description of the basic Arduino PSD device
Contents
1. As the project progresses there are small modifications that will be made to some of the components I analyzed this quarter For instance we may want to change the Bluetooth pairing code from its default value Eventually it will also be necessary to replace the broken GPS module for this PSD to be complete and compact With the addition of this GPS Breakout onto the Arduino a potential addition to the security mechanism may take into consideration the location of the patient when their medical device receives commands If we can obtain a fix on the location of the PSD and know the location of the home station which is assumed to be stationary GPS would be another means of detecting whether the medical device is receiving data from an authorized source since it should only get such data when it is near the base station The GPS breakout also can log data for up to 16 hours which may prove useful for a tracking feature later on However the largest changes in the project will most likely be in the code of the defense mechanism Currently the code developed by Pournaghshband is on a full fledged Linux machine with substantially more memory than an Arduino microcontroller even if we were to mount a shield with additional RAM or use the storage on some of the modules attached to the shield Next quarter my plan is to go through the code fully understand the algorithm and see which areas can be optimized or substituted with more memory conservative m2. and green LEDs on the RN XV 171 will blink quickly Once I entered command mode and set the SSID to a valid name I saved the settings and rebooted the device which outputted information regarding MAC IP and gateway addresses of the network if it successfully connected The red light disappeared while the green LED flashed less frequently I imported the WiFlyHQ Library which abstracts some of the ad hoc commands I had manually done for the connection setup into a function The library also provides sample programs to test TCP connectivity as well as code to set the microcontroller up as a HTTP client or server The figure below is the output of executing one of those example programs as a server WiFly HTTP Server Examp x Quon sabe gt C D 169 232 198 101 ye 0g Free memory 7032 Apps News 5 Web 2 Other bookmarks Already joined network vac 00 06766 50 74 e5 Hello Karen IP 169 232 198 101 Ready Got GET request Sent index page Unexpected GET favicon ico HITP 1 1 Sending 404 Got POST Sent greeting page E Autoscroll Carriage return lt 115200 baud lt Global Positioning System GPS The GPS functionality is supported by an Adafruit Ultimate GPS Breakout Version 3 The module has an internal patch antenna as well as a connector for an external active antenna though we just use the former for this device There exists an ENABLE pin on the module that wh
3. 6 34 072208 118 451141735 03 14 2014 17 18 30 750 189 10 311 46 1 15 NW 8766 33 95 NE 850 10 0 5 136 34 072212 118 451148735 03 14 2014 17 18 31 750 189 10 300 29 1 43 WNW 8766 33 95 NE 1020 12 0 5 136 34 072216 118 451156704 03 14 2014 17 18 32 719 188 90 300 13 2 04 WNW 8766 33 95 NE 1190 14 0 5 136 34 072216 118 451164756 03 14 2014 17 18 33 770 188 80 296 68 1 93 WNW 8766 33 95 NE 1360 16 0 5 136 34 072216 118 451187770 03 14 2014 17 18 34 784 188 60 290 32 2 00 WNW 8766 33 95 NE 1530 18 0 5 136 34 072216 118 451187798 03 14 2014 17 18 35 812 188 40 285 96 2 00 WNW 8766 33 95 NE 1700 20 0 5 136 34 072212 118 451202808 03 14 2014 17 18 36 822 188 20 285 53 2 32 WNW 8766 33 95 NE 1870 22 it 5 136 34 072212 118 451210758 03 14 2014 17 18 37 775 186 00 288 88 2 33 WNW 8766 33 95 NE 2040 24 o 7 Autoscroll Carriage return w 115200 baud y One issue with this module was that the GPS that is currently mounted on the shield is not responding to the power supply and hence does not turn on I worked with Dr Sarrafzadeh s lab to detach the module but as of now unsoldering the GPS module may damage the shield Consequently a GPS module of the same model and manufacturer sits on a breadboard right now and is wired externally into the Serial3 pins on the Arduino Liquid Crystal Display LCD shield The topmost shield of the PSD is a LCD screen with a keypad This module has a blue backlight LCD displaying white characters It consists
