HD404639R Datasheet, PDF (16/135 Pages) Renesas Technology Corp – 4-Bit Single-Chip Microcomputer

HD404639R Series
Table 1 Initial Values After MCU Reset
Item
Abbr.
Initial Value Contents
Program counter
(PC)
$0000
Indicates program execution point
from start address of ROM area
Status flag
(ST)
1
Enables conditional branching
Stack pointer
(SP)
$3FF
Stack level 0
Interrupt
Interrupt enable flag (IE)
flags/mask
0
Inhibits all interrupts
Interrupt request flag (IF)
0
Indicates there is no interrupt
request
Interrupt mask
(IM)
1
Prevents (masks) interrupt
requests
I/O
Port data register
(PDR)
All bits 1 Enables output at level 1
Data control register (DCD0–DCD2) All bits 0
Turns output buffer off (to high
impedance)
(DCR0–DCRC) All bits 0
Port mode register A (PMRA)
0000
Refer to description of port mode
register A
Port mode register B (PMRB)
0000
Refer to description of port mode
register B
Port mode register C (PMRC3, PMRC1, 000
bits 3, 1, 0
PMRC0)
Refer to description of port mode
register C
Detection edge select (ESR1)
register 1
0000
Disables edge detection
Detection edge select (ESR2)
register 2
0000
Disables edge detection
Timer/
counters,
Timer mode register A (TMA)
0000
Refer to description of timer mode
register A
serial
interface
Timer mode register B1 (TMB1)
0000
Refer to description of timer mode
register B1
Timer mode register B2 (TMB2)
- - 00
Refer to description of timer mode
register B2
Timer mode register C1 (TMC1)
0000
Refer to description of timer mode
register C1
Timer mode register C2 (TMC2)
- 000
Refer to description of timer mode
register C2
Timer mode register D1 (TMD1)
0000
Refer to description of timer mode
register D1
Timer mode register D2 (TMD2)
0000
Refer to description of timer mode
register D2
Notes: 1. The statuses of other registers and flags after MCU reset are shown in the following table.
2. X indicates invalid value. – indicates that the bit does not exist.
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