Microprocessor: MC68HC11

1. Oct 5, 2011

phsyics_197

1. The problem statement, all variables and given/known data

Write a program that shifts two 1's from left to right and back as output of Ports C & B
by sending the patterns shown below to PORTC & PORTB in the following order: Pattern 1,
2, 3, 4, 5, 6, 7, 8, 7, 6, 5, 4, 3, 2, 1, 2, 3, ... and repeat the cycle indefinitely.

2. Relevant equations

3. The attempt at a solution

When the program is run, the LED's should look like:

PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0
Pattern 1: ( )( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( )
Pattern 2: ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) (O) (O) ( ) ( ) ( ) ( ) ( ) ( )
Pattern 3: ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( )
Pattern 4: ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( )
Pattern 5: ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( )
Pattern 6: ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( )
Pattern 7: ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( )
Pattern 8: (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O)

I am having trouble with creating this program because I do not fully understand how it works. I was wondering if someone could at least help me out with a "Flow chart" by explaining step-by-step instructions, and then from there, maybe, I could actually write the program.

Thanks.

2. Oct 5, 2011

lewando

Your program will generate data that will drive the port pins of the two 8-bit data ports (B and C) as specified in your question, resulting in an "animation" of the LED array.

This assignment is mildly cool, so I hope you figure it out.

Maybe the alignment is confusing you so I straightened it out:

I take it "(O)" means the LED is on and that this happens when a "1" is written to the corresponding port pin.

Code (Text):
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0
Pattern 1: ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( )
Pattern 2: ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) (O) (O) ( ) ( ) ( ) ( ) ( ) ( )
Pattern 3: ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( )
Pattern 4: ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( )
Pattern 5: ( ) ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( ) ( )
Pattern 6: ( ) ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( ) ( )
Pattern 7: ( ) (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O) ( )
Pattern 8: (O) (O) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) (O) (O)