Name (Last, First)
UNIVERSITY OF CALIFORNIA
College of Engineering
Electrical Engineering and Computer Sciences Department
EECS 145M: Microcomputer Interfacing Laboratory
Spring Midterm #2
Monday, April 21, 1997
•Closed book- calculators OK
•Many equations are listed at the back of the exam
•You must show your work to get full credit
PROBLEM 1 (50 points)
Design a computer controlled system for the automatic testing of 12-bit A/D converters.
You are provided with the following:
•A microcomputer equipped with a 16-bit parallel input port, and a 16-bit parallel output port.
•A 16-bit D/A converter with ±1 LSB absolute accuracy.
You may assume the following:
•The 16-bit parallel output port is in “transparent” mode. A 16-bit word A written to the output
port using the command outport(1, A) immediately appears on the output lines.
•The 16-bit parallel input port requires a low-to-high edge on a “strobe” input line for external
data to be latched onto the 16 bit registers. The program can read these registers using the
command B = inport(1).
•The parallel input port has an “input data available” line that can be asserted high or low by an
external device and read by the program using the command C = inport(2).
•The parallel input port has an external “ready for input data” line that can be set high using the
program command outport(2,1), and set low using outport(2,0).
•The A/D converter requires a “start conversion” low-to-high signal and after conversion
provides a “data ready” low-to-high signal that goes low when “start conversion” goes low.
•The A/D reference voltages are Vref– = 0.0000 V and Vref+ = 4.095 V
•The D/A reference voltages are Vref– = 0.0000 V and Vref+ = 4.096 V
EECS145M 1997 Midterm #2 Page 1 Derenzo
