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i n t e r f a c e s w i t h P I A U 7 0 6 .
W i t h r e g a r d t o t h e F r o n t P a n e l , a l l d i s p l a y i n f o r m a t i o n f o r t h e L C D a n d L E D
b a r g r a g h s , a l o n g w i t h t h e o p e r a t i o n o f t h e k e y p a d i s f a c i l i t a t e d v i a t h e s y s t e m
d a t a b u s s a n d f i r s t f o u r a d d r e s s l i n e s . T h e L C D d i s p l a y i s a s e l f - c o n t a i n e d
d i s p l a y m o d u l e t h a t d i r e c t l y c o n n e c t s t o t h e m i c r o p r o c e s s o r . T h e I n v e r t e r
M o d u l e l o c a t e d o n t h e F r o n t P a n e l c i r c u i t b o a r d c r e a t e s t h e H i g h V o l t a g e f o r t h e
B a c k l i g h t o f t h e L C D m o d u l e .
N O T E : T h i s m o d u l e i s c o n v e r t i n g 1 0 V A C a t 5 0 / 6 0 H z t o @ 1 0 0 0 V A C a t @ 3 2
k H z . B e C a r e f u l !
T h e L E D d i s p l a y s o p e r a t e i n a s c a n n e d m a t r i x m a n n e r . T h i s m e a n s t h a t o n l y o n e
L E D i s o n a t a t i m e . S i n c e i t h a p p e n s s o f a s t , i t a p p e a r s t h a t a l l L E D S a r e l i t a l l
a t o n c e . O n t h e F r o n t P a n e l c i r c u i t b o a r d , U 1 - U 5 , a n d U 8 - U 1 2 p r o v i d e t h e
d e c o d i n g a n d c u r r e n t d r i v i n g f o r t h e L E D m o d u l e s . U 8 - U 1 2 p e r f o r m t h e
d e c o d i n g , a n d U 1 - U 5 a c c o m p l i s h t h e c u r r e n t d r i v i n g .
T h e k e y p a d a l s o o p e r a t e s u s i n g t h e s c a n n e d m a t r i x d a t a t h a t a l s o c o n t r o l s t h e
L E D d i s p l a y s . N o t i c e t h e f i r s t f o u r b i t s o f U 1 1 . T h e s e a r e r o u t e d b y t h e w a y o f
e a c h p u s h b u t t o n o f t h e k e y p a d . W i t h a n y c l o s u r e o f t h e k e y p a d , t h a t s p e c i f i c
a d d r e s s l i n e i s r e a d b a c k i n t o t h e s y s t e m . D e p e n d i n g w h i c h a d d r e s s i s r e a d , w i l l
d e c o d e a s t o w h i c h b u t t o n w a s p u s h e d .
DIGITAL ALGORITHM
The technique by which all dynamic processing is accomplished, is known as Digital Sampled
Analog.
This approach was chosen for two specific reasons. First it is capable of exceptional audio
performance. Second it provides absolutely no time delay to the signal passed through it. For those of
you who wish to claim that this is an analog function, you are incorrect. This procedure actually
samples the analog signal digitally and performs immediate digital adjustments to it.
Using a single bit digital gain cell, and a sampling frequency of 152 kHz, accurate level changes with
precise resolution, are faithfully performed on the audio signal. Because of the high sampling
frequency, very gentle reconstruction filters are used to remove any residual sampling energy. This is
especially important since it provides excellent group delay through the system. As the signal path is
explained, you will be able to see how this technology is applied.
SIGNAL PATH
T h e a u d i o s i g n a l p a t h i s c o n t a i n e d o n c i r c u i t b o a r d s # 2 , W B - A G C , # 3 & # 6 ,
S i g n a l P r o c e s s o r s , a n d o n # 8 , l o w p a s s f i l t e r . E a c h b o a r d w i l l b e e x p l a i n e d
