
XR88C681
6/
Register
Contents
Resulting Action
$ -(% "
=
/
! *0 ' 2!$ *( 5 J
$ -(% "
/
! *0 ' 2!$ *( 5 J
$ -(% *" *
/
! *0 ' 2!$ *( 5 J
$ -(% *" *
*
/
! *0 ' 2!$ *( 5 J
Table 19. Command Register Controls Over the Extend Bit
Note:
IftheuserprogramseithernibbleoftheClockSelectRegister(CSRn[7:4]orCSRn[3:0])withvaluesrangingfrom016toC16,
thentheuserisusingtheBRGasasourcefortiming. However, thesestandard bitrates (presentedin Table 18)apply onlyif
theX1/CLKpinisdrivenwitha3.6864MHzsignal. Ifasignalwithadifferentfrequency(fo)isappliedtotheX1/CLKpin,then
the DUART channel is running at the following baud rate:
Actual Baud Rate =
N / *$ ;O R +
1/=/< 8I
provided that fo is between 2.0 MHz and 4.0 MHz.
Additionally, as in the case for standard baud rates, the actual frequency of the clock signal will be 16 times these values.
1X vs 16X Clock Signals
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Figure 29
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Figure 29. Example of a Serial Data
Transmission System
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Figure 30
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