The $SL WAKE,<cause> message is emitted after the Modem wakes from a user-commanded
sleep mode. The value of cause will be one of the following:
GPIO input changed from inactive to active state
Activity was detected on the RX pin of the Modem's UART
The S or U parameter time has been reached
If UART activity wakes the Modem, the TIMEOUT message will not be emitted as the Modem is
now awake.
In sleep mode, the real-time clock is not GPS disciplined, and is therefore subject to some
degree of drift. The longer the device is asleep, the more the drift will accumulate. The drift is
estimated to be 20ppm, so if the Modem is commanded to sleep for 100 hours, the drift may
result in the Modem actually sleeping in the range of 99.998 to 100.002 hours. The user should
be aware of this when selecting a sleep with a long duration.
If the GPIO1 pin is configured as an input to wake the Modem, the sleep mode will be
terminated if activity occurs on GPIO1. If the GPIO1 pin is configured as an output that indicates
the Modem's sleep mode, GPIO1 will transition to the appropriate state if the $SL OK message
is emitted.
November 2021 Swarm M138 Modem Manual - Rev 1.00 68/77
To Next Page
Loading...