Fujitsu MB90390 Series Hardware Manual page 422

CHAPTER 20 UART2, UART3
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Inter-CPU connection
As shown in Figure 20.7-11, interconnect two CPUs in UART2, UART3 mode 2
Figure 20.7-11 Connection Example of UART2, UART3 Mode 2 Bidirectional Communication
CPU-1 (Master)
●
Communication procedures
Communication will start at any timing from the transmission side when the transmission data is ready.
When the reception side received the data, ANS is returned regularly (every 1 byte in the following
example). Figure 20.7-12 shows one example bidirectional communication flowchart.
Figure 20.7-12 Example of Bidirectional Communication Flowchart
NO
394
SOT
SIN
Output
SCK
(Transmission side)
Start
Operating mode setting
(either 0 or 2)
Set 1-byte data to TDR2/
TDR3 and communicate
With reception data
YES
Read reception data
and process
Input
Operating mode setting
(match the transmission side)
Transmission of data
NO
Transmission of data
1-byte data transmission
(ANS)
SOT
SIN
SCK
CPU-2 (Slave)
(Reception side)
Start
With reception data
YES
Read reception data
and process