Ultra Trace Cargo Monitoring Final Report Kevin Kurtz - ECE Jacob Klapheke - ECE Nick Searcy - ECE Nick Wood - ME Jason Guelda - ME

Ultra Trace Cargo Monitor Pulls ambient air through MEMs capture device via a fan Targeted particulates are captured and stored on these MEMs devices Monitoring missions last up to two weeks long. The MEMs device is attached to the Vapor Tracer detector once a mission has been accomplished. Stand alone monitor without needing IMS present.

Project Overview Develop custom printed circuit to control and monitor different parameters Develop custom code for operation Create a GUI for user interfacing Fabricate enclosure to house all components

Operational Concept Unattended operation for a mission as long as two weeks Configurable Fan-Run time and Temperature Thresholds Turn on fan for five minutes every hour – If fan fails, switch to redundant backup fan Monitor temperature for extremes – Temp < 0 C (No available vapor) – Temp > 80 C (Analyte will not attach) Record time and temperature of every fan run Indicate good/bad data at end of mission If data is bad continue, but flag for temp out of range Record fan failures in run log (uploaded to PC)

System Diagram

Controller Specifications Pic 18F2520 Microprocessor Monitors Fan Controllers to Detect Fan Failures Turns fans on/off when needed Communicates the real-time clock for accurate timekeeping USB Interface to Laptop

Fan Controller Maxim MAX6684. Fan Fail Detector – Relays digital signal (high +5v, low 0v) if fan is functioning correctly. Fan On Signal – Allow fan to be turned on and off with the Micro-controller without a separate transistor. Convenient +5v Operation

USB Interface USB to UART Convertor for easy communication with a PC. UART from the microcontroller is converted to USB via a separate IC. Appears as a virtualized COM port on the PC for easy interfacing with programs.

On Board Memory 8KB EEPROM for data collection purposes. Storing Temperature and Timestamp data once an our for 2 full weeks (336 Hours) I 2 C Interface to conveniently communicate on same 2 lines as the RTC. Required 2016 Bytes of data.

USB Configuration Interface Initial Configuration Set-Up -Auto-Detects COM ports -High and Low Temperature Thresholds -Amount of time per hour that the fan is on -Set the Device Time Import data from the EEPROM -Pulls in data as CSV file for use in excel

Detailed System Diagram

Microcontroller System Microcontroller – PIC18F2520 – 25 available I/O ports Need >18 – I 2 C and UART friendly – Compatible with existing development Real Time Clock – DS1307Z+ – Keeps accurate timestamp. – Backup power via a 3V coin cell battery. – I 2 C Memory (EEPROM) – 24AA64 – 64Kb total memory Requirement > 16Kb – I 2 C

Fan Control MAX6684 Two fans  Two controllers The fan controllers switch fans on and monitor for fan failures. Fans powered via the 7.4V battery (through resistor to 5V) ‘Fail signal notifies micro of failure.

USB System USB-UART – MCP2200 – Uses standard Windows drivers for Virtual Com Port. XP/Vista/7 USB-micro – External interface – Widely available standard. – Compact

Power System Battery – 7.4V – Li-Ion – Compact – Charging electronics included in battery system – Requirement: >2700mAh Voltage Regulator – KF50BDT – 5V – Very low dropout voltage (0.4V)

Human Interface Switch – Controls battery supply power 2 Buttons – Test: for displaying the status of the data and fans – Reset 2 1-color LEDs – Signal fan failure 2-color LED – Green/Red for data good/bad

Printed Circuit Board Size constraints (3.5” x 2.5”) necessitated use of SMT components. 2-sided board

Test Results (TBD) Power System (Voltage Regulation): unverified untested Computer-System Communication: verified, untested EEPROM: verified, untested Real Time Clock: verified, untested Fan Operation: verified, untested Fan Redundancy: verified, untested Temperature Sensor: verified, untested Battery Life: verified, untested

Recommendations The fans are very expensive. We recommend finding a less expensive alternative. The battery and charger need to be replaced with a manufacturing ready product instead of a hobbyist kit. There are less expensive options. The micro controller can be replaced with a less expensive 20 pin unit, if you repurpose the programming pins through a jumper and remove the external 4mhz oscillator in favor of the 8mhz internal. (saving $3 on the micro and $1 on the oscillator) A charging circuit should be integrated onto the spare space on the board instead of using an external lithium ion smart charger. The final device should use a wall wart.

Conclusion The most challenging part of the experience was TERRIBLE documentation on the part of the manufacturers. The data sheets are lacking in many areas of practical use. Another area of challenge was the UART-to-USB convertor is a microchip part, as well as the micro-controller. The ICD3 picks up both devices and therefore you can not communicate through USB with the device from the same machine that is debugging it. Very inconvenient.