High Speed Wired Data Collection Final Report Iowa State University Department of Electrical and Computer Engineering Senior Design December 2010 Team 04 Team Zachary Coffin and Radell Young Faculty Advisor Dr. Zhengdao Wang Client Honeywell Date Submitted: 2010.12.06.
Revised Project Plan Problem Statement Honeywell needs to transmit 64 Mb/sec of experimental data across 300ft of cable. The transmitting device will be destroyed at the end of each test. Since they plan on running hundreds of tests, reducing cost is a high priority. Their previous data collection methods were both too slow and prone to error. Solution Cost was kept to a minimum by using commercial off-the-shelf components instead of designing our own application specific integrated circuit (ASIC). Power is supplied to our device by an on-board battery Functional Requirements Every sample sent from the sensors must be sent individually to reduce the loss of samples due to destruction at the end of each test. Receiver needs to identify when the transmitter is destroyed and stop trying to collect data. Signals need to be sent across 300ft of cable while minimizing error. Non-Functional Requirements The Transmitter must fit in a small (3 x 3 x½ ) cavity. The device must withstand the force of acceleration beginning at each trial. Transmitter should cost at most $100. The devices will be made from pre-existing components (primarily to reduce cost) Project task Breakdown Per Team Member Task Zach Coffin Radell Young Mazdee Masud Bill Zimmerman Chipset Specification 50% 45% 5% Documentation 30% 70% Schematics 100% Testing 40% 40% 20% Poster 45% 55% Revised Project Design Implementation Transmitter Device The transmitter device samples analog data from four piezoelectric sensors, applies simple parity encoding, serializes the bits and transmits them using a standard low-voltage differential signaling (LVDS) method. To achieve this, the device regulates two voltage levels of 1.8V and 3.3V, generates a clock signal using a crystal, and employs a counter for serialization.
Transfer Medium Category 5e cable was selected for the cable based on its availability, cost, and known effectiveness in transmitting data at similar rates to those required by the project. Three twisted pairs are employed in transferring the data signals while one twisted pair is dedicated to the clock signal. Receiver Device The receiver device regenerates the transmitted clock signal, decodes the LVDS bit-stream, and transmits the data via a USB UART protocol to be interpreted on a Windows PC. Obstacles The PCB design couldn t be finalized before receiving chipset. A few datasheets did not include the device dimensions Losing another team member early on significantly reduced availability of the man hours and became a detriment to the feasible scope of our project. The complexity of the system made a software simulation unrealistic. The prototype construction fo the system itself required resources and time which were out of the scope for a two person project. Chip Set Measurement Specialties, - Inc. LDT 1-028K/L (Piezo, 4x) Texas Instruments - TPS76918DBVR (Voltage Regulator, 2x) Texas Instruments - TPS76933DBVR (Voltage Regulator, 2x) Texas Instruments - ADS931E (AtoD, 4x) Texas Instruments - CD74AC280M96 (Parity, 4x) Texas Instruments - ADG706BRUZ (MUX, 3x) ECS Inc. - ECS-240-12-4X (24MHz Crystal) Texas Instruments - CDCE913PW (Clock Generator, 2x) Texas Instruments - CD74HCT163E (Counter) National Semiconductor - DS92LV040ATLQA (LVDS Transceiver, 2x) ST Ericsson - ISP1506ABS (USB Transceiver) Fairchild Semiconductor - 74VHC04MX (Inverters) Texas Instruments - SN74LV27ADR (NOR gates)
System Block Diagram
Schematic
Testing Cat-5e bottom left; Piezo sensors bottom right Typical sensors (piezos supplied by Honeywell) deliver ±150V 300ft of Cat-5e cable was tested for crosstalk and signal degradation Signal loss measured as -10dB at 24MHz Cross-talk between twisted pairs was minimal Evaluation The original plan was to demo a finished product on site at Honeywell s Kansas City Plant. However, due to frequent losses in team members, budget cuts, and clearance issues at Honeywell the scope of the product was reduced. Our evaluation will now be on the basis of our final schematic and system design. All schematics and test data will be submitted to Honeywell for further development.
Appendix Operation Manual High level Objective The high level objective of this project is to transmit data across 300 feet of cable at 64 Mb/sec. Functional Requirements Every sample must be sent individually to reduce the loss of samples due to destruction at the end of each test. The receiver needs to identify when the transmitter is destroyed and stop trying to collect data. Signals need to be sent across 300ft of cable while minimizing error. Already Implemented The team has been working on designing the system chipset for most of their time. This has required most of their man-hours to complete because they lost team members and because this type of project is not directly related to their fields of study. How to Setup the System Set up transmitter to begin sending data over the 3 channels Begin sampling analog (flick) signals with the transmitter Set up receiver to receive data from all 3 channels Link receiver with hyper terminal to view output Connect transmitter and receiver with cat5 cable Send data from transmitter to receiver over 3 data channels at a combined rate of 64 Mb/sec View output on hyper terminal Test Results Observed The team began by testing individual components then they can move to testing the overall system. First they tested each Piezo sensors for analog generation, they determined that these sensors will work sufficiently to complete the project, however better options may be available later. They have also tested the cable to be sure that it can support the required data rate; originally they wanted to use coax cable which could have easily handled the transmission, however, at the request of the client they switched to cat5 cable. They determined that cat5 cable could support the desired rate however they lose ~10 db at this speed, they believe they could solve this with differential signals.
Our Critique Constructing this device out of commercial off the shelf products presents a strength and a weakness, it s a strength being that the parts a cheaper. The weakness is that it will not be as efficient because it isn't designed specifically for this scenario. Although this implementation has not fully been constructed, it appears as though it is on the path to meeting the specification. A strength of the system is that it is modular. It seems that one of the three main components of the system could be replaced without too much change to the rest of the system. The implementation of the system, when it is complete, will meet the specification. As long as the cat5 cable can support the amount of data that the transmitter is sending, the system will perform its desired task.