> Van: Pedro Barrios <barrios@nanofab.physics.tamu.edu>
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: 32 bit rotate
> Datum: dinsdag 9 juni 1998 20:59
>
> Hi everyone,
>
> I'm trying to find a way of displaying a message in a 5x7 LED
> array. Basically, I don't have a good idea of how this is
> usually done, but since I have worked a little bit with the
> 16C84, I thought I give it a try.
>
> I was thinking about having a message array 32 bits long by
> 5 bit wide containing the information I want to display. I would
> then take each one of the 32 bit words and rotate sequentially
> bit by bit and display the 7 most significant bits after each

And see a dark line every 8 leds (horizontal) ?  I would not do that.
Just shift every line (of 4 * 8 bits) one bit to the left. you could shift
the new data (one bit) in when shifting the right-most byte.  Repeat this
for every line.

> rotation. I would do this for each of the 5 rows of the LED display.
> I will appreciate any help on how I do this 32 bit rotation with
> the PIC, and also any suggestions or comments as of how messages
> can be displayed in LED display arrays with the PIC.
>
> Best Regards,
>
> Pedro

A 32-bit rotation (Left) :

movwf {data to shift in}
rrf {data to shift in}
rlf {line1+3}
rlf {line1+2}
rlf {line1+1}
rlf {line1+0}
rrf {data to shift in}
rlf {line2+3}
rlf {line2+2}
rlf {line2+1}
rlf {line2+0}

etc.

{data to shift in} contains 5 bit of data.  Bit 0 is the bit shifted into
line #1. Bit 1 is the bit shifted into line #2. etc etc etc.

{Line1+3} is the right-most byte to be displayed (bit 0 at the right-most
position, bit 7 at the left-most).

Greetz,
  Rudy Wieser

P.s.
  Need more info ?  Just tell me.