C8051F320 Silicon Laboratories Inc, C8051F320 Datasheet - Page 194

• Manufacturer Part Number: C8051F320
• Description: IC 8051 MCU 16K FLASH 32LQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F320

• 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: 25
• 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 17x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

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
with Auto-Reload” on page
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. For any given
Timer 1 clock source, the UART0 baud rate is determined by Equation 17.1.
Where T1
Timer 1 clock frequency is selected as described in
baud rates and system clock frequencies is given in Table 17.1 through Table 17.6. Note that the internal oscillator
may still generate the system clock when the external oscillator is driving Timer 1.
194
CLK
is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload value).
Detected
Start
219). The Timer 1 reload value should be set so that overflows will occur at two times
Figure 17.2. UART0 Baud Rate Logic
RX Timer
UartBaudRate
Equation 17.1. UART0 Baud Rate
Timer 1
TH1
TL1
Section “19. Timers” on page
Overflow
Overflow
Rev. 1.1
=
------------------------------ -
(
256 T1H
T1
–
Section “19.1.3. Mode 2: 8-bit Counter/Timer
CLK
2
2
)
×
UART
1
-- -
2
217. A quick reference for typical
RX Clock
TX Clock