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U A R T s — I n t e l
8 1 3 4 1 a n d 8 1 3 4 2
1 5 . 4 . 1 2 U A R T x A u t o - B a u d C o n t r o l R e g i s t e r
T h i s r e a d / w r i t e r e g i s t e r h a s n o e f f e c t o n t h e U A R T . I t i s i n t e n d e d a s a s c r a t c h p a d
r e g i s t e r f o r u s e b y p r o g r a m m e r s .
T a b l e 5 7 9 . U A R T x A u t o - B a u d C o n t r o l R e g i s t e r - ( U x A B R )
s
3 1
t e
P
b u
r v
I O
r i
t t
A
e s
u t
I
P C
i b
n a
t r
A t
U n i t #
0
1
B i t
31:4
3
2
1
0
D e c e m b e r 2 0 0 7
O r d e r N u m b e r : 3 1 5 0 3 7 - 0 0 2 U S
2 8
2 4
r v
r v
r v
r v
r v
r v
r v
r v
r v
r v
n a
n a
n a
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n a
n a
®
I n t e l X S c a l e
C o r e i n t e r n a l b u s a d d r e s s
+ 2 3 2 8 H ( D L A B = x )
+ 2 3 6 8 H ( D L A B = x )
D e f a u l t
000 0000h
Reserved
Auto-Baud Table (ABT): Directs the auto-baud circuitry within the UART to use a
table when selecting the final baud rate programmed into the Divisor Latch registers
and written into the Auto-Baud Count register (ACR). When a table is not used, any
value allowed in
Section 15.3.5, "Auto-Baud-Rate Detection" on page 886
0
2
auto-baud.
0 = Formula used to calculate baud rates allowing all possible baud rates to be
chosen by UART
1 = Table used to calculate baud rates which limits UART to choosing common
baud rates.
Auto-Baud UART Program (ABUP): Allows the UART to automatically program the
Divisor Latch registers (DLL and DLH) when the auto-baud circuit has detected the
baud rate, regardless of the state of the divisor-latch access bit (DLAB). For this to
occur, the auto-baud enable (ABE) bit must be set. Clearing this bit allows the
0
processor to read the Auto-Baud Count register (ACR) and determine the baud rate
2
using its own algorithm rather than using the UARTs.
0 = Software programs Divisor Latch Registers.
1 = UART Programs Divisor Latch Registers
Auto-Baud Lock Interrupt Enable (ABLIE): Enables the ABL Interrupt which
occurs when the auto-baud circuit has detected the baud rate and written the value
into the Auto-Baud Count register (ACR). The Divisor Latch registers can then be
programmed by the processor or auto-baud circuitry as dictated by the state of the
0
2
ABPP.
0 = Autobaud Lock Interrupt Disabled
1 = Autobaud Lock Interrupt Enabled
Auto-Baud Enable (ABE): Enables the auto-baud circuitry within the UART. The
circuitry counts the number of clocks in the start bit and writes this count into the
Autobaud Count register (ACR). It then interrupts the processor when the auto-baud
lock interrupt-enable (ABLIE) bit is set. It also automatically programs the Divisor
0
2
Latch registers (DLL and DLH) when the auto-baud UART program (ABUP) bit is
set.
0 = Autobaud Disabled
1 = Autobaud Enabled
2 0
1 6
1 2
r v
r v
r v
r v
r v
r v
r v
r v
r v
r v
n a
n a
n a
n a
n a
n a
n a
n a
n a
n a
A t t r i b u t e L e g e n d :
R V = R e s e r v e d
P R = P r e s e r v e d
R S = R e a d / S e t
D e s c r i p t i o n
Equation 34 on page 886
can be selected by the UART. See
Equation 34 on page
886.
I n t e l
8
4
r v
r v
r v
r v
r v
r v
r v
r w
r w
r w
n a
n a
n a
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n a
n a
n a
n a
n a
R W = R e a d / W r i t e
R C = R e a d C l e a r
R O = R e a d O n l y
N A = N o t A c c e s s i b l e
for more information on
®
8 1 3 4 1 a n d 8 1 3 4 2 I / O P r o c e s s o r s
D e v e l o p e r ' s M a n u a l
0
r w
n a
9 0 7
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