for my new project, im looking for some possibilities to establish a connection between smartphone/tablet and the esp32 with the primary goal, to keep the power consumption of the esp32 as low as possible. My idea is to create a simple smartphone app which communicates with the esp32, to read some values or to do some controlling stuff (light on/off, select color...). It could be a webserver based application or an BLE android app, so im open with wifi and bluetooth.
The only thing: the esp32 is my server and if I want to use wifi, the ESP32 will work in AP mode. I found a solution where the esp32 is switching between active mode and modem sleep while the connection is still active (DTIM beacon mechanism). But this was only for wifi and only if the esp32 is in sta mode. Unfortunately I could not find any information, how much power could be saved with this method.
My client (tablet) is always close to the esp32 and the connection actually only needs to be establish if I unlock my screen and start the app. But how can I tell the esp32: "hello server, im ready for a connection, please wake up and start ble or wifi". The client could also be connected to the server all the time but it would be great to save some power like with the example with the DTIM beacons..
Are there any other solutions?
Thank you very much