Serial Peripheral Interface (SPI)

See Quickstart guide for SAM SPI driver.

The SPI circuit is a synchronous serial data link that provides communication with external devices in Master or Slave mode. Connection to Peripheral DMA Controller channel capabilities optimizes data transfers.

Macros
#define	SPI_WPMR_WPKEY_PASSWD   SPI_WPMR_WPKEY((uint32_t) 0x535049)

Functions
int16_t	spi_calc_baudrate_div (const uint32_t baudrate, uint32_t mck)
	Calculate the baudrate divider. More...
void	spi_configure_cs_behavior (Spi *p_spi, uint32_t ul_pcs_ch, uint32_t ul_cs_behavior)
	Configure CS behavior for SPI transfer (spi_cs_behavior_t). More...
void	spi_disable_clock (Spi *p_spi)
	Disable SPI clock. More...
void	spi_enable_clock (Spi *p_spi)
	Enable SPI clock. More...
uint32_t	spi_get_writeprotect_status (Spi *p_spi)
	Indicate write protect status. More...
spi_status_t	spi_read (Spi *p_spi, uint16_t *us_data, uint8_t *p_pcs)
	Read the received data and it's peripheral chip select value. More...
int16_t	spi_set_baudrate_div (Spi *p_spi, uint32_t ul_pcs_ch, uint8_t uc_baudrate_divider)
	Set Serial Clock Baud Rate divider value (SCBR). More...
void	spi_set_bits_per_transfer (Spi *p_spi, uint32_t ul_pcs_ch, uint32_t ul_bits)
	Set number of bits per transfer. More...
void	spi_set_clock_phase (Spi *p_spi, uint32_t ul_pcs_ch, uint32_t ul_phase)
	Set Data Capture Phase. More...
void	spi_set_clock_polarity (Spi *p_spi, uint32_t ul_pcs_ch, uint32_t ul_polarity)
	Set clock default state. More...
void	spi_set_delay_between_chip_select (Spi *p_spi, uint32_t ul_delay)
	Set delay between chip selects (in number of MCK clocks). More...
void	spi_set_peripheral_chip_select_value (Spi *p_spi, uint32_t ul_value)
	Set Peripheral Chip Select (PCS) value. More...
void	spi_set_transfer_delay (Spi *p_spi, uint32_t ul_pcs_ch, uint8_t uc_dlybs, uint8_t uc_dlybct)
	Configure timing for SPI transfer. More...
void	spi_set_writeprotect (Spi *p_spi, uint32_t ul_enable)
	Enable or disable write protection of SPI registers. More...
spi_status_t	spi_write (Spi *p_spi, uint16_t us_data, uint8_t uc_pcs, uint8_t uc_last)
	Write the transmitted data with specified peripheral chip select value. More...

#define SPI_WPMR_WPKEY_PASSWD   SPI_WPMR_WPKEY((uint32_t) 0x535049)

Referenced by spi_set_writeprotect().

int16_t spi_calc_baudrate_div	(	const uint32_t	baudrate,
		uint32_t	mck
	)

Calculate the baudrate divider.

Parameters

baudrate	Baudrate value.
mck	SPI module input clock frequency (MCK clock, Hz).

Returns

Divider or error code.

Return values

>	0 Success.
<	0 Error.

References div_ceil.

void spi_configure_cs_behavior	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint32_t	ul_cs_behavior
	)

Configure CS behavior for SPI transfer (spi_cs_behavior_t).

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
ul_cs_behavior	Behavior of the Chip Select after transfer.

References SPI_CS_KEEP_LOW, SPI_CS_RISE_FORCED, and SPI_CS_RISE_NO_TX.

void spi_disable_clock

(

Spi *

p_spi

)

Disable SPI clock.

Parameters

p_spi

Pointer to an SPI instance.

References sysclk_disable_peripheral_clock(), and UNUSED.

void spi_enable_clock

(

Spi *

p_spi

)

Enable SPI clock.

Parameters

p_spi

Pointer to an SPI instance.

References sysclk_enable_peripheral_clock(), and UNUSED.

Referenced by spi_master_initialize(), and spi_slave_initialize().

uint32_t spi_get_writeprotect_status

(

Spi *

p_spi

)

Indicate write protect status.

Parameters

p_spi

Pointer to an SPI instance.