4. A Detailed Breakdown of the Personal Security Device CS199 Final Report Karen Truong UID 304019042 Introduction My research project this quarter was a portable personal security device PSD for the Laboratory for Advanced Systems Research The personal security device was physically assembled by Dr Sarrafzadeh s Embedded Systems Lab It consists of an Arduino Mega 2560 with 16 analog input pins 54 digital I O pins and a USB connection to power and upload sketches 1 In regards to memory this Arduino has 256KB flash memory 8KB SRAM and 4KB EEPROM which is an important design limitation we will consider as we develop the device A shield is attached on top of the microcontroller to add space for other modules that were soldered on including Bluetooth GPS Wi Fi and an inertial measurement unit IMU Lastly an LCD keypad shield is attached atop the first shield for use as a display later on In order to support all the additional modules mounted on the Arduino shield several new libraries had to be added All of the supplemental libraries were found online on open source sites and then imported into the Arduino IDE 1 0 5 an open source application which compiles and uploads sketches to Arduino platforms I will discuss the procedure issues and results I obtained when testing each module of the personal security device Bluetooth The PSD includes a JY MCU Bluetooth serial port module onto the shield to add wireless capabi
5. before it can be loaded onto the microcontroller 6 The amount of flash memory used is easy to determine as the IDE outputs that information when you compile a sketch Meanwhile EEPROM usage is based on the user s code so it remains the same throughout the execution of the sketch There are more complex measurements made dynamically when analyzing SRAM usage Consequently I imported the MemoryFree library found in the Arduino Playground that had several methods of determining the amount of available SRAM 2 The simplest version of the function is shown below int freeRam extern int heap start brkval int v return int amp v _ brkval 0 int amp heap start int _ brkval Encryption Software In order to do an initial test of a security feature on the Arduino I imported the Advanced Encryption Standard AES library a block cipher where the block size is 128 bits and key lengths of 128 196 and 256 are used for several rounds of processing and encryption that include permutations substitutions and additions among other operations The experiments run were mostly meant to verify the results found in the work of a previous graduate student who ran similar memory metrics on AES and worked on the encryption side of the PSD 3 The success of those tests indicates that it will be reasonable to load cryptographic software on this device and still have room to fit the other functionalities Future Work
6. d TXD pins were connected to Seriall Data sent from my terminal to the shield was not processed correctly at Seriall so I decided to wire the transmission and receive pins of the Bluetooth board to digital pins 10 and 11 respectively Digital pins can be used to simulate serial ports using the SoftwareSerial library provided by the IDE I made this decision based on previous examples found in tutorials online and the support for a BluetoothSerial class in the SoftwareSerial library I also consulted the graduate student who put together the PSD to confirm that the Bluetooth communication from laptop to Arduino was producing garbled data over the Seriall pins Wi Fi A Roving Networks RN XV W Fi module provides additional wireless support This particular version incorporates 802 11 b g radio 32 bit SPARC processor TCP TP stack real time clock crypto accelerator power management unit and analog sensor interface 8 The module has two modes ad hoc command and data mode Under ad hoc mode a user can use SET commands to change WLAN IP and hardware settings Similar GET and status commands exist to access metadata about the module Functionally there are also commands like ping and close to take action at the TCP and ICMP level as well as file I O interface Lastly there are three LEDs a red and green light to represent TCP and IP interface and a yellow one to indicate RX TX data transfers Initially when powered both the red
7. en pulled to ground can turn off the module as well as a red LED and pulse per second PPS output FIX that indicate if the GPS has made a fix on its location When the module is still searching for satellites the LED blinks at roughly 1Hz Once it has established a fix the LED blinks once every 15 seconds to conserver power 4 Many of the SET commands one can use with this GPS module is encapsulated in functions provided by the Adafruit GPS library The library also provides a parsing method to extract data including the satellites used to find the fix on our location and the coordinates of that location The figure below is a screenshot of some of that metadata formatted in a table for better comprehension com3 Gma x o Send Adafruit GPS library basic test Sats HDOP Latitude Longitude Fix Date Time Date Alt Course Speed Card Distance Course Card Chars Sentences Checksum deg deg Age Age m from GPS to London RX RX Fail RK KKK KKH KKK KKK RRR RRR KKK hema KKK KK KK Rk kkk kK 0 0 0 5 136 34 072200 118 451141686 03 14 2014 17 18 26 700 189 10 341 32 0 09 NNW 8766 33 95 NE 170 2 0 5 136 34 072200 118 451141693 03 14 2014 17 18 27 708 189 10 341 32 0 33 NNW 8766 33 95 NE 340 4 it 5 136 34 072200 118 451141713 03 14 2014 17 18 28 728 189 10 316 53 1 15 NW 8766 33 95 NE 510 6 0 5 136 34 072208 118 451141737 03 14 2014 17 18 29 753 189 10 315 39 1 15 NW 8766 33 95 NE 680 8 0 5 13
