cc2538 Synchronous Serial Interface

Driver for the cc2538 SPI peripheral. More...

Files
file	spi.c
	Implementation of the cc2538 SPI peripheral.
file	ssi.h
	Header file for the cc2538 Synchronous Serial Interface.

Functions
void	spi_init (void)
	Initialize the SPI bus. More...
void	spi_cs_init (uint8_t port, uint8_t pin)
	Configure a GPIO to be the chip select pin.
void	spi_enable (void)
	Enables the SPI peripheral.
void	spi_disable (void)
	Disables the SPI peripheral. More...
void	spi_set_mode (uint32_t frame_format, uint32_t clock_polarity, uint32_t clock_phase, uint32_t data_size)
	Configure the SPI data and clock polarity and the data size. More...

Base register memory locations.
#define	SSI0_BASE   0x40008000
	Base address for SSI0.
#define	SSI1_BASE   0x40009000
	Base address for SSI1.

SSI register offsets
#define	SSI_CR0   0x00000000
	Control register 0.
#define	SSI_CR1   0x00000004
	Control register 1.
#define	SSI_DR   0x00000008
	Access the TX and RX FIFO.
#define	SSI_SR   0x0000000C
	Meta information about FIFO.
#define	SSI_CPSR   0x00000010
	Clock divider.
#define	SSI_IM   0x00000014
	Interrupt mask.
#define	SSI_RIS   0x00000018
	Raw interrupt status.
#define	SSI_MIS   0x0000001C
	Masked interrupt status.
#define	SSI_ICR   0x00000020
	Interrupt clear register.
#define	SSI_DMACTL   0x00000024
	DMA control register.
#define	SSI_CC   0x00000FC8
	Clock configuration.

