Retreive/sync data off external wifi sd card flashair.

I want to use a pro mini to sleep (its solar/battery powered system so any power save great if possible) and wake to RETREIVE new data on a flashair card in another device. This is to be saved and retransmitted via lorawan to a backup location.

Searching reveals heaps of stuff about a onboard flashair but nothing about retreival of the data via wifi.

Any links much appreciated.

Option a- Use pro mini to switch power on to arduino mega to do heavy lifting operations.

B- Use pro mini get data from other device to onboard sd, then reduce speed lorawan and transmit.

Syncing data from external sd seems to be the biggest hurdle.

The beauty of this is that I can sync from any device sd card (camera, environmental data logger, another uno) to be transmitted to base.