LTE Standard Module Series
EC21 Mini PCIe Hardware Design
EC21_Mini_PCIe_Hardware_Design 33 / 67
Table 13: Airplane Mode Controlled by Software Method
3.8.4. PERST# Signal
The PERST# signal can be used to force a hardware reset on the card. The module can be reset by
driving the PERST# signal low for 150ms~460ms and then releasing it. The PERST# signal is sensitive to
interference. The traces should be as short as possible and be surrounded with ground. The reset
scenario is illustrated in the following figure.
V
IL
≤0.5V
V
IH
≥2.3V
VCC_3V3
≥150ms
Resetting
Module
Status
Running
PERST#
Restart
≤460ms
Figure 12: Timing of Resetting Module
3.8.5. LED_WWAN# Signal
The LED_WWAN# signal of EC21 Mini PCIe is used to indicate the network status of the module, and can
absorb a current up to 40mA. According to the following circuit, in order to reduce the current of the LED,
a resistor must be placed in series with the LED. The LED is emitting light when the LED_WWAN# output
signal is active low.
The LED is emitting light when the LED_WWAN# output signal is low.
AT+CFUN=?
RF Function Status
Module Operation Mode
0
RF and (U)SIM disabled
Minimum functionality mode
1
RF enabled
Normal mode
4
RF disabled
Airplane mode
