Datasheet

21.5.6.2. 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 (11 bits min., 28 bits max. — 13 bits nominal),
the BREAK is refused. The re-synchronization is done by adjusting 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]. The re-synchronization implemented in the controller tolerates a clock deviation of ±20% and
adjusts the baud rate in a ±2% range.
The new LBT[5..0] value will be used up to the end of the response. Then, the LBT[5..0] will be reset to
32 for the next header.
The LINBTR register can be used to re-calibrate the clock oscillator.
The re-synchronization is not performed if the LIN node is enabled as a master.
21.5.6.3. Handling LBT[5:0]
LDISR bit of LINBTR register is used to:
• To enable the setting of LBT[5:0] (to manually adjust the baud rate especially in the case of UART
mode). A minimum of eight is required for LBT[5:0] due to the sampling operation
• Disable the re-synchronization in LIN Slave Mode for test purposes
Note that the LENA bit of LINCR register is important for this handling.
Figure 21-8. Handling LBT[5:0].
Write in LINBTR register
LENA ?
(LINCR bit 4)
LDISR
to write
=0
=0
=1
LBT[5..0] forced to 0x20
LDISR forced to 0
Enable re-synch. in LIN mode
LBT[5..0] = LBT[5..0] to write
(LBT[5..0]
min
=8)
LDISR forced to 1
Disable re-synch. in LIN mode
=1
21.5.7. Data length
LIN commands describes how to set or how are automatically set the LRXDL[3..0] or LTXDL[3..0] fields of
LINDLR register before receiving or transmitting a response.
In the case of Tx Response the LRXDL[3..0] will be used by the hardware to count the number of bytes
already successfully sent.
In the case of Rx Response the LTXDL[3..0] will be used by the hardware to count the number of bytes
already successfully received.
If an error occurs, this information is useful to the programmer to recover the LIN messages.
21.5.7.1. Data length in LIN 2.1
• If LTXDL[3..0]=0 only the CHECKSUM will be sent
• If LRXDL[3..0]=0 the first byte received will be interpreted as the CHECKSUM
• If LTXDL[3..0] or LRXDL[3..0] >8, values will be forced to eight after the command setting and
before sending or receiving of the first byte
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
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