Wireless Status Indicator for Seating on a Chair

In this article I will describe how to make a light sign shows status that someone sitting on chair in real time.

The sign is written in Hebrew, it's mean "Eli is not in the office" (the word "not" will light on\off according to the seating status)
Eli is my boss ;)

The project include two parts:
- The chair - when someone is sitting on the chair - the RF transmitter will send "seating" status to the sign, If noone is sitting on the chair for more than 5 seconds the transmitter will send "not seating" status to the sign.

- The sign - The lighted sign show the status it gets from the transmitter located on the chair, another option is changing the status manually by using a button placed on the sign.

You can make this project as it is or use parts of it to build something esle.


Enjoy!

Step 1: Materials and Tools

Materials:
- Pillow for chair
- Nice box
- polystyrene
- 2 cardboards or Plastic boards

Electronics products:
- Arduino uno
- Breadboard
- Wireless Transmitter and reciver - Link to the online store
- Attainy 85 - Link to the online store
- Home made burner (to burn the attainy)
- USB cables (for 5 volt power input)
- Switch for power
- Switch for local changing mode
- Red and green Leds
- Resistors for leds and switchs
- Soldering board
- Bank power - battery 5 volt

Tools:
- Soldering iron and solder
- Glue gun
- Driller
- Multimeter (optional)
- Knife, cutter...

Step 2: Programming and Testing

First I designed the electric circuit and the arduino program.

The program is writen for arduino uno and I burned it to micro chip Attainy 85.
Use the Attainy is a great way minimize the cost and electronic circuit size of your product.

You can see how to burn the attainy with the arduino program in the Link
In the first picture you can see the burner my brother made, and in the second picture the Attainy 85 architecture.

The source code files are attached.

After you burn the micro chips connect all the pieces to testing breadboard before soldering.


Only if it works well continue to the next step.

Step 3: Electronics for the Chair

This electronic circuit should be really small because it needs to get into a chair pillow.

I Used 5 volt power input, and connect it to regular rechargeable battery.

Connect the Click Button by long wire to the chip.
If the button is hold down the Tx will send '1' to the sign,

Else, if the button is free for 5 seconds the Tx will send '0' to the sign.


I used one led as an indication light built on the chair circuit.

Step 4: Electronics for the Sign

This curciut contains:

- 5 volt USB port

- on\off power switch

- changing mode button, to get manual indication directly from the sign (without useing wireless communication)

- Micro chip

- Reciver (Rx)

- Red leds parallel string every led is connected with 330 ohm resistor

- Green leds parallel string every led is connected with 270 ohm resistor

The chip is programed this way: when the Rx get "seating" status indication the red light string will turn off.

Preper all the circuit and solder it only if it fit to your box, in my case I solder the USB cable and the change mode button only after placing the circuit and drilling holes in the box.

Step 5: Pillow for the Chair

Take a nice pillow fits to the chair size it's better to use pillow with a zipper.
Cut 2 plastic boards or cardboards and glue the switch sensor between them.

Check the switch is hold down when sitting and free when noone is sitting.

Use some sponge between the plastics boards to balance the tens on the button.

Connect a bank power to the 5 volt Usb port.

Hide the electric circuit and the bank power well and comfortably in the chair pillow.

Step 6: Design the Sing

Print on a paper your sentence in big font.
Cut the letters with a knife and make a pattern.
Use the pattern to cut the letters from the polystyrene than cut the whole sign around to fit your box frame size.

Hope you found a nice box.
Drill 3 holes on the box: power cable, on\off switch, manual change mode button.

Connect the on/off switch and the changing mode switch.

Solder the power cable to the electric circuit only after the power cable passed through the hole.

After shhiling the power cable thru the hole, solder it to electric circuit.

Organize the leds on the letters (the red ones on the word "not" in office)

Drill another hole behind to hang it on the wall.

Place all the products in the box close the polystyrene on it and the sign is ready to use..

Step 7: It's Really Work All Together!

Connect the final products to power and test it!
I found the wireless connectivity works fine in range of 10 meters.


Great Thanks to my brother Barak for helping me a lot, I couldn't do it without you.

I may have some technical or grammer mistakes, let me know to make this article beter.

Have a nice work and Good luck :)