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Controller Area Network
LH75400/01/10/11 (Preliminary) User’s Guide
22-10
6/17/03
22.3.2.3 Status Register
SR is the Status Register. The SR Register reflects the status of the CAN Controller. It
appears to the CPU as Read Only memory.
If bits [5] and [4] are both 0, the CAN bus is idle. If both bits are 1, the Controller is waiting
to become idle again. After a System Reset, Idle state is entered once the Bus Free
sequence (11 consecutive recessive bits) is detected. After a Bus Off event, 128 Bus Free
sequences must be received before Idle state is entered.
When using this register:
• If both the Receive Status and the Transmit Status bits are '0', the CAN bus is idle. If
both bits are '1', the CAN Controller is waiting to become idle again. After a System
Reset, Idle state is entered once the Bus Free sequence (11 consecutive recessive bits)
is detected. After a Bus Off event, 128 Bus Free sequences must be received before Idle
state is entered.
• For bit [1], the overrun condition is only indicated if the entire message was received. No
overrun condition is shown if the message did not complete (e.g., due to an error).
Table 22-6. SR 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
///
BS
ES
TS
RS
TCS
TBS
DOS
RBS
RESET
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
ADDR
0xFF 0x08