Microcomputers Topics


#21

That Vero 2 gadget looks interesting.


#22

Check this out

“The Moto Mods HAT Adapter Board is Raspberry Pi HAT compatible and allows the use of commercially available HATs. It includes the 40-pin Header, Camera, and Display connectors in the proper locations.”


#23

Yes its is great and we can have our own prototype of the same using a raspberry pi as a starting point.


#24

I would like us to round up the specifics of the HAT so we can begun on the schematics and later on the board layout. @Michael did a very good job of summarizing the requirements, i will relist them once more and we can add

SENSORS

  1. Temperature sensor & smoke detector (Fire detection)
  2. PIR (Room Occupancy detection)
  3. Nanny cam (Videos and pictures)
  4. LPG GAS sensor( gas leakage)

ACTUATORS

  1. Relays (for sockets, lamps)
  2. Solenoid valve (For water pipes)

COMMUNICATION

  1. Bluetooth modlule ( System to custom phone app for user interface)
  2. RF modules (Mesh networking between sensors, actuators and the Data acquisition point)
  3. WIFI module (streaming nanny cam videos and pictures over internet)

Looking forward to start the schematic design from 5th Jan 2017, lets contribute before then.


#25

Can as well have the design be compatible with the moto mod as suggested by @AYSande above, still reading through to understand it better.:slight_smile:


#26

We can look at the Moto mod separately so as not to derail this smart home controller project. We picked up some good direction with the features distilled above.


#27

Can we optionally incorporate sensors for window and door opening detection and a way to show who is at the gate and optionally open it, then send alarms to phone numbers (SMS or WhatsApp/Telegram)?


#28

Great, for the windows and door sensors we can use Hall sensors. To send text will need a GSM module, unless there is another way we can do that, open for other options. But for telegram we don’t really need a GSM module, it has a desktop application independent of the phone.


#29

Great! @cyrus.
I think we should add flow sensor for water pipes to the sensor List.


#30

I have a question please, Cyrus - how are we intending to fix the hall sensor on the Window?

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Suppose we have a break in situation, where someone shatters or cuts the window glass, rather than opening - any solutions? I am thinking of a piezo vibration sensor, or maybe a special microphone detector to pick high frequency waves of a breaking glass. Its a raw idea, any views


#31

Hey @Cyrus

Do you have links to the specific component data sheets? That would help with moving the project forward.

Kind regards,


#32

Hello Guys, Its time we begun the circuit design for the HAT, I appreciate your contribution and input in this topic. As we move to the next phase (schematic design) will have to go through several datasheets and compare and contrast several components, will need your help in performing this task. Below i have included links to several sensors suggest here. Please have a look and comment.

1.Smoke sensor https://cdn.sparkfun.com/assets/learn_tutorials/5/7/7/MAX30105_3.pdf

  1. PIR sensor https://cdn-learn.adafruit.com/assets/assets/000/010/134/original/RE200B.pdf

  2. LPG Gas sensor. https://cdn.sparkfun.com/datasheets/Sensors/Biometric/MQ-6%20Ver1.3%20-%20Manual.pdf

  3. Water flow sensor https://store.nerokas.co.ke/index.php?route=product/product&keyword=flow%20sens&product_id=1324

  4. Bluetooth http://cdn.sparkfun.com/datasheets/Wireless/Bluetooth/Bluetooth-RN-42-DS.pdf

6.Radio module https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjGxOHh-63RAhVBbRQKHUFkA-8QFggbMAA&url=https%3A%2F%2Fwww.sparkfun.com%2Fdatasheets%2FComponents%2FSMD%2FnRF24L01Pluss_Preliminary_Product_Specification_v1_0.pdf&usg=AFQjCNG9L4nJkLzsHDzTsCXNrA016LMA6Q&sig2=RPQYh5x-HSPRLlapXiP2ug


#33

The above components are not conclusive and changes can e made anytime, feel free to give suggestions. Also i have not exhausted all the components needed, you can add some more. Looking forward to start the schematic designs at circuits.io


#34

I was thinking of having the Hall sensor on the window frame and a magnet on the window its self. When never the window is opened, the hall sensor would detect the absence of the magnetic field.

Sincerely, had not thought of someone cutting the glass on the window or even smashing it :smile:, brilliant @Michael . Do you have a specific sensor in mind we can use to detect the vibrations?


#35

Hey cyrus… sorry i’ve taken long to reply.

So, the specific sensor is called a glass break detector it can be based on one of two technologies;

  1. Narrowband frequency filtration (simplest) - sound processing circuit is tuned to typical shattering frequencies of glass and detects frequencies in this region comparing their magnitude with the set threshold. if they are greater, an alarm is raised
  2. Complex sound analysis algorithms - as the name suggests, signal transforms are used to compare the sound analysis to one or more glass breaking profiles.

source: https://en.wikipedia.org/wiki/Glass_break_detector

The latter is of course complex and expensive, but better in performance.


#36

If its okay, we can build our own glass break detector based on the first principle,
it can be as simple as this (with some modifications, it can work satisfactorily):-

To a good design as this one (Though abit more complex ) http://www.best-microcontroller-projects.com/glass-break-detector.html
when a window is struck, the first process of shattering is the inward flexing of the glass, which produces low frequency sound in the range of 50Hz to 100Hz, then when it goes beyond elastic limit and shatters, sound waves in the region of 8KHz - 20KHz are generated. This model detects these two processes to accurately determine a window break-in event
I think the latter one is more professional, and more immune to errors

finally, there is also this type http://www.ti.com/lit/an/slaa351/slaa351.pdf


#37

Well… we can also fore-go the hectic building process and just buy one ready built, at a cheap price of 3.60 USD
http://www.ebay.com/itm/Glass-Break-Window-Sensor-Detector-Home-Security-System-Door-Wired-Alarm-/122089786871

Interfacing with our PI Hat is WAY TOO EASY. These devices have an output contact that is Normally Closed (N.C) which forms part of a current loop to the piHAT. when a break-in occurs, the N.C contacts are opened by the detector, breaking the current loop.


#38

Thanks @Michael, I would prefer the ready made for now, don’t what others think.


#39

I support you Cyrus. It’ll save alot of design time, so that we focus on major things. Atleast we have known how it operates