Rainbow Electronics ATmega64C1 - Manual (Page 213)

213
7647A–AVR–02/08
ATmega32/64/M1/C1
Figure 17-8. Handling LBT[5..0]
17.5.7 Data Length
Section 17.4.6 “LIN Commands” on page 207 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.
17.5.7.1 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 8 after the command setting and
before sending or receiving of the first byte.
17.5.7.2 Data Length in LIN 1.3
• LRXDL and LTXDL fields are both hardware updated before setting LIDOK by decoding the
data length code contained in the received PROTECTED IDENTIFIER (LRXDL = LTXDL).
• Via the above mechanism, a length of 0 or >8 is not possible.
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