M38867E8AHP MITSUBISHI [Mitsubishi Electric Semiconductor], M38867E8AHP Datasheet - Page 35

• Manufacturer Part Number: M38867E8AHP
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER??
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

BUS INTERFACE
The 3886 group has a 2-byte bus interface function which is al-
most functionally equal to MELPS8-41 series and the control
signal from the host CPU side can operate it (slave mode).
It is possible to connect the 3886 group with the RD and WR
separated CPU bus directly. Figure 34 shows the block diagram of
the bus interface function.
The data bus buffer function I/O pins (P4
P5
0 (data bus buffer enable bit) of the data bus buffer control regis-
ter (address 002A
port I/O pins. When it is “1,” these bits become the data bus buffer
function I/O pins.
Fig. 32 Interrupt request circuit of data bus buffer
3
, P8) also function as the normal digital port I/O pins. When bit
O u t p u t b u f f e r
f u l l f l a g 0
O u t p u t b u f f e r
f u l l f l a g 1
I n p u t b u f f e r
f u l l f l a g 0
I n p u t b u f f e r
f u l l f l a g 1
(
(
O B F
O B E
O B F
O B E
I B F
I B F
I B F
O B E
16
) is “0,” these pins become the normal digital
O B F
O B F
0
I B F
I B F
0
1
0 )
1
1 )
0
1
0
1
O B E
O B E
R i s i n g e d g e
d e t e c t i o n c i r c u i t
R i s i n g e d g e
d e t e c t i o n c i r c u i t
0
1
2
, P4
R i s i n g e d g e
d e t e c t i o n c i r c u i t
R i s i n g e d g e
d e t e c t i o n c i r c u i t
3
, P4
6
, P4
7
, P5
O n e - s h o t p u l s e
g e n e r a t i n g c i r c u i t
O n e - s h o t p u l s e
g e n e r a t i n g c i r c u i t
0
–
O n e - s h o t p u l s e
g e n e r a t i n g c i r c u i t
I n t e r r u p t r e q u e s t i s s e t a t t h i s r i s i n g e d g e
O n e - s h o t p u l s e
g e n e r a t i n g c i r c u i t
I n t e r r u p t r e q u e s t i s s e t a t t h i s r i s i n g e d g e
The selection of either the single data bus buffer mode, which
uses 1 byte: data bus buffer 0 only, or the double data bus buffer
mode, which uses 2 bytes: data bus buffer 0 and data bus buffer
1, is performed by bit 1 (data bus buffer function selection bit) of
the data bus buffer control register (address 002A
comes S
written from the host CPU side, an input buffer full interrupt oc-
curs. When data is read from the host CPU, an output buffer
empty interrupt occurs. This microcomputer shares two input
buffer full interrupt requests and two output buffer empty interrupt
requests as shown in Figure 32, respectively.
1
input in the double data bus buffer mode. When data is
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
I n p u t b u f f e r f u l l i n t e r r u p t
r e q u e s t s i g n a l I B F
O u t p u t b u f f e r e m p t y i n t e r r u p t
r e q u e s t s i g n a l O B E
3886 Group
16
). Port P4
7
be-
35