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13
(5) Operation after receiving a remote frame
The operation performed after receiving a remote frame differs depending on how automatic
response is set.
When automatic response is disabled
The slot which finished receiving goes to an inactive state and remains inactive (neither
transmit nor receive) until it is newly set in software.
When automatic response is enabled
After receiving a remote frame, the slot automatically changes to a data frame transmit slot
and performs the transmit operation described below. In this case, the transmitted data
conforms to the ID and DLC of the received remote frame.
• 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.
• 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.
• If the CAN module failed to gain control of the bus or a CAN bus error occurs
If the CAN module failed to gain control of the bus 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.
• 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.
13.8 Receiving Remote Frames
13-79
CAN MODULE
Ver.0.10
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