FlexCAN Module
Freescale Semiconductor
24-21
PXR40 Microcontroller Reference Manual, Rev. 1
24.3.4.3
Free Running Timer (FLEXCAN_x_TIMER)
This register represents a 16-bit free running counter that can be read and written by the CPU. The timer
starts from 0x0000 after Reset, counts linearly to 0xFFFF, and wraps around.
The timer is clocked by the FlexCAN 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. During Freeze Mode,
the timer is not incremented.
The timer value is captured at the beginning of the identifier field of any frame 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.
Writing to the timer is an indirect operation. The data is first written to an auxiliary register and then an
internal request/acknowledge procedure across clock domains is executed. All this is transparent to the
user, except for the fact that the data will take some time to be actually written to the register. If desired,
software can poll the register to discover when the data was actually written.
Figure 24-7. Free Running Timer (FLEXCAN_x_TIMER)
Base + 0x0008
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
TIMER
W
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Summary of Contents for PXR4030
Page 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
Page 30: ...PXR40 Microcontroller Reference Manual Rev 1 Freescale Semiconductor xxx...
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Page 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
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