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Chapter 32 USART (LIN / FIFO)
7.USART Operation
■ Master-slave Communication Function
The settings shown in figure 7-10 are required to operate USART in multiprocessor mode (operation mode 1).
Figure 7-10 Settings for USART operation mode 1
■ Inter-CPU Connection
As shown in figure 7-11, a communication system consists of one master CPU and multiple slave CPUs
connected to two communication lines. USART can be used for the master or slave CPU.
Figure 7-11 Connection example of USART master-slave communication
■ Function Selection
Select the operation mode and data transfer mode for master-slave communication as shown in table 7-3.
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
SCR04,SMR0
4
PEN P SBL CL AD CRE RXE TXE MD1 MD0 OTO EXT REST UPCL SCKE SOE
Mode 1 x x 0 0 1 x 0 0 0 1
SSR04,
TDR04/RDR04
PE ORE FRE RDRF TDRE BDS RIE TIE
Set transmission data (during writing)
Retain reception data (during reading)
Mode 1 x
Bit is used
x Bit is not used
0 / 1 Set bit to 0 / 1
Master CPU
SIN
SIN
SOT
SOT
SIN SOT
Slave CPU #2Slave CPU #1