Breaking down 32 output's into 4 separate ports

Brian_B · 2008-07-29 01:23

Hi,
·I've been playing around with a keyboard scan routine for some time now . Say you break up the 32 outputs into 4 separate sections , say 0..7 port one,· 8..15 port two, ect . I'm trying to make out0 high then shift left to out1 , I don't want to go any further than out7 and I want to start over again.

·I have experimented with using TEST , CMP and MAX·but It's seems like I end up with alot of extra code. Is there a simple way to JMP back to out0 after shift left reaches out7 ?

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Thank's Brian

·"Imagination is more important than knowledge..." ·· Albert Einstein

www.PropelX.com

www.NorthStarMachining.com

sstandfast · 2008-07-29 01:33

Let me see if I understand exactally what you want to do. You want to count 0, 1, 2, 4, 8, 16, 32, 64, 128 and then back to 0 or back to 1? I also assume that you do not want your operations to effect the other three ports correct? A little more information please.

Shawn

Brian_B · 2008-07-29 02:24

Yes, 1 of the eight pins is "on" at any given time . %00000001 ,%00000010, %00000100 ,ect. Here is a modified version of one of Beau's sample programs that I'm using it·to test the results on a video screen. This version has a little bug, It hanges on bit 7 twice as long as the others.

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Thank's Brian

·"Imagination is more important than knowledge..." ·· Albert Einstein

www.PropelX.com

www.NorthStarMachining.com

Post Edited (Brian Beckius) : 7/29/2008 2:30:18 AM GMT

Beau Schwabe · 2008-07-29 05:42

Brian Beckius,

I just·tested this with the demo board LED's, and it appears to do what I think you want it to do.

CON
  _clkmode = xtal1 +pll16x
  _xinfreq =  5_000_000
PUB Shift_Test
    cognew(@ShiftTest, 0) 
    repeat
 
DAT
              org       0
ShiftTest
              mov       LEDs_OUT,               #%00000001
              shl       LEDs_OUT,               #16
              mov       LEDs_DIR,               #%11111111
              shl       LEDs_DIR,               #16
              mov       dira,                   LEDs_DIR

              mov       time,                   cnt
              add       time,                   delay
MainLoop
              waitcnt   time,                   delay
 
              cmp       LEDs_OUT,               Limit   wc
       if_c   shl       LEDs_OUT,               #1
       if_nc  shr       LEDs_OUT,               #7
 
              mov       outa,                   LEDs_OUT
 
              jmp       #MainLoop                    
 
Limit         long      %00000000_10000000_00000000_00000000
delay         long      40_000_000
 
LEDs_OUT      res       1
LEDs_DIR      res       1
time          res       1

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Brian_B · 2008-07-29 12:30

Perfect Beau !
Now that opens the door up to having cog1 shifting 0..7 cog2 shifting 8..15 ,cog3 shifting 16..23 and cog4 shifting 24..31 ( I don't need the code for that, now that you have me over the hump).

Is adding delay to the time just to be safe ? I see in a lot of sample programs that only add $FF to the time.

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Thank's Brian

·"Imagination is more important than knowledge..." ·· Albert Einstein

www.PropelX.com

www.NorthStarMachining.com

Breaking down 32 output's into 4 separate ports

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