SPI driver

group nrfx_spi

Serial Peripheral Interface master (SPI) driver.

Defines

NRFX_SPI_INSTANCE(id)

Macro for creating an instance of the SPI master driver.

NRFX_SPI_PIN_NOT_USED

This value can be provided instead of a pin number for signals MOSI, MISO, and Slave Select to specify that the given signal is not used and therefore does not need to be connected to a pin.

NRFX_SPI_DEFAULT_CONFIG(_pin_sck, _pin_mosi, _pin_miso, _pin_ss)

SPI master instance default configuration. This configuration sets up SPI with the following options:

  • over-run character set to 0xFF

  • clock frequency 4 MHz

  • mode 0 enabled (SCK active high, sample on leading edge of clock)

  • MSB shifted out first

  • MISO pull-up disabled

Parameters

  • _pin_sck – [in] SCK pin.

  • _pin_mosi – [in] MOSI pin.

  • _pin_miso – [in] MISO pin.

  • _pin_ss – [in] SS pin.

NRFX_SPI_SINGLE_XFER(p_tx, tx_len, p_rx, rx_len)

Macro for setting up single transfer descriptor.

This macro is for internal use only.

NRFX_SPI_XFER_TRX(p_tx_buf, tx_length, p_rx_buf, rx_length)

Macro for setting the duplex TX RX transfer.

NRFX_SPI_XFER_TX(p_buf, length)

Macro for setting the TX transfer.

NRFX_SPI_XFER_RX(p_buf, length)

Macro for setting the RX transfer.

Typedefs

typedef void (*nrfx_spi_evt_handler_t)(nrfx_spi_evt_t const *p_event, void *p_context)

SPI master driver event handler type.

Enums

enum nrfx_spi_evt_type_t

SPI master driver event types, passed to the handler routine provided during initialization.

Values:

enumerator NRFX_SPI_EVENT_DONE

Transfer done.

Functions

nrfx_err_t nrfx_spi_init(nrfx_spi_t const *p_instance, nrfx_spi_config_t const *p_config, nrfx_spi_evt_handler_t handler, void *p_context)

Function for initializing the SPI master driver instance.

This function configures and enables the specified peripheral.

Parameters

  • p_instance – [in] Pointer to the driver instance structure.

  • p_config – [in] Pointer to the structure with the initial configuration.

  • handler – [in] Event handler provided by the user. If NULL, transfers will be performed in blocking mode.

  • p_context – [in] Context passed to the event handler.

Return values

  • NRFX_SUCCESS – Initialization was successful.

  • NRFX_ERROR_INVALID_STATE – The driver was already initialized.

  • NRFX_ERROR_BUSY – Some other peripheral with the same instance ID is already in use. This is possible only if Peripheral Resource Sharing (PRS) module is enabled.

void nrfx_spi_uninit(nrfx_spi_t const *p_instance)

Function for uninitializing the SPI master driver instance.

Parameters

  • p_instance – [in] Pointer to the driver instance structure.

nrfx_err_t nrfx_spi_xfer(nrfx_spi_t const *p_instance, nrfx_spi_xfer_desc_t const *p_xfer_desc, uint32_t flags)

Function for starting the SPI data transfer.

If an event handler was provided in the nrfx_spi_init call, this function returns immediately and the handler is called when the transfer is done. Otherwise, the transfer is performed in blocking mode, which means that this function returns when the transfer is finished.

Parameters

  • p_instance – Pointer to the driver instance structure.

  • p_xfer_desc – Pointer to the transfer descriptor.

  • flags – Transfer options (0 for default settings). Currently, no additional flags are available.

Return values

  • NRFX_SUCCESS – The procedure is successful.

  • NRFX_ERROR_BUSY – The driver is not ready for a new transfer.

  • NRFX_ERROR_NOT_SUPPORTED – The provided parameters are not supported.

void nrfx_spi_abort(nrfx_spi_t const *p_instance)

Function for aborting the ongoing transfer.

Parameters

  • p_instance – [in] Pointer to the driver instance structure.

struct nrfx_spi_t
#include <nrfx_spi.h>

Data structure of the Serial Peripheral Interface master (SPI) driver instance.

Public Members

NRF_SPI_Type *p_reg

Pointer to a structure with SPI registers.

uint8_t drv_inst_idx

Index of the driver instance. For internal use only.

struct nrfx_spi_config_t
#include <nrfx_spi.h>

Configuration structure of the SPI master driver instance.

Public Members

uint8_t sck_pin

SCK pin number.

uint8_t mosi_pin

MOSI pin number (optional).

Set to NRFX_SPI_PIN_NOT_USED if this signal is not needed.

uint8_t miso_pin

MISO pin number (optional).

Set to NRFX_SPI_PIN_NOT_USED if this signal is not needed.

uint8_t ss_pin

Slave Select pin number (optional).

Set to NRFX_SPI_PIN_NOT_USED if this signal is not needed. The driver supports only active low for this signal. If the signal must be active high, it must be controlled externally.

Note

Unlike the other fields that specify pin numbers, this one cannot be omitted when both GPIO configuration and pin selection are to be skipped, as the driver must control the signal as a regular GPIO.

uint8_t irq_priority

Interrupt priority.

uint8_t orc

Overrun character.

This character is used when all bytes from the TX buffer are sent, but the transfer continues due to RX.

nrf_spi_frequency_t frequency

SPI frequency.

nrf_spi_mode_t mode

SPI mode.

nrf_spi_bit_order_t bit_order

SPI bit order.

nrf_gpio_pin_pull_t miso_pull

MISO pull up configuration.

bool skip_gpio_cfg

Skip GPIO configuration of pins.

When set to true, the driver does not modify any GPIO parameters of the used pins. Those parameters are supposed to be configured externally before the driver is initialized.

bool skip_psel_cfg

Skip pin selection configuration.

When set to true, the driver does not modify pin select registers in the peripheral. Those registers are supposed to be set up externally before the driver is initialized.

Note

When both GPIO configuration and pin selection are to be skipped, the structure fields that specify pins can be omitted, as they are ignored anyway. This does not apply to the ss_pin field.

struct nrfx_spi_xfer_desc_t
#include <nrfx_spi.h>

Single transfer descriptor structure.

Public Members

uint8_t const *p_tx_buffer

Pointer to TX buffer.

size_t tx_length

TX buffer length.

uint8_t *p_rx_buffer

Pointer to RX buffer.

size_t rx_length

RX buffer length.

struct nrfx_spi_evt_t
#include <nrfx_spi.h>

SPI master event description with transmission details.

Public Members

nrfx_spi_evt_type_t type

Event type.

nrfx_spi_xfer_desc_t xfer_desc

Transfer details.