HUAWEI MU709 Series HSPA+ LGA Module
Hardware Guide
Description of the Application Interfaces
Issue 09 (2017-12-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
29
Figure 3-6
Connections of the RESIN_N pin
As the RESIN_N and POWER_ON_OFF signals are relatively sensitive, it is
recommended that you install a 10 nF
–0.1 µF capacitor near the RESIN_N and
POWER_ON_OFF pins of the interface for filtering. In addition, when you design a
circuit on the PCB of the interface board, it is recommended that the circuit length not
exceed 20 mm and that the circuit be kept at a distance of 2.54 mm (100 mil) at least
from the PCB edge. Furthermore, you need to wrap the area adjacent to the signal
wire with a ground wire. Otherwise, the module may be reset due to interference.
The MU709 module supports hardware reset function. If the software of the MU709
module stops responding, you can reset the hardware through the RESIN_N signal as
shown in Figure 3-7 .When a low-level pulse is supplied through the RESIN_N pin, the
hardware will be reset. After the hardware is reset, the software starts powering on the
module and reports relevant information according to the actual settings. For example,
the AT command automatically reports ^SYSSTART.
Figure 3-7
Reset pulse timing
The RESIN_N pin must not be pulled down for more than 1s. Otherwise, the module will be
powered off.
3.4.4 WAKEUP_IN Signal
WAKEUP_IN pin is the authorization signal of MU709 entering sleep mode. It is
internally pulled down, so it can be floating if not used.
Table 3-3 shows the definition of the WAKEUP_IN signal.
The module cannot enter sleep mode when this pin is pulled up (1.8 V), and the
module should be waked up when the pin is pulled up for 1s.
