C8051F321-GMR Silicon Laboratories Inc, C8051F321-GMR Datasheet - Page 188

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

Specifications of C8051F321-GMR

• 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
• Processor Series: C8051F3x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 2.25 KB
• Interface Type: I2C, SMBus, SPI, UART, USB
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 21
• Number Of Timers: 4
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F320DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 13 Channel / 10 bit, 7 Channel
• Package: 28MLP
• Device Core: 8051
• Family Name: C8051F321
• Maximum Speed: 25 MHz
• Operating Supply Voltage: 3.3 V
• For Use With: 336-1480 - DAUGHTER CARD TOOLSTCK C8051F321336-1449 - ADAPTER PROGRAM TOOLSTICK F321336-1260 - DEV KIT FOR C8051F320/F321
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

C8051F320/1
17.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 17.2), which is not user-
accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “19.1.3. Mode 2: 8-bit Coun-
ter/Timer with Auto-Reload” on page 211). The Timer 1 reload value should be set so that overflows will
occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six
sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an exter-
nal input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 17.1.
Where T1
value). Timer 1 clock frequency is selected as described in Section “19. Timers” on page 209. A quick ref-
erence for typical baud rates and system clock frequencies is given in Table 17.1. Note that the internal
oscillator may still generate the system clock when the external oscillator is driving Timer 1.
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.
188
CLK
is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
Detected
Start
Figure 17.2. UART0 Baud Rate Logic
RX Timer
Equation 17.1. UART0 Baud Rate
UartBaudRate
Timer 1
TH1
TL1
Overflow
Overflow
Rev. 1.4
=
------------------------------ -

256 T1H
T1
–
CLK
2
2


UART
1
-- -
2
RX Clock
TX Clock