Chapter 18 LIN Physical Layer (S12LINPHYV2)
MC9S12ZVM Family Reference Manual Rev. 1.3
Freescale Semiconductor
677
If LPWUE is set the receiver is able to pass wake-up events to the SCI (Serial Communication Interface).
If the LIN Physical Layer receives a dominant level longer than t
WUFR
followed by a rising edge, it sends
a pulse to the SCI which can generate a wake-up interrupt.
Once the device exits stop mode, the LIN Physical Layer returns to normal or receive only mode depending
on the status of the RXONLY bit.
NOTE
Since the wake-up interrupt is requested by the SCI, the wake-up feature is
not available if the SCI is not used.
The internal pullup resistor is selectable only if LPWUE = 1 (wake-up enabled). If LPWUE = 0, the
internal pullup resistor is not selectable and remains at 330 k
Ω
regardless of the state of the LPPUE bit.
If LPWUE = 1, selecting the 330 k
Ω
pullup resistor (LPPUE = 0) reduces the current consumption in
standby mode.
NOTE
When using the LIN wake-up feature in combination with other non-LIN
device wake-up features (like a periodic time interrupt), some care must be
taken.
If the device leaves stop mode while the LIN bus is dominant, the LIN
Physical Layer returns to normal or receive only mode and the LIN bus is
re-routed to the RXD pin of the SCI and triggers the edge detection interrupt
(if the interrupt’s priority of the hardware that awakes the MCU is less than
the priority of the SCI interrupt, then the SCI interrupt will execute first). It
is up to the software to decide what to do in this case because the LIN
Physical Layer can not guarantee it was a valid wake-up pulse.