SSI Bitmasks and shifts
#define	SSI_CR0_SCR_M   0x0000FF00
	Serial clock rate mask.
#define	SSI_CR0_SCR_S   8
	Serial clock rate shift.
#define	SSI_CR0_SPH_M   0x00000080
	Serial clock phase (H) mask.
#define	SSI_CR0_SPH_S   7
	Serial clock phase (H) shift.
#define	SSI_CR0_SPO_M   0x00000040
	Serial clock phase (O) mask.
#define	SSI_CR0_SPO_S   6
	Serial clock phase (O) shift.
#define	SSI_CR0_FRF_M   0x00000030
	Frame format select mask.
#define	SSI_CR0_FRF_S   4
	Frame format select shift.
#define	SSI_CR0_DSS_M   0x0000000F
	Data size select mask.
#define	SSI_CR0_DSS_S   0
	Data size select shift.
#define	SSI_CR1_SOD_M   0x00000008
	Slave mode output disable mask.
#define	SSI_CR1_SOD_S   3
	Slave mode output disable shift.
#define	SSI_CR1_MS_M   0x00000004
	Master and slave select mask.
#define	SSI_CR1_MS_S   2
	Master and slave select shift.
#define	SSI_CR1_SSE_M   0x00000002
	Synchronous serial port enable mask.
#define	SSI_CR1_SSE_S   1
	Synchronous serial port enable shift.
#define	SSI_CR1_LBM_M   0x00000001
	Loop-back mode mask.
#define	SSI_CR1_LBM_S   0
	Loop-back mode shift.
#define	SSI_DR_DATA_M   0x0000FFFF
	FIFO data mask.
#define	SSI_DR_DATA_S   0
	FIFO data shift.
#define	SSI_SR_BSY_M   0x00000010
	Busy bit mask.
#define	SSI_SR_BSY_S   4
	Busy bit shift.
#define	SSI_SR_RFF_M   0x00000008
	Receive FIFO full mask.
#define	SSI_SR_RFF_S   3
	Receive FIFO full shift.
#define	SSI_SR_RNE_M   0x00000004
	Receive FIFO not empty mask.
#define	SSI_SR_RNE_S   2
	Receive FIFO not empty shift.
#define	SSI_SR_TNF_M   0x00000002
	Transmit FIFO not full mask.
#define	SSI_SR_TNF_S   1
	Transmit FIFO not full shift.
#define	SSI_SR_TFE_M   0x00000001
	Transmit FIFO empty mask.
#define	SSI_SR_TFE_S   0
	Transmit FIFO empty shift.
#define	SSI_CPSR_CPSDVSR_M   0x000000FF
	Clock prescale divisor mask.
#define	SSI_CPSR_CPSDVSR_S   0
	Clock prescale divisor shift.
#define	SSI_IM_TXIM_M   0x00000008
	Transmit FIFO interrupt mask mask.
#define	SSI_IM_TXIM_S   3
	Transmit FIFO interrupt mask shift.
#define	SSI_IM_RXIM_M   0x00000004
	Receive FIFO interrupt mask mask.
#define	SSI_IM_RXIM_S   2
	Receive FIFO interrupt mask shift.
#define	SSI_IM_RTIM_M   0x00000002
	Receive time-out interrupt mask mask.
#define	SSI_IM_RTIM_S   1
	Receive time-out interrupt mask shift.
#define	SSI_IM_RORIM_M   0x00000001
	Receive overrun interrupt mask mask.
#define	SSI_IM_RORIM_S   0
	Receive overrun interrupt mask shift.
#define	SSI_RIS_TXRIS_M   0x00000008
	SSITXINTR raw state mask.
#define	SSI_RIS_TXRIS_S   3
	SSITXINTR raw state shift.
#define	SSI_RIS_RXRIS_M   0x00000004
	SSIRXINTR raw state mask.
#define	SSI_RIS_RXRIS_S   2
	SSIRXINTR raw state shift.
#define	SSI_RIS_RTRIS_M   0x00000002
	SSIRTINTR raw state mask.
#define	SSI_RIS_RTRIS_S   1
	SSIRTINTR raw state shift.
#define	SSI_RIS_RORRIS_M   0x00000001
	SSIRORINTR raw state mask.
#define	SSI_RIS_RORRIS_S   0
	SSIRORINTR raw state shift.
#define	SSI_MIS_TXMIS_M   0x00000008
	SSITXINTR masked state mask.
#define	SSI_MIS_TXMIS_S   3
	SSITXINTR masked state shift.
#define	SSI_MIS_RXMIS_M   0x00000004
	SSIRXINTR masked state mask.
#define	SSI_MIS_RXMIS_S   2
	SSIRXINTR masked state shift.
#define	SSI_MIS_RTMIS_M   0x00000002
	SSIRTINTR masked state mask.
#define	SSI_MIS_RTMIS_S   1
	SSIRTINTR masked state shift.
#define	SSI_MIS_RORMIS_M   0x00000001
	SSIRORINTR masked state mask.
#define	SSI_MIS_RORMIS_S   0
	SSIRORINTR masked state shift.
#define	SSI_ICR_RTIC_M   0x00000002
	Receive time-out interrupt clear mask.
#define	SSI_ICR_RTIC_S   1
	Receive time-out interrupt clear shift.
#define	SSI_ICR_RORIC_M   0x00000001
	Receive overrun interrupt clear mask.
#define	SSI_ICR_RORIC_S   0
	Receive overrun interrupt clear shift.
#define	SSI_DMACTL_TXDMAE_M   0x00000002
	Transmit DMA enable mask.
#define	SSI_DMACTL_TXDMAE_S   1
	Transmit DMA enable shift.
#define	SSI_DMACTL_RXDMAE_M   0x00000001
	Receive DMA enable mask.
#define	SSI_DMACTL_RXDMAE_S   0
	Receive DMA enable shift.
#define	SSI_CC_CS_M   0x00000007
	Baud and system clock source mask.
#define	SSI_CC_CS_S   0
	Baud and system clock source shift.

