Kenwood DP-1100 B Service Manual page 126

D P - 1 1 0 0 B II
3-2 DATA TRANSMISSION RECEPTION BETWEEN IC15 (TMP4740N : MAIN CPU) AND IC1
(TMP47C41N : DISPLAY MICROPROCESSOR)
a . Data t r a n s m i s s i o n
( T M P 4 7 C 4 1 N )
1 . Pin D A T 2 1 is m a d e " H " . (IC15 ( T M P 4 7 4 0 N ) )
2 . Pin D A T 2 1 is c h e c k e d in periods of 4 m s e c . If it is " H " ,
r e c e p t i o n p r o c e s s i n g starts. 4 bits of transfer c l o c k pulses
are g e n e r a t e d . T h e r e b y , 4 - b i t data is received f r o m IC15
( T M P 4 7 4 0 N ) . (IC1 ( T M P 4 7 C 4 1 N ) )
3 . IC15 ( T M P 4 7 4 0 N )
ready. IC1 ( T M P 4 7 4 1 N )
(SCK) until the data is c o m p l e t e l y t r a n s m i t t e d .
4 . After t r a n s m i s s i o n of the t r a n s m i s s i o n c o m p l e t i o n d a t a ,
pin D A T 2 1 is r e t u r n e d t o " L " a n d t r a n s m i s s i o n is c o m ­
p l e t e d .
Fig. 3 - 2 A Operation timing diagram of data transmission from I C 1 5 ( T M P 4 7 4 0 N ) to IC1
130
3. OPERATION OF MAIN MICROPROCESSOR
from I C 1 5 ( T M P 4 7 4 0 N ) to
m a k e s the next t r a n s m i s s i o n
o u t p u t s transfer c l o c k
IC1 b. Data t r a n s m i s s i o n from IC1
( T M P 4 7 4 0 N )
1 . T h e d a t a
( T M P 4 7 C 4 1 N ) )
2 . Pin IRQ is m a d e " L " . (IC1 ( T M P 4 7 C 4 1 N ) )
3 . 4 bits of transfer c l o c k pulses (SCK) are o u t p u t .
( T M P 4 7 4 0 N ) )
data 4 . 4 - b i t data is r e c e i v e d . (IC15 ( T M P 4 7 4 0 N ) )
pulses 5. For r e c e p t i o n of the next w o r d , step 3 is e x e c u t e d . (IC15
( T M P 4 7 4 0 N ) )
6. The s e c o n d 4 - b i t data is r e c e i v e d . (IC15 ( T M P 4 7 4 0 N ) )
7. O u t p u t pin
T h e r e b y , c o m m u n i c a t i o n
t r a n s m i s s i o n
( T M P 4 7 4 1 N ) .
This is n o r m a l m o d e .
( T M P 4 7 C 4 1 N )
t o be t r a n s m i t t e d is p r e p a r e d .
IRQ to IC1 ( T M P 4 7 C 4 1 N ) is m a d e
m o d e is c h a n g e d
f r o m IC 1 5 ( T M P 4 7 4 0 N )
( T M P 4 7 C 4 1 N )
to I C 1 5
(IC1
(IC15
" L " .
t o the
t o I C 1