Fujitsu FR81S User Manual
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
7. Operation of LIN Interface (v2.1)
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
288
From ID Field Reception to Data Field Transmission/Reception
After the ID Field is received, specify whether to transmit the Data Field to the master device or receive it.
⋅
In the case of Data Field transmission:
⋅
After the ID Field is received, write data in the transmit data register (TDR). At this time,
transmission interrupts must be enabled (SCR:TIE=1).
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In the case of Data Field reception:
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For every Data Field reception, the SSR:RDRF bit is set to "1". If reception interrupts are enabled
(SCR:RDRF=1) at this time, a reception interrupt occurs.
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The start bit is detected when the falling edge is detected after data passes the noise filter (majority
decision by sampling the serial data input with the bus clock three times), and the passed data detects
"L" at the sampling point.
Figure 7-36 From ID Field Reception to Data Field Transmission/Reception
From ID Field Reception to Data Field Transmission
LIN bus
DATA Field transmission
ID Field reception
RDR
read
SSR:RDRF
Sync Field
SSR:TDRE
SCR:TIE
TDR
write
From ID Field Reception to Data Field Reception
Notes:
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Although the noise filter (where the serial data input is sampled three times with the bus clock and
decided by majority) is built in, design the board so that the noise should not pass this filter or
communicate so that noise passing may not become a problem (for instance, when the error occurs due to
adding the checksum of data at the end, send it again).
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If a falling edge of serial data is detected at the same time as the sampling point of the stop bit or before
one to two bus clocks during reception, the data may not be received with the edge disabled. It is
recommended to leave a space between frames if successive frames are to be output.
LIN bus
DATA Field
transmission
ID Field reception
RDR read
SSR:RDRF
Sync Field
MB91520 Series
MN705-00010-1v0-E
1601