Sierra Wireless WISMO218 - Manual (Page 69)

WA_DEV_W218_PTS_002 Rev 005 Page 69 of 109
Product Technical Specification &
Customer Design Guidelines
Min Typ. Max Unit
T
ready
4 5 7 s
T
rampup
- - 120 ms
The ON/~OFF signal level is detected about 250ms after VBATT is available. Note that this timing
might be temperature dependant.
The voltage of this signal has to be pulled LOW for at least 685ms for powering ON. Within this
685ms, the WISMO_READY signal will initially reset to HIGH for about 135ms and then resume to
LOW.
During the power ON sequence, an internal reset is automatically performed for 38ms (typically).
During this phase, any external reset should be avoided.
Once the WISMO218 is properly powered ON, the WISMO_READY pin will set to HIGH level to
acknowledge the successful powering ON of the WISMO218 before it is ready to operate. The
ON/~OFF signal can be left at LOW level until power off.
Please note that temperature conditions may affect the timing for powering up.
The recommended way to release the ON/~OFF signal is to detect the WISMO_READY signal within
685ms of powering ON while the level pulse of the ON/~OFF signal is set to LOW, and wait until the
WISMO_READY signal goes HIGH again.
Power OFF
The WISMO218 can be powered off by either software or hardware.
Software power off
AT command: AT+CPOF is used to power off the WISMO218.
Note: If the ON/~OFF pin is maintained at LOW level when AT+CPOF is used, the module can’t be
switched OFF.
Hardware power off
A LOW level pulse is applied on the ON/~OFF pin for 5.5sec. AT+CPOF will then be automatically
sent to the WISMO218.
Once the WISMO218 receives the AT+CPOF command, the WISMO218 will be deregistered from the
network. The WISMO_READY pin will become LOW to indicate that AT commands are no longer
available for the WISMO218. If the ON/~OFF signal is HIGH, then the WISMO218 will also be
switched off.