MPC555
/
MPC556
CAN 2.0B CONTROLLER MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
16-31
16.7.8 Free Running Timer
16.7.9 Receive Global Mask Registers
TIMER —
Free Running Timer Register
0x30 708A
0x30 748A
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
TIMER
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 16-19 TIMER Bit Descriptions
Bit(s)
Name
Description
0:15
TIMER
The free running timer counter can be read and written by the CPU. The timer starts from
zero after reset, counts linearly to 0xFFFF, and wraps around.
The timer is clocked by the TouCAN bit-clock. During a message, it increments by one for
each bit that is received or transmitted. When there is no message on the bus, it increments
at the nominal bit rate.
The timer value is captured at the beginning of the identifier field of any frame on the CAN
bus. The captured value is written into the “time stamp” entry in a message buffer after a suc-
cessful reception or transmission of a message.
RXGMSKHI —
Receive Global Mask Register High
0x30 7090, 0x30 7490
RXGMSKLO —
Receive Global Mask Register Low
0x30 7092, 0x30 7492
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
MID28 MID27 MID26 MID25 MID24 MID23 MID22 MID21 MID20 MID19
MID18
0
1
MID17 MID16 MID15
RESET:
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
MID14 MID13 MID12 MID11 MID10
MID9
MID8
MID7
MID6
MID5
MID4
MID3
MID2
MID1
MID0
0
RESET:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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