Introduction:
You work for the ACME Weather Co. and one of your valued customers has asked you to design a new quick-view weather station (QWS). The new QWS will provide current information on weather conditions using only 10 LEDs. This will allow the customer to get a "quick view" of the weather conditions before determining what weather conditions need to be further analyzed.
The QWS receives digital signals from the outdoor weather sensors and processes (or decodes) those digital signals. Depending on the states of the sensors (0's & 1's), the QWS displays the current conditions on the weather indicator display. There are 4 types of sensors that will provide signals to the QWS: the temperature sensor, the barometric pressure sensor, the wind speed sensor, and the wind direction sensor. The signals from the sensors are digital with +5V = 1 and 0V = 0. The wind direction sensor provides 3 bits of information, the temperature and barometric pressure sensors each provide 2 bits of information, and the wind speed sensor provides 1 bit of information.
Prelab:
Your completed prelab is due at the beginning of lecture on the day of your lab period. Use the following Boolean variables for your design:
Step 1 - Using the Boolean variables as defined in the tables above, develop the truth tables necessary to describe the relationship between the inputs to the QWS and the outputs to the LEDs. Use the appropriate truth table templates posted to Blackboard in the folder for this lab. In your truth table, enter a "0" to indicate LED = ON and a "1" to indicate LED = OFF.
HINTS:
- Blank truth tables with many rows and columns are provided. You may or may not need all the rows or columns!
- There are 10 LEDs, so make sure that you understand which LEDs are lit for each possible condition or possible conditions.
- Since there are multiple inputs and multiple outputs, consider whether it is simplest to combine all of the inputs and all of the outputs into a single truth table or if more than one truth table would simplify the design process. Carefully examine the dependencies between all of the inputs as well as whether an output is dependent on all the inputs.
Step 2 - Use Karnaugh maps to determine the minimized SOP boolean expressions for each of the 10 QWS LEDs. Use the appropriate 3 variable or 4 variable K-Map templates provided and record your answers on the SOP template provided; both are posted to Blackboard in the folder for this lab.
Step 3 - Determine the all-NAND equivalent of the minimized Boolean expressions for the QWS outputs. Use the all-NAND template as posted to Blackboard in the folder for this lab.
Your prelab results should consist of the following:
- Lab cover sheet
- Truth tables
- Karnaugh maps
- Resulting minimized SOP Boolean expressions
- All-NAND equivalent equations for the 10 QWS LEDs
Procedure:
Step 1 - Using the all-NAND equivalent equations as derived in your prelab, simulate your QWS design in Multisim.
If it is helpful to you, you may create a schematic on paper before inputting the design into Multisim, but it is not necessary for your lab write-up.
Hints for Multisim:
- The NAND and NOT gates needed for your circuit can be found under "Place- Component-Misc Digital-TIL".
- The LEDs needed can be found under "Place-Component-Diodes-LED". Choose single LEDs
- Use multiple pages in your schematic to help with debugging.
- Use net colors to tracking connectivity through your schematic.
Demonstrate your results to your instructor. Save a copy of your Multisim schematic to print out for your lab report.
Step 2 - Add IC identifiers and pin numbers to your gate-level schematic in preparation for building your circuit in hardware.
Step 3 - Build and test only the weather condition portion of your QWS design (the 6 LEDs representing temperature, pressure, and storm indicators).
If it is helpful to you, you may create a wiring diagram for your circuit, but it is not necessary for your lab write-up.
Demonstrate your results to your instructor.
Results:
Your lab report for this lab consists of the following and is due at the start of next week's lab period:
- Completed ELET215/CPET215 cover sheet with name and date lab performed.
A copy of the cover sheet can be found on Blackboard under Lab Content/Lab Reference Material.
- Completed prelab, including any corrections made to the prelab during the lab period.
- A complete printed schematic in Multisim. Each schematic page must include:
o Schematic title
o Name and date of lab procedure
o Neatly labeled appropriate Boolean expressions
o Inputs and outputs labeled so they can be easily recognized
o IC identifiers and pin numbers used in your hardware implementation
Attachment:- ELET215 - Weather.pdf