ST72T331N2T6 STMicroelectronics, ST72T331N2T6 Datasheet - Page 64

• Manufacturer Part Number: ST72T331N2T6
• Description: 8-bit Microcontrollers - MCU OTP EPROM 8K SPI/SCI
• Manufacturer: STMicroelectronics

Specifications of ST72T331N2T6

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: ST7
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 16 MHz
• Program Memory Size: 8 KB
• Data Ram Size: 384 B
• On-chip Adc: Yes
• Package / Case: TQFP-64
• Mounting Style: SMD/SMT
• A/d Bit Size: 8 bit
• A/d Channels Available: 8
• Interface Type: SCI, SPI
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 44
• Number Of Timers: 2
• On-chip Dac: No
• Program Memory Type: EPROM
• Factory Pack Quantity: 90
• Supply Voltage - Max: 5.5 V
• Supply Voltage - Min: 3.5 V

ST72E331 ST72T331
SERIAL COMMUNICATIONS INTERFACE (Cont’d)
5.5.4.4 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 SCP0 & SCP1 bits)
TR = 1, 2, 4, 8, 16, 32, 64,128
(see SCT0, SCT1 & SCT2 bits)
RR = 1, 2, 4, 8, 16, 32, 64,128
(see SCR0,SCR1 & SCR2 bits)
All this bits are in the BRR register.
Example: If f
PR=13 and TR=RR=1, the transmit and receive
baud rates are 19200 baud.
Note: the baud rate registers MUST NOT be
changed while the transmitter or the receiver is en-
abled.
5.5.4.5 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 Figure 3..
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
ERPR or the ETPR register.
Note: the extended prescaler is activated by set-
ting the ETPR or ERPR register to a value other
64/107
64
Tx =
(32
f
CPU
*
PR)
CPU
*
TR
is 8 MHz (normal mode) and if
Rx =
(32
f
CPU
*
PR)
*
RR
than zero. The baud rates are calculated as fol-
lows:
with:
ETPR = 1,..,255 (see ETPR register)
ERPR = 1,.. 255 (see ERPR register)
5.5.4.6 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.
Tx =
16
f
CPU
*
ETPR
Rx =
16
f
CPU
*
ERPR