Home control/security system

Hello everyone,

I am designing an arduino based home control/security system.
i have some ideas but i want to get some advice if some notice something that may be better.

at first the base station wil be a console on my wall. with an 2,8inch tft touch screen and an RFID reader.

when te system is armed the touch screen shows a numpad for entering the code or you just can unarm the security with your rfid tag. only break in sensors wil be disarmed and fire, temp, water leakage sensors will be detected.

but here is the point i want some advice, the base station gets a 433mhz rf receiver.
each wireless sensor gets an 433mhz transmitter.

the sensors will be build with an attiny84 or attiny85 which i have in spare.
the idea is that i want to use virtual link on arduino with the rf transmitters always in off state.

if for example the fire alarm is triggered this wireless sensor turns the rf transmitter in on state and let it send a string trough virtual link "hallway fire alarm" is triggered and set turns te rf transmitter in off state ignoring the on trigger for 1 minute. after 1 min the sensor is triggered again unless it was false alarm.

meanwhile in that particular minute other sensors have the change to trigger if fire is spreading.
example the fire alarm in the living room is triggered by smoke, this sensors to this alarm is turning its transmitter to on state and send the string "living room fire alarm" and 1 min off state.

and so on for all sensors

so the base station knows halway and living room alarms triggered after 2 minutes the base station will reset the events and wil log the trigger as false alarm unless its triggered 3 time's or more.

is this a reliable concept which is cheap and easy ?

i wont like using xbee for multiple connections at the same time.

i am awaiting any idea's or improvements.

best regards,
Dennis

Will one receiver work with multiple transmitters?

What happens if 2 or more alarms trigger at the same time?

It's doable. What do you have so far, what parts and code?

What are you using for the "base station"?

I have a similar project, for which I built a set of ATTINY85 transmitters and an ATTINY84 receiver connected to a Raspberry Pi. I found that with the 433MHz radio modules (like these ones), the range was extremely limited (less than 5m).

I learned a lot about the ATTINY84 during that build; I think I read the entire datasheet by the time I was done, all so that I could decode the wireless signal. The 433MHz receiver module that I used had both a digital and analog output. I used the analog output in conjunction with the ATTINY84's Analog Comparator and Input Capture (see "ACIC" in the ATTINY84 datasheet).

Long story short: I was disappointed with the reliability and range of the 433MHz radio modules that I had. The latest iteration of my project includes additional sensor nodes like you're describing, but I've opted for NRF24L01+ modules (similar to these, but cheaper!).

bluejets:
Will one receiver work with multiple transmitters?

What happens if 2 or more alarms trigger at the same time?

Thats why i will add 1 min transmitter shutdown with a 2 min limit at de base station allowing for other triggers to get trough.

But in the case you are telling it might be handy to have a small offset shutdown of each transmitter like the first stop 1 min and the 2nd stops 50 sec for example.

After 2 minutes no reactivation of the trigger it wil be logged as false alarm.

HazardsMind:
It's doable. What do you have so far, what parts and code?

As far i have now is an arduino nano, and some left overs attiny84 and attiny85.
I want to get things sorted out before buying stuff which i couldnt use after all.

darrylh:
What are you using for the "base station"?

.........

Long story short: I was disappointed with the reliability and range of the 433MHz radio modules that I had. The latest iteration of my project includes additional sensor nodes like you're describing, but I've opted for NRF24L01+ modules (similar to these, but cheaper!).

The base station will be made with the arduino nano, if needed i will add pin extender chip for more digital outs.

Also there will be a raspberry pi as communication server for web console, email, text message to phone.

I am going to take a look for NRF24L01+ modules can you tell me the range that you think you can get from it ?

Best regards,
Dennis

I just find the NRF24L01+ and find out it is a six channel transceiver.

I could program it to have a listening cycle
To listen every 6 seconds to al 6 sensors as example that is 1 sec per sensor.

I like this way more than my original plan
Only thing what if i need more sensors for example 9 ?

Best regards,
Dennis

for those who are interested i got an 3d sketch of the base unit design.

if the keypad stays in the design depends how the touch screen numpad works.
if this work good enough the membrame keypad will be removed from the design.

at the power indicator led the design sketch shows them both lighting up.
but in real only the blue or orange will light up depending on it's current power source.

in case of an power outage the backup battery kicks in controlled by a solid state relais.