We expect most EE445L students to power their system with one battery and a 33V

We expect most ee445l students to power their system

This preview shows page 2 - 4 out of 7 pages.

We expect most EE445L students to power their system with one battery and a 3.3V regulator, but you are free to design the system at any voltage that works. Preparation (do this before your lab period) 1. Choose for which of the 3 previous labs you want to design your PCB. Decide which microcontroller you want to use. You are free to use any microcontroller you want, however we expect most EE445L students will choose the LM3S811 in a 48-pin LQFP package. If you want to choose a different microcontroller than this, please get approval from your TA. You will find three LM3S chips in the EE345L library for PCB Artist. The specific part number most students will use is the LM3S811. As an option for Labs 8, 9 and 11, we have LM3S811 parts to distribute to students. You will begin by downloading the Lab6_artistStarter.sch and Lab6_artistStarter.pcb files, changing the file names, leaving the Lab6 , but adding your names, e.g., Lab6_Valvano_Bard. The SCH and PCB files are connected, so they need the same name, but different extensions. Next, you make a copy of the SCH file for your lab solution. Then, you delete the existing LM3S1968 component and all the nets that connect the LM3S1968 to your circuit (essentially editing the copy of your lab solution SCH). Next, you copy the circuit from your lab solution into the renamed Lab6 starter SCH file. Pay careful attention that all the +3.3V connections are one net, and all the ground connections are one net. You must reconnect the I/O pins to reestablish the functionality of the lab. You may add other hardware beyond what was needed for the lab if you choose, but it is not necessary to add more I/O functionality. You will have to add some switches to provide user input (switches on the PCB use part B4F-1050, for off board switches use part OffBoardSwitch) . Watch this 7½ minute movie 2. As part of Labs 3, 4, and 5, you measured the supply current required to run your system. Choose a battery that will power your system for at least 24 hours. For the stepper motor system, you can run your system for 4 hours instead of 24 if you want. For example, if your system draws 50 mA, then a 1200 mAh battery will operate 24 hours between charges. Go to a battery manufacturer (like ) and select a Li-ion or Li-poly battery pack to run your system. You will need to know its dimensions, weight, cost, and energy storage capacity. To get the price, you can search a retailer (like ) or a search engine like Google. It is not necessary, but just for fun, look at Figure 1 of the data sheet for the MAX1873; it shows a charging circuit that would allow you to charge your Li-ion battery. If you were to place this circuit on your PCB, then you could simply plug your system into a charging station without needing to disconnect the battery from the box. Lab 6 does not require an on-board charging circuit.
Image of page 2