ST72361 datasheet(220/224 Pages) STMICROELECTRONICS

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ST72361

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IMPORTANT NOTES (Cont’d)

16.1.5 Header Time-out Does Not Prevent

Wake-up from Mute Mode

Normally, when LINSCI is configured in LIN slave

mode, if a header time-out occurs during a LIN

header reception (that is, header length > 57 bits),

the LIN Header Error bit (LHE) is set, an interrupt

occurs to inform the application but the LINSCI

should stay in mute mode, waiting for the next

header reception.

Problem Description

The LINSCI sampling period is Tbit / 16. If a LIN

Header time-out occurs between the 9th and the

15th sample of the Identifier Field Stop Bit (refer to

Figure 132), the LINSCI wakes up from mute

mode. Nevertheless, LHE is set and LIN Header

Detection Flag (LHDF) is kept cleared.

In addition, if LHE is reset by software before this

15th sample (by accessing the SCISR register and

reading the SCIDR register in the LINSCI interrupt

routine), the LINSCI will generate another LINSCI

interrupt (due to the RDRF flag setting).

Impact on application

Software may execute the interrupt routine twice

after header reception.

Moreover, in reception mode, as the receiver is no

longer in mute mode, an interrupt will be generat-

ed on each data byte reception.

Workaround

The problem can be detected in the LINSCI inter-

rupt routine. In case of timeout error (LHE is set

and LHLR is loaded with 00h), the software can

check the RWU bit in the SCICR2 register. If RWU

is cleared, it can be set by software. Refer to Fig-

ure 133 on page 221. Workaround is shown in

bold characters.

Figure 132. Header Reception Event Sequence

LIN Synch

Identifier

Field

Break

THEADER

Active mode is set

RDRF flag is set

Critical

Window

ID field STOP bit

(RWU is cleared)

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