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Controller Area Network
LH75400/01/10/11 (Preliminary) User’s Guide
22-8
6/17/03
22.3.2 CAN Register Definitions
22.3.2.1 Mode Register
MOD is the Mode Register. The active bits used in this register are Read/Write.
The MOD Register allows the selection of:
• Acceptance Filter Mode
• Self Test Mode
• Listen Only Mode
• Reset Mode.
Bits [3:1] can be written in both Operating Mode and Reset Mode.
Table 22-2. MOD Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
///
AFM
STM
LOM
RM
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
RW
R
R
R
R
R
R
R
R
R
R
R
RW
RW
RW
RW
RW
ADDR
0xFF 0x00
Table 22-3. MOD Register Definitions
BIT NAME
DESCRIPTION
31:5
///
Reserved
Writing to these bits has no effect. Reading returns 0.
4
///
Reserved
Do not modify. Read as 0.
3
AFM
Acceptance Filter Mode
0 = Dual filter. Receive data is filtered using two shorter filters.
1 = Single filter. Receive data is filtered using one 4-byte filter.
2
STM
Self Test Mode
0 = Normal operation. An acknowledge is required for successful transmission.
1 = Enable Self Test Mode. In this mode, a full node test is possible without any other active
node on the bus using the Self-Reception request command.
1
LOM
Listen Only Mode
0 = Normal operation. The error counters cannot be changed unless in Reset Mode.
1 = Enable Listen Only Mode. In this mode, the CAN Controller does not send an acknowledge
to the CAN bus, even when a message is received successfully.
0
RM
Reset Mode
0 = Normal Operation. The CAN Controller returns to Operating Mode on the 1-to-0 transition
of this bit.
1 = Reset Mode. Any message currently being transmitted or received is aborted and Reset
Mode is entered.