EE 476: Homework 1

1. Read all of Lab 1. You should come to lab with a good first draft of the code assignment, but the code is not part of this homework.
2. Reading from the schematics in the hardware description, determine:
   1. if the LEDs are lit when a logic high or low is applied to the connector.
   2. if the switches outputs are logic high or low when pushed.
3. List all jumpers which should be installed for the first lab assignment and describe why you need each one. Assume that the 8515 operates at Vcc=5 volts.
4. Estimate the Thevinin equvalent output resistance of an i/o pin from the AT90S8515 data sheet. There will be two separate estimates corresponding to whether the output is logic-high or logic-low.
5. Assuming that an LED has a turn-on voltage of about 1.5 volts, and draws about 20 millamps, how many LEDs can you operate from 8515 i/o ports before exceeding the chip rating.