Temperature Indicator

Design Challenge 3


In this challenge you will be asked to build and minimize a combinational circuit using K-Map that outputs a signal when temperature is in a specific range.

Before you begin, you should:
  • Have the Xilinx® ISE WebPACK™ installed.
  • Have your FPGA board set up.
  • Be able to describe digital circuits using logic operators.
  • Be able to write a test bench and simulate circuits using ISim.
  • Be able to derive a minimized logic expression from truth tables using K-Map.
After you're done, you should:
  • Be able to design a minimal digital circuit to implement required functionality.


Qty Description
1 Digilent® Nexys™4, Nexys™3, Nexys™2, or Basys™2 FPGA Board
1 Xilinx ISE Design Suite: WebPACK (14.6 Recommended)
1 Digilent Adept

Temperature Indicator

A digital thermometer produces a continuously varying voltage signal between 0V and 5V, where 0V represents 0 degrees and 5V represents 100 degrees. The thermometer outputs an 8-bit binary number proportional to the temperature—“00000000” represents 0 degrees and “11111111” represents 100 degrees. Each time the binary number is increased it represents a temperature rise of 100/256 degrees. Your challenge is to design a minimized logic circuit that outputs a logic high signal whenever the temperature is between 50 and 60 degrees. Use switches to emulate the thermometer output and an LED to indicate when the temperature is within the desired range. Write a test bench to simulate your design before implementing it on your board.

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