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CHAPTER 17 UART
17.7.4
Master-slave Communication Function (Multiprocessor
Mode)
With UART, communication with multiple CPUs connected in master-slave mode is
available in operation mode 1. However, UART can be used only from the master
system.
■ Master-slave Communication Function
The settings shown in Figure 17.7-7 are required to operate UART in multiprocessor mode (operation
mode 1).
SCR0/SCR1,
SMR0/SMR1
SSR0/SSR1,
SIDR0/SIDR1
SODR0/SODR1
DDR4 (UART0)
DDR6 (UART1)
: Bit used
x : Bit not used
1 : Set "1"
0 : Set "0"
: Set "0" to use an input pin
●
Inter-CPU connection
As shown in Figure 17.7-8, a communication system consists of one master CPU and multiple slave CPUs
connected to two communication lines. UART can be used only from the master CPU.
Figure 17.7-8 Connection Example of UART Master-slave Communication
SOT0/SOT1
SIN0/SIN1
Master CPU
506
Figure 17.7-7 Settings for UART Operation Mode 1
bit 15
14
13
12
11
PEN P SBL
CL AD
0
×
1
PE OREFRE
RDRFTDRE
×
SOT
Slave CPU #0
10
9
8
7
6
5
REC
RXE
MD1 MD0 CS2
TXE
0
0
1
Set transmission data (during writing).
BDS
RIE TIE
Retain receive data (during reading).
SIN
SOT
Slave CPU #1
4
3
2
1
0
CS1 CS0
RST
SCKE SOE
×
0
SIN
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