F U N C T I O N A L D E S C R I P T I O N
B i t s B I , F E , P E , a n d O E a r e t h e s o u r c e s o f r e c e i v e r
line status interrupts. The bits are reset by reading
t h e l i n e s t a t u s r e g i s t e r . I n F I F O m o d e , t h e s e b i t s
a r e a s s o c i a t e d w i t h a s p e c i f i c c h a r a c t e r i n t h e F I F O
a n d t h e e x c e p t i o n i s r e v e a l e d o n l y w h e n t h a t c h a r a c t e r
reaches the top of the FIFO.
BI - Break Interrupt:
I n d i c a t e s t h e r e c e i v e d a t a i n p u t h a s b e e n i n t h e
s p a c i n g s t a t e ( l o g i c 0 ) f o r l o n g e r t h a n o n e f u l l
word transmission time.
FIFO mode:
O n l y o n e z e r o c h a r a c t e r i s l o a d e d i n t o t h e F I F O
a n d t r a n s f e r s a r e d i s a b l e d u n t i l S I N g o e s t o t h e
m a r k s t a t e ( l o g i c 1 ) a n d a v a l i d s t a r t b i t i s
received.
FE - Framing Error:
I n d i c a t e s t h e r e c e i v e d c h a r a c t e r h a d a n i n v a l i d
s t o p b i t . T h e s t o p b i t f o l l o w i n g t h e l a s t d a t a
or parity bit was a 0 bit (spacing level).
PE - Parity Error:
I n d i c a t e s t h a t t h e r e c e i v e d d a t a d o e s n o t h a v e
the correct parity.
OE - Overrun Error:
I n d i c a t e s t h e r e c e i v e b u f f e r w a s n o t r e a d b e f o r e
t h e n e x t c h a r a c t e r w a s r e c e i v e d a n d t h e c h a r a c t e r
is destroyed.
FIFO mode:
I n d i c a t e s t h e F I F O i s f u l l a n d a n o t h e r c h a r a c t e r
h a s b e e n s h i f t e d i n . T h e c h a r a c t e r i n t h e s h i f t
r e g i s t e r i s d e s t r o y e d b u t i s n o t t r a n s f e r r e d t o
the FIFO.
DR - Data ready:
I n d i c a t e s d a t a i s p r e s e n t i n t h e r e c e i v e b u f f e r
o r F I F O . D R i s r e s e t b y r e a d i n g t h e r e c e i v e
buffer register or receiver FIFO.
iii
