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Webtrain Decoupling Adam Kadolph EE451 Bradley University Advisors: Dr. Irwin, Dr. Schertz Design Review Presentation - Week 12 Tuesday 3/6 Outline • • • Introduction Timeline Weeks 8-12 – Sensor – Test Programs – Automatic Decoupling • The Current Problem 2 Introduction • The goal of this project is to design a system to automatically decouple cars from the train. • Recalling from last semester – I began to research sensors – Made a test program to decouple train cars with a few train controls 3 Timeline 4 Week 8 • Test sensors and determine one most suitable for webtrain – Photocell • Pros: Small, simple to use, very sensitive to light • Cons: Slow switching time – Phototransistor • Pros: Efficient • Cons: Narrow angle of detection, difficult to use, would have to be mounted on the sides of track 5 Sensor • CdS Photocell – Resistance between 1k (light) and 100k (dark) Ohms – Fits nicely in the track (only 1 tie removed) – Simple to use • Determined voltages that correspond to different situations with a train car – Three states: nothing, coupler, and train 6 Week 9 Built Test Track with Sensor Designed circuit for Photocell 7 Week 9 • Determined voltage thresholds for three states (nothing, coupler, train) • Coded program to measure and display voltages from circuit 8 Voltage Thresholds Nothing State: 0-0.28 V and 0.52-0.84V 9 Voltage Thresholds Coupler State: 0.28-0.52 V 10 Voltage Thresholds Train State: 0.84 to 5.00 V 11 Test Programs • Sensorx (working) – Program to test one photocell – Display on LCD – Used with test track • Sensor4x (working) – Program to test four photocells – Display voltages on LCD 12 Week 10-12 • Coded a basic program to send DCC signals to the train depending on the measured voltages from the sensor • Coded another program to measure values from four photocells 13 Test Programs • Autodecouple (not working) – Exclusively for Automatic Decoupling – Voltage from photocell circuit will change train speed • Decouple (semi-working) – Manual Decoupling Testing – Automatic Decoupling Testing 14 The Current Problem • Timing issues with DCC signals being sent to the train – Test program is sending signal too fast causing the Microcontroller to reset itself – The problem may lie in the previous year’s code used to create the DCC signals 15 Fixing the Problem • The timing contraints of DCC signals – ‘1’ bit has 58 us low and high time – ‘0’ bit has >95 us low and high • Use of Timer 2 to fix problem – Pro: Advanced timing features allow faster more efficient timing • Previous Code uses Timer 0 – Con: Time spent setting up Timer 16 Questions? The End 17