SSI Register Values
#define	SSI_CR0_SPH   0x00000080
	Serial clock phase (H)
#define	SSI_CR0_SPO   0x00000040
	Serial clock phase (O)
#define	SSI_CR0_FRF_MOTOROLA   0x00000000
	Motorola frame format.
#define	SSI_CR0_FRF_TI   0x00000010
	Texas Instruments frame format.
#define	SSI_CR0_FRF_MICROWIRE   0x00000020
	National Microwire frame format.
#define	SSI_CR1_SOD   0x00000008
	Slave mode output disable.
#define	SSI_CR1_MS   0x00000004
	Master and slave select.
#define	SSI_CR1_SSE   0x00000002
	Synchronous serial port enable.
#define	SSI_CR1_LBM   0x00000001
	Loop-back mode.
#define	SSI_SR_BSY   0x00000010
	Busy bit.
#define	SSI_SR_RFF   0x00000008
	Receive FIFO full.
#define	SSI_SR_RNE   0x00000004
	Receive FIFO not empty.
#define	SSI_SR_TNF   0x00000002
	Transmit FIFO not full.
#define	SSI_SR_TFE   0x00000001
	Transmit FIFO empty.
#define	SSI_IM_TXIM   0x00000008
	Transmit FIFO interrupt mask.
#define	SSI_IM_RXIM   0x00000004
	Receive FIFO interrupt mask.
#define	SSI_IM_RTIM   0x00000002
	Receive time-out interrupt mask.
#define	SSI_IM_RORIM   0x00000001
	Receive overrun interrupt mask.
#define	SSI_RIS_TXRIS   0x00000008
	SSITXINTR raw state.
#define	SSI_RIS_RXRIS   0x00000004
	SSIRXINTR raw state.
#define	SSI_RIS_RTRIS   0x00000002
	SSIRTINTR raw state.
#define	SSI_RIS_RORRIS   0x00000001
	SSIRORINTR raw state.
#define	SSI_MIS_TXMIS   0x00000008
	SSITXINTR masked state.
#define	SSI_MIS_RXMIS   0x00000004
	SSIRXINTR masked state.
#define	SSI_MIS_RTMIS   0x00000002
	SSIRTINTR masked state.
#define	SSI_MIS_RORMIS   0x00000001
	SSIRORINTR masked state.
#define	SSI_ICR_RTIC   0x00000002
	Receive time-out interrupt clear.
#define	SSI_ICR_RORIC   0x00000001
	Receive overrun interrupt clear.
#define	SSI_DMACTL_TXDMAE   0x00000002
	Transmit DMA enable.
#define	SSI_DMACTL_RXDMAE   0x00000001
	Receive DMA enable.

Detailed Description

Driver for the cc2538 SPI peripheral.

Register and bitmask definitions based on the Foundation Firmware from Texas Instruments.

Function Documentation

void spi_disable

(

void

)

Disables the SPI peripheral.

Note

Call this function to save power when the SPI is unused.

Definition at line 123 of file spi.c.

References SYS_CTRL_RCGCSSI.

void spi_init

(

void

)

Initialize the SPI bus.

This SPI init() function uses the following #defines to set the pins: SPI_CLK_PORT SPI_CLK_PIN SPI_MOSI_PORT SPI_MOSI_PIN SPI_MISO_PORT SPI_MISO_PIN

This sets the mode to Motorola SPI with the following format options: Clock phase: 1; data captured on second (rising) edge Clock polarity: 1; clock is high when idle Data size: 8 bits

Definition at line 66 of file spi.c.

References GPIO_PERIPHERAL_CONTROL, IOC_OVERRIDE_DIS, ioc_set_over(), ioc_set_sel(), IOC_SSIRXD_SSI0, spi_enable(), SSI0_BASE, SSI_CC, SSI_CPSR, SSI_CR0, SSI_CR0_SPH, SSI_CR0_SPO, SSI_CR1, and SSI_CR1_SSE.

void spi_set_mode	(	uint32_t	frame_format,
		uint32_t	clock_polarity,
		uint32_t	clock_phase,
		uint32_t	data_size
	)

Configure the SPI data and clock polarity and the data size.

This function configures the SSI peripheral to use a particular SPI configuration that a slave device requires. It should always be called before using the SPI bus as another driver could have changed the settings.

See section 19.4.4 in the CC2538 user guide for more information.

Parameters

frame_format	Set the SSI frame format. Use SSI_CR0_FRF_MOTOROLA, SSI_CR0_FRF_TI, or SSI_CR0_FRF_MICROWIRE.
clock_polarity	In Motorola mode, set whether the clock is high or low when idle. Use SSI_CR0_SPO or 0.
clock_phase	In Motorola mode, select whether data is valid on the first or second edge of the clock. Use SSI_CR0_SPH or 0.
data_size	The number of bits in each "byte" of data. Must be between 4 and 16, inclusive.

Definition at line 129 of file spi.c.

References SSI0_BASE, SSI_CR0, SSI_CR1, and SSI_CR1_SSE.