Data Frame Transmit Operation - Mitsubishi Electric M32R Series User Manual

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13.5.2 Data Frame Transmit Operation

The following describes data frame transmit operation. The operations described below are
automatically performed in hardware.
(1) Selecting a transmit frame
The CAN module checks slots which have transmit requests (including remote frame transmit
slots) every intermission to determine the frame to transmit. If there are multiple transmit slots,
frames are transmitted in order of slot numbers beginning with the smallest.
(2) Transmitting a data frame
After determining the transmit slot, the CAN module sets the corresponding CAN Message Slot
Control Register's TRSTAT (Transmit/Receive Status) bit to 1, thereby starting transmission.
(3) If the CAN module lost bus arbitration or a CAN bus error occurs
If the CAN module lost bus arbitration or a CAN bus error occurs while transmitting, the CAN
module clears the CAN Message Slot Control Register's TRSTAT (Transmit/Receive Status) bit
to 0. If the CAN module requested a transmit abort, the transmit abort is accepted and writing to
the message slot is enabled.
(4) Completion of data frame transmission
When data frame transmission is completed, the CAN Message Slot Control Register's TRFIN
(Transmit/Receive Finished) bit and the CAN Slot Interrupt Status Register are set to 1. Also, a
time stamp count value at the time transmission was completed is written to the CAN Message
Slot Time Stamp (C0MSLnTSP), and the transmit operation is thereby completed.
If the CAN slot interrupt has been enabled, an interrupt request is generated at completion of
transmit operation. The slot which has had transmission completed goes to an inactive state and
remains inactive (neither transmit nor receive) until it is newly set in software.
13.5 Transmitting Data Frames
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CAN MODULE
Ver.0.10