BCM4339 Preliminary Data Sheet
UART Interface
Table 13: Example of Common Baud Rates
Desired Rate
Actual Rate
Error (%)
4000000
3692000
3000000
2000000
1500000
1444444
921600
460800
230400
115200
57600
4000000
3692308
3000000
2000000
1500000
1454544
923077
461538
230796
115385
57692
0.00
0.01
0.00
0.00
0.00
0.70
0.16
0.16
0.17
0.16
0.16
0.00
0.16
0.00
0.16
0.00
38400
38400
28800
28846
19200
19200
14400
14423
9600
9600
Figure 18: UART Timing
UART_CTS_N
1
2
UART_TXD
Midpoint of STOP bit
Midpoint of STOP bit
UART_RXD
3
UART_RTS_N
Table 14: UART Timing Specifications
Min.
Ref No. Characteristics
Typ.
Max.
Unit
1
2
3
Delay time, UART_CTS_N low to UART_TXD valid
–
–
–
–
–
–
1.5
0.5
0.5
Bit period
Bit period
Bit period
Setup time, UART_CTS_N high before midpoint of stop bit
Delay time, midpoint of stop bit to UART_RTS_N high
Broadcom®
November 17, 2014 • 4339-DS106-R
Page 60
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