Philips CEM2100/00, Service Manual

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Page 143
T
5CL8
12.4 Transfer Rate
The baud rate of UART1 is set of UART1CR1<BRG>. The example of the baud rate are shown as follows.
When TC3 is used as the UART1 transfer rate (when UART1CR1<BRG> = “110”), the transfer clock and transfer
rate are determined as follows:
Transfer clock [Hz] = TC3 source clock [Hz] / TTREG3 setting value
Transfer Rate [baud] = Transfer clock [Hz] / 16
12.5 Data Sampling Method
The UART1 receiver keeps sampling input using the clock selected by UART1CR1<BRG> until a start bit is
detected in RXD1 pin input. RT clock starts detecting “L” level of the RXD1 pin. Once a start bit is detected, the
start bit, data bits, stop bit(s), and parity bit are sampled at three times of RT7, RT8, and RT9 during one receiver
clock interval (RT clock). (RT0 is the position where the bit supposedly starts.) Bit is determined according to major-
ity rule (The data are the same twice or more out of three samplings).
Figure 12-4 Data Sampling Method
Table 12-1 Transfer Rate (Example)
BRG
Source Clock
16 MHz 8 MHz 4 MHz
000 76800 [baud] 38400 [baud] 19200 [baud]
001 38400 19200 9600
010 19200 9600 4800
011 9600 4800 2400
100 4800 2400 1200
101 2400 1200 600
RT0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11
Bit 0 Start bit
Bit 0 Start bit
(a) Without noise rejection circuit
RT clock
Internal receive data
RT0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11
Bit 0 Start bit
Bit 0 Start bit
RT clock
Internal receive data
(b) With noise rejection circuit
RXD1 pin
RXD1 pin