I'm evaluating nRF9160 + Serial LTE Modem application for a battery powered device that uploads data via HTTP POST 8-12 times per day. Since all interactions are initiated from the device its desirable to achieve a very low power level between communications. Currently I'm sending +CFUN=0 for this state, however power measured with the nrf9160-DK is still around 2.5mW (0.5 mA @ 5V).
What steps should I take to achieve a lower standby/quiescent power state?
Does +CPSMS help after +CFUN=0 has been sent?
Is it necessary to sleep the UART ?
Yes, we are aware of this and this was a choice our developers made. That said, customers are free to implement wake on UART by them selves. The RX pin can be used as a GPIO when UART is not enabled.Please…
Hello, Have you tried with the SLM proprietary AT command #XSLEEP?
Yes I tried it yesterday afternoon, I did get current down to 10 uA with #XSLEEP.
I noticed the documentation for #XSLEEP does not match the implementation discussed here in devzone.
According to the docs:
0 - Enter Idle. You can also use the syntax AT#XSLEEP.
1 - Enter Sleep.
In case of Idle, it will exit by sending data over UART.
In case of Sleep, it will wake up by GPIO or reset.
Anthony Ambuehl said:According to the docs:
The documentation was not correct. Please see latest documentation for update/fix: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/applications/serial_lte_modem/doc/Generic_AT_commands.html#power-saving-xsleep
In the case of XSLEEP=2, one must use GPIO to wake up.
Let me know how that works for you.
Requiring an additional GPIO to wake the device seems inefficient, why not just utilize the serial pins to wake the device ? Its a pretty common method, and gives a much more stream-lined solution without consuming another pin from the controlling MCU.
Yes, we are aware of this and this was a choice our developers made. That said, customers are free to implement wake on UART by them selves. The RX pin can be used as a GPIO when UART is not enabled.Please note that the external device must be configured correctly, so that it does not unintentionally wake device.