Transfer Data Format - Renesas 7700 FAMILY User Manual

7.3.2 Transfer data format

LSB first or MSB first can be selected as the transfer data format. Table 7.3.3 lists the relationship between
the transfer data format and writing/reading to and from the UARTi transmit/receive buffer register.
The transfer format select bit (bit 7 at addresses 34
bit is cleared to "0," the set data is written to the UARTi transmit buffer register as the transmit data as
it is. Similarly, the data in the UARTi receive buffer register is read out as the receive data as it is. (Refer
to the upper row in Table 7.3.3.)
When this bit is set to "1," each bit's position of set data is reversed, and the resultant data is written to
the UARTi transmit buffer register as the transmit data. Similarly, each bit's position of data in the UARTi
receive buffer register is reversed, and the resultant data is read out as the receive data. (Refer to the
lower row in Table 7.3.3.)
Note that only the method of writing/reading to and from the UARTi transmit/receive buffer register is
affected by selection of the transfer data format, and that the transmit/receive operation is unaffected by
it.
Table 7.3.3 Relationship between transfer data format and writing/reading to and from UARTi transmit/
receive buffer register
Transfer format Transfer data format
select bit
0
(Least Significant Bit)
1
(Most Significant Bit)
Writing to UARTi transmit buffer
register
Data bus
DB7
DB6
LSB
DB5
first DB4
DB3
DB2
DB1
DB0
Data bus
DB7
DB6
DB5
MSB
DB4
first
DB3
DB2
DB1
DB0
7751 Group User's Manual
7.3 Clock synchronous serial I/O mode
, 3C ) selects the transfer data format. When this
16 16
Reading from UARTi receive
buffer register
UARTi transmit
buffer register
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
UARTi transmit
buffer register
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SERIAL I/O
Data bus UARTi receive
buffer register
DB7
D
7
DB6
D
6
DB5
D
5
DB4
D
4
DB3 D
3
DB2
D
2
DB1
D
1
DB0
D
0
Data bus UARTi receive
buffer register
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
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