= Sensor Nodes =
The goal is to have a working, mesh network of sensors (i.e. light, temperature, presence) and actuators (motors to open / close a window, turn lights on and off, etc.).
The solution is centred around a '''raspberry pi''' that has a '''NRF24L01+''' chip, and works as a central point for gathering all of the data received via the radio. It then builds a webpage transmitting the data in real time and then rules are applied so that we can say, activate one motor if the value of a sensor is below 20°
The nodes are based on the '''ATTiny85''' AVR micro-controller and another NRF24L01+ chip.
== Parts ==
* x + 1 NRF24L10+ chips, where x is the number of nodes
* x ATTiny
* Tool to flash the ATTiny, this can either be an arduino (using the [https://www.arduino.cc/en/Tutorial/ArduinoISP Arduino as ISP] sketch) or a dedicated AVR USB programmer
== Sensors ==
Here is a list of the sensors I made, complete with Kicad files (schematics and PCB layouts)
=== Sensors ===Here is a list of the sensors I made/will made, complete with Kicad files (schematics and PCB layouts) ==== Light Sensor ====[[File:Light-B Cu.svg]]
Uses a light dependant resistor
(todo)
==== Temperature & Humidity ====
(todo)
==== Presence (PIR) ====
(todo)
==== Gaz ====
(todo)
==== Piezo ====
(todo)
==== Sound ====
(todo)
=== Actuators ======= RGB Led strip ====
Be able to change the color
==== Window opening ====
Use a motor to open / close a window
==== Blinders ====
(todo)
==== Sound ====
(todo)
== Code ==
On the final destination node (raspi): There will be 2 parts of code running in parallel. The first one will get the values through the NRF24L01+ and parse them into a json file that will be used for a web interface. The other part will allow the dynamic creation of rules that have to be applied (e.g. turn on the lights if the presence sensor activates, etc.).
=== Transmission ===
The radio packets contains 4 values to transmit:
* The ID of the node (unsigned int_8) -> max nodes = 255
* The type of value (temperature/presence/humidity/light) or the type of "activator" (blinders/doors/lights)
* The value to transmit as a signed int8_t (from -128 to 127) (Note: maybe this is not enough, try other sizes)
Notes:
The next step will be to add mesh-networking capabilities by sending a broadcast packet and waiting for the reply from the others nodes, and create a table of reachable nodes.
It would be nice to add some randomness in the delays of transmission otherwise we will only receive packets from nodes emitting at a precise moment.
Also, at the moment the packets are received in a dumb fashion, so we are not sure if the values will correctly update. We could correct this by adding a fifo queue on the receiving node (the raspi) and treat the packets one by one, not ignoring some while the last packet is treated.