D&B Change History

Change Date	Description
12-30-2006	Updated hardware schematics. Reorganized and consolidated propeller I/O pin usage. Moved grade crossing LED's to I/O pins to facilitate direct pulse width modulation by propeller chip.
12-06-2006	Added schematics and descriptions for propeller based hardware.
11-29-2006	Added pages for Parallax Propeller based redesign of the control electronics. Added software flow charts for Propeller code.
11-11-2006	Converted web pages to non-frame fromat in preparation for next phase of project.
2-03-2006	Added two photos to Photos Page 5. Added ten photos to Photos Page 6.
12-15-2005	Updated semaphore code to move arm at a more prototypical rate.
12-11-2005	Added video clips to the "Ride The D&B" page.
12-07-2005	Added a new clip to the "Ride The D&B" page. Also added "Boil That Cabbage Down" by the Smothers Brothers; railroad pretzels and vicious puma's.
11-24-2005	Added a new page; "Ride The D&B". This page contains video clips that were created using a wireless video camera mounted on a flat car.
5-03-2005	Added the turntable version 2 updates. Version 2 includes changes to the hardware and electrical design. Software changes include code optimizations, the use of 8x micro-stepping, and adjustments to timing constants. Additional code description text was also added.
4-27-2005	Added video clips to the Turntable and Video Clips pages.
4-23-2005	Added link in index to video clips page.
4-18-2005	Added video clips to grade crossing page.
4-16-2005	Updated the grade crossing code and description pages with version 2 of the program code. Added a flow chart of the train detection logic.
3-06-2005	Added some progress pictures of the backdrop to Photos Page 5.
9-05-2004	Updated More Photos Pages. Rearranged and added pictures of El Capitan.
8-15-2004	New progress photos added to More Photos Page5.
6-19-2004	New progress photos added to More Photos Page4 and Page5. Added links to mirror server. Non 24 hour uptime for now but no advertising banners or bandwidth limitations.
6-16-2004	General html updates to improve performance and correction of broken links.
3-28-2004	Added More Photos page 4.
2-16-2004	Code correction and new functionality added to the Turntable code. Included a gear backlash movement into the initial home sensor find operation. This results in more consistent turntable bridge positioning from session to session. The turntable bridge can now be randomly positioned if no commanded activity has been performed for a user specified time interval. To enable this feature, the RandomMove constant must be set to a non-zero value. An initial automatic move to a turntable bridge position at power up can now specified. To enable this feature, the InitPos and InitEnd constants must be set to non-zero values.
2-07-2004	Minor updated to the mainline code. Added functionality to alternate usage of the Block1 and Block2 holdover tracks when neither are occupied.
12-20-2003	Updated turntable code and description. New command for re-indexing the turntabe to the home position sensor in operate mode. Added code to position the turntable to track one on power up following home sensor seek operation.
10-21-2003	Added turntable page and pictures.
10-20-2003	Updated turntable schematic. Changed RC1 and RC2 resistors from 56k to 39k to eliminate motor step "chirping".
10-09-2003	Added turntable hardware description page.
10-05-2003	Added turntable control schematic. Added October pictures to More Photos Page 3.
9-28-2003	Added turntable and associated tracks to track plan.
9-11-2003	Added pictures to the 'Grade Grossing' and 'More Photos Page 3' pages. Crossing gates now operational. GradeCrossing.zip, code, and description pages updated to reflect operational code.
8-15-2003	Updated block signal code. Added code to maintain semaphore servo position during long periods of inactivity. Updated grade crossing page, broke up more photos page into multiple pages, and added pictures of grade crossing.
8-08-2003	Updated block signal code, block detector schematic, and block detector hardware description. Changed block detector circuit to a voltage doubler design to improve sensitivity. Optimized block signal code to reduce program size and improve performance.
8-04-2003	Updated block signal schematic. Added alternate circuit for balancing red/green Led intensity using two diodes and a variable resistor.
7-31-2003	Updated mainline code and schematic. Sensors were added to detect train position on hidden hold over tracks. Code was added to illuminate panel indicators based upon sensor input. Removed midway siding code that was added for automatic handling of an occupied siding. Automatic functions interfered with manually entered turnout positioning.
7-29-2003	Updated block signal code. Added code to the signal color setting logic to ensure proper color priority; red (highest), yellow, and green (lowest) are displayed. Updated mainline code. Added logic to set the midway siding turnouts properly if the primary siding route is occupied. Updated yard route code. Reduced storage size of turnout addresses from WORD to BYTE to reduce overall code size.
7-23-2003	Updated block signal code and associated schematic. Signal L8 is now a semaphore signal and uses a R/C servo to position the semaphore arm. Added pictures to 'Block Signal' page and 'More Photos' page.
7-15-2003	Updated block signal code and associated schematic to show the use of diodes for yellow signal color adjustment.
7-07-2003	Updated grade crossing code. Refined time values and added code to stop signal for stationary train.
6-20-2003	Updated block detector schematic. Added missing resistor and updated notes on page.
6-15-2003	Updated grade crossing code, hardware and software description pages, and schematic. Updated GradeCrossing.zip file with new code. Added pictures to More Photos page.
6-10-2003	Updated grade crossing code and description pages. Updated GradeCrossing.zip file with new code. Updated grade crossing schematic and hardware description.
6-06-2003	Added functionality to grade crossing code for R/C servo control of gates. Updated code and description pages. Updated GradeCrossing.zip file with new code.
6-05-2003	Added functionality to grade crossing code to produce a gradual on/off effect for signal lamp Led's. Updated code and description pages. Updated GradeCrossing.zip file with new code.
6-02-2003	Added block signal hardware description. Updated block signal page; added pictures and logic table.
5-29-2003	Updated block signal code and code description.
5-25-2003	Updated grade crossing related information. Added disclaimer to initial page.
5-18-2003	Added thumbnails to "MorePhotos" page. Added 7 photos.
5-15-2003	Initiated change history page. Added yard hardware description page and added link in schematic section of index.