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CHAPTER 13 UART
MB90560 series
13.7 Operation of UART
UART operates in operation modes 0 and 2 for normal bidirectional serial
communication and in operation mode 1 for master-slave communication.
I
Operation of UART
G
Operation modes
There are three UART operation modes: modes 0 to 2. As listed in Table 13.7-1, an operation
mode can be selected according to the inter-CPU connection method and data transfer mode.
Table 13.7-1UART operation mode
–
: Setting not possible
*1
: "+1" indicates the address/data selection bit (A/D) for communication control.
*2
:During reception, only one stop bit can be detected.
<Check>
Operation mode 1 of UART is used only from the master system during master-slave
connection.
G
Inter-CPU Connection Method
One-to-one connection (normal mode) and master-slave connection (multiprocessor mode) can
be selected. For either connection method, the data length, whether to enable parity, and the
synchronization method must be common to all CPUs. Select an operation mode as follows:
In the one-to-one connection method, operation mode 0 or 2 must be used in the two CPUs.
Select operation mode 0 for asynchronous transfer mode and operation mode 2 for
synchronous transfer mode.
Select operation mode 1 for the master-slave connection method and use it from the master
system. Select "When parity is disabled" for this connection method.
G
Synchronization Method
Asynchronous mode (start-stop synchronization) or clock synchronous mode can be selected in
any operation mode.
G
Signal
UART can treat data only in non-return to zero (NRZ) format.
Operation mode
Data length
Synchronizati
on mode
Stop bit length
When parity is
disabled
When parity is
enabled
0
Normal mode
7 or 8 bits
Asynchronous
1 or 2 bits *
2
1
Multiprocessor
8+1*
1
–
Asynchronous
2
Normal mode
8
–
Synchronous
None