Week 8

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1. Add 74LS244 buffers to your Vector board computer to allow use of the test-stand. The buffer is used to condition signal lines between port B of the VIA at A000 and the 44-pin edge connector. The STANDARD BOARD has a listing of the required connections. The wiring of the 74LS244 buffer is included in the "CIRCUITS" page on the MAE 412 web-site. Note that some of the lines from the VIA are outputs and some are inputs. Use this wiring as a model later when you need to buffer control and signal lines on and off your Vector board.


2. Modify the ECHO program v3.1 so that the NTRAIN mailbox is displayed in the left TIL 311 and the STRAIN mailbox is in the right TIL 311. The code for doing this will replace the 'LDA RDATA' line in the ECHO program. It is possible to display both NTRAIN and STRAIN values simultaneously because they are 4-bit numbers with values between 0 and F.
• To compress both mailboxes into one, try the following:
1. Load NTRAIN into the ACCUMULATOR
2. Shift the ACCUMULATOR left 4 positions using the ASL command
3. Use the ORA command with STRAIN to set the low 4-bits of the ACCUMULATOR
4. Store the ACCUMULATOR to location the displays
• Make sure you change the computer number in the code as described on the "PROGRAMS" page. Burn this modified program in an EEPROM. Also burn the original ECHO (v3.1) program in another EEPROM. You will use both programs to test the test-stand.


3. Check that your computer supports all test-stand operations. If things are working properly the signal lights on the test-stand will change as trains enter and leave each block. If the ECHO Program is running, you may send data to your computer. If the Bar-Code Test Program is running, the number of the train occupying each block will be seen on the appropriate TIL 311 display. Don't forget to test the relays on the test-stand which should automatically kill power to the entrance track while the block is occupied. When the relay works properly, a second train will appear to wait for the signal light to change from red before entering the block.


4. Begin working with the AnyRail or the Right Track Software (on the desktop). This CAD package is located in the MAE412 folder on your desktop. The AnyRail software is more user friendly than the RTS software. The RTS software is a little crude, but it is still very useful in helping to plan your project. Remember that the minimum radius for track on the main line is 9.75 inches. Also remember that you must include the central (bi-directional) track. If you add a crossing between the mainline and the central track you will need to provide an interlocking to prevent possible collisions between trains on the central track and those on the mainline. (You cannot specify that the central track is not to be used -- it would defeat the modularity objective as discussed in the NTRAK materials in volume 1 of the on-line manual.)
• When you first open AnyRail, open any one of the "Standard Board ____.any" files from your MAE412 folder. Save a new copy of this diagram and use it as the basis for your project design.
• Click on the Track libraries tab, then click on Atlas, then N Atlas Code 80 to bring up the library of parts. Flex track is part 2500 and can be used for long straights are odd bends.
• Tutorials on how to use this software can be found within the help menu.
• When you first open RTS, a diagram of the basic test stand will appear. Save a new copy of this diagram and use it as the basis for your project design.
• Tutorials on how to use this software can be found within the help menu.


5. Document your vector board computer using Eagle or ORCAD. This is required for the final report.