ST92F150-EVAL STMicroelectronics, ST92F150-EVAL Datasheet - Page 243

• Manufacturer Part Number: ST92F150-EVAL
• Description: BOARD EVALUATION FOR ST9 SERIES
• Manufacturer: STMicroelectronics

Specifications of ST92F150-EVAL

• Processor To Be Evaluated: ST90158 and ST92F1x Daughter Board
• Interface Type: I2C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-2905

ASYNCHRONOUS SERIAL COMMUNICATIONS INTERFACE (Cont’d)
10.6.4.4 Conventional Baud Rate Generation
The baud rate for the receiver and transmitter (Rx
and Tx) are set independently and calculated as
follows:
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)
RR = 1, 2, 4, 8, 16, 32, 64,128
(see SCR[2:0] bits)
All this bits are in the SCIBRR register.
Example: If f
TR=RR=2, the transmit and receive baud rates are
57700 baud.
Note: The baud rate registers MUST NOT be
changed while the transmitter or the receiver is en-
abled.
10.6.4.5 Extended Baud Rate Generation
The extended prescaler option gives a very fine
tuning on the baud rate, using a 255 value prescal-
er, whereas the conventional Baud Rate Genera-
tor retains industry standard software compatibili-
ty.
The extended Baud Rate Generator block diagram
is described in the
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.
Note: The extended prescaler is activated by set-
ting the SCIETPR or SCIERPR register to a value
other than zero. The baud rates are calculated as
follows:
with:
ETPR = 1,..,255 (see SCIETPR register)
ERPR = 1,.. 255 (see SCIERPR register)
Tx =
Tx =
16
(16
*
ETPR*(PR*TR)
f
CPU
*
f
PR)
CPU
CPU
*
TR
Figure
is 24 MHz and if PR=13 and
ASYNCHRONOUS SERIAL COMMUNICATIONS INTERFACE (SCI-A)
Rx =
119.
Rx =
16
*
ERPR*(PR*TR)
(16
f
CPU
f
*
CPU
PR)
*
RR
10.6.4.6 Receiver Muting and Wake-up Feature
In multiprocessor configurations it is often desira-
ble that only the intended message recipient
should actively receive the full message contents,
thus reducing redundant SCI service overhead for
all non addressed receivers.
The non addressed devices may be placed in
sleep mode by means of the muting function.
Setting the RWU bit by software puts the SCI in
sleep mode:
All the reception status bits can not be set.
All the receive interrupt are inhibited.
A muted receiver may be awakened by one of the
following two ways:
– by Idle Line detection if the WAKE bit is reset,
– by Address Mark detection if the WAKE bit is set.
Receiver wakes-up by Idle Line detection when
the Receive line has recognised an Idle Frame.
Then the RWU bit is reset by hardware but the
IDLE bit is not set.
Receiver wakes-up by Address Mark detection
when it received a “1” as the most significant bit of
a word, thus indicating that the message is an ad-
dress. The reception of this particular word wakes
up the receiver, resets the RWU bit and sets the
RDRF bit, which allows the receiver to receive this
word normally and to use it as an address word.
SB : Start Bit
STB : Stop Bit
PB : Parity Bit
Note: In case of wake up by an address mark, the
MSB bit of the data is taken into account and not
the parity bit
M Bit
0
0
1
1
PCE Bit
1
0
0
1
| SB | 7-bit data | PB | STB |
| SB | 8-bit data PB | STB |
| SB | 8 bit data | STB |
| SB | 9-bit data | STB |
SCI Frame
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