ESP32 Forum

Hi esp32 expert

I'm starting my new projet based on three esp32 and their BLE module.

Purpose is two have two peripheral esp32 sensor modules that connect to a third esp32 central display module.

For peripheral connected to sensors, i wanted to use gatt_server_service_table example project to start implementing code of my sensors.
For the central display module code, i think to use the gatt_client example.

Yesterday, i flashed the gatt_server_service_table. I'm able to see ESP_GATT_DEMO peripheral with my smartphone. Via Android, i can't connect to it. If i use Nordic nRF android app, i can see much more like attribut etc. I also see in the esp32 console event occurs so i guess it works. But it is still non connected mode. I read esp32 ble doc and i know that it is possible to share data without being connected. Is it the case in this example ?

As it is a batterie project , i would like to wake up periodically the esp32 peripheral, try to connect to central. If central answer, peripheral go in running mode ( communicate with sensors and share info to central via BLE). If central is off, advertising will fail and i go back to sleep.

My questions concern the fact that, on all the training i follow on ble, it speak about peripheral, central , observer, scanner etc... In the gatt_server_service_table, i'm not sur i'm really in peripheral mode.

Do you think gatt_server_service_table example is the good soft to start this kind of architecture please?

Thanks a lot for this open general discussion on BLE.

No body specialist of ble ?

Its hard to find on this forum ble expert that is willing to help and answer questions.
I am not expert, more like apprentice. Here you have some links that may help you:

https://github.com/cypresssemiconductorco/PSoC-4-BLE

https://github.com/cypresssemiconductor ... caster.pdf

https://github.com/cypresssemiconductor ... pheral.pdf

Its not about esp32, but you can find useful information about server, client vs central, peripheral or broadcaster vs observer and how you can mix those types.
In most cases, like gatt_server_service_table, peripheral is working in server mode, but you can have both, server and client setup to advertise itself and can be discovered. This is achieved by GAP component, which handles advertising and scanning events. You have also GATT component which is handling serving and discovering attributes.

Thanks a lot for your reply,

I measured the consumption, and with this exemple i get 100mA continous.

It is really too much for my batterie application even if i play with sleep mode.

Is it possible to reduce it drastically? ( around 30 or 40mA should be good)

Here is another link with very good description ble roles:
http://emmayannzhang.com/understanding- ... e-devices/


About power consumption, sorry but i cant help you with that. I dont have tools to make measurements.
I can only advise to decrease tx power if its possible in your application, setup longer min and max advertising intervals, decrease CPU core speed to 80MHz. Maybe there is something else but i cant think anything now.