T120     09 0305

IC03-50 Stepper Motor and Two Limit Switches, Part 2
40 points
OEET 120

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  1. Construct the circuit of IB26-18 on a relay board.
    • Draw lines on a relay board schematic.
    • Make a wire list, including wire colors
    • Wire up a relay board, using pushbuttons in place of the limit switches.
    • NO WIRING JUNGLES! Have your wires lying down flat, and don't use wires that are more than an inch or two longer than necessary.
    • Have very little, if any, bare wire showing.
  2. Get the circuit working.
  3. If a mock-up unit is available, connect your circuit to the microswitches on it. (The microswitches will replace the pushbuttons.) Then, get it to work.
  4. If a mock-up is not available (or if you have already connected your circuit to one) connect wires from the CW, CCW, and GND signals on the relay board to the ribbon cable from the microcontroller board (that's part of the circuit you constructed in IB26-19). 
    • You will need to first remove the 4-switch board from the circuit.
  5. Connect the wires from the stepper motor on the mock-up unit to the power transistors on the breadboard.
  6. When the lever attached to the motor hits one of the microswitches, the motor should automatically reverse and then run until it hits the other microswitch. It should then keep going back and forth like a windshield wiper.
    • If the motor does not reverse directions when it hits a microswitch, try swapping the CW and CCW wires.
  7. Try speeding up the motor by turning on some of the right three switches next to the group of five LEDs on the microcontroller board.
    • If the three switches are all off (LEDs off), the motor will be running at the slowest speed.
    • If the three switches are all on (LEDs on), the motor will be running at the fastest speed.
    • To increase the speed gradually, follow this sequence: 000, 001, 010, 011, 100, 101, 110, 111, where 1 means "on" and 0 means "off."

 
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