LIN Controller (LINFlex)
MPC5606S Microcontroller Reference Manual, Rev. 7
834 Freescale Semiconductor
23.5.3 Low-power mode (Sleep)
To reduce power consumption, LINFlex has a low-power mode called Sleep mode. To enter Sleep mode,
software sets the SLEEP bit in the LINCR1. In this mode, the LINFlex clock is stopped. Consequently, the
LINFlex will not update the status bits but software can still access the LINFlex registers.
LINFlex can be awakened (exit Sleep mode) either by software clearing the SLEEP bit or on detection of
LIN bus activity if automatic wakeup mode is enabled (AWUM bit is set).
On LIN bus activity detection, hardware automatically performs the wakeup 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 wakeup event occurs.
23.6 Test modes
Two test modes are available to the user: Loopback 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.
23.6.1 Loopback mode
LINFlex can be put in Loopback mode by setting the LBKM bit in the LINCR. In Loopback mode, the
LINFlex treats its own transmitted messages as received messages.
Figure 23-4. LINFlex in Loopback 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.
23.6.2 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 Loopback 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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