ST72F324J4TCTRS 데이터 시트보기 (PDF) - STMicroelectronics

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ST72F324J4TCTRS

8-bit MCU for automotive, 3.8 to 5.5V operating range with 8 to 32 Kbyte Flash, 10-bit ADC, 4 timers, SPI, SCI

STMicroelectronics 

ST72324xx-Auto

On-chip peripherals

Conventional baud rate generation

The baud rate for the receiver and transmitter (Rx and Tx) are set independently and

calculated as follows:

Tx = fCPU

(16*PR)*TR

fCPU

Rx =

(16*PR)*RR

with:

PR = 1, 3, 4 or 13 (see SCP[1:0] bits)

TR = 1, 2, 4, 8, 16, 32, 64,128 (see SCT[2:0] bits)

Obsolete Product(s) - Obsolete Product(s) Note:

RR = 1, 2, 4, 8, 16, 32, 64,128 (see SCR[2:0] bits)

All these bits are in the SCI Baud Rate Register (SCIBRR) on page 128.

Example: If fCPU is 8 MHz (normal mode) and if PR = 13 and TR = RR = 1, the transmit and

receive baud rates are 38400 baud.

The baud rate registers MUST NOT be changed while the transmitter or the receiver is

enabled.

Extended baud rate generation

The extended prescaler option gives a very fine tuning on the baud rate, using a 255 value

prescaler, whereas the conventional baud rate generator retains industry standard software

compatibility.

The extended baud rate generator block diagram is described in Figure 57.

The output clock rate sent to the transmitter or to the receiver will be the output from the 16

divider divided by a factor ranging from 1 to 255 set in the SCIERPR or the SCIETPR

register.

The extended prescaler is activated by setting the SCIETPR or SCIERPR register to a value

other than zero. The baud rates are calculated as follows:

Tx =

fCPU

Rx =

fCPU

16*ETPR*(PR*TR)

16*ERPR*(PR*RR)

with:

ETPR = 1,..,255, see SCI Extended Transmit Prescaler Division Register (SCIETPR) on

page 129.

ERPR = 1,.. 255, see SCI Extended Receive Prescaler Division Register (SCIERPR) on

page 129.

Doc ID 13841 Rev 1

119/193

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