This assignment is worth 60% of the "exercises and labs" component of the course. You must do this assignment either individually or in groups of two - anybody found copying will fail CEG2400.

Start early, make sure you understand what you are doing and make sure you leave yourself plenty of time to debug your system! Elegant designs using less hardware and/or simpler software will be rewarded with higher marks. You should refer to the WWW site http://www.national.com/ for LM35 and ADC0804 data sheets.

The assignment will be to develop the hardware and software to implement a digital thermometer. The IBM-PC will be used as a CPU and you will design a prototype board which plugs into the IBM-PC and has the following peripherals using the I/O space starting at 300h

• an ADC0804 analogue to digital converter which is used to convert the output of a LM35 temperature sensor chip to a digital value (for data sheets, see
• a 8253 timer chip which generates the timing for the stopwatch by generating an interrupt to the CPU every 5 seconds (your program MUST be interrupt driven and not polled)

Accompanying software which makes use of your hardware to implement a stopwatch must be written entirely in 8088 assembly language.

There are 3 milestones to this assignment and late penalties will be 15% per day. No extensions to any of these milestones will be given and demonstrations can only be done during scheduled lab times.

1. (20%) Schematic diagram, circuit description and flowchart of the software for your design, maximum 10 pages (you will probably need to update your design as you discover limitations and bugs in your design, but just do the best you can for now). Your thermometer should be capable of reading temperatures from 0 to 128 degrees centigrade. The software should simply print out the temperature in degrees celcius every 5 seconds. One report is required per group and you must keep the same partner for the other two parts of the project. Due Wed 18th March.
2. (20%) Demonstrate to the tutor that you have constructed your printed circuit board and can get logic analyzer traces of I/O read and write cycles to your board. You don’t need to have any software working to demonstrate this milestone. Due Wed 1st April.
3. (60%) Demonstration of working digital thermometer project. If you don’t get it working you should demonstrate what you have and explain the problems encountered At the same time you should submit your board, a 4 page description of how the hardware and software of the final design works and a program listing (also email the source file with the subject line being your student number to "kslee"). Due Wed 15th April.