(Click to enlarge)
Although our motor driver circuit can drive fairly large motors, it can only drive them in one direction. If our application requires bidirectional drive, we will need a more sophisticated circuit, such as the H-bridge. Fortunately, complete H-bridge circuits are available in a single, easy to use chip, so building an improved motor driver shouldn't be too difficult.
Design and layout a motor driver module that will replace the one used in the previous section of this exercise. Your design should utilize the Rohm BD6621 H-bridge driver chip. It should use the same form factor as the existing board and connect to the CPU module using the same interface. You need not provide current monitoring, nor the two SMB connectors which interface to the potentiometer and the scope. The function of the SMB connectors will be provided by the new SMB feedthru module. You do not need to provide for external power, use the +15 V breadboard supply (which will be set to 7.5 V). A board outline file (BRD2x1d.brd) is available in this week's zip file. You should provide for mounting a Pololu Micro Metal Gearmotor on the left hand side of the board, with the shaft overhanging the edge, as shown in the photograph below:
As was the case for Exercise 3, the instructor will fabricate your board (you'll start fabricating your own in the next exercise). Again, as with Exercise 3, there will be two due dates: You should deliver your completed layout to the instructor by Friday, October 2. Your writeup will be due the following Friday, October 9.