C8051F85X86X Datasheet, PDF (272/290 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

C8051F85x/86x
Baud Rate Generator
(In Timer 1)
TL1
2
TX Clock
START
Detection
TH1
RX Timer
2
RX Clock
Figure 26.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload. 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. For any given Timer 1 overflow rate, the UART0 baud rate is determined by Equation 26.1.
UartBaudRate
=
1--
2
 T1_Overflow_Rate
Equation 26.1. UART0 Baud Rate
Timer 1 overflow rate is selected as described in the Timer section. A quick reference for typical baud rates and
system clock frequencies is given in Table 26.1.
Preliminary Rev 0.6
279