LIN Controller (LINFlex) RM0046
490/936 Doc ID 16912 Rev 5
On LIN bus activity detection, hardware automatically performs the wake-up sequence by
clearing the SLEEP bit if the AWUM bit in the LINCR1 is set. To exit from Sleep mode if the
AWUM bit is cleared, software clears the SLEEP bit when a wake-up event occurs.
21.6 Test modes
Two test modes are available to the user: Loop Back mode and Self Test mode. They can be
selected by the LBKM and SFTM bits in the LINCR1. These bits must be configured while
LINFlex is in Initialization mode. Once one of the two test modes has been selected, LINFlex
must be started in Normal mode.
21.6.1 Loop Back mode
LINFlex can be put in Loop Back mode by setting the LBKM bit in the LINCR. In Loop Back
mode, the LINFlex treats its own transmitted messages as received messages.
Figure 233. LINFlex in loop back mode
This mode is provided for self test functions. To be independent of external events, the LIN
core ignores the LINRX signal. In this mode, the LINFlex performs an internal feedback from
its Tx output to its Rx input. The actual value of the LINRX input pin is disregarded by the
LINFlex. The transmitted messages can be monitored on the LINTX pin.
21.6.2 Self Test mode
LINFlex can be put in Self Test mode by setting the LBKM and SFTM bits in the LINCR. This
mode can be used for a “Hot Self Test”, meaning the LINFlex can be tested as in Loop Back
mode but without affecting a running LIN system connected to the LINTX and LINRX pins. In
this mode, the LINRX pin is disconnected from the LINFlex and the LINTX pin is held
recessive.
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