ATtiny167-ESSZ datasheet(172/282 Pages) ATMEL

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172

7728D–AVR–07/09

ATtiny87/ATtiny167

When the busy signal is set, some registers are locked, user writing is not allowed:

• “LIN Control Register” - LINCR - except LCMD[2..0], LENA & LSWRES,

• “LIN Baud Rate Registers” - LINBRRL & LINBRRH,

• “LIN Data Length Register” - LINDLR,

• “LIN Identifier Register” - LINIDR,

• “LIN Data Register” - LINDAT.

If the busy signal is set, the only available commands are:

• LCMD[1..0] = 00

b, the abort command is taken into account at the end of the byte,

• LENA = 0 and/or LCMD[2] = 0, the kill command is taken into account immediately,

• LSWRES = 1, the reset command is taken into account immediately.

Note that, if another command is entered during busy signal, the new command is not vali-

dated and the LOVRERR bit flag of the LINERR register is set. The on-going transfer is not

interrupted.

15.5.5.2

Busy Signal in UART Mode

During the byte transmission, the busy signal is set. This locks some registers from being

written:

• “LIN Control Register” - LINCR - except LCMD[2..0], LENA & LSWRES,

• “LIN Data Register” - LINDAT.

The busy signal is not generated during a byte reception.

15.5.6

Bit Timing

15.5.6.1

Baud rate Generator

The baud rate is defined to be the transfer rate in bits per second (bps):

• BAUD: Baud rate (in bps),

•

fclki/o: System I/O clock frequency,

• LDIV[11..0]: Contents of LINBRRH & LINBRRL registers - (0-4095), the pre-scaler

receives clki/o as input clock.

• LBT[5..0]: Least significant bits of - LINBTR register- (0-63) is the number of samplings in a

LIN or UART bit (default value 32).

Equation for calculating baud rate:

BAUD = fclki/o / LBT[5..0] x (LDIV[11..0] + 1)

Equation for setting LINDIV value:

LDIV[11..0] = ( fclki/o / LBT[5..0] x BAUD ) - 1

Note that in reception a majority vote on three samplings is made.

15.5.6.2

Re-synchronization in LIN Mode

When waiting for Rx Header, LBT[5..0] = 32 in LINBTR register. The re-synchronization

begins when the BREAK is detected. If the BREAK size is not in the range (10.5 bits min., 28

bits max. — 13 bits nominal), the BREAK is refused. The re-synchronization is done by adjust-

ing LBT[5..0] value to the SYNCH field of the received header (0x55). Then the PROTECTED

IDENTIFIER is sampled using the new value of LBT[5..0].

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