XR68C681J-F Datasheet, PDF (30/75 Pages) Exar Corporation – CMOS Dual Channel UART(DUART)

XR68C681
,%    Table 6 '% +   %  %'(+&  
+( - %4

M@N    % %(- (+('  ( * +   !(
(&
  -(%
 5    2! $ (

M@N (%   * +   !((& '  -(%"  $
' %(&  -$ & (( - !!!!!!! 
!!!!!!!   
" ( $  %  '"
%'(&
(Note: the b suffix denotes a binary expression. x = don’t care
value).
5    ' 2! $ (
2'  %(  $ '(" ( (     % 
! $ (   '  %  '$ & (( -  
( $    '  .% ' $ -(%
 -  (% ( +( '  + $ ( Table 1
Table 10 %(G%  % ' $%"  $  ( ++'
   ! $ (%
Register

 $ -(% "


 $ -(% "


 $ -(% *"
*

 $ -(% *"
*
Contents
<^/
^/
 ^/
*^/
Resulting Action
 ! *0 ' 2! $ *( 5 J 

 ! *0 ' 2! $ *( 5 J 
 ! *0 ' 2! $ *( 5 J 

 ! *0 ' 2! $ *( 5 J 
Table 10. Command Register Control Over the Extend Bit
Note: if the user programs either nibble of the Clock
Select Register (CSRn[7:4] or CSRn[3:0]) with values
ranging from 0¹⁶ to C¹⁶, then the user is using the BRG as
a source for timing. However, these standard bit rates
(presented in Table 9) apply only if the X1/CLK pin is
driven with a 3.6864 MHz signal. If a signal with a different
frequency (fo) is applied to the X1/CLK pin, then the
DUART channel is running at the following baud rate:
Actual Baud Rate =
MTable  Baud Rate ValueN • fo
1/</= MHz
provided that fo is between 2.0 MHz and 4.0 MHz.
$$(( &" % (   '% + % $$ $ %"  
' +C '& +   ''3 %(-  (  / (%  %
%
1X vs 16X Clock Signals
  % H5
'3I  $ H/5
'3I   ($
 -   (% !  +" ( (% (   $(%'%%
 (  ( -  $ %(- (+(' ' H/5
'3I
%%   '($ %( $ &  +' + /
A %  H5
'3I  & %%   %(- %  ' 
( ($   (%"   % $ ''& ' '$  
- '''&  (  %  ' ($ (
  % +   /5 ''3 ( ( +   5 ''3  
+( - - % ( '(+&   % %
'( (   +     '  % (% ''3$ & 
' (( - %' +   (( - '  '3 #+  (%
'( (% '(  $ (% '(( - $ +  
%(  %("    %( (% % ''3$ & (%
 ' (( - %' 9 '"   (%  - 
    ''3 +C '& +   '( (% !'&  
% %   +     %(  (% (% 
' '(%(' + %& '  % %( $
' ('(   -   '(  $ 
 %(   -$  '(  $
 %( $  !'&   % $ " %++('( 
$(++ '% (   +C '(% +    ''3 %'%
' '(  $   %( ' ' ( 
( % (   '(( - '%%" % % $ (  
+( - $(%'%%( 
%      %( $  %(%%( %&%
% $('$ ( Figure 10  (% %&% ' %(%% +  
 %( ₅"  $  ' '( ₅
 
1