ST62T18CB6 STMicroelectronics, ST62T18CB6 Datasheet - Page 54

• Manufacturer Part Number: ST62T18CB6
• Description: 8-bit Microcontrollers - MCU OTP EPROM 8K SPI/UAR
• Manufacturer: STMicroelectronics

Specifications of ST62T18CB6

• Core: ST6
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 8 MHz
• Program Memory Size: 7948 B
• Data Ram Size: 192 B
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 6 V
• Package / Case: PDIP-20
• Mounting Style: Through Hole
• A/d Bit Size: 8 bit
• A/d Channels Available: 7
• Data Rom Size: 64 B
• Interface Type: UART
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 12
• Number Of Timers: 1
• Program Memory Type: EPROM
• Factory Pack Quantity: 20
• Supply Voltage - Max: 6 V
• Supply Voltage - Min: 3.6 V

ST62T18C/E18C
U. A. R. T (Cont’d)
4.5.2 Clock Generation
The UART contains a built-in divider of the MCU
internal clock for most common Baud Rates as
shown in
calculated from the chosen oscillator frequency di-
vided by the Divisor value shown.
The divided clock provides a frequency that is 8
times the desired baud rate. This allows the Data
reception mechanism to provide a 2 to 1 majority
voting system to determine the logic state of the
asynchronous incoming serial logic bit by taking 3
timed samples within the 8 time states.
The bits not sampled provide a buffer to compen-
sate for frequency offsets between sender and re-
ceiver.
4.5.3 Data Transmission
Whatever the format selected as MCU option, 10-
bit or 11-bit frame, the start and stop bit are auto-
matically generated by the UART. Only the re-
maining 8 (Resp. 9) bit in the 10-bit (Resp. 11-bit)
frame are under control of the user.
Transmission is started by writing the Data Regis-
ter, after having previously set the transmission
software options, the baudrate and the parity ena-
ble. In case of 11-bit frame, the 9th bit must then
be set before into the LSB of the UART Control
Register. Bit 9 remains in the state programmed
for consecutive transmissions until changed by the
user or until a character is received when the state
of this bit is changed to that of the incoming bit 9.
The UARTOE signal switches the output multi-
plexer to the UART output and a start bit is sent (a
0 for one bit time) followed by the data bit with the
Figure 31. 11-bit Character Format Example
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54
POSITION
BIT
START
START OF DATA
BIT
Table
D0 D1
1
19. Other baud rate values can be
2
D7 D8
8
9
10
CHARACTER
STOP
BIT
POSSIBLE
START
NEXT
VR02012
LSB D0 at first.. The output is then set to 1 for a
period of one bit time to generate a Stop bit, and
then the UARTOE signal returns the TXD1 line to
its alternate I/O function. The end of transmission
is flagged by setting TXMT to 1 and an interrupt is
generated if enabled. The TXMT flag is reset by
writing a 0 to the bit position, it is also cleared au-
tomatically when a new character is written to the
Data Register. TXMT can be set to 1 by software
to generate a software interrupt so care must be
taken in manipulating the Control Register.
4.5.3.1 Character Format
Once the MCU option is set as 10-bit or 11-bit
frame, the frame length is fixed. Within these 8 or 9
remaining bit, any format can be used as shown in
the
putation in the 10-bit frame is available. Any other
parity bit can however be software computed and
processed as a data bit
Table 18. Character Options
Figure 32. UART Data Output
Start Bit
Start Bit
Start Bit
Start Bit
Start Bit
Start Bit
Start Bit
UARTOE
Table
TXD
PORT DATA
OUTPUT
18. Only the even parity automatic com-
8 Data
7 Data
7 Data
8 Data
9 Data
8 Data
7 Data
10 bit frame
11 bit frame
No Parity
1 Even Parity (Auto)
1 Software Parity
1 Software Parity
No Parity
No Parity
1 Software Parity
1
0
MUX
VR02011
1 Stop
1 Stop
1 Stop
1 Stop
1 Stop
2 Stop
2 Stop
TXD1