M451
May. 4, 2018
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Rev.2.08
M4
51
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measurement is stored in an internal 13-bit register and the UART_BAUD register value will be
automatically updated at the end of the fifth falling edge. If the measure timer (13-bit) overflows
before five falling edges, then the header error flag SLVHEF (UART_LINSTS [1]) will be set.
start
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
stop
UART_BAUD
(m)
UART_BAUD
(n)
Measurement time
Break field
LIN Bus
UART_BAUD
Update baud rate if auto re-sync
function enable
Figure 6.13-18 LIN Sync Field Measurement
When operating in Automatic Resynchronization (AR) mode, software must select the desired
baud rate by setting the UART_BAUD register and hardware will store it at internal TEMP_REG
register, after each LIN break field, the time duration between five falling edges is sampled on
peripheral clock and the result of this measurement is stored in an internal 13-bit register
BAUD_LIN and the result will be updated to UART_BAUD register automatically.
To guarantee the transmission baud rate, the baud rate generator must reload the initial value
before each new break reception. The initial value is programmed by the application during
initialization (TEMP_REG). User can set SLVDUEN (UART_LINCTL [3]) to enable auto reload
initial baud rate value function. If the SLVDUEN (UART_LINCTL [3]) is set, when received the
next character, hardware will auto reload the initial value to UART_BAUD, and when the
UART_BAUD be updated, the SLVDUEN (UART_LINCTL [3]) will be cleared automatically. The
behavior of LIN updated method as shown in the Figure 6.13-19 and Figure 6.13-20.
Note1:
It is recommended to set the SLVDUEN bit before every checksum reception.
Note2:
When a header error is detected, user must write 1 to SLVSYNCF (UART_LINSTS[3]) to
re-search new frame header. When writing 1 to it, hardware will reload the initial baud rate
TEMP_REG and re-search new frame header.
Note3:
When operating in Automatic Resynchronization mode, the baud rate setting must be
operated at mode2 (BAUDM1 (UART_BAUD [29]) and BAUDM0 (UART_BAUD[28]) must be 1).
Data 1
Data 2
Data N
Check
Sum
Protected
Identifier
field
Response
Inter-
frame
space
Frame slot
Synch
field
Break
Field
Measurement
time
(n)
(m)
(n)
S/W set LINS_DUM_ EN to 1
_ BAUD register
(
_ BAUD = BAUD_ LIN value)
Both of TEMP_REG and BAUD_LIN are internal register
H/W auto -reload initial baud
Rate which back up in
TEMP_REG and cleared
LINS_DUMP_EN to 0 by H/W
UART_BAUD
UART_BAUD
UART_BAUD
update UART
UART
TEMP_REG value is UART_BAUD(n)
BAUD_LIN value is UART_BAUD(m)
