Wouldn't PIR sensors be better?

johno1234:

 

Wouldn't PIR sensors be better?

 

Dont trigger if you're not moving. Combined with door sensors and lots of logic you can get an ok idea of what room one person is in, but add multiple people to the house or be one of those people that leaves doors open and you have no idea.

richms:

 

johno1234:

 

Wouldn't PIR sensors be better?

 

 

Dont trigger if you're not moving. Combined with door sensors and lots of logic you can get an ok idea of what room one person is in, but add multiple people to the house or be one of those people that leaves doors open and you have no idea.

 

If I'm not moving after 10 minutes I'm either dead or asleep so probably want the lights off. 

For the mmwave sensors, what do they detect? How do they know if there's a person in the room?

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I got off my arse and looked it up - I see they detect tiny movements of anything. That would work but would also detect pets and anything inanimate such as a flower swaying in the breeze of a fan etc. I still suspect a PIR with a long enough countdown timer would be suitable for this purpose.

Athom have a combo PIR/mmwave sensor so both richms and I can be happy!

johno1234:

 

If I'm not moving after 10 minutes I'm either dead or asleep so probably want the lights off. 

 

For the mmwave sensors, what do they detect? How do they know if there's a person in the room?

 

 

 

 

 

I got off my arse and looked it up - I see they detect tiny movements of anything. That would work but would also detect pets and anything inanimate such as a flower swaying in the breeze of a fan etc. I still suspect a PIR with a long enough countdown timer would be suitable for this purpose.

 

mmWave  can often detect smaller movements, and detect behind walls, chairs, TVs, etc. Some are sensitive enough to detect your chest moving as you breathe.

It's basically a mini radar detector, so you can use the distance of a person to the sensor as a means of zones. E.g. Closer to the sensor is a lounge area, further away is the kitchen.

In regards of zones for an open-plan room, you could detect someone in the kitchen to turn lights on but not if they're in the lounge.

PIRs can be falsely triggered by other heat sources. E.g. heat from a pot on the stove's radiating heat.

Username1: 
That looks interesting, what do you connect the sensor to? I want to put a sensor in all the rooms to control the lights for now so want something that isn't to expensive as it will all add up quickly. Can these mmwave sensors go through objects or where would you get a case designed for it? I was wanting something clean and out of the way on the ceiling.

AndreasSpiess on YouTube did a detailed video on these... https://www.youtube.com/watch?v=dAzHXpP3FcI

I've not put mine into production, although I did quite a bit of testing with the software and it seemed to work fine. Even detected movement from behind a piece of plywood, so potentially these could be installed in the ceiling and be completely invisible. From memory, I needed to reduce the sensitivity close-up to avoid false detection from the plywood.

muppet:

MadEngineer: What’s the purpose? Turning off the office light when you’ve gone out?

I use it to determine if to turn the house "alarm" on or not.  It's entirely automated and works very well, no having to remember to set or unset the house alarm.  If we're not detected home the alarm turns on, any motion sensors triggering will alert us, if it's after dark random lights in the house will turn on and off at random times to give the impression of the house being lived in etc.

Soon as we're detected home all the crap turns off and the front door autmatically unlocks.

MadEngineer:

 

So, break into the house and the alarm unsets itself? How does it determine it’s yourself vs someone that shouldn’t be there?

I think the idea is that if the house is unoccupied, the alarm will turn itself on after a period of inactivity. A window of inactivity before self-activating (where someone could theoretically break in after you leave) is still better than not setting the alarm at all.

Obviously, disabling it will require a PIN or other mechanism to verify the occupants should be there.

MadEngineer:

muppet:

 

MadEngineer: What’s the purpose? Turning off the office light when you’ve gone out?

 

I use it to determine if to turn the house "alarm" on or not.  It's entirely automated and works very well, no having to remember to set or unset the house alarm.  If we're not detected home the alarm turns on, any motion sensors triggering will alert us, if it's after dark random lights in the house will turn on and off at random times to give the impression of the house being lived in etc.

 

Soon as we're detected home all the crap turns off and the front door autmatically unlocks.

 

So, break into the house and the alarm unsets itself? How does it determine it’s yourself vs someone that shouldn’t be there?

The presence detection is smart.  It's looking for particular devices to be attached to the Wifi, particular BT devices to be seen by particular sensors etc.

If it senses presence that it can't map to a trusted user, the alarm goes off.  And it won't arm the alarm if there's still "someone" inside the house when it thinks it should turn the alarm on (means when a babysitter is looking after the kids etc it won't turn on)

It's not perfect, but it's better than having to remember to set and unset an alarm like the oldschool days.

Username1: That looks interesting, what do you connect the sensor to?

Sorry, forgot to answer that question.

I will be connecting mine up to a optocoupler board. The board is connected to a Raspberry Pi running my own software that monitors for state changes and sends events via MQTT to be picked up by NodeRED. I can replace my PIRs by switching one setting that inverts the output (PIRs are active low, these boards are active high).

I massively overbuilt mine - with a Ubiquiti PoE Switch, & PoE to USB Converters. PoE has a maximum distance of 100M, so I didn't even think about it.

Username1: What would be a good way of powering multiple of these 5v presence sensors in the ceiling? Any particular power supply or cable that anyone would recommend? Is there any limit on how long the cable can be?

Assuming you're using the LD2410, these will work on 5-12V, so I would probably use a 12V power supply.

I'm not sure what the output voltage is. I expect it's the same as the input, but I need to confirm (I have cables and another five units on order).

SirHumphreyAppleby:

 

I will be connecting mine up to a optocoupler board. The board is connected to a Raspberry Pi running my own software that monitors for state changes and sends events via MQTT to be picked up by NodeRED. I can replace my PIRs by switching one setting that inverts the output (PIRs are active low, these boards are active high).

 

I am involved in a little open source project called OXRS (https://oxrs.io) which does something very similar. 

Might be worth a look if you are at all interested. We have a discord server and a reasonable web page with docs (although it needs a bit of work).

I have just built a new house and am running everything on OXRS based devices. The State Monitor or Security Monitor firmware does something very similar by the sounds of it, but we have nice rack mounted hardware options and a firmware eco-system for administration and OTA updates via a web browser.

It is very small with not many users but we are always looking to spread the word, so sing out if you have any questions (or join the discord server).

Sorry for the off-topic reply :).