3822_03 Datasheet, PDF (178/328 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.5 Serial I/O
sData transfer rate (baud rate)
When an internal clock is used, the data transfer rate (baud rate), which is a shift clock frequency in
the UART mode, is determined by baud rate generator (BRG). When the BRG count source selection
bit (bit 0) of the serial I/O control register (address 001A16) is “0,” XIN pin input clock is input to the
BRG, when this bit is “0,” XIN pin input clock divided by 4 is input to the BRG. The expression for baud
rate is shown below.
qWhen selecting an internal clock (Using BRG)
Baud rate =
XIN pin input
[bps]
Division ratio ^V1 ! (BRG setting value ^V2 + 1) ! 16
V1 Division ratio; Select “1,” or “4”
V2 BRG setting value; 0 to 255 (0016 to FF16)
qWhen selecting an external clock
Baud rate =
[bps]
Frequency of input clock to P46/SCLK pin
16
Table 2.5.1 Baud rate selection table (reference values)
Baud rates [bps]
At XIN input = 4.9152 MHz
300
600
1200
2400
4800
9600
19200
38400
76800
153600
307200
At XIN input = 8 MHz
488.28125
976.5625
1953.125
3906.25
7812.5
15625
31250
62500
125000
250000
500000
BRG count source
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input/4
XIN input
XIN input
BRG setting value
255 (FF16)
127 (7F16)
63 (3F16)
31 (1F16)
15 (0F16)
7 (0716)
3 (0316)
1 (0116)
0 (0016)
1 (0116)
0 (0016)
2–112
3822 GROUP USER’S MANUAL