Voice Controlled Home Automation System Group 13 Zhe Gong Hongchuan Li

Introduction  A voice controlled switch system to create an automated and comfortable home environment  Turn on and off multiple sockets remotely

Objective User-customized voice command Control devices in all rooms Enable/disable voice control for specific power socket

Original Design Overview

Core Unit

Remote Unit

Power Electronics InputWall outlet AC Output5 VDC ± 20mv to all parts HardwareVSK-S10-5UA AC-DC converter

Power Electronics RequirementVerification Wall outlet transform to 5 VDC ± 0.02V Connect the power electronics circuit to wall outlet. Use volt-meter to measure the output voltage. Verify the voltage is 5 VDC ± 0.02V.

Power Electronics

Transmitter and Receiver Transmitter (Core Unit): Receiver (Remote Unit): Inputdigital data from microprocessor OutputRF signal to receiver HardwareTXM-418-LC InputRF signal at 418MHz Outputanalog signal to microcontroller HardwareTXM-418-LC

Transmitter and Receiver

RequirementVerification Stable data transmission from transmitter (core unit) to receiver (remote unit) Input a signal to transmitter using function generator and make transmitter transmits the signal. Connect oscilloscope to receiver to verify the received signal.

Transmitter and Receiver

Relay Input Low/high voltage from microcontroller 120V AC Output120V AC

Microprocessor Input Voice data from microphone Ethernet or Wi-Fi USB mouse/keyboard Output Digital command to transmitter HDMI output to screen Speaker for voice communication with user Hardware Raspberry pi model B/B+ Wi-Fi adaptor attached to Raspberry pi’s USB port USB speaker Software Rasbian OS Jasper (voice recognition software) Own program for analyzing and RF transmission

Microprocessor RequirementVerification Microprocessor can recognize the voice command. Say a voice command to microphone and verify that the text printed out by microprocessor is correct. Microprocessor can send data to transmitter, thus communicate with remote strip unit. Connect the microprocessor to Arduino to test if the microprocessor can send correct data

Microprocessor (Raspberry pi )

Microcontroller Input Serial signal from receiver OutputLow/high voltage to relays HardwareArduino UNO for testing, atmage328P for PCB

Microcontroller RequirementVerification Microcontroller converts data received back to command. Configure the microprocessor to send commands to microcontroller, verify the output of microcontroller to be high or low correspondingly. Based on command, microcontroller sends high or low signals to relay.

Microcontroller

Serial communication Challenges The wireless module TRM-418-LT doesn’t support the USART (Universal Synchronous/Asynchronous Receiver/Transmitter) Raspberry Pi doesn’t have a RTC to provide accurate interrupt Solutions Implement our own serial communication Continue to pull out the system time Block the interrupt

Serial communication count’ Send 0x0C(DATA)3 In binary 0b bitsData+0011 Send from right to left, each bit at a time Set the gpio pin23 to HIGH or LOW correspondingly Continuously shift the input into a buffer Process if the data satisfy the pattern Baud rate = 500 Too fast, inaccurate Too slow, the chip cannot handle

Encoding Using hamming to encode the data Able to correct 1 bit error and detect 2 bits error

Encode/Decode API API in python encH1511(n, debug = False) decH1511(n, debug = False) API in C: int encH1511(int n); int decH1511(int n);

Protocol 11 bits of data 0b Bit 10-7 Core ID Generated from the CPU’s ID, each raspberry has a different number Bit 6-3 Remote ID Assigned to each remote unit (EEPROM) Bit 2-0 CMD (distance = 2) ON = 0(0b000) OFF = 3(0b011) TOGGLE = 5(0b101) ACK = 6(0b110) Devices are paired and the data is kept by both remote and core unit to avoid malfunction

Keywords Only process if contains “SWITCH” TURN ON/OFF Remote ID TOGGLE REMOTE ID If the remote id exist, then cmd is sent to the remote unit

Functional Tests Bread board test for wireless communication of transmitter and receiver

Wireless communication of test result Function Generator Output Receiver Output

Test of microcontroller with wireless communication

Microcontroller test results

Test with all PCB components

Test Results of PCB

Success and Challenges All verifications are met. Successfully turn on and off power socket by voice control – achieved overall functional objective

Challenges Noise affect the voice recognition accuracy and response speed Performance of microphone affects the voice recognition accuracy Long Distance and signal noise with similar frequency can affect wireless communication

Recommendations for further work Noise handling: noise filter or algorithm, limited command pick up time Add microphone in remote unit and enable bidirectional communication between core unit and remote unit: control the socket far away from the core unit, when you are near the socket

Strengths:  Multiple socket control  Possible expansion of new sockets  Cost effective Conclusion Weakness:  Susceptible to Noise  Susceptible to long distance in large house