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May 10, 2017
4. Transmission Using Transmit Queue
The transmit queue is used to transmit data frames or remote frames.
The transmit queue is allocated up to 16 buffers per channel, and the transmit buffer [16 x m + 15] is the common
access window.
The functions of the transmit queue are shown below. For the configuration settings for using the transmit queue,
refer to "CAN Configuration Application Note".
• ・Message transmission function
• ・Transmit abort function
4.1 Message Transmission Function
This is the function to transmit data frames or remote frames.
When using the transmit queue, set the message priority to ID priority.
All messages in the transmit queue are subject to transmit priority determination and are sent in order of ID priority,
regardless of the order in which they were stored. If two messages with the same ID are stored in the transmit queue, the
order in which these messages are sent may differ from the order in which they were stored in the transmit queue.
Figure 4-1 shows the operation of the transmit queue.
Figure 4-1 Transmit Queue Operation
:Transmit queue interrupt source is "when the transmit queue is empty"
(When the TXQIM bit of the TXQCCm register is “0”)
: Transmit queue interrupt source is "every time one message is transmitted"
(When the TXQIM bit of the TXQCCm register is “1”)