HMCS404C----------------------------------------------------------------
• D-port
D-port
is
I-bit I/O port, and it has 16 Input/Output common
pins.
It
can be set/reset by the SED/RED and SEDD/REDD
instructions, and can be tested by the TD and TOD instructions.
Table
17
shows the classification
of
standard pins, high voltage
pins and the Input/Output pins circuit types.
• R-port
R-port
is
4-bit I/O port.
It
provides 20 input/output com-
mon
pins,
16
output-only pins, and 6 input-only pins. Data
input
is
processed using the LAR and LBR instructions and data
output
is
processed using the LRA and LRB instructions. The
MCV
will
not
be affected by writing into the input-only and/or
non-existing ports, invalid data will be read
by
reading from the
<iutput-only and/or non-existing ports .
The
R3~33,
R40,
R41
and
R4:i
pins are also used
as
the INTo,
INTI, SCK,
SI
and
SO
pins respectively. Table
17
shows the
classification
of
standard pins, high voltage pins and Input/
Output pins circuit types.
•
RESET
The
MCV
is
reset by setting RESET pin to
"I".
At
power
ON
or
recovering from stop mode, apply RESET input more
than
tRe
to
obtain the necessary time for oscillator stabiliza-
tion. In other cases, the
MCV
reset requires at least two instruc-
tions cycle time
of
RESET input.
Table 19 shows initialized items
by
MCV
reset and each
status after reset.
Table 19 Initial Value by
MCU
Reset
Items
Initial value by
Contents
MCU reset
Program counter
(PC)
$0000
Execute program from the
top
of
ROM
address.
Status (ST)
"1"
Enable
to
branch
with
conditional branch instructions.
Stack pointer
(SP)
$3FF
Stack level
is
O.
(A) Without pull-
"1"
Enable
to
input.
upMOS
Standard pin
(B)
With pull-up
"1"
Enable
to
input
MOS
(C)
CMOS
"1"
-
I/O
pin
(0)
Without
pull-
output
register
"0"
Enable
to
input.
High
voltage
down MOS
pin
(E) With
pull-
"0"
Enable
to
input.
down
MOS
Interrupt Enable Flag
(I/E)
"0"
Inhibit
all interrupts.
Interrupt flag Interrupt Request Flag (I F)
"0"
No interrupt request.
Interrupt Mask
(1M)
"1"
Mask interrupt request.
Port Mode Register
(PM
R)
"0000"
See
Item
"Port
Mode Register".
Mode register
Serial Mode Register (SMR)
"0000"
See
Item "Serial Mode Register".
Timer Mode Register A (TMA)
"000"
See
Item
"Timer
Mode Register
A".
Timer Mode Register B (TMB)
"0000"
See
Item
"Timer
Mode Register
B".
Prescaler
$000
-
Timer/Counter A (TCA)
$00
-
Timer/Counter,
Timer/Event Counter B (TCB)
$00
-
Serial interface
Timer Load Register (TLR)
$00
-
Octal Counter
"000"
-
(Note) MCU reset affects
to
the rest
of
registers
as
follows:
Item
After
recovering
from
STOP mode
After
MCU reset except
for
by MCU reset the
left
condition
Carry
(CA)
Accumulator
(A)
The contents
of
the items before The contents
of
the items before
B Register
(B)
MCU reset
are
not
retained. MCU reset
are
not
retained.
W Register
(W)
It
is
necessary
to
intialize them
It
is
necessary
to
initialize them
X/SPX Registers
(X/SPX)
by
software again.
by
software again.
Y
/SPY Registers
(Y/SPY)
Serial Data Register
(SR)
Same
as
above
Same
as
above
The contents
of
RAM
before MCU
RAM
reset (just before STOP
instruction)
Same
as
above
are
retained.
246
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