Wireless Switch For Household Appliances

1. Wireless Switch For Household Appliances ECE 445 – Senior Design Project Presentation Low Tze Ming Ungku Fazri

2. Introduction Motivation • Help physically handicapped users improve living conditions by reducing physical movements Practical Applications • Allows users to control multiple devices (on/off/different levels of speed/brightness) in multiple units from far by remote control

3. Introduction Technical Objectives • To design a device that can send instructions from transmitter to receiver: • Correctly (with error checking) • Safe and secure (without being hijacked possibly by other devices) • Without causing/receiving interference from other electronic devices • Small, portable, easy to use, safe and low power consumption device • Transmission range of more than 2 rooms (~10m)

4. Design Description Transmitter • Powered by 3 AA batteries (~1.5 Volts) • Components : Keypad, FPGA(microcontroller), Encoder & RF Transmitter • Function : User keys in instructions to be sent wirelessly to appliance

5. Design Description Receiver • Powered by wall outlet • Components : RF Receiver, Decoders, Logic Gates and Relays • Function : Receives instruction from transmitter, decodes information and interfaces between appliance and logic gates.

6. Transmitter

7. Start State Turn Everything Off? no Enter Unit Number no Is it a valid unit number? no yes Confirm? yes yes Enter Appliance Number Turn Everything Off no Is it a valid appliance number? Turn Appliance On/Off/Speed yes yes Is it a valid number? (on/off/speed) Enter Appliance State (ON/OFF/SPEED/ BRIGHTNESS) no Software Flow Chart

8. Off Unit 1 App #1 Start On Off S1 Unit 2 App #2 S2 All Off App #4 S3 App #3 Off Confirmation On S1 S2 S3 Off Unit1, App1, Off Unit1, App1, Off Unit1, Ap2, Off Unit1, App3, Off Unit2, App1, Off State Diagram

9. Code Snippet for Output Assignment of State Diagram when u2app2s2 => Aout(2) <='1'; Aout(1) <='1'; Dout(9) <='1'; Dout(8) <='0'; TE_bar <='0'; when others => Aout(2) <='0'; Aout(1) <='0'; Dout(9) <='0'; Dout(8) <='0'; TE_bar <='1'; end case; end process;

10. Design Overview – LINX & Decoder

11. Design Overview – Single Bulb

12. Design Overview – Dimmable Light

13. Testing – Operating Range • Most of our tests are done in the lab since the transmitting side requires a 120V power outlet • We have the transmitting part moved incrementally further away from the receiver to test the transmitting range. • The circuit functions correctly up to the west stairway, which is more than 10m. • We also verified that the circuit would cease to function outside the building.

14. Testing – LINX HP3 chips Output: Vpp = 5V @ 20kHz Input: Vpp= 4.55V @ 20kHz • To test the LINX chips we verify that the input waveform on the transmitted side recovered at the receiver side.

15. IC = 81.42mA IB= 4.953mA Resistor Bulb Power Line Current Measured Calculated R1= 0 100 W 0.8377A 0.8333A R2= 60  50 W 0.6699A 0.5882A R3= 144  25 W 0.5400A 0.4167A Testing – Currents in Circuit

16. Successes • Operating range is more than our needs. • Circuit functions as predicted. Difficulties • Unable to get the “All Off” function to work. - Suspect that the FPGA is switching too fast • Power source for transmitter is not suitable. - FPGA draws a lot of current (~0.145A) - Drains the 3 serial AA batteries

17. Costs of Parts

18. Improvements • Mobility - Use 16 button keypad in place of keyboard - Use PICAXE-18X in place of FPGA - Use a PCB to reduce footprint of circuit • Costs - Use PICAXE-18X which costs only $10 • Power Supply - Use a PICAXE-18X since it can run off batteries

19. Acknowledgements Special thanks to • Jing Tang • Marty Cantzler • Mo Zhou • Adam Gustafson • Jonathan Holm • Parts Shop Staff

20. QUESTIONS?