Thread: Port Power (almost finished now)

mmm....well my circuit finally completely works...ive got the 8 data pins on the 25-pin connector wired up to the 8 pins of the LCD im using....ive got the 25th pin (which is grounde) wired up to the cathode pin on the LCD....now when I plug it in to the parallel port, they all immediately light up....

Code:

outportb(0x378,0x28);

I thought by using this code, I'd be sending the hex value of 28 to the LCD...the hex value of 28 in binary is of course: 00101000. I figure this would go like this

Code:

2^0 - 1st Data Pin -       0
2^1 - 2nd Data Pin -      0
2^2 - 3rd Data Pin -       0
2^3 - 4th Data Pin -       1
2^4 - 5th Data Pin -       0
2^6 - 6th Data Pin -       1
2^7 - 7th Data Pin -       0
2^8 - 8th Data Pin -       0

(that's not really code, just what would get sent to each pin I think). A 1 would supply the current to light up that part of the LCD, and the 0's would do nothing.


Anyone know why it's already lighting up? Am I using the outportb(0x378,0x28) command right....will that do what I think it is?

Also could the problem be the cable I'm using? I think it's an odd one....it's a 25 pin Male/Male but it says Direct Cable Connection (PC-to-PC File Transfer) ....on the back it says it CAN'T be used with switchboxes...it's only made for PC-PC file transfer..should this cable work, or is this the possible cause of my problem? Thanks.

> Also could the problem be the cable I'm using?
Yes - those kinds of pc-to-pc cables look like this

Code:

Tx----   ------Tx
      \ /
       X
      / \
Rx----   ------Rx

The bits which you think are being sent out are being mixed by the cross-over (and some of them won't even make it)

You need a simple cable which just joins pin1 to pin1, pin2 to pin2 etc.

Mmm, maybe this will help
http://vv.carleton.ca/~neil/lpt/