|
Experiment # 2 August 2006 |
EE 201P
Digital Electronics Laboratory II
| HOME | EXPERIMENTS | SCHEDULE | USEFUL LINKS | LAB QUIZZES | GRADES |
|
(a) Design of a combinational logic circuit.
(b) Implementation of the designed combinational logic circuit using minimum hardware.
Only for students with EVEN bench/table numbers
Four large tanks at a chemical plant contains different liquids being heated. Liquid-level sensors are being used to detect whenever the level in tank A or tank B raises above a predetermined level. Temperature sensors in tanks C and D detect when the temperature in either of these tanks drops below a prescribed temperature limit. Assume that the liquid-level sensor outputs A and B are LOW when the level is satisfactory and HIGH when the level is too high. Also, the temperature sensor outputs C and D are LOW when are temperature is satisfactory and HIGH when the temperature is too LOW. Design a logic circuit that will detect whenever the level in tank A or tank B is too high at the same time the temperature in either tank C or D is too low. The logic circuit should be implemented in the lab (but designed before arriving in the lab) and shown to the available instructor.
Only for students with ODD bench/table numbers
Following figure shows the intersection of a main highway with a secondary access road. Vehicle detection sensors are placed along lanes C and D (main road) and lanes A and B (access road). These sensor outputs are LOW (0) when no vehicle is present and HIGH (1) when a vehicle is present. The intersection traffic light is to be controlled according to the following logic.
1. The east-west (E-W) traffic lights will be green whenever both lanes C and D are occupied.
2. The E-W lights will be green whenever either C or D is occupied but lanes A and B are not both occupied.
3. The north-south (N-S) light will be green whenever both lanes A and B are occupied but C and D are not both occupied.
4. The N-S light will also be green when either A or B is occupied while C and D are both vacant.
5. The E-W light will be green when no vehicles are present.
Using the sensor outputs A, B, C, and D as inputs, design a logic circuit to control the traffic light. There should be two outputs, N-S and E-W, which go high when the corresponding light is to be green. Simplify the circuit as much as possible and show all steps. The logic circuit should be implemented in the lab (but designed before arriving in the lab) and shown to the available instructor.
III. Components Required
The required circuit(s) should be implemented as per problem statement using TTL ICs familiarized in previous experiments. All the product datasheets (pin diagrams) are available online and should be used to construct the circuit diagram. The LEDs and resistances (if required) can be used to display the logic output.
IV. Other Pre-Lab Exercises
(a) Compute the minimum value of resistor R when it is used as current limiting resistor for LED in a circuit when connected to Vcc supply of 5.0 V. Assume that the forward biased LED junction voltage is 1.2 V and the maximum current that LED can handle is 10 mA. To what would value you change the resistance if the LED is connected to a TTL chip such as 74LS00? You can use online data sheet for the second part.
(b) Realize two input NOR gate using a single 7400 chip.
(c) Realize a two input EX-OR gate using 7400 chip.
Please make sure that you have shown the result of your implementation to the lab instructor (or TA) and obtained his/her signature. The two partner's in each group must obtain the signatures and attach with the lab/experiment report.
