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The timer is incremented by the CAN bit clock, which defines the baud rate on the CAN
bus. During a message transmission/reception, it increments by one for each bit that is
received or transmitted. When there is no message on the bus, it counts using the
previously programmed baud rate. The timer is not incremented during Disable, Doze,
Stop and Freeze modes.
The timer value is captured when the second bit of the identifier field of any frame is on
the CAN bus. This captured value is written into the Time Stamp entry in a message
buffer after a successful reception or transmission of a message.
If bit CAN_CTRL1[TSYN] is asserted, the Timer is reset whenever a message is
received in the first available Mailbox, according to CAN_CTRL2[RFFN] setting.
The CPU can write to this register anytime. However, if the write occurs at the same time
that the Timer is being reset by a reception in the first Mailbox, then the write value is
discarded.
Reading this register affects the Mailbox Unlocking procedure, see Section "Mailbox
Lock Mechanism".
Address: Base a 8h offset
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R
W
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
CANx_TIMER field descriptions
Field
Description
31–16
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
TIMER
Timer Value
Contains the free-running counter value.
43.4.5 Rx Mailboxes Global Mask Register (CANx_RXMGMASK)
This register is located in RAM.
RXMGMASK is provided for legacy application support.
• When the CAN_MCR[IRMQ] bit is negated, RXMGMASK is always in effect (the
bits in the MG field will mask the Mailbox filter bits).
• When the CAN_MCR[IRMQ] bit is asserted, RXMGMASK has no effect (the bits in
the MG field will not mask the Mailbox filter bits).
Chapter 43 Flex Controller Area Network (FlexCAN)
KV4x Reference Manual, Rev. 2, 02/2015
Freescale Semiconductor, Inc.
Preliminary
1097
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