EE192: Mechatronics Design Lab

Checkpoint 4: PCB Schematic and layout

In preparation for printed circuit design, turn in complete schematic for all electronics you want on your PCB. This includes motor driver, and DC-DC buck converter. Include values, and part numbers. Note there is a breakout card, not the SMD package if using A4915 brushless driver. Also include connectors (marked clearly!), and mounting holes as needed for standoffs or heatsinks. You might have a battery cable wired to this board, or motors as well. These would need mounting holes for large gauge wire as well. It is recomended that copper traces not be added yet until you get feedback on schematic.

Checkpoint 4: motor from battery

This checkpoint is largely a simple extension of the previous one, except the motor must be powered from the battery. Like checkpoint 2, this is so you can dedicate time to finishing and iterating on your circuit boards designs.

Checkoff Procedure

Your motor should be properly attached to the chassis and must drive the wheels. Motor power must come from the battery and control signals must be generated by your microcontroller board running your code (single program). You may use the serial terminal to send manual control signals (like setting the motor duty cycle). You may continue to power the microcontroller board from the USB port as you won't have your DC/DC converters yet.

You will be quizzed to demonstrate how to use the battery. All power connection must be soldered properly. Your hardware should not be damaged (i.e. components should not catch fire) during any of these tests.

Demonstrate your motor driver circuit works and is safe running from your battery (in any order, instructor's choice):

Brushed motor (Using 11.1 LiPo battery)

• Full on (40% duty cycle)

• Full off (0% duty cycle)

• 15% duty cycle

• Full on (40% duty cycle) from complete stop

• Stall test at 25% duty cycle for 5 seconds

  • The intent is to ensure proper thermal design on your transistors and ensure your designs are safe under worst-case scenarios

  • You must disable any software overcurrent protections or cut-offs (worst-case scenario includes a software fault)

  • You may retain any hardware overcurrent protections or cut-offs, but permanent fusing is disallowed (I may decide to run this test first)

(Alternative checkoff option) Brushless motor user

For brushless motor user, you may power the motor with the bench power supply at 11V. However, you still will be quizzed to demonstrate how to use the battery. You may continue to power the microcontroller board from the USB port as you won't have your DC/DC converters yet.

Brushless motor (Using bench)

• Forward (25% duty cycle)

• Full off (0% duty cycle)

• Stall test at 10% duty cycle for 5 seconds