ST72561 Datasheet, PDF (143/262 Pages) STMicroelectronics – 8-BIT MCU WITH FLASH OR ROM, 10-BIT ADC, 5 TIMERS, SPI, LINSCI , ACTIVE CAN

ST72561
LINSCI SERIAL COMMUNICATION INTERFACE (LIN Mode) (Cont’d)
10.7.9.4 LIN Error Detection
LIN Header Error Flag
The LIN Header Error Flag indicates that an invalid
LIN Header has been detected.
edge of the Synch Field. Let’s refer to this period
deviation as D:
If the LHE flag is set, it means that:
D > 15.625%
When a LIN Header Error occurs:
If LHE flag is not set, it means that:
– The LHE flag is set
D < 16.40625%
– An interrupt is generated if the RIE bit is set and
the I[1:0] bits are cleared in the CCR register.
If autosynchronization is enabled (LASE bit =1),
this can mean that the LIN Synch Field is corrupt-
ed, and that the SCI is in a blocked state (LSF bit is
set). The only way to recover is to reset the LSF bit
and then to clear the LHE bit.
– The LHE bit is reset by an access to the SCISR
register followed by a read of the SCIDR register.
LHE/OVR Error Conditions
When Auto Resynchronization is disabled (LASE
bit =0), the LHE flag detects:
– That the received LIN Synch Field is not equal to
55h.
– That an overrun occurred (as in standard SCI
mode)
– Furthermore, if LHDM is set it also detects that a
LIN Header Reception Timeout occurred (only if
LHDM is set).
When the LIN auto-resynchronization is enabled
(LASE bit=1), the LHE flag detects:
If 15.625% ≤ D < 16.40625%, then the flag can
be either set or reset depending on the dephas-
ing between the signal on the RDI line and the
CPU clock.
– The second check is based on the measurement
of each bit time between both edges of the Synch
Field: this checks that each of these bit times is
large enough compared to the bit time of the cur-
rent baud rate.
When LHE is set due to this error then the SCI
goes into a blocked state (LSF bit is set).
LIN Header Time-out Error
When the LIN Identifier Field Detection Method is
used (by configuring LHDM to 1) or when LIN
auto-resynchronization is enabled (LASE bit=1),
the LINSCI automatically monitors the
T_{HEADER_MAX} condition given by the LIN protocol.
If the entire Header (up to and including the STOP
bit of the LIN Identifier Field) is not received within
the maximum time limit of 57 bit times then a LIN
Header Error is signalled and the LHE bit is set in
the SCISR register.
– That the deviation error on the Synch Field is
outside the LIN specification which allows up to
+/-15.5% of period deviation between the slave
and master oscillators.
– A LIN Header Reception Timeout occurred.
If T_HEADER > T_{HEADER_MAX} then the LHE flag is
set. Refer to Figure 82. (only if LHDM is set to 1)
– An overflow during the Synch Field Measure-
ment, which leads to an overflow of the divider
registers. If LHE is set due to this error then the
SCI goes into a blocked state (LSF bit is set).
– That an overrun occurred on Fields other than
the Synch Field (as in standard SCI mode)
Deviation Error on the Synch Field
The deviation error is checking by comparing the
current baud rate (relative to the slave oscillator)
with the received LIN Synch Field (relative to the
master oscillator). Two checks are performed in
parallel:
– The first check is based on a measurement be-
tween the first falling edge and the last falling
Figure 82. LIN Header Reception Timeout
LIN Synch LIN Synch Identifier
Break
Field
Field
T_HEADER
The time-out counter is enabled at each break de-
tection. It is stopped in the following conditions:
- A LIN Identifier Field has been received
- An LHE error occurred (other than a timeout er-
ror).
- A software reset of LSF bit (transition from high to
low) occurred during the analysis of the LIN Synch
Field or
If LHE bit is set due to this error during the LIN
Synchr Field (if LASE bit = 1) then the SCI goes
into a blocked state (LSF bit is set).
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