Week 7

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This work is not required before midterm break. If you would like to get ahead, this is what you should be working on.

  1. After your computer is working on the Vector Board you should add a 74LS244 buffer. 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. After the buffer wiring is complete, test your computer by plugging it in to the STANDARD BOARD. The STANDARD BOARD ALLOWS YOU TO VERIFY THAT YOUR COMPUTER WORKS PROPERLY WITH THE TEST-STAND CIRCUITS. With the ECHO program running on your computer, test both bar-code readers (do this by sending a train with a bar-code past the sensor -- if the bar-code is recognized the signal light should automatically turn to red). Test both clear sensors (send a train with a reflector at clear sensor height past the clear sensor -- the red signal light should change back to orange or green). Test both RR signal heads (this should have already been done in the previous tests -- the lights should change from green to red for ECHO version 2.0 or from orange to red for ECHO versions 3.0 and 3.1, when the train is recognized by the bar-code). Test both track-kill relays (when the signal is red the relay should open so that another train will stop at the signal light -- when the signal clears the train will automatically enter your board -- this concept of only 1 train per "block" as governed by signals is how many railroads operate). When you are finished with this step you may get a plywood project board and begin planning your term project.

  3. Congratulations, you have now finished the basic test stand computer. You may now start planning your term project.