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FlexCAN Module
MPC5644A Microcontroller Reference Manual, Rev. 6
1406
Freescale Semiconductor
WAK_SRC
Wake Up Source
This bit defines whether the integrated low-pass filter is applied to protect the Rx CAN input from
spurious wake up. See
1: FlexCAN uses the filtered Rx input to detect recessive to dominant edges on the CAN bus
0: FlexCAN uses the unfiltered Rx input to detect recessive to dominant edges on the CAN bus.
SRX_DIS
Self Reception Disable
This bit defines whether FlexCAN is allowed to receive frames transmitted by itself. If this bit is
asserted, frames transmitted by the module will not be stored in any message buffer, regardless
if the message buffer is programmed with an ID that matches the transmitted frame, and no
interrupt flag or interrupt signal will be generated due to the frame reception.
1: Self reception disabled
0: Self reception enabled
MBFEN
Backwards Compatibility Configuration
This bit is provided to support Backwards Compatibility with previous FlexCAN versions. When
this bit is negated, the following configuration is applied:
• For MCUs supporting individual Rx ID masking, this feature is disabled. Instead of individual ID
masking per message buffer, FlexCAN uses its previous masking scheme with RXGMASK,
RX14MASK and RX15MASK.
• The reception queue feature is disabled. Upon receiving a message, if the first message buffer
with a matching ID that is found is still occupied by a previous unread message, FlexCAN will
not look for another matching message buffer. It will override this message buffer with the new
message and set the CODE field to ‘0110’ (overrun).
Upon reset this bit is negated, allowing legacy software to work without modification.
1: Individual Rx masking and queue feature are enabled.
0: Individual Rx masking and queue feature are disabled.
LPRIO_EN
Local Priority Enable
This bit is provided for backwards compatibility reasons. It controls whether the local priority
feature is enabled or not. It is used to extend the ID used during the arbitration process. With this
extended ID concept, the arbitration process is done based on the full 32-bit word, but the actual
transmitted ID still has 11-bit for standard frames and 29-bit for extended frames.
1: Local Priority enabled
0: Local Priority disabled
AEN
Abort Enable
This bit is supplied for backwards compatibility reasons. When asserted, it enables the Tx abort
feature. This feature guarantees a safe procedure for aborting a pending transmission, so that no
frame is sent in the CAN bus without notification.
1: Abort enabled
0: Abort disabled
Table 32-8. Module Configuration Register (MCR) field descriptions
Field
Description
Summary of Contents for MPC5644A
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