Defined behavior

Detailed Description

Defined behavior

• spi_init initializes the spi_t control structure
• spi_init configures the pins used by SPI
• spi_free returns the pins owned by the SPI object to their reset state
• spi_format sets the number of bits per frame
• spi_format configures clock polarity and phase
• spi_format configures master/slave mode
• spi_frequency sets the SPI baud rate
• spi_master_write writes a symbol out in master mode and receives a symbol
• spi_master_block_write writes tx_length words to the bus
• spi_master_block_write reads rx_length words from the bus
• spi_master_block_write returns the maximum of tx_length and rx_length
• spi_master_block_write specifies the write_fill which is default data transmitted while performing a read
• spi_get_module returns non-zero if a value is available to read from SPI channel, 0 otherwise
• spi_slave_read returns a received value out of the SPI receive buffer in slave mode
• spi_slave_read blocks until a value is available
• spi_slave_write writes a value to the SPI peripheral in slave mode
• spi_slave_write blocks until the SPI peripheral can be written to
• spi_busy returns non-zero if the peripheral is currently transmitting, 0 otherwise
• spi_master_transfer starts the SPI asynchronous transfer
• spi_master_transfer writes tx_len words to the bus
• spi_master_transfer reads rx_len words from the bus
• spi_master_transfer specifies the bit width of buffer words
• The callback given to spi_master_transfer is invoked when the transfer completes (with a success or an error)
• spi_master_transfer specifies the logical OR of events to be registered
• The spi_master_transfer function may use the DMAUsage hint to select the appropriate async algorithm
• spi_irq_handler_asynch reads the received values out of the RX FIFO
• spi_irq_handler_asynch writes values into the TX FIFO
• spi_irq_handler_asynch checks for transfer termination conditions, such as buffer overflows or transfer complete
• spi_irq_handler_asynch returns event flags if a transfer termination condition was met, otherwise 0
• spi_abort_asynch aborts an on-going async transfer
• spi_active returns non-zero if the SPI port is active or zero if it is not

Undefined behavior

• Calling spi_init multiple times on the same spi_t without spi_free
• Calling any function other than spi_init on a non-initialized or freed spi_t
• Passing pins that cannot be on the same peripheral
• Passing an invalid pointer as obj to any function
• Passing an invalid pointer as handler to spi_master_transfer
• Calling ::spi_abort while no async transfer is being processed (no transfer or a synchronous transfer)

Function Documentation