February 26, 1997 page 1 S. Derenzo
Solutions for Midterm #1 - EECS 145M Spring 1998
1a
Temperature sensor
12
"take data"
"data available"
Digital
output
port
Digital
input
port
Micro-
computer
temperature
1b
1The program outputs a one to the digital output port, which makes “take data” high
2The program starts a loop that continuously reads the 16 bits of data and exits when the
“output data available” line goes high.
3The temperature sensor detects a one on “take data”, senses the temperature, converts to into a
12-bit number
4The temperature sensor asserts the 12-bit number on the 12 output lines
5The temperature sensor makes the “output data available” line high
6The program detects the “output data available” signal, and exits the loop
7The program masks the 12-bit number from the 16 bit data
8The program makes “take data” low
9The sensor makes “output data available” low
[4 points off if the computer never reads “output data available”]
[2 points off if computer makes “take data” low before reading data]
1c Take data
Data valid No NoYes
Data available
Temperature sensed
and converted
Computer reads data
