Fujitsu MB96300 series Hardware Manual page 544

CHAPTER 20 USART
the synch break can not be correctly checked against the minimum requirement of the LIN specification (13
master bit time and 11 slave bit time).
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Bus idle function
The Bus Idle Function cannot be used in synchronous slave mode mode 2.
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AD bit (serial control register (SCRn): address/data type select bit)
Special care has to be taken when using the AD bit (Address-Data-Bit for multiprocessor mode 1) of the
Serial Control Register. This bit is both a control and a flag bit, because writing to it sets the AD bit for
transmission, whereas reading from it returns the last received AD bit. Internally, the received and the
transmitted value are stored in different registers, but in Read-Modify-Write instructions, the received value
is read, modified and then written back for transmission. This can lead to a wrong value in the AD bit, when
one of the other bits in the same register is accessed by an instruction of this kind.
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Clearing reception errors
Clearing reception errors resets the reception state machine. Therefore check any reception errors before the
next start-bit or start condition is met, to not disturb any ongoing reception.
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LIN Synch field wait state
In mode 3 (LIN operation), the LBD bit in the ESCRn register is set to "1" if the input signal is kept at "0" for
more than equal to 11-bit time. Then the USART waits for the following synch field to be received. If the
USART is set into this state for other reasons than the synch break, it should be initialized by the software
reset (SMRnSCRn:UPCL=1).
In mode 3, LIN-Break detection is always working in the background and is level sensitive. Be careful in
case of a bus error (bus always dominant). The LIN-Break detection flag (LBD) will go "1" or stay "1" after
each 11 bit times independent from enabled or disabled LIN break detection interrupt. If you use LIN-Break
detection interrupt, be sure to check and clear always this flag in your receive interrupt handler.
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Baud Rate detection using the Input Capture Units (ICU)
The USARTs provide the signal LSYN that can be connected to the ICU so that LSYN's pulse length can be
measured to derive the baud rate. The connection of the LSYN signals to the ICUs is controlled by the Port
14 function register PFR and EPFR.
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MB96300 Super Series Hardware Manual