I am currently grappling with this same issue. I have developed a medical data logger for use in clinical trials. It creates two 0.5 MHz data files per day. These are recorded on sd card using SDFat. They are currently recovered when the patient hands back the device after a period at home.
It is desirable to be able to transmit a summary record in real time following each session and to retrieve some or all of data files once the unit is back in the lab. The Electron or E series is ideal from the real time perspective but is hideously expensive for the file transfer requirement.
Use oh the mobile options is possible but requires use of a different carrier. Particle’s partner in Australia is notoriously more expensive than other networks - using the Optus network it is possible to get a data plan with 250MB/month for $5 which would be more than sufficient. I am concerned about reliability of the physical sim in the electron in the event that the device is not handled with kid gloves. The E series is attractive for a number of reasons including the sim but it is apparently not posssible to have that programmed for an alternative network,
Hence my interest in adding a wifi capability for periodic exflitration of files in the lab. There have been several posts relating to connection of a wifi module to an electron but I have been unable to find a post with a working solution. Has anyone cracked this particular issue.?
Any suggestions would be welcome.