Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller TSSOP 28 16-Bit 16 MHz I/O number 24

421

422

423

424

425

426

427

428

429

430

N N

UCBRFx = round ( ( – INT( ) ) × 16 )

16 16

UCBRx = INT( )

BRCLK

N =

Baud rate

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USCI Operation: UART Mode

Table 15-3. BITCLK16 Modulation Pattern

No. of BITCLK16 Clocks After Last Falling BITCLK Edge

UCBRFx

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

00h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

01h 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

02h 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1

03h 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1

04h 0 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1

05h 0 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1

06h 0 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1

07h 0 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1

08h 0 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1

09h 0 1 1 1 1 1 0 0 0 0 0 0 1 1 1 1

0Ah 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1

0Bh 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1

0Ch 0 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1

0Dh 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1

0Eh 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1

0Fh 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

15.3.10 Setting a Baud Rate

For a given BRCLK clock source, the baud rate used determines the required division factor N:

The division factor N is often a non-integer value thus at least one divider and one modulator stage is

used to meet the factor as closely as possible.

If N is equal or greater than 16 the oversampling baud rate generation mode can be chosen by setting

UCOS16.

15.3.10.1 Low-Frequency Baud Rate Mode Setting

In the low-frequency mode, the integer portion of the divisor is realized by the prescaler:

UCBRx = INT(N)

and the fractional portion is realized by the modulator with the following nominal formula:

UCBRSx = round( ( N – INT(N) ) × 8 )

Incrementing or decrementing the UCBRSx setting by one count may give a lower maximum bit error for

any given bit. To determine if this is the case, a detailed error calculation must be performed for each bit

for each UCBRSx setting.

15.3.10.2 Oversampling Baud Rate Mode Setting

In the oversampling mode the prescaler is set to:

and the first stage modulator is set to:

421

SLAU144J–December 2004–Revised July 2013 Universal Serial Communication Interface, UART Mode

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