C8051F321 Silicon Laboratories Inc, C8051F321 Datasheet - Page 195

• Manufacturer Part Number: C8051F321
• Description: IC 8051 MCU 16K FLASH 28MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F321

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 21
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 13x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

17.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is selected by
the S0MODE bit (SCON0.7). Typical UART connection options are shown below.
17.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data
are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data bits are stored in
SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag
(SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any
time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will
be loaded into the SBUF0 receive register if the following conditions are met: RI0 must be logic 0, and if MCE0 is
logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the
SBUF0 receive register and the following overrun data bits are lost.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the RI0 flag is
set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt
will occur if enabled when either TI0 or RI0 is set.
SPACE
MARK
BIT TIMES
BIT SAMPLING
START
BIT
D0
Figure 17.4. 8-Bit UART Timing Diagram
Figure 17.3. UART Interconnect Diagram
D1
RS-232
MCU
D2
TX
RX
D3
Rev. 1.1
RS-232
LEVEL
XLTR
OR
D4
RX
RX
TX
TX
C8051Fxxx
D5
C8051Fxxx
D6
C8051F320/1
D7
STOP
BIT
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