How do I setup DIRA when pins are scattard around?

xsmoker

I need to have pins that are not grouped together set as output for a byte. I need P9,10,11,15,24,25,28,29 set with DIRA command with P9 the lowbit. How would I use the DIRA command with staggard pins?

Thanks,

X

Mike Green

You can't do it directly. You'll have to shift the bits into position and use XOR (^) if you want to change all the bits at the same time. Since you sound like you want to just set them for output, you can just use a logical OR (|) with a constant like:

DIRA |= %00_11_00_11_00000000_1_000_111_000000000

xsmoker

Thanks Mike, One more ??

Ok, that works for DIRA, but how about for OUTA? How do I get data from a variable out to these pins? Unfortunately I'm using all the pins so I can't just group them together.

In other words, I can't use:

outa[noparse][[/noparse]29,28,25,24,15,11,10,9]:= data

Post Edited (xsmoker) : 4/4/2008 5:12:22 AM GMT

Mike Green

Like I said, you'll have to shift the bits into position in a 32 bit value. You should extract the "current" value in OUTA using the bitmask above and XOR it with the new bits. Take that result and XOR it with OUTA. You can do this all in one statement if you want.

If an OUTA bit is 1 and you want to change it to 0, OUTA = OLD ^ (OLD ^ NEW) = 1 ^ (1 ^ 0) = 0

If an OUTA bit is 0 and you want to change it to 1, OUTA = OLD ^ (OLD ^ NEW) = 0 ^ (0 ^ 1) = 1

If an OUTA bit is 1 and it's to be left unchanged, OUTA = OLD ^ (OLD ^ NEW) = 1 ^ (1 ^ 1) = 1

If an OUTA bit is 0 and it's to be left unchanged, OUTA = OLD ^ (OLD ^ NEW) = 0 ^ (0 ^ 0) = 0

See if you can work out the Spin statement for the whole thing.