Automatic Start

9 thoughts on “Automatic Start

  1. Hi

    What is best practise to start the module automatically when applying power? My module is operating independantly without any external micro processor. I currently start the module by tying the ON-OFF line low permanently. This is against the instruction provided in the hardware user guide, but I see no other way to start the module by it self.

    Any help will be appreciated.


    Henro Ritchie

          1. Hi,

            unfortunately there aren’t other manner for performing the start of the module by it self, without using further components.

          2. Would tying the ON-OFF line low permanently cause any problems? Are there any negatives to this approach?

          3. Hi,

            the permanently connection of ON-OFF pin to GND isn’t a problem, it does not damage the modules.

            However it imply a slightly increasing of the current consumption, 0.1 – 0.2 mA in relation to the particular xE910 module; this value is reported in the Hardware User Guide (HUG), for example for the GE910-GNSS this current consumption is 0.2 mA (see below sentence from GE910 HUG): 

            “The maximum current that can be drained from the ON-OFF* pad is 0.2mA.”


            Another thing that should be considered, is regarding the UE910 and HE910 modules. If the VBATT slew rate isn’t greater than 153 V/sec, the module does not turn on, so it is required to act on the HW_SHUTDOWN* line for turning on the module.

          4. Hi

            I have now stumbled into a new problem. The modem runs off external power. When external power is disconnected it switches over to a battery backup. When the battery gets close to being depleted it can no longer supply enough current to the modem during a data call. If this happens the modem shutdown.

            I need more information about the modem shutting down under this circumstance. Please assist.

            Due to the modem being tied to GND permanently it will not turn on again when external power is restored. How do I force the modem return to normal operation after shutting down due to a lack of battery power?

            Would it be possible to adjust the firmware of the modem to turn on when the on line is tied to GND and turn off when the on line is tied left floating?

          5. Hello

            For HE910 I was once instructed by Telit Support to use a simple reset circuit to toggle the HW_SHUTDOWN* pin, while connecting the ON_OFF* pin permanently to GND, via a 1kohm resistor for protection.

            Has worked well, sofar.

            Try circuits like:
              OnSemi NCP803SN293T1G (threshold min 2.85 V),
              TI TLV803SDBZT (threshold min. 2.87).

            See also “HE910 Hardware User Guide”.