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HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide
3.7 W_DISABLE# Signal
The W_DISABLE# signal is provided to allow users to disable wireless
communications add-in cards. When the W_DISABLE# signal is asserted, all radios
should be disabled. When the W_DISABLE# signal is not asserted, the radio may
transmit signals if it is not disabled by other means such as software.
The W_DISABLE# signal is an active low signal with internal 100 kΩ pull-up resistor
that disables radio operation when being asserted (driven low) by the system.
The combination of the software state and W_DISABLE# assertion state must be
determined before the normal operation is resumed. Table 3-10 lists this requirement
for W_DISABLE# and the software control setting. For example, the radio RF
operation remains disabled unless both the hardware and software are set to enable
the RF features of the card.
Table 3-9 W_DISABLE_N signal
Pins
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Table 3-10 Radio operational states
W_DISABLE# SW Control Setting*
High
High
Low
Low
* This control setting is implementation specific; this column represents the collective intention of
the host software to manage radio operation.
3.8 LED_WWAN# Signal
The LED_WWAN signal of the EM820W can allow the voltage of 3.3 V and absorb
the current from 5 mA to 40 mA. According to the given circuit, in order to reduce the
current of the LED, a resistance of 1 kΩ must be placed in series with the LED.
Issue 01 (2010-12-09)
Name
W_DISABLE_N
Enabled
Disabled
Enabled
Disabled
If you do not turn off the radio manually, the radio will be on when the module is powered on.
End users need to turn off the radio in some situations such as when being on an airplane.
According to Mini-PCIE specification, the radio must be turned off through hardware or
software. Nearly all PC companies comply with this specification.
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Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
Description
Close wireless communications
Radio Operation
Enabled
Disabled
Direction to Module
Input
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