Hitachi AP1 Data Book page 323

--------------------------------------------------------------------------HMCS404AC
• D-port
O-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 TO and TOO 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
MCU will not be affected by writing into the input-only and/or
non-existing ports, invalid data will be read by reading from the
output-only and/or non-existing ports .
The
R3~33,
R40, R41 and R42 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 MCU 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 MCU reset reqUires at least two instruc-
tions cycle time of RESET input.
Table 19 shows initialized items by MCU 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 (PMR) "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)
(8)
The contents of the items before The contents of the items before
8 Register
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.
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