Hi,
I see there is a differenece between v1.0.0 and v1.1.0 in the asset tracrker's main loop.
i.e. poll function vs the sleep function.
does this result in a change in the current consumption in PSM mode?
Hi,
I see there is a differenece between v1.0.0 and v1.1.0 in the asset tracrker's main loop.
i.e. poll function vs the sleep function.
does this result in a change in the current consumption in PSM mode?
Hi Moshe,
The PSM floor current will be the same for the modem side unless you are using a really old modem firmware version.
I have not measured if the application side is using less avg. current when the modem is in PSM from v1.0.0 to v1.1.0, but I would assume that the application is optimized in this regard as well.
To improve the avg. current consumption you can disable peripherals that are not in use, e.g. turn off the logging through the UART.
(CONFIG_SERIAL=n)
please check out this tutorial for more info on PSM mode.
Let's discuss the details about PSM mode and the eDRX interval which has a great impact on the avg. current consumption for the modem.
In the Figure above we see the three different states the cellular modem can be in.
We have three modes:
In this mode, the radio is active and the modem has to stay in sync. with the network, which needs the high accuracy timers to be enabled.
In this mode, you do not need to stay in sync. with the network. The transceiver is turned OFF and you utilize the eDRX intervals to sleep in between the paging windows where you turn ON the receiver to check if there is some data from the network that you can receive. The device can request the eDRX interval, but the network decides if it will allow you this interval or not. What we usually see is that networks usually approve extending this interval vs. shortening it.
NOTE: When we discuss eDRX intervals we are actually talking about "idle eDRX" (iDRX), not "connected eDRX" (cDRX) since iDRX has a huge impact on avg. current consumption while cDRX has very little impact on the current consumption.
In this mode, you turn OFF the radio all together and the device is unreachable from the network side. The device can stay in PSM mode for ~6 minutes up to several weeks.
What should be noted is that the nrf91 device can itself wake up when it wants to in PSM mode and go to RRC Connected mode if it needs to send data, e.g. an alarm.
PSM floor current is 4µA for the nRF9160.
The GPS can only be used when the nrf9160 device is either in PSM mode or in between the eDRX intervals. (GPS current consumption)
Best regards,
Martin L.