Looking for the ultimate cheap China PIR

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I want to use several PIR sensors in my home, but I don’t want to make them myself.
As for now I have received 2 cheap PIR sensors from the great Chinese people. Both work without a problem in Pimatic. One PIR sensor just burst whenever there is movement. In a ‘busy’ room this would lead to a burst every 6 or 7 seconds. there are no jumpers on the PCB.

The other PIR is almost perfect. Again a known pimatic protocol, but this PCB also has jumpers. You can change the interval to 5 seconds, 50 seconds or 5 minutes. Perfect for what I want. Unfortunately it’s made with Chinese precision, resulting in a interval every 4 minutes when set to every 5 minutes :D
Even better would be the same PIR with the same protocol but sending in a 315 Mhz or 868 Mhz frequency, This would offload the 433Mhz channel a lot.
Problem is : it’s China. Not always is there info about interval / jumper setting so you have to wait until you have the device in your hands. after that you have to test if the protocol is recognized at all.

Has anyone bought some Cchina PIRs for a low price with all these requirements? Tips are welcome.

I’ve used ikea molgan lights for this. They are cheap, have a housing fitted and work well. Had to modify the PCB/components though and fit an Arduino pro with NRF24 in.
So it is now connected to mysensors.
Hope this helps you

Thanks, but now what I’m looking for

unfortunately the ikea tradfri movement sensors are not available stand alone(you always get a bulb with it, the set costs about 25 euro)… these should work with the new tradfri plugin. if ikea would sell them solo for appr. 15 euro it would be a good approach for an affordable pir network (if you already own tradfri)

Yeah, they look pretty expensive, and I would need a tradfri hub also

Still waiting for some new 315Mhz PIR’s in transit from China, but in the meantime started playing with attiny.
Had to dust of the programmer and chips, but for now it looks promising.
I have created a sketch that will go into deepsleep when started and only wakes by PIR interrupt. There is some extra code that will compare some time between the last send update and current to avoid to much RF traffic. Same goes for sending battery percentage, it’s only allowed to send at least after 24 hour since last transmit.
When it doesn’t get out of sleep for a couple of days it won’t transmit battery percentage.

PIR info is send with kaku protocol, battery percentage with pimatic_generic protocol. Hopefully later this day I can add the physical PIR to the chip and start testing how long it will run on 2 AA batterys. Perhaps I will be making my own PIR’s after all

Nice!
How do you track time of 24h? If you go to sleep the timers are disabled normally to save extra battery power.

You are right, I made an assumption that the millis() counter continues, have to test if that’s working or not. As far as I found out with some testing changing variables are kept in memory during sleep.

Did some more testing, and my assumption was wrong. The millis() is not reset upon waking up, but simply stops during sleep. When waking up the millis() continue to addup where it left at going into sleep mode.
Found this : https://arduino.stackexchange.com/questions/30077/how-to-keep-accurate-millis-while-using-adc-sleep-mode but it’s a bit above my skill to understand.

That only applies to the millis timer during an AD conversion, not while it is asleep as it is stopped completely.
There is a timer running but it is less accurate. You can wake up on that timer (as well as the PIR interrupt) and then send the battery value. I’m not sure if it is as long as 24h though…

Currently looking into the following solution:

• Powerup
• sleep with watchdogtimer (max 8s)
• When wakeup on timer, count how many times
• When 75 times watchdog startup reached (75 * 8s = 10 minutes)
• Disable watchdog timer and goto sleep with interrupt wakeup
• When wakeup on interrupt, reset watchdog counter and go sleeping with watchdog timer

What about the other way around: when the sensor wakes up, also request time from the controller. Store that and compare with the last stored value. If the difference is bigger than 86400000 (time is sent in “geek-time” - milliseconds since 1st of Jan, 1970), then send a battery report.

Should be simple and save a lot of battery as timed sleep eats around 20 times as much battery as interrupt sleep…

You mean adding a RF receiver to the PIR?
That would generate a lot of RF traffic and does exactly what I want to prevent : unnecessaryRF broadcasts

Aw crap! You’re on 433MHz homeduino! I have made all my sensors MySensors which is two-way…

My humble apologies! I will let myself out now… 😬

I have bought a handfull different China PIR’s. The better ones are on 433 Mhz and have 5 minute timeout jumper. Havn’t found any PIR one 315 Mhz with 5 minute timeout jumper.
The 315 Mhz work flawless with Pimatic, but they will broadcast every few seconds when there is movement detected continously.