EE 476: Homework 3
- The keypad scanning routine given in Lab 3 uses a scheme where the upper
and lower nibbles of an i/o register are alternately used for input and output.
Figure out a way to scan a 4x4 keypad which drives the vertical wires as 4
output bits and reads the horizontal wires as inputs, with no i/o swapping.
Does either scheme have an advantage?
- Discuss how you will implement the required
Note that any scheme which involves reloading timer0 will not be accurate
enough. You must use timer1
Copyright Cornell University Jan 2004