1. ECE 477 Design Review – Spring 2010 Team 15

2. Team Members

3. Outline Project Motive Project Overview Project-Specific Success Criteria Block Diagrams Component Selection Rationale Packaging Schematic PCB Layout Preliminary Software Design Software Status Project Timeline

4. Project Motive Green Energy Management System aims to conserve electric power by facilitating remote management of household appliances through a web interface and a touch screen.

5. Project Overview Adapter Connects to two appliances Monitor usage of power over time Communicates with a base-unit using R/F Can turn devices on/off on receiving appropriate command

6. Project Overview Base Touch-Screen Interface Communicates with adapter using R/F Stores appliance usage data Usage based alerts, modes and statistics Hosts server and web-services for remote access

7. Project-Specific Success Criteria An ability to measure power consumption of plugged-in devices over time An ability to communicate with a base unit using RF and to upload recorded information on a web server using the Ethernet interface An ability to turn devices on/off remotely An ability to set up intelligent power plans to turn off devices either after a fixed amount of time or after fixed power consumption An ability to use touch screen interface to control operating parameters of the power management system

8. Block Diagram Current Sensor AC in AC out MC9S12A512 (uC) ATD Solid State Relay Current Sensor AC in AC out Solid State Relay Transceive r TRM315LT ATD Rx Tx RF Transformer ( steps down voltage for voltage sensing ) Adapter Unit

9. Block Diagram Transceive r TRM315LT MC9S12A512 (uC) Intel Atom Board LCDLCD Touch screen RS232VGA USB Tx Rx RF Base Unit

10. Component Selection Rationale Current Sensor - Must be able to tolerate huge amounts of current (up to 25A). - Must be able to measure alternating current - Muse be cheap and easy to use. Solid State RelayOpto 22 – 120D25 Carlo Gavazzi – RA 2410LA Optical IsolationYesNo Zero SwitchingYes Control Voltage3-32 Price$26.50$36

11. Component Selection Rationale Solid State Relay - Optical Isolation for protecting the rest of the circuit from current surges. - Zero crossing for switching inductive loads. - Control voltage should be low enough to be produced by microcontroller. Current SensorTamura - L18P***D15Allegro - ACS710 Output Voltage4V2.5V Accuracy+-1%+-2.2% Price$12.50$22.00

12. Component Selection Rationale Microcontroller - Low power consumption - Multiple ATD channels. - SCI interface or built-in RF interface - Cost effective (Must be cheap as it would have to be installed in every power adapter.)

13. Component Selection Rationale MicrocontrollerATMEGA128RFA1Freescale mc9S12A512 # of pins64 112 # of I/O pins38 54 Program Memory (kB)128k(Flash) 4k(EEPROM) 14k (RAM), 4K(EEPROM) Flash (kB)16k 512K ATD resolution 8 bit 10 bit Power Consumption16mW 25 mW DocumentationYes Price Sample Available AvailabilityShipping DelayedAvailable

14. Packaging Solid State Relay Plug point Fuse box and switch PCB 4 cm7.5 cm 2.5 x 3.5 cm 6 cm18 cm 7 cm 3.3cm Adapter Unit

15. Packaging Base Unit

16. Schematic & Theory of Operation Main Components Power Supply Circuit Voltage Regulator circuits Microcontroller Circuit Current Sensor Circuits Voltage Sensor Circuits

17. 120 V AC voltage stepped down to 25V using simple center – tapped step down transformer 3 sets of rectifier circuits connected to specific voltage regulators to generate a regulated DC supply +/- 15 V (7915,7815) +/-5V (7905,7805) +/-2.5V (2937,2837) Power Supply

18. Schematic Power Supply

19. Schematic Voltage Regulator Circuit

20. Voltage Sensors Stepped down voltage to 5Vpp V out shifted up by 2.5 V to get accurate value on ATD of microcontroller Voltage shift is done using adder circuits using 741 operational amplifiers

21. Schematic Voltage Sensor

22. Current Sensors work on hall effect principle Small in size PCB mountable Keeps direct line current away from PCB The output voltage varies between +/- 4 Vpp based on amount of current The output voltage is shifted up by 2.5 V to get accurate reading on the ATD. Current Sensors

23. Schematic Current Sensor

24. Solid State Relays The solid state relays work on DC control which varies between 3V – 32V Allows current to flow above 3.5 V Provides optical isolation to rest of the circuit when switched off

25. Microcontroller Sample the voltages from current sensor and voltage sensor circuits Transmit the collected data to the base station Receive control signals from the base station and control the appliances accordingly

26. Schematic Microcontroller Circuit

27. PCB Design Considerations 2 PCB boards Power Adapter: Small, narrow to allow for portability. Base Unit: Must be able to fit a small LCD display (10”) Microchip Transceiver close to PCB edge. Current Sensor must be close to PCB edge. High Electromagnetic Interference from the power lines and most electric lines.

28. Microcontroller Layout Decoupling capacitors must be placed as close to the IC as possible. Voltage regulators must be used to ensure that maximum input voltage of ATD is not exceeded. The supply voltage to the microcontroller must be satisfied from the power line voltage. This requires the use of current rectifiers and regulators to supply DC voltage. Tri-state buffers are required for the Tx/Rx pins

29. Microcontroller Layout Bypass filters placed close to micro controller Pierce oscillator circuit for generating clock Regulated 2.5 V power supply

30. Power Supply The following voltage supplies are needed for different circuit components - +15,-15,+5,-5,+2.5V The power supply needed by most of the components is DC thereby requiring the use of rectifiers and voltage regulators. Requires circuit components which can tolerate high amounts of current(0-20A) and voltage fluctuations.

31. Power Supply 3 sets of regulated voltage supply ( +/- 15V,+/-5V, 2.5V) Rectifier circuits placed at the edges

32. PCB Layout

33. Voltage Regulator +/-15V Voltage Regulator +/- 5V Voltage Regulator +/- 2.5V MC9S12A512 RF transceiver & tristate buffer Current Sensors BDM

34. Preliminary Software Design Power Adapter Unit Decided on TCP/IP like protocol to communicate with base station. Used Real-time interrupts of the microcontroller to initiate the ATD conversion. Multi-Channel ATD conversion carried across three channels. (2 for current sensor and 1 for voltage sensor) Send the recorded values using Serial Communication Interface to the RF transceiver. Check for incoming commands from the base station at regular intervals

35. Preliminary Software Design Base Station Receive data sets from the RF transceiver using the serial port Buffer any on/off signals for devices and transmit them at regular intervals Send the data sets to the Intel Atom Board using the COM port Host a web-server on the Intel Atom board so that it could be accessed using a web-browser

36. Software Status Adapter Unit Majority of software complete except for interface with R/F module and network protocol Base Unit XP has been installed Apache Servers installed Touch Screen interfaced (Drivers, etc.)

37. Project Timeline Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 Week 16 1-Mar8-Mar15-Mar22-Mar5-Apr12-Apr19-Apr26-Apr3-May Design Review Finalizing PCB design ATD module Setting up RF interface using SCI Debugging data transmission errors Configuring firmware and web- server on Intel Atom Board Setting up RF interface on base station GUI development for base station Writing Web Services Packaging Debugging

38. Questions