ESP32 Forum

I have been building a project where low power is critical as the system is going to be located in a very remote place.
The unit will spend a fair bit of time in sleep mode, wake up, take sensor readings then go back to sleep.
however if someone arrives at the site (or close to it) it would be nice to have the WiFi fire up so they can download the data and check various settings without opening the box given the hostile environment.

The solution seemed's to be to have the unit fire up in passive mode, do a quick scan for mac addresses and if a mac matched one in the database the WiFi will fire up and the deep sleep will be turned off until the user disconnects.

That got me thinking, Since you can essentially receive some information while in passive mode if you had another device that had to send its data I wondered if it would be possible to just send a kind of blind beacon with the data and a checksum from the remove unit. A kind of raw transmission using the WiFi radio. I know its going to lack security and because there is no handshaking you are not going to know if the data was received however I suspect the speed and power requirements to do this would be a lot lower than having both units fire up in AP/Station mode and send the data that way.

Really just a random thought at the moment but would love to hear anyone's thoughts on this.

Hello vangalvin

I think you need to specify how much data you will produce and how often you will collect it. If low power is a need, having the the unit wake every second to check for a wifi that will be close once per week is a waste of power.

I am working in a project where I use a beacon to wake an APP on a smartphone and make the app connect to the unit and download the data that it accumulated.

Sometimes a simple push button would save a lot of energy instead of doing something automatic.

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bonadio wrote: ↑

Mon Oct 14, 2019 12:38 am

I am working in a project where I use a beacon to wake an APP on a smartphone and make the app connect to the unit and download the data that it accumulated.

Sometimes a simple push button would save a lot of energy instead of doing something automatic.

The probelm with this unit is that the client may not be able to get to the unit to press the button. due to the conditions and sub zero temperatures I would prefer to ensure the case stays sealed as we are alsu purging them with nitrogen once they are all built up.