Returns

SPI_WPSR value.

spi_status_t spi_read	(	Spi *	p_spi,
		uint16_t *	us_data,
		uint8_t *	p_pcs
	)

Read the received data and it's peripheral chip select value.

While SPI works in fixed peripheral select mode, the peripheral chip select value is meaningless.

Parameters

p_spi	Pointer to an SPI instance.
data	Pointer to the location where to store the received data word.
p_pcs	Pointer to fill Peripheral Chip Select Value.

Return values

SPI_OK	on Success.
SPI_ERROR_TIMEOUT	on Time-out.

References SPI_ERROR_TIMEOUT, spi_get_peripheral_select_mode(), SPI_OK, and SPI_TIMEOUT.

Referenced by SPI_Handler(), and spi_master_transfer().

int16_t spi_set_baudrate_div	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint8_t	uc_baudrate_divider
	)

Set Serial Clock Baud Rate divider value (SCBR).

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
uc_baudrate_divider	Baudrate divider from MCK.

Returns

Return values

is	0 Success.
is	-1 Error.

Referenced by spi_master_initialize().

void spi_set_bits_per_transfer	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint32_t	ul_bits
	)

Set number of bits per transfer.

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
ul_bits	Number of bits (8~16), use the pattern defined in the device header file.

Referenced by spi_master_initialize(), and spi_slave_initialize().

void spi_set_clock_phase	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint32_t	ul_phase
	)

Set Data Capture Phase.

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
ul_phase	Data capture on the rising/falling edge of clock.

Referenced by spi_master_initialize(), and spi_slave_initialize().

void spi_set_clock_polarity	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint32_t	ul_polarity
	)

Set clock default state.

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
ul_polarity	Default clock state is logical one(high)/zero(low).

Referenced by spi_master_initialize(), and spi_slave_initialize().

void spi_set_delay_between_chip_select	(	Spi *	p_spi,
		uint32_t	ul_delay
	)

Set delay between chip selects (in number of MCK clocks).

If DLYBCS <= 6, 6 MCK clocks will be inserted by default.

Parameters

p_spi	Pointer to an SPI instance.
ul_delay	Delay between chip selects (in number of MCK clocks).

void spi_set_peripheral_chip_select_value	(	Spi *	p_spi,
		uint32_t	ul_value
	)

Set Peripheral Chip Select (PCS) value.

Parameters

p_spi	Pointer to an SPI instance.
ul_value	Peripheral Chip Select value. If PCS decode mode is not used, use spi_get_pcs to build the value to use. On reset the decode mode is not enabled. The decode mode can be enabled/disabled by follow functions: spi_enable_peripheral_select_decode, spi_disable_peripheral_select_decode.

Referenced by spi_master_initialize(), and spi_slave_initialize().

void spi_set_transfer_delay	(	Spi *	p_spi,
		uint32_t	ul_pcs_ch,
		uint8_t	uc_dlybs,
		uint8_t	uc_dlybct
	)

Configure timing for SPI transfer.

Parameters

p_spi	Pointer to an SPI instance.
ul_pcs_ch	Peripheral Chip Select channel (0~3).
uc_dlybs	Delay before SPCK (in number of MCK clocks).
uc_dlybct	Delay between consecutive transfers (in number of MCK clocks).

Referenced by spi_master_initialize().

void spi_set_writeprotect	(	Spi *	p_spi,
		uint32_t	ul_enable
	)

Enable or disable write protection of SPI registers.

Parameters

p_spi	Pointer to an SPI instance.
ul_enable	1 to enable, 0 to disable.

References SPI_WPMR_WPKEY_PASSWD.

spi_status_t spi_write	(	Spi *	p_spi,
		uint16_t	us_data,
		uint8_t	uc_pcs,
		uint8_t	uc_last
	)

Write the transmitted data with specified peripheral chip select value.

Parameters

p_spi	Pointer to an SPI instance.
us_data	The data to transmit.
uc_pcs	Peripheral Chip Select Value while SPI works in peripheral select mode, otherwise it's meaningless.
uc_last	Indicate whether this data is the last one while SPI is working in variable peripheral select mode.

Return values

SPI_OK	on Success.
SPI_ERROR_TIMEOUT	on Time-out.

References SPI_ERROR_TIMEOUT, spi_get_peripheral_select_mode(), SPI_OK, and SPI_TIMEOUT.

Referenced by SPI_Handler(), spi_master_transfer(), and spi_slave_transfer().