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Chapter 32 USART (LIN / FIFO)
8.Notes on using USART
■ Baud Rate Detection Using the Input Capture Units
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 :
If the PFR bit equals ‘1’ and the EPFR bits equals ‘0’, the ICU is connected to its corresponding input pin IN.
If the PFR bit equals ‘1’ and the EPFR bits equals ‘1’, the USARTs are connected to the ICU.
The user has to take into account that:
• ICU4 and ICU5 share one free running timer (prescaler).
LIN-UART4
LSYN
ICU4
IN
ICU5
IN
FREE RUN TIMER4
Pin IN4
S
11
10
PFR[4] & EPFR[4]
S
11
10
Pin IN5
LIN-UART5
LSYN
PFR[5] & EPFR[5]