Webtrain Decoupling Adam Kadolph EE451 Bradley University Advisors: Dr. Irwin, Dr. Schertz Design Review Presentation - Week 12 Tuesday 3/6

2 Outline Introduction Timeline Weeks 8-12 –Sensor –Test Programs –Automatic Decoupling The Current Problem

3 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

4 Timeline

5 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

6 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

7 Week 9 Built Test Track with Sensor Designed circuit for Photocell

8 Week 9 Determined voltage thresholds for three states (nothing, coupler, train) Coded program to measure and display voltages from circuit

9 Voltage Thresholds Nothing State: V and V

10 Voltage Thresholds Coupler State: V

11 Voltage Thresholds Train State: 0.84 to 5.00 V

12 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

13 Week 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

14 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

15 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

16 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

17 Questions? The End