Chapter 23 LIN Physical Layer (S12LINPHYV2)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
Freescale Semiconductor
769
23.4.4
Interrupts
The interrupt vector requested by the LIN Physical Layer is listed in
. Vector address and
interrupt priority is defined at the MCU level.
The module internal interrupt sources are combined into a single interrupt request at the device level.
23.4.4.1
Overcurrent Interrupt
The transmitter is protected against overcurrent. In case of an overcurrent condition occurring within a
time frame called t
OCLIM
starting from LPTxD falling edge, the current through the transmitter is limited
(the transmitter is not shut down). The masking of an overcurrent event within the time frame t
OCLIM
is
meant to avoid “false” overcurrent conditions that can happen during the discharging of the LIN bus. If an
overcurrent event occurs out of this time frame, the transmitter is disabled and the LPOCIF flag is set.
In order to re-enable the transmitter again, the following prerequisites must be met:
1) Overcurrent condition is over
2) LPTxD is recessive or the LIN Physical Layer is in shutdown or receive only mode for a
minimum of a transmit bit time.
To re-enable the transmitter then, the LPOCIF flag must be cleared (by writing a 1).
NOTE
Please make sure that LPOCIF=1 before trying to clear it. It is not allowed
to try to clear LPOCIF if LPOCIF=0 already.
After clearing LPOCIF, if the overcurrent condition is still present or the LPTxD pin is dominant while
being in normal mode, the transmitter remains disabled and the LPOCIF flag is set again after a time to
indicate that the attempt to re-enable has failed. This time is equal to:
•
minimum 1 IRC period (1 us) + 2 bus periods
•
maximum 2 IRC periods (2 us) + 3 bus periods
If the bit LPOCIE is set in the LPIE register, an interrupt is requested.
shows the different scenarios for overcurrent interrupt handling.
Table 23-10. Interrupt Vectors
Module Interrupt Source
Module Internal Interrupt
Source
Local Enable
LIN Interrupt (LPI)
LIN Txd-Dominant Timeout
Interrupt (LPDTIF)
LPDTIE = 1
LIN Overcurrent Interrupt
(LPOCIF)
LPOCIE = 1
