ST72361AR4-Auto datasheet(179/279 Pages) STMICROELECTRONICS

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ST72361xx-Auto

LINSCI serial communication interface (LIN master/slave)

Doc ID 12468 Rev 3

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worst case: This occurs when the LIN identifier lasts exactly 10 TBIT_MASTER periods. In this

case, the LIN break and synch fields last 49 - 10 = 39TBIT_MASTER periods.

Assuming the slave measures these first 39 bits with a desynchronized clock of 15.5%. This

leads to a maximum allowed header length of:

39 x (1/0.845) TBIT_MASTER + 10TBIT_MASTER = 56.15 TBIT_SLAVE

A margin is provided so that the time-out occurs when the header length is greater than 57

TBIT_SLAVE periods. If it is less than or equal to 57 TBIT_SLAVE periods, then no timeout

occurs.

LIN header length

Even if no timeout occurs on the LIN header, it is possible to have access to the effective LIN

header length (THEADER) through the LHL register. This allows monitoring at software level

the TFRAME_MAX condition given by the LIN protocol.

This feature is only available when LHDM bit = 1 or when LASE bit = 1.

Mute mode and errors

In mute mode when LHDM bit = 1, if an LHE error occurs during the analysis of the LIN

synch field or if a LIN header time-out occurs then the LHE bit is set but it does not wake up

from mute mode. In this case, the current header analysis is discarded. If needed, the

software has to reset LSF bit. Then the SCI searches for a new LIN header.

In mute mode, if a framing error occurs on a data (which is not a break), it is discarded and

the FE bit is not set.

When LHDM bit = 1, any LIN header which respects the following conditions causes a wake-

up from mute mode:

●

A valid LIN break field (at least 11 dominant bits followed by a recessive bit)

●

A valid LIN synch field (without deviation error)

●

A LIN identifier field without framing error. Note that a LIN parity error on the LIN

identifier field does not prevent wake-up from mute mode.

●

No LIN header time-out should occur during header reception.

Figure 83.

LIN synch field measurement

LIN Synch Break

Extra

’1’

Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7

Start

Bit

Stop

Bit

Start

Bit

LIN Synch Field

Measurement = 8.TBR = SM.tCPU

LPR(n)

LPR(n+1)

LPR = tBR / (16.tCPU) = Rounding (SM / 128)

tCPU = CPU period

tBR = Baud Rate period

tBR

tBR = 16.LP.tCPU

SM = Synch Measurement Register (15 bits)

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