st2064b Sitronix Technology Corporation, st2064b Datasheet - Page 45

• Manufacturer Part Number: st2064b
• Description: 8 Bit Microcontroller With 64k Bytes Rom
• Manufacturer: Sitronix Technology Corporation

1
ST2064B has a built-in low voltage detector for power
management. When LVDET is set, detector circuit is
enabled and the detection result will be outputted at the
same bit after 3 ms. Using read instruction twice can get this
result: first read will enable initial stableness control.
Start:
Low_Voltage:
Normal_Voltage:
Ver. 3.0
1
Address Name
7
7
.
$030
SMB0
CLC
BBR0
BBR0
SEC
RMB0
.
Bit 0: LVDET : Low voltage detect
L
L
Wait 3 ms
O
:
:
O
W
W
SYS
<SYS
<SYS,$+3
<SYS,Normal_Voltage
<SYS
1 = Enable detector (write) / Low voltage (read)
0 = Disable detector (write) / Normal voltage (read)
V
V
O
O
L
R/W
R/W
L
; enable detector
; disable detector
T
T
A
A
G
G
XSEL
Bit 7
E
E
D
D
TABLE 17-1 System Control Register (SYS)
E
E
OSTP
Bit 6
T
T
E
E
C
C
T
T
XSTP
Bit 5
O
O
R
R
45/57
TEST
Bit 4
Second read equal '1' represents 'low voltage'. Once low
voltage detector is enabled, it keeps on consuming power.
So it is important that remember to write “ 0” to LVDET to
disable the detector after detection is completed. One
sample program is shown below:
WSKP
Bit 3
Bit 2
WAIT
Bit 1
-
LVDET
Bit 0
0000 00-0
Default
ST2064B
5/8/09