Chapter 23 LIN Physical Layer (S12LINPHYV2)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
766
Freescale Semiconductor
Please note that if the bit time is smaller than the parameter t
OCLIM
(please refer to electricals), then no
overcurrent is reported nor does an overcurrent shutdown occur. However, the current limitation is always
engaged in case of a failure.
23.4.3
Modes
shows the possible mode transitions depending on control bits, stop mode, and error
conditions.
23.4.3.1
Shutdown Mode
The LIN Physical Layer is fully disabled. No wake-up functionality is available. The internal pullup
resistor is high ohmic only (330 k
)
to maintain the LIN Bus pin in the recessive state. LPTxD is not
monitored in this mode for a TxD-dominant timeout. All the registers are accessible.
Setting LPE causes the module to leave the shutdown mode and to enter the normal mode or receive only
mode (if RXONLY bit is set).
Clearing LPE causes the module to leave the normal or receive only modes and go back to shutdown mode.
23.4.3.2
Normal Mode
The full functionality is available. Both receiver and transmitter are enabled. The internal pullup resistor
can be chosen to be high ohmic (330 k
) if LPPUE = 0, or LIN compliant (34 k
if LPPUE = 1.
If RXONLY is set, the module leaves normal mode to enter receive only mode.
If the MCU enters stop mode, the LIN Physical Layer enters standby mode.
23.4.3.3
Receive Only Mode
Entering this mode disables the transmitter and immediately stops any on-going transmission. LPTxD is
not monitored in this mode for a TxD-dominant timeout.
The receiver is running in full performance mode in all cases.
To return to normal mode, the RXONLY bit must be cleared.
If the device enters stop mode, the module leaves receive only mode to enter standby mode.
23.4.3.4
Standby Mode with Wake-Up Feature
The transmitter of the LIN Physical Layer is disabled and the receiver enters a low power mode.
NOTE
Before entering standby mode, ensure no transmissions are ongoing.
If LPWUE is not set, no wake up feature is available and the standby mode has the same electrical
properties as the shutdown mode. This allows a low-power consumption of the device in stop mode if the
wake-up feature is not needed.
