 Home Security System Willard Stanley

Motivations  Commercial security systems have a monthly cost  Designing my own allows for greater extensibility

Design Goals  Core feature parity with commercial system  Cost of less than $100  Low power  Web configurable

Design Constraints  The Arduino Uno has 32KB of program memory  There are 13 I/O pins  The device has no threading, multitasking, or OS.  The TCP stack for the Arduino Ethernet module only supports 4 socket connections

Client Circuit Design

Client Software Design  Client Protocol Grammar: --> | | --> login -> [0-9]+ --> --> heartbeat --> [0-9a-f]{50} --> sensor -->.

Server Software Design  Server Protocol Grammar: --> |null --> | | --> start --> panic --> flash|noflash

Server Database Design

Client Implementation  Built using the Arduino’s development toolkit  Based on a subset of C  Since there is no multitasking, the client is simply a loop.  Program size turned out to be around 13KB  Pseudo Code: Loop{ if !check_for_tcp_connection(){ establish_tcp_connection(server) } new_sensor_data = read_in_sensor_data() if new_sensor_data != old_sensor_data{ update_LEDs(new_sensor_data) send_event_to_server(new_sensor_data) old_sensor_data = new_sensor_data} else{ send_heartbeat(server) } } //End Loop

Server Implementation  Built using Python 2.7  Designed and tested on FreeBSD 8.2  Uses a synchronous threading model  Uses MySQL for the database