st2024c Sitronix Technology Corporation, st2024c Datasheet - Page 44

• Manufacturer Part Number: st2024c
• Description: 24k 8-bit Single Chip Microcontroller
• Manufacturer: Sitronix Technology Corporation

1
The ST2024C has three power down modes: WAI-0, WAI-1
and STP. The instruction WAI will enable mode WAI-0 or
WAI-1, which are controlled by WAIT(SYS[2]). The
16.1 WAI-0 Mode:
When WAIT is cleared, WAI instruction lets MCU enter
WAI-0 mode. In the mean time, oscillator circuit is be active
and interrupts, timer/counter, and PSG will all be working.
Under such circumstance, CPU stops and the related
instruction execution will stop. All registers, RAM, and I/O
pins will retain their states before the MCU enter standby
mode. WAI-0 mode can be wake-up by reset or interrupt
16.2 WAI-1 Mode:
When WAIT is set, WAI instruction let MCU to enter WAI-1
mode. In this mode, the CPU will stop, but PSG,
timer/counter won’t stop if the clock source is from OSCX.
16.3 STP Mode:
STP instruction will force MCU to enter stop mode. In this
mode, MCU stops, but PSG, timer/counter won’t stop if the
clock source is from OSCX. In power-down mode, MCU only
(SYSCK source from OSC)
(SYSCK source from OSCX)
Ver 2.2
1
6
6
LDA #$00
STA SYS
WAI
LDA #$04
STA SYS
WAI
:
STP
:
:
.
.
Mode
Mode
WAI-0
WAI-1
WAI-0
WAI-1
STP
STP
P
P
O
O
W
W
FIGURE 16
FIGURE 16
imer1
imer1
; WAI 0 mode
; WAI 1 mode
Stop
Stop
Stop
Stop
E
E
R
R
D
D
SYSCK OSC OSCX
SYSCK OSC OSCX
Stop
Stop
Stop
Stop
O
O
TABLE 16-38: STATUS UNDER POWER DOWN MODE
W
W
N
N
Stop
Stop
M
M
O
O
D
D
E
E
Timer
Timer
Base
Base
Retain
Retain
Retain
Retain
Retain
Retain
44/54
RAM REG. LCD
RAM REG. LCD
instruction WAI (WAI-0 and WAI-1 modes) can be wake-up
by interrupt. However, the instruction of STP can only be
wake-up by hardware reset.
request. If user disable interrupt(CPU register I=’1’), MCU
will still be wake-up but not go into the interrupt service
routine. If interrupt is enabled(CPU register I=’0’), the
corresponding interrupt vector will be fetched and interrupt
service routines will executed.
The sample program is showed as followed:
The wake-up procedure is the same as the one for WAI-0.
But the warm-up cycles are occur when WAI-1 wake-up.
The sample program is shown as the following:
be wake-up by hardware reset, and the warm-up cycles are
occur at the same time.
The sample program is showed as the following:
I/O
I/O
Wake-up condition
Wake-up condition
Reset, Any interrupt
Reset, Any interrupt
Reset, Any interrupt
Reset, Any interrupt
Reset
Reset
ST2024C
1/31/08