Updated Oct. 13, 2003
Counters and PALs : Flip flops will do our bidding.
EE481 Logical Design Lab
Fall 2003, Lab #6
- Write PAL Language source code (for PALASM compiler) that
implements 7-segment BCD driver for Common Anode display (e.g. a "0"
turns on the display).
- Calculate drop-resistor value for a 7-segment LED display, using
LED specs given in ealier labs.
- Crudely estimate the power consumption of a mod-8 counter
including
7-segment LED display driver implemented with TTL flip-flops and the
LED display driver (exclude the actual current consumed by the LED
display). Crudely estimate how many wires do you need to wire this
circuit?
- Design and implement the following circuit using a provided
PAL/PLD
device (PLD,PDF data file for 22v10). (Use
drop resistors in series with the display.)
- Count the total number of wires used for this PAL design.
- Measure the average current that the PAL uses without having the
LEDs connected and compare to your calculated estimate of the discrete
logic design.
- Are there any cost savings in using PAL over discrete logic
gates? (Assume that a PAL chip costs $4.00 and all TTL logic chips
costs $0.50.
You can also assume that 1 square inch of a PCB costs $1.00.)
- Would you choose to use PALs if you were a designer? If you were
an
accountant worried about product costs, what would you choose?
This question is tricker than you think.
EE481