Defined behavior

Detailed Description

Defined behavior

• i2c_init initializes i2c_t control structure
• i2c_init configures the pins used by I2C
• i2c_free returns the pins owned by the I2C object to their reset state
• i2c_frequency configure the I2C frequency
• i2c_start sends START command
• i2c_read reads length bytes from the I2C slave specified by address to the data buffer
• i2c_read reads generates a stop condition on the bus at the end of the transfer if stop parameter is non-zero
• i2c_read reads returns the number of symbols received from the bus
• i2c_write writes length bytes to the I2C slave specified by address from the data buffer
• i2c_write generates a stop condition on the bus at the end of the transfer if stop parameter is non-zero
• i2c_write returns zero on success, error code otherwise
• i2c_reset resets the I2C peripheral
• i2c_byte_read reads and return one byte from the specfied I2C slave
• i2c_byte_read uses last parameter to inform the slave that all bytes have been read
• i2c_byte_write writes one byte to the specified I2C slave
• i2c_byte_write returns 0 if NAK was received, 1 if ACK was received, 2 for timeout
• i2c_slave_mode enables/disables I2S slave mode
• i2c_slave_receive returns: 1 - read addresses, 2 - write to all slaves, 3 write addressed, 0 - the slave has not been addressed
• i2c_slave_read reads length bytes from the I2C master to the data buffer
• i2c_slave_read returns non-zero if a value is available, 0 otherwise
• i2c_slave_write writes length bytes to the I2C master from the data buffer
• i2c_slave_write returns non-zero if a value is available, 0 otherwise
• i2c_slave_address configures I2C slave address
• i2c_transfer_asynch starts I2C asynchronous transfer
• i2c_transfer_asynch writes tx_length bytes to the I2C slave specified by address from the tx buffer
• i2c_transfer_asynch reads rx_length bytes from the I2C slave specified by address to the rx buffer
• i2c_transfer_asynch generates a stop condition on the bus at the end of the transfer if stop parameter is non-zero
• The callback given to i2c_transfer_asynch is invoked when the transfer completes
• i2c_transfer_asynch specifies the logical OR of events to be registered
• The i2c_transfer_asynch function may use the DMAUsage hint to select the appropriate async algorithm
• i2c_irq_handler_asynch returns event flags if a transfer termination condition was met, otherwise returns 0.
• i2c_active returns non-zero if the I2C module is active or 0 if it is not
• i2c_abort_asynch aborts an on-going async transfer

Undefined behavior

• Calling i2c_init multiple times on the same i2c_t
• Calling any function other than i2c_init on a non-initialized i2c_t
• Initialising the I2C peripheral with invalid SDA and SCL pins.
• Passing pins that cannot be on the same peripheral
• Passing an invalid pointer as obj to any function
• Use of a null pointer as an argument to any function.
• Initialising the peripheral in slave mode if slave mode is not supported
• Operating the peripheral in slave mode without first specifying and address using i2c_slave_address
• Setting an address using i2c_slave_address after initialising the peripheral in master mode
• Setting an address to an I2C reserved value
• Specifying an invalid address when calling any read or write functions
• Setting the length of the transfer or receive buffers to larger than the buffers are
• Passing an invalid pointer as handler
• Calling ::i2c_abort_async when no transfer is currently in progress

Function Documentation