Energy harvesting lightswitches


#1

Goo day all,

At some places i need wireless lightswitches.
However i want a stable maintanace free system.

KaKu (433mhz) isn’t stable enough
WIFI will use to much power
So i ended by BLE. (Bluetooth Low Energy)
I have a Arduino in close range to the location of the switches so connectivity should be no problem.

Now i am looking at the energy harvesting switches. so there is no battery at all.
The switch will use the movement of the buttons to generate power.
https://www.enocean.com/en/enocean_modules_2.4ghz_ble/single-double-rocker-wall-switch-for-ble-eswsb-edwsb/

Now i am compleetly new to BLE. after some research i found a lot of "Serial interfaces over Bluetooth"
However after reading the user manual / Datasheet it didn’t look like an serial interface to me.

is there someone who has experience with BLE lightswitches and can give me some starting?

Kind regards
Mark


#2

That is a very interesting idea - It is great that someone has a ready-made solution for this.

I don’t have much experience with creating bluetooth devices but my greatest reservation for this application is lag.
The BLE chip needs to power up, establish connection, transmit in less than about 0.1 seconds. Generally for GUI / HMI interactions anything more than 1 /10 second is perceivable lag.
We should have @jon add this to our suggestion for a light switch shootout :slight_smile:

I checked two of their vendors (DigiKey and Newark) and couldn’t find the same lightswitches.


#3

Bluetooth Low Energy (BLE) Advertising

I believe the Advertising messages (and much of BLE, unlike regular BT) are connectionless? In which case they could indeed squawk out a message, and with no perceivable added lag.

Although, I wonder how immune it is to noise and collisions, presumably there wouldn’t be much scope for resend, so if the environment is a little noisy in the wrong frequencies, you might find yourself having to flick the switch a couple times for it to respond — and then a brief hiccup in the automation, and you’ve just turned it off after finally getting it to come on.


#4

Hey,

Let’s first talk about the delay.
Current solution.
Search for my phone
Unlock it
Start the app
Scrol to the right lightswitch
Lock the phone.
So i guess that a second delay wouldn’t be a problem :slight_smile:

The lightswitch will repeat its command 3 or 4 times on one flip.
So it is theoretically possible to lose the message in the noise. But i think it will still be a acceptable solution.

But before I order them the question will be. “is it possible to connect them to a arduino at all” (or a raspberry, or a windows /Linux server) so i can bridge it with mqtt.