End-of-message handling and interrupt generation in a CAN module providing hardware assembly of multi-frame CAN messages

A CAN microcontroller that supports a plurality of uniquely-numbered message objects, comprising:

• a processor core that runs CAN applications;
• a plurality of message buffers associated with respective ones of the message objects;
• a plurality of individual message object registers associated with each message object, including at least one control register that contains an interrupt-enable control bit, a transmit enable bit, and a receive enable bit;
• a plurality of global message object control registers, including:
• at least one message complete status register that contains a plurality of status flag bits for respective ones of the message objects;
• at least one interrupt flag register that contains a receive complete interrupt flag bit and a transmit complete interrupt flag bit;
• and,
• a message complete info register that contains a plurality of message object identification bits and a status bit;
• a CAN/CAL module that automatically assembles fragmented, multi-frame messages, wherein the CAN/CAL module includes:
• a message handling function that automatically transfers successive frames of an incoming multi-frame message to the message buffer associated with a corresponding message object;
• an end-of-message detection function that detects an end-of-message condition which occurs when the last frame of the accepted incoming multi-frame message has been stored in the message buffer associated with the corresponding message object;
• and,
• an end-of-message detection handling and interrupt generation function that, in response to the detection of the end-of-message condition:
• sets the status flag bit contained in the at least one message complete status register associated with the corresponding message object;
• sets the receive complete interrupt flag bit contained in the at least one interrupt flag register, if the interrupt-enable control bit contained in the at least one control register associated with the corresponding message object is set;
• and,
• sets the status bit contained in the message complete info register, if the interrupt-enable control bit contained in the at least one control register associated with the corresponding message object is set.

A CAN microcontroller that supports a plurality of uniquely-numbered message objects, comprising:

• a processor that runs CAN applications;
• means for selectively enabling any one or more of the message objects for interrupt generation;
• means for monitoring incoming messages to determine when an end-of-message condition occurs;
• means for generating a completed message status flag for a particular message object in response to a determination that an end-of-message condition has occurred with respect to that particular message object;
• means for generating a message-complete interrupt to the processor in response to a determination that an end-of-message condition has occurred with respect to any message object that has been interrupt-enabled;
• and
• means for generating an indication of the lowest-numbered message object for which it has been determined an end-of-message condition has occurred.