Particle Cloud Session-Restore with EN pin sleep on BORON

[SammyG]

I have a number of low-power BORONs out in the field. The ensure their long battery life, the device is on a sleep timer with a TPL5110.
The device is on for about 30 seconds and sends less than 1200 bytes of data, after which
the TPL disables the device via the EN pin for an hour.

The issue I have is that the particle handshake takes 5kb-6kb of data on every reconnect. It is my understanding that Particle’s “session restore”, feature that normally reduces the amount of data needed to restore a session, won’t work with when the EN pin is used because the "session restore’ data is stored in RAM, which is cleared when the device is disabled through the EN pin.

I know the new sleep modes are coming out in deviceOS2.x, but no sleep mode can match the low-power of the TPL5110 (35nA).

SO, is there (or will there) be any way to keep the “session restore” data in the flash? This way we could use the EN pin for ultra low-power but not have to go over 5mb/month on just handshake data consumption? not to mention the extra mA used to send all this extra data.

I think that without this feature, the EN pin is pretty much out of the question for low power solutions…

[rickkas7]

That is correct, the EN pin will clear the session restore data because the nRF52 retained memory is cleared when de-powered, which occurs when EN is pulled low.

There is a possibility that the session restore data will be moved to the LittleFS flash file system. This is not in the roadmap yet, but is under consideration for this reason.