Back to work

 Since 2018 I didn't wrote any posts (was busy with family).

Now I'm collecting new materials for posts related to smart home (my long R&D pet project).

Some words about it.

Several years ago I've decided to make my flat smart. But most of devices in production didn't fit my requests and expectations. I want to have full control over device behavior and independence of external cloud services (for scenarios, etc.).

I remember Google cloud failure, when a lot of people couldn't ever switch on/off lights or heating. I don't like wireless technologies related to other than outdoor temperature sensors, also wireless communication may be a honey target for hack. So, critical systems must be wired and isolated from any external intruders.

At 2017 I made first version of module network. UART over current loop. It was slow, really slow. Even on 4800 baud due to slow optocoupler turn-off (~150nS falling and ~1.2mS rising). Version 2020 uses CAN over old current loop, I've improved transceiver schematic that reduced transition delays to ~33nS falling and ~85nS rising edge, so overall baud rate is now 115200 without any packet loss. Also migrating to CAN gave me a freedom of multi-mastering nodes. Also current loop works fine with mixed topology (already tested on overall >100m cable with stubs 5-12m, even not twisted pair).

Yes, I'm going to make support for wireless nodes later. My choice now is RFM69 868MHz due to low bandwith usage (2.4GHz is very noisy now) and hardware AES encrypt engine.

Global profit of this work is that system can work even gateway is down. Most links and node configuration can be made once at install. Gateway/local cloud make this system smart, but if it's down, you can use all devices locally. All nodes have duplicate IO ports for generic switches/buttons or remote panel support.

When I look at modern smart home devices it seems like marketers are making them for sales, not people. 

So I'm trying to make smart home in old school style, where reliability, security and convenience are at first place.

If you want to look some photos, follow me at Instagram @kabansanych. I didn't make special tag for project, it will come soon.

UPD: New tag for Instagram #kssmarthome

Greets to all, Kabanski.