ST92196A STMicroelectronics, ST92196A Datasheet - Page 193

• Manufacturer Part Number: ST92196A
• Description: 8/16-bit Mcu For Tv Applications With Up To 96k Rom, On-screen-display And 1 Or 2 Data Slicers
• Manufacturer: STMicroelectronics

SERIAL COMMUNICATIONS INTERFACE (Cont’d)
Figure 83. SCI Functional Schematic
8.11.2 SCI Operation
Each data bit is sampled 16 times per clock period.
Figure 84. SCI Operating Modes
8.11.3 Serial Frame Format
Characters sent or received by the SCI can have
some or all of the features in the following format,
depending on the operating mode:
Figure 85. SCI Character Formats
(1)
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- SERIAL COMMUNICATIONS INTERFACE (SCI)
CLOCK
# bits
states
Baud rate
generator
LSB First
INTCLK
I/O
START BIT
16
RX buffer
TX buffer
RX shift
register
TX shift
register
register
register
START
0, 1
16
LBEN
DATA
5, 6, 7, 8
DATA
AEN
(1)
PARITY
STOP BIT
16
VA00271
SIN
SOUT
PARITY
NONE
EVEN
ODD
0, 1
START: the START bit indicates the beginning of
a data frame. The START condition is detected as
a high to low transition.
DATA: the DATA word length is programmable
from 5 to 8 bits. LSB are transmitted first.
PARITY: The Parity Bit is optional, and can be
used with any word length. It is used for error
checking and is set so as to make the total number
of high bits in DATA plus PARITY odd or even, de-
pending on the number of “1”s in the DATA field.
ADDRESS/9TH: The Address/9th Bit is optional
and may be added to any word format. It is used to
indicate that the data is an address (bit set).
The ADDRESS/9TH bit is useful when several mi-
crocontrollers are exchanging data on the same
serial bus. Individual microcontrollers can stay idle
on the serial bus, waiting for a transmitted ad-
dress. When a microcontroller recognizes its own
address, it can begin Data Reception, likewise, on
the transmit side, the microcontroller can transmit
another address to begin communication with a
different microcontroller.
The ADDRESS/9TH bit can be used as an addi-
tional data bit or to mark control words (9th bit).
STOP: Indicates the end of a data frame. The
STOP bit can be programmed to be 1, 1.5, 2, 2.5
or 3 bits long, depending on the mode. It returns
the SCI to the quiescent marking state (i.e., a con-
stant high-state condition) which lasts until a new
start bit indicates an incoming word.
ADDRESS
OFF
0, 1
ON
0, 1, 1.5, 2, 2.5
STOP