ST72321B Datasheet, PDF (113/187 Pages) STMicroelectronics – 64/44-pin 8-bit MCU with 32 to 60K Flash/ROM, ADC, five timers, SPI, SCI, I2C interface

SERIAL COMMUNICATIONS INTERFACE (Cont’d)
EXTENDED RECEIVE PRESCALER DIVISION EXTENDED TRANSMIT PRESCALER DIVISION
REGISTER (SCIERPR)
REGISTER (SCIETPR)
Read/Write
Read/Write
Reset Value: 0000 0000 (00h)
Reset Value:0000 0000 (00h)
Allows setting of the Extended Prescaler rate divi- Allows setting of the External Prescaler rate divi-
sion factor for the receive circuit.
sion factor for the transmit circuit.
7
0
ERPR ERPR ERPR ERPR ERPR ERPR ERPR ERPR
7
6
5
4
3
2
1
0
7
0
ETPR ETPR ETPR ETPR ETPR ETPR ETPR ETPR
7
6
5
4
3
2
1
0
Bits 7:0 = ERPR[7:0] 8-bit Extended Receive
Prescaler Register.
The extended Baud Rate Generator is activated
when a value different from 00h is stored in this
register. Therefore the clock frequency issued
from the 16 divider (see Figure 63) is divided by
the binary factor set in the SCIERPR register (in
the range 1 to 255).
The extended baud rate generator is not used af-
ter a reset.
Bits 7:0 = ETPR[7:0] 8-bit Extended Transmit
Prescaler Register.
The extended Baud Rate Generator is activated
when a value different from 00h is stored in this
register. Therefore the clock frequency issued
from the 16 divider (see Figure 63) is divided by
the binary factor set in the SCIETPR register (in
the range 1 to 255).
The extended baud rate generator is not used af-
ter a reset.
Table 22. Baudrate Selection
Symbol
Parameter
f_CPU
Conditions
Accuracy vs
Standard
Prescaler
Conventional Mode
TR (or RR)=128, PR=13
TR (or RR)= 32, PR=13
TR (or RR)= 16, PR=13
~0.16% TR (or RR)= 8, PR=13
f_{Tx Communication frequency 8 MHz}
f_Rx
TR (or RR)= 4, PR=13
TR (or RR)= 16, PR= 3
TR (or RR)= 2, PR=13
TR (or RR)= 1, PR=13
~0.79%
Extended Mode
ETPR (or ERPR) = 35,
TR (or RR)= 1, PR=1
Standard
Baud
Rate
Unit
300 ~300.48
1200 ~1201.92
2400 ~2403.84
4800 ~4807.69
9600 ~9615.38
10400 ~10416.67 ^Hz
19200 ~19230.77
38400 ~38461.54
14400 ~14285.71
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