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	Value	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¶

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

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

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

Return

See the enum definition.

Value	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

Parameter	Description
`spi_id`	Peripheral id.

Return

See the enum definition.

Value	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

Parameter	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

See the enum definition.

Value	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

Parameter	Description
`spi_id`	Peripheral id.

Return

See the enum definition.

Value	Description
`MIRA_TRUE`	SPI transfer is in progress.
`MIRA_FALSE`	SPI transfer is not in progress.