C8051F352-GQR Silicon Laboratories Inc, C8051F352-GQR Datasheet - Page 172

• Manufacturer Part Number: C8051F352-GQR
• Description: IC 8051 MCU 8K FLASH 32LQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F35xr

Specifications of C8051F352-GQR

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 50MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: POR, PWM, Temp Sensor, WDT
• Number Of I /o: 17
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x16b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Core: 8051
• Processor Series: C8051F3x
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 50 MHz
• Data Ram Size: 768 B
• Data Rom Size: 128 B
• On-chip Adc: Yes
• Number Of Programmable I/os: 17
• Number Of Timers: 4 bit
• Operating Supply Voltage: 2.7 V to 3.6 V
• Mounting Style: SMD/SMT
• A/d Bit Size: 16 bit
• A/d Channels Available: 8
• Height: 1.4 mm
• Interface Type: I2C, SMBus, SPI, UART
• Length: 7 mm
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.7 V
• Width: 7 mm
• For Use With: 336-1083 - DEV KIT FOR F350/351/352/353
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

C8051F350/1/2/3
20.1. 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 20.2), 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 “22.1.3. Mode 2: 8-bit
Counter/Timer with Auto-Reload’ on page 197). 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
external input T1. The UART0 baud rate is determined by Equation 20.1-A and Equation 20.1-B.
Where T1
value). Timer 1 clock frequency is selected as described in Section “22. Timers’ on page 195. A quick ref-
erence for typical baud rates and system clock frequencies is given in Table 20.1 through Table 20.6. Note
that the internal oscillator may still generate the system clock when the external oscillator is driving
Timer 1.
172
CLK
is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
Detected
Start
B)
A)
Figure 20.2. UART0 Baud Rate Logic
UartBaudRate
T1_Overflow_Rate
RX Timer
Equation 20.1. UART0 Baud Rate
Timer 1
TH1
TL1
=
Overflow
Overflow
Rev. 1.1
1
-- -
2
×
=
T1_Overflow_Rate
------------------------- -
256 TH1
T1
–
CLK
2
2
UART
RX Clock
TX Clock