ST7LITE3 datasheet(117/167 Pages) STMICROELECTRONICS

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ST7LITE3

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LINSCI

™ SERIAL COMMUNICATION INTERFACE (LIN Mode) (Cont’d)

LIN HEADER LENGTH REGISTER (LHLR)

Read Only

Reset Value: 0000 0000 (00h).

Note: In LIN Slave mode when LASE = 1 or LHDM

= 1, the LHLR register is accessible at the address

of the SCIERPR register.

Otherwise this register is always read as 00h.

Bit 7:0 = LHL[7:0] LIN Header Length.

This is a read-only register, which is updated by

hardware if one of the following conditions occurs:

- After each break detection, it is loaded with

“FFh”.

- If a timeout occurs on THEADER, it is loaded with

00h.

- After every successful LIN Header reception (at

the same time than the setting of LHDF bit), it is

loaded with a value (LHL) which gives access to

the number of bit times of the LIN header length

(THEADER). The coding of this value is explained

below:

LHL Coding:

THEADER_MAX = 57

LHL(7:2) represents the mantissa of (57 - THEAD-

ER)

LHL(1:0) represents the fraction (57 - THEADER)

Example of LHL coding:

Example 1: LHL = 33h = 001100 11b

LHL(7:3) = 1100b = 12d

LHL(1:0) = 11b = 3d

This leads to:

Mantissa (57 - THEADER) = 12d

Fraction (57 - THEADER) = 3/4 = 0.75

Therefore:

(57 - THEADER) = 12.75d

and THEADER = 44.25d

Example 2:

57 - THEADER = 36.21d

LHL(1:0) = rounded(4*0.21d) = 1d

LHL(7:2) = Mantissa (36.21d) = 36d = 24h

Therefore LHL(7:0) = 10010001 = 91h

Example 3:

57 - THEADER = 36.90d

LHL(1:0) = rounded(4*0.90d) = 4d

The carry must be propagated to the matissa :

LHL(7:2) = Mantissa (36.90d) + 1= 37d =

Therefore LHL(7:0) = 10110000= A0h

LHL7

LHL6

LHL5

LHL4

LHL3

LHL2

LHL1

LHL0

LHL[7:2]

Mantissa

(57 -

THEADER)

Mantissa

(

THEADER)

...

39h

3Ah

3Bh

Never Occurs

...

3Eh

Never Occurs

3Fh

Initial value

LHL[1:0]

Fraction (57 -

THEADER)

1/4

1/2

3/4

ST7LITE3 数据表(PDF) 117 Page - STMicroelectronics

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