m38039mf-xxxsp Mitsumi Electronics, Corp., m38039mf-xxxsp Datasheet - Page 50

• Manufacturer Part Number: m38039mf-xxxsp
• Description: Single-chip 8-bit Cmos Microcomputer
• Manufacturer: Mitsumi Electronics, Corp.

SERIAL I/O
Serial I/O1
Serial I/O1 can be used as either clock synchronous or asynchro-
nous (UART) serial I/O. A dedicated timer is also provided for
baud rate generation.
Fig. 40 Block diagram of clock synchronous serial I/O1
Fig. 41 Operation of clock synchronous serial I/O1
50
b u f f e r r e g i s t e r ( a d d r e s s 0 0 1 8
W r i t e p u l s e t o r e c e i v e / t r a n s m i t
R e c e i v e e n a b l e s i g n a l S
(f(X
( 1 / 2 t o 1 / 2 0 4 8 o f t h e i n t e r n a l
P 4
P4
c l o c k , o r a n e x t e r n a l c l o c k )
P4
P4
N o t e s 1 : A s t h e t r a n s m i t i n t e r r u p t ( T I ) , w h i c h c a n b e s e l e c t e d , e i t h e r w h e n t h e t r a n s m i t b u f f e r h a s e m p t i e d ( T B E = 1 ) o r a f t e r t h e
CIN
7
6
4
5
/S
/ S
/R
/T
f(X
) in low-speed mode)
RDY1
C L K 1
X
X
D
D
IN
T r a n s f e r s h i f t c l o c k
2 : I f d a t a i s w r i t t e n t o t h e t r a n s m i t b u f f e r r e g i s t e r w h e n T S C = 0 , t h e t r a n s m i t c l o c k i s g e n e r a t e d c o n t i n u o u s l y a n d s e r i a l d a t a
3 : T h e r e c e i v e i n t e r r u p t ( R I ) i s s e t w h e n t h e r e c e i v e b u f f e r f u l l f l a g ( R B F ) b e c o m e s “ 1 ” .
S e r i a l o u t p u t T x D
S e r i a l i n p u t R x D
1
)
1
t r a n s m i t s h i f t o p e r a t i o n h a s e n d e d ( T S C = 1 ) , b y s e t t i n g t h e t r a n s m i t i n t e r r u p t s o u r c e s e l e c t i o n b i t ( T I C ) o f t h e s e r i a l I / O 1
c o n t r o l r e g i s t e r .
i s o u t p u t c o n t i n u o u s l y f r o m t h e T x D p i n .
B R G c o u n t s o u r c e s e l e c t i o n b i t
F/F
R D Y 1
1 6
1
1
)
T B E = 0
1 / 4
F a l l i n g - e d g e d e t e c t o r
T B E = 1
T S C = 0
Receive buffer register 1
D
D
R e c e i v e s h i f t r e g i s t e r 1
0
0
Transmit buffer register 1
T r a n s m i t s h i f t r e g i s t e r 1
D a t a b u s
Data bus
D
D
1
1
Address 0018
Shift clock
Baud rate generator 1
Serial I/O1 synchronous
clock selection bit
Frequency division ratio 1/(n+1)
Address 0018
Shift clock
Address 001C
D
D
2
2
(1) Clock Synchronous Serial I/O Mode
Clock synchronous serial I/O1 mode can be selected by setting
the serial I/O1 mode selection bit of the serial I/O1 control register
(bit 6 of address 001A
For clock synchronous serial I/O, the transmitter and the receiver
must use the same clock. If an internal clock is used, transfer is
started by a write signal to the transmit/receive buffer register.
16
Clock control circuit
16
D
D
Clock control circuit
16
3
3
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Serial I/O1 control register
Transmit interrupt source selection bit
Serial I/O1 status register
Receive buffer full flag (RBF)
1/4
D
D
4
4
MITSUBISHI MICROCOMPUTERS
16
Receive interrupt request (RI)
) to “1”.
D
D
5
5
Transmit buffer empty flag (TBE)
Transmit shift completion flag (TSC)
3803/3804 Group
Transmit interrupt request (TI)
D
D
6
6
A d d r e s s 0 0 1 A
Overrun error (OE)
detection
Address 0019
R B F = 1
T S C = 1
D
D
7
7
1 6
16