SPI¶

The Serial Peripheral Interface bus (SPI) is a synchronous serial communication interface specification used for short distance communication, primarily for inter-chip communication within a single PCB.

SPI devices communicate in full duplex mode using a master-slave architecture with a single master.

MiraOS supports multiple independent instances. Only SPI master is currently supported.

Enums¶

mira_spi_mode_t¶

Name	Description
`MIRA_SPI_MODE_0`	SPI mode 0. CPOL=0, CPHA=0. Clock idle low, sample data on leading clock edge.
`MIRA_SPI_MODE_1`	SPI mode 1. CPOL=0, CPHA=1. Clock idle low, sample data on trailing clock edge.
`MIRA_SPI_MODE_2`	SPI mode 2. CPOL=1, CPHA=0. Clock idle high, sample data on leading clock edge.
`MIRA_SPI_MODE_3`	SPI mode 3. CPOL=1, CPHA=1. Clock idle high, sample data on trailing clock edge.

Structs¶

mira_spi_config_t¶

Name	Type	Description
`frequency`	`uint32_t`	SPI clock frequency in Hz. The frequency will be set to the closest, lower or equal, supported frequency.
`sck_pin`	`mira_gpio_pin_t`
`mosi_pin`	`mira_gpio_pin_t`
`miso_pin`	`mira_gpio_pin_t`
`ss_pin`	`mira_gpio_pin_t`
`mode`	`mira_spi_mode_t`
`bit_order`	`mira_bit_order_t`

Functions¶

mira_spi_init¶

mira_status_t mira_spi_init(uint8_t spi_id, const mira_spi_config_t *config);

Initialize SPI peripheral.

Before calling this function again mira_spi_uninit has to be called.

Parameters

Name	Description
spi_id	Peripheral id.
config	Configuration. Can be discarded after the return of this function.

Return value

Name	Description
MIRA_SUCCESS	The SPI interface was successfully initialized.
MIRA_ERROR_UNKNOWN	An unknown error occurred.
MIRA_ERROR_INVALID_ID	The SPI id is invalid.
MIRA_SPI_ERROR_CONFIG	The config is invalid.
MIRA_SPI_ERROR_MODE	The mode is invalid.

mira_spi_uninit¶

mira_status_t mira_spi_uninit(uint8_t spi_id);

Uninitialize SPI peripheral.

Parameters

Name	Description
spi_id	Peripheral id.

Return value

Name	Description
MIRA_SUCCESS	The SPI interface was successfully uninitialized.
MIRA_ERROR_UNKNOWN	An unknown error occurred.
MIRA_ERROR_INVALID_ID	The SPI id is invalid.

mira_spi_transfer¶

mira_status_t mira_spi_transfer(uint8_t spi_id, uint8_t *tx_buffer, uint16_t tx_buffer_length, uint8_t *rx_buffer, uint16_t rx_buffer_length);

Transmit and receive data.

The process calling this function will be sent a PROCESS_EVENT_POLL event after the transmission has completed.

Parameters

Name	Description
spi_id	Peripheral id.
tx_buffer	Buffer containing the data to transmit.
tx_buffer_length	Number of bytes to transmit.
rx_buffer	Buffer where to store data received while transmitting.
rx_buffer_length	Max number of bytes to receive.

Return value

Name	Description
MIRA_SUCCESS
MIRA_ERROR_UNKNOWN	An unknown error occurred.
MIRA_ERROR_INVALID_ID	The SPI id is invalid.
MIRA_ERROR_NOT_INITIALIZED	The SPI interface is not initialized.
MIRA_SPI_ERROR_BUSY	The SPI interface is busy.

mira_spi_transfer_is_in_progress¶

mira_bool_t mira_spi_transfer_is_in_progress(uint8_t spi_id);

Check if an SPI transfer is in progress.

Parameters

Name	Description
spi_id	Peripheral id.

Return value

Name	Description
MIRA_TRUE	SPI transfer is in progress.
MIRA_FALSE	SPI transfer is not in progress.