HD404459 Datasheet, PDF (17/122 Pages) Renesas Technology Corp – 4-bit HMCS400-series microcomputers

HD404459 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)
0
flags/mask
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, All bits 0 Turns output buffer off (to high impedance)
DCD1)
(DCD2) - - 00
(DCR0– All bits 0
DCR8)
(DCR9) - 000
Port mode register A
(PMRA) - - 00 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 bits (PMRC2, - 000
2, 1, 0
PMRC1,
PMRC0)
Refer to description of port mode register C
Detection edge select
register 1
(ESR1) 0000
Disables edge detection
Detection edge select
register 2
(ESR2) 00 - -
Disables edge detection
Timers/
counters,
serial
interface
Timer mode register A
(TMA)
0000
Refer to description of timer mode register A
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
Serial mode register A (SMRA) 0000
Refer to description of serial mode register A
Serial mode register B (SMRB) - - 00 Refer to description of serial mode register B
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