Abstract: A CAN module receives a message from a CAN bus to store the same in a message box unit of a message box. A reception request signal is output from the message box unit to a DMAC/IF. The DMAC/IF outputs a 7-bit encoded address together with a transfer request signal. A DMAC accesses a selected message box unit of the CAN module and a memory based on the transfer request signal and the 7-bit encoded address to transfer the message stored in the selected message box unit to the memory.

Abstract: A serial network controller contains control logic to analyze and determine a duration of a proper frame time slot. A number of data fields in a transmission is ascertained from an identifier field supplied in a header field. The number of data fields plus a margin for data framing overhead is calculated to determine the frame time slot duration. A timer is programmed with the calculated frame time slot duration. The timer is clocked at each bit period of the transmission until the calculated duration of the frame time slot is reached. At the frame time slot value, a transmit ready flag is unmasked, allowing termination of the frame with a proper margin. By managing frame time slot calculation, timer operations, and interrupt handling, the control logic relieves a microprocessor core and other system resources from network timing details. The control logic frees system resources for other applications.