Homini Complete Room Sensor Module?

[Samuel235]

The last sensor to be configured and to actually even get working now is the optical smoke sensor. I'm currently having some issues and troubles with even getting the concept of the reflective IR optical sensor to work. Been attempting for days now, hopefully will get this issue sorted ASAP as this is the really holding the module still now. Once this is done, i have a little work on the external powering to do but that shouldn't be too trivial and we can get the board sent off to the board house for manufacturing then.

[Samuel235]

Optical Sensors

While we're on the topic of optical sensors, all the market research that i am doing currently regarding these types of sensors just shows how many products are using optical sensors in the reflective setup, where the smoke causes the IR light to be reflected from the LED into a phototransistor and then therefor change the analog reading of the transistor. They seem to be choosing this over the 'Interrupt' method of having a IR LED shining into a Phototransistor and then smoke interrupting the light rays and therefor changing the properties of the transistor.

Can anyone see an advantage from this other than i would personally feel it is less likely to produce false triggers?

If this is the only reason it would be more beneficial to use the reflective method, i'm thinking about attempting to overcome the false triggers as the 'interrupt' setup method uses a much lower area on the board. If we could work around these false triggers i feel that it would benefit this setup much more.

I'm pretty sure that the power usage is the same because the LED would be permanently on at the same level for both methods.

[Samuel235]

I have just purchased some photo diodes rather than photo transistors to attempt to get this working. From what i have been reading, the photo transistors are around 100 times more sensitive than photo diodes and therefor i'm thinking that it could be this that is causing me an issue with trying to record the reflecting IR Light off of the smoke.

[Samuel235]

To keep you guys updated regarding the progress of this module;

I've been having some issues with creating a chamber that is capable of holding the diodes, transistors and the smoke without letting ambient light in (Due to materials and method, not due to design ability). So I decided to purchase a cheap (£10) Optical Smoke Detector from my local merchants, turns out to be a pretty nice device for the price. I have opened up the unit to find the smoke chamber and various other electronics inside, looks pretty nicely made. After a few google searches i have discovered what appears to be a full blown MCU inside of there, i will do some more investigation and post some part numbers up here soon for you guys to have a look around for interest sake. But normally i see smoke application specific IC's inside of these, so i was shocked at the MCU that is in there with no mention to smoke on the datasheet from what i could see. I'm now wondering if there would be some what to interface with this MCU to my ATMEGA. We will see with some further investigations.

My initial plans for this now were to rip out the chamber and the detection hardware inside of this chamber, and allocate a space on my module to receive this hardware rather than making my own, saving time and hassle as this is already a proved to work method.

P.S - I'm working on a double relay board that uses its own AC INPUT line to feed the live power to the relays and therefor not needing multiple AC supply to power something. This module is allowed to power two devices at a maximum of 2A on each relay, protected through 2 2A SMD fuses. I will release details very soon ;)

[Samuel235]

I'm currently spending today reverse engineering a optical smoke alarm to see how its chamber is connected to its op amp. It is taking an awfully long time due to the black silkscreen. Very hard to trace the routes from components.

[Samuel235]

UPDATE:

We now have the optical smoke sensor working, sort of. The only issue we have now is that the output on the OP AMP for the smoke sensor is oscillating, soon as i can rectify this to a DC voltage, we should be good to go with this module. Looking forward to layout this board!

[Samuel235]

UPDATE:

We now have a working optical smoke sensor!

Just to recap on the sensors on board:

• Optical Smoke Sensor
• Electrochemical Carbon Monoxide Sensor
• Motion Sensor
• Temperature Sensor
• Humidity Sensor
• Light Sensor

I'm just wondering if there will be enough on-board memory for the software and libraries for these sensors. I suppose the sensible thing to do here would be to get the software to a somewhat working state and then we could see how much memory we really need....

Software Gurus, please come forward and make yourself known please!

I do plan on having multiple states/profiles allowed on this module, something like Day state, Night state and an away state maybe. Not sure how much extra software that would take, not much i should imagine as it would only be to change a few states of the sensors.

But seriously, anyone involved with software that seems interested in being involved with this, please make yourself known here or message me and we can progress from here.

Thanks,
Sam.

[scalz]

hi.
cool :) perhaps you should try to draft a sketch and see what you get for memory usage. always good to check this before ;)
i am actually busy doing sw for my different modules so i won't have too much time on my side :confused: and there are so much things i would like to do! But if you need some help, you still can ask, we will try to help :smile:

[Samuel235]

@scalz, thank you. I'm sure I will need help from someone at some point, however i will keep this thread updated with my position on the software for this module. I know this is taking me a long time but this is a very complex module for me, hardware and software, the most complex i have ever done with electronics up to this point, but i'm loving every single instance of problem solving i'm going through!

A quick sketchup will be done ASAP hopefully to see the memory usage, i'm just wondering if there is any point in putting external memory on-board just for the sake of it, not much added to the cost and will allow for future capabilities.

[gohan]

@Samuel235 I am looking at a CO sensor too, do you have any updates on the ones you are using? What is the exact model?