PXD10RM Datasheet, PDF (838/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

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 wake-up mode is enabled (AWUM bit is set).
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.
23.6 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.
23.6.1 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.
LINFlex
Tx
Rx
LINTX
LINRX
Figure 23-4. 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.
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 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.
23-6
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor