7540 datasheet(188/366 Pages) RENESAS

188 / 366 page

2-112

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

APPLICATION

7540 Group

2.6 Serial I/O1

BRG count source

f(XIN) / 4

f(XIN)

BRG set value

255 (FF16)

127 (7F16)

63 (3F16)

31 (1F16)

15 (0F16)

7 (0716)

3 (0316)

1 (0116)

3 (0316)

1 (0116)

0 (0016)

Transfer bit rate (bps)

At f(XIN) = 4.9152 MHz

300

600

1200

2400

4800

9600

19200

38400

76800

153600

307200

At f(XIN) = 8 MHz

488.28125

976.5625

1953.125

3906.25

7812.5

15625

31250

62500

125000

250000

500000

2.6.5 Application example of clock asynchronous serial I/O1

For clock asynchronous serial I/O1 (UART), the transfer formats used by a transmitter and receiver must

be identical.

In the 7540 Group, eight serial data transfer formats can be selected.

(1) Data transfer rate

The transfer bit rate is calculated by the following formula;

q When the internal clock is selected (when baud rate generator is used)

Transfer bit rate [bps] =

Division ratio*1 : “1” or “4” is selected (set by bit 0 of serial I/O1 control register)

BRG setting value*2 : 0 to 255 (0016 to FF16) is set

q When the external clock is selected

Transfer bit rate [bps] = Clock input to SCLK1 pin/16

Table 2.6.1 shows the setting example of baud rate generator and transfer bit rate values.

Table 2.6.1 Setting example of baud rate generator (BRG) and transfer bit rate values

f(XIN)

Division ratio *1 ✕ (BRG setting value *2 + 1) ✕ 16

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