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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
TwinCAN Module
User’s Manual
21-44
V2.2, 2004-01
TwinCAN_X1, V2.1
21.1.8
Loop-Back Mode
The TwinCAN module’s loop-back mode provides the means to internally test the
TwinCAN module and CAN driver software. CAN driver software can be developed and
tested without being connected to a CAN bus system.
In loop-back mode, the transmit pins deliver recessive signals to the transceiver. The
transmit signals are combined together and are connected to the internal receive signals,
as shown in
. The receive input pins are not taken into account in loop-back
mode.
Figure 21-25 Loop-back Mode
Loop-back mode is controlled by bits LBM in the bit timing registers of Node A and
Node B according to
.
Table 21-5
Loop-Back Mode
ABTR.LBM
BBTR.LBM
Description
0
0
Loop-back mode is disabled.
0
1
Loop-back mode is disabled.
1
0
Loop-back mode is disabled.
1
1
Loop-back mode is enabled.
MCA05495
MUX
1
0
1
TxDCB
MUX
1
0
1
TxDCA
&
TwinCAN
Kernel
MUX
0
1
MUX
0
1
RxDCA
RxDCB
LBM