WM620 Hardware User Guide
V1.1
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Page 7
While the WM620 is in running mode, low level pulse can put the module system into shutdown procedure.
And then the module would power off within after 5S.
Instead of ON_OFF pin, An AT command can also shutdown the module. For more specific, please refer to the
WM620’s AT command manual.
Keeps the ON_OFF low or connecting to GND, WM620 can automatically power up when VBAT is supplied.
High level pulse control circuit of ON_OFF is shown in Figure 2-5
：
Figure 2-5
2.2.2 RESET_N
RESET_N is an active low signal with an internal pull-up resistance and acts as hardware reset input.
Low level pulse longer than
20mS
can reset the WM620. After reset the module, power on operations, such as
launch a low level pulse to the ON_OFF pin, must be done again. The recommended reset pulse is
50ms,
but
can not exceed
2S
. Otherwise, the WM620 module will power off.
If keeps the ON_OFF low or connecting to GND, the WM620 can automatically power up after reset the
module.
2.3 Module Status Output
2.3.1 LED Indicator
PIN
Signal Name
I/O
Function Description
DC Characteristics (V)
48
SIG_LED
O
running status indication
Min
typical
max
-0.3
2.6
2.9
SIG_LED is the WM620’s working status output. The SIG_LED pin can supply 8mA drive current. WM620
provide several flash mode to indicate different running status. For more specific, please refer to the WM620’s
AT command manual.
SIG_LED can drive the LED directly, shown in Figure 2-6a. Figure 2-6b is the reference circuit to increase the
brightness of LED. The LED’s brightness depends on the value of R1 and VCC.
