C8051F321R Silicon Laboratories Inc, C8051F321R Datasheet - Page 196

• Manufacturer Part Number: C8051F321R
• Description: IC 8051 MCU 16K FLASH 28MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F321R

• 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: -
• Other names: 336-1067-2

C8051F320/1
17.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth
data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80 (SCON0.3), which
is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection,
or used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the stop bit
is ignored.
Data transmission begins when an instruction 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 ‘1’. After the stop bit is received, the data byte will
be loaded into the SBUF0 receive register if the following conditions are met: (1) RI0 must be logic 0, and (2) if
MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the state of the ninth data bit is unimportant). If
these conditions are met, the eight bits of data are stored in SBUF0, the ninth bit is stored in RB80, and the RI0 flag is
set to ‘1’. If the above conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to
‘1’. A UART0 interrupt will occur if enabled when either TI0 or RI0 is set to ‘1’.
Figure 17.5. 9-Bit UART Timing Diagram
MARK
START
STOP
D0
D1
D2
D3
D4
D5
D6
D7
D8
BIT
BIT
SPACE
BIT TIMES
BIT SAMPLING
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