UCR CS122A
Prof. Frank Vahid
Homework 4

Working in groups is encouraged. 5% extra credit for groups of 3 or
more working together for an hour or more. Write down each others'
names, and when/where you met. Every student should still solve
every problem and submit his/her own solutions; working together is 
useful to understand the problems, discussion solution ideas,
and compare answers. Each problem is worth 1 point, except for
problem 2, which is worth 3 points.

1. Provide a summary, in 150 or less of your own words, of the key 
   points of Gelsinger's DAC 2004 keynote talk. Assume your readers
   to be fellow engineers at your company, who want to learn the main 
   lessons of the talk in a short, concise, easy to understand summary. 

2. Design a proportional closed-loop controller of a water heater. The 
   heater has an actuator that can be set from
   0 to 100 to control the heater's flame (0 means no flame, 100 means
   full flame). The heater has an output T indicating the present
   water temperature. The controller has an input R indicating the
   desired temperature. 

   Implement the controller on a microcontroller, having
   8-bit ports P0, P1, P2 and P3 available. Don't assume any
   external error detector (no external subtractor) -- just the
   microcontroller and the water heater itself with an actuator.

   (a) Draw a block diagram of the system.

   (b) Implement a proportional controller of the system. Included in
       your code should be the error detection (don't assume an external
       subtractor). You must decide on the constant to be used in
       your proportional controller. A good control designer would use
       physics equations to model the water's reaction to the flame,
       and then analytically derive a good constant. Assuming we don't 
       have such equations, we might instead run experiments and tune the
       constant according to the water response we see. Provide a sample 
       of such experiments -- you can create and draw your own "sample" 
       responses to different constants. 

3. Explain the intuition of the P, I and D terms in a PID controller,
   including how each influences the system response. Include figures
   in your explanation. Use 150 words or less for each term (P, I and D). 

4. Explain how Moore's Law results in low-cost low-end chips, rather
   than the well-known higher-performance chips. 

5. Using 150 or less of your own words, define a wireless sensor network.

6. Describe two examples of useful applications of sensor networks proposed
   by companies or research groups.  Be sure to reference your sources.

7. Design an eBlock system to implement a system that turns on a light
   outside of a building after you *leave* the building. There is a motion
   sensor *inside* the building. As long as motion is detected, the
   light should stay off. As soon as motion is not detected, the
   light should turn on for 10 seconds.  You may select from the
   following blocks: motion sensor, combine (logic), toggle, 
   once-yes-stays-yes, prolonger (adjustable from 1-10 seconds), 
   pulse generator (adjustable 1-10 seconds high, 1-10 seconds low),
   and electric relay.


8. Extend the previous example to allow a yes/no switch inside the
   building. When set to yes, the light stays on. When set to no,
   the light only turns on as in the previous problem (for 10
   seconds when changing from motion to no motion). You may use
   a yes/no block.

9. Extend the example even further so that the light can be forced
   off by a second yes/no switch inside.

10. Write VHDL code for an FPGA to generate an output pulse with a 100 ms
    high time and 900 ms low time. Assume the FPGA has a 1 MHz clock input.