HD404019R Datasheet, PDF (34/65 Pages) Renesas Technology Corp – CMOS 4-bit single-chip microcomputers

HD404019R Series
Reset
Pulling the RESET pin high resets the MCU. At power-on or when cancelling the stop mode, the reset must
satisfy t_RC for the oscillator to stabilize. In all other cases, at least two instruction cycles are required for the
MCU to be reset.
Table 19 shows the components initialized by MCU reset, and the status of each.
Table 19 Initial Values After MCU Reset
Item
Initial Value by
MCU Reset Contents
Program counter (PC)
$0000
Execute program from the top of
ROM address
Status flag (ST)
1
Enable branching with conditional
branch instructions
Stack pointer (SP)
$3FF
Stack level is 0
I/O pins, output Standard
register
pins
(A) Without pull-up 1
MOS
Enable to input
(B) With pull-up 1
MOS
Enable to input
(C) CMOS
1
—
High-voltage (D) Without pull- 0
pins
down MOS
Enable to input
(E) With pull- down 0
MOS
Enable to input
Interrupt flags Interrupt enable flag (IE)
0
Inhibit all interrupts
Interrupt request flag (IF)
0
No interrupt request
Interrupt mask (IM)
1
Mask interrupt request
Mode registers Port mode register (PMR)
0000
See Port Mode Register section
Serial mode register (SMR)
0000
See Serial Mode Register section
Timer mode register A (TMA)
000
See Timer Mode Register A section
Timer mode register B (TMB)
0000
See Timer Mode Register B section
Timer/counters Prescaler
$000
—
Timer counter A (TCA)
$00
—
Timer counter B (TCB)
$00
—
Timer load register (TLR)
$00
—
Octal counter
000
—
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