8. ethods so that the Arduino can accommodate both the defense mechanism and the existing modules on the PSD moving us closer to the end goal of a fully functioning portable PSD prototype References Arduino Mega 2560 Arduino ArduinoBoardMega2560 2014 lt http arduino cc en Main arduinoBoardMega2560 UyNCiPIdV8E gt Available Memory Arduino Playground AvailableMemory 2014 lt http playground arduino cc Code AvailableMemory gt Gupta Priyansha Implementing Security in a Personal Security Device 2013 Ladyada Adafruit Ultimate GPS 2013 lt http learn adafruit com downloads pdf adafruit ultimate gps pdf gt Liquid Crystal Hello World Arduino LiquidCrystal 2014 lt http arduino cc en Tutorial LiquidCrystal gt Pournaghshband Vahab Majid Sarrafzadeh and Peter Reiher Securing Legacy Mobile Medical Devices Wireless Mobile Communication and Healthcare Lecture Notes of the Institute for Computer Sciences Social Informatics and Telecommunications Engineering 61 163 172 2013 Roving Networks Bluetooth Product User Manual 21 Nov 2011 lt http ww1 microchip com downloads en DeviceDoc Bluetooth RN UM pdf gt Roving Networks RN 171 XV 802 11 b g Wireless LAN Module 29 Oct 2012 lt http ww1 microchip com downloads en DeviceDoc m 171 xv ds v1 04r pdf gt
9. lity via serial port communication This component of the PSD was arguably the most important functionality to verify first as the medical devices will be communicating to the PSD and home station over Bluetooth I first tested command mode of the device to verify that I could change the settings on the Bluetooth module e g name baud rate etc These commands are described in detail in the Advanced User Manual from Roving Networks 7 Keeping the device in its default slave operation state and switching it back to data mode I used a Bluetooth dongle attached to my laptop to discover the device and establish a Bluetooth connection which is confirmed by a solid red LED on the device I experimented with the Bluetooth communication by using the serial monitor to transmit data to the laptop and a terminal emulation application such as PuTTY and HyperTerminal to secure a connection over the COM port corresponding to the outgoing channel of the pairing which provides the laptop a means of sending data to the Arduino Simple print statements on both ends verified that the data was reaching each end host correctly Red LED blinking if not paired on if paired RXD 3 3V level Microcontroller to Bluetooth Module TXD 3 3V level Bluetooth Module to Microcontroller GND VCC 3 6 6V KEY Pull high for AT command p I ran into some problems with the transmissions to the Bluetooth module particularly because its RXD an
10. of 6 keys select reset up right down and left which are all connected to analog input pin AO The pins on the upper edge of the shield include a register select RS pin that controls where in the LCD s memory you write data to a read write pin RW an enable pin E display contrast pin Vo and eight data D0 D7 pins that will be the bits written to the register Additionally there is a potentiometer that had to be adjusted with a screw driver to increase the contrast enough to display the segments on the screen clearly LCD Contrast Potentiometer ICSP S AATE Try 5 Keys connect to Analog Input Pind The Arduino IDE already comes preloaded with the LiquidCrystal library that supports the LCD keypad shield once the interface pins are assigned 5 Using a digital multimeter I identified which pins on the module corresponded to the parameters in the LiquidCrystal class constructor Different shields have a different ordering of the pins but for future reference the configuration of our shield is to use LiquidCrystal lcd 8 9 4 5 6 7 Memory Measurement One of the main objectives of this quarter of the project was to be able to measure the available memory that would remain after loading all the necessary programs that support the modules analyzed in the previous sections It is critical to know how much space is left on the device as it will help decide what needs modifying on the existing defense mechanism
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