
}
//frequency
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_ASC_MASK;
SPI_CTAR_REG(spi,0) |= 1<<SPI_CTAR_ASC_SHIFT;
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_PASC_MASK;
SPI_CTAR_REG(spi,0) |= 0<<SPI_CTAR_PASC_SHIFT;
SPI_CTAR_REG(spi,0) &= ~SPI_CTAR_DBR_MASK;
SPI_CTAR_REG(spi,0) |= 0<<SPI_CTAR_DBR_SHIFT;
// Fifo
SPI_MCR_REG(spi) &= ~SPI_MCR_DIS_TXF_MASK;
SPI_MCR_REG(spi) != 0<<SPI_MCR_DIS_TXF_SHIFT;
//Enable
SPI_MCR_REG(spi) &= ~SPI_MCR_MDIS_MASK;
SPI_MCR_REG(spi) != 0<<SPI_MCR_MDIS_SHIFT;
// Start hardware
SPI_MCR_REG(spi) &= ~SPI_MCR_HALT_MASK;
SPI_MCR_REG(spi) |= 0<<SPI_MCR_HALT_SHIFT;
return 0;
}
[/code]
Solved! Go to Solution.
Hello,
Please verify that you enabled the clock gate for the port and that you configured the signal multiplexing for the SPI clock signal, this is done in the PORTx_PCRn[MUX] register (please refer to the pinout table in the section 10.3 "Pinout" in the MK64F Reference Manual).
Also, I recommend you to take a look into the message Re: [Help]K64F SPI Bare Metal example which contains a working SPI example in baremetal for the MK64F MCU. It could be useful for you.
Best regards,
\ER.
Hello,
Please verify that you enabled the clock gate for the port and that you configured the signal multiplexing for the SPI clock signal, this is done in the PORTx_PCRn[MUX] register (please refer to the pinout table in the section 10.3 "Pinout" in the MK64F Reference Manual).
Also, I recommend you to take a look into the message Re: [Help]K64F SPI Bare Metal example which contains a working SPI example in baremetal for the MK64F MCU. It could be useful for you.
Best regards,
\ER.
Hi Earl,
Thanks for the input and the example! Indeed the multiplexing was not done yet.
Another mistake was a "auto-filling" mistake of my editor:
SPI_MCR_REG(spi) &= ~SPI_MCR_CONT_SCKE_MASK;
SPI_MCR_REG(spi) |= (FRDM_ENABLE<<SPI_MCR_CLR_RXF_SHIFT);
should be
SPI_MCR_REG(spi) &= ~SPI_MCR_CONT_SCKE_MASK;
SPI_MCR_REG(spi) |= (FRDM_ENABLE<<SPI_MCR_CONT_SCKE_SHIFT);
Kind Regards,
Roel