5.8 Powering the Module ON and OFF (PON_L, PON_H)Pin | | Name | | Direction | | Function |
| | | | | | |
21 | | PON_H | | Input | | Device On/Off control |
33 | | PON_L | | Input | | Device On/Off control |
The GS64 offers two hardware methods to power up and down the module.
The PON_L signal utilizes a momentary switching mechanism to alternate between power-on and power-off sequences. PON_L is held high to VCC by an internal pull- up resistor. The user asserts PON_L by pulling this signal low for a pre-defined period to initiate powering-on of the module. The user re-asserts PON_L with a subsequent low transition, which is held low for a pre-defined period, to power-off the module.
The PON_H signal is designed to be pulled high and maintained high for the power on period. PON_H is held low by an internal pull-down resistor. The user asserts PON_H by pulling this signal high to VCC in order to initiate powering-on of the module, then maintains it constantly high during normal use. A subsequent de- assertion, marked by a transition of PON_H from high to low, and then maintaining the signal low, will initiate the power-off process.
Only one input should be exercised for each Power-on to Power-off event.
5.8.1 VREF as a Power Indicator
Presence of the VREF signal can be used as a useful indicator that power-on has been successfully initiated. The absence of VREF can be used a successful indicator that the power-off sequence is complete.
The initial presence of VREF indicates that the LDOs are powered, however the module will be establishing network connectivity and registration at this point. Communications between the host application and the module can commence shortly thereafter, however completion of the network registration will be sometime afterwards (the period is dependent upon network loading at the time of attempted registration).
Once the power-off sequence has been initiates, shutting-down the LDOs is the last action in the process. The absence of VREF is an indication that network de- registration and shut-down is complete.
