Parallel port problems

[Guest]

Archived from groups: alt.comp.hardware.homebuilt (More info?)

I have a 603TCF 1 Ghz Motherboard that has an onboard parallel port and I
also have an additional Siig second parallel port with a PCI connector.
The problem I am having is that both the onboard and pci parallel port logic
low is 1.7VDc. Logic high is 4.2VDC. Then 1.7V logic low is causing me a
problem when trying to interface it with a TTL compatible device.The logic
low should be much less.
Any idea's of how to fix this problem?
TIA
Dan

 

[Guest]

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Mon, 24 May 2004 06:37:15 -0700, "Dan Mauch" <dmauch@seanet.com> wrote:

>I have a 603TCF 1 Ghz Motherboard that has an onboard parallel port and I
>also have an additional Siig second parallel port with a PCI connector.
>The problem I am having is that both the onboard and pci parallel port logic
>low is 1.7VDc. Logic high is 4.2VDC. Then 1.7V logic low is causing me a
>problem when trying to interface it with a TTL compatible device.The logic
>low should be much less.
>Any idea's of how to fix this problem?
>TIA
>Dan
>

Use a POT to pull the line a little further down (to ground) to a level
where the device is operational?

 

[Guest]

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Mon, 24 May 2004 06:37:15 -0700, "Dan Mauch" <dmauch@seanet.com>
put finger to keyboard and composed:

>I have a 603TCF 1 Ghz Motherboard that has an onboard parallel port and I
>also have an additional Siig second parallel port with a PCI connector.
>The problem I am having is that both the onboard and pci parallel port logic
>low is 1.7VDc. Logic high is 4.2VDC. Then 1.7V logic low is causing me a
>problem when trying to interface it with a TTL compatible device.The logic
>low should be much less.
>Any idea's of how to fix this problem?
>TIA
>Dan

AFAIK, the outputs should be TTL compatible, but try 4K7 pullup
resistors on each of the data lines just in case they aren't. Can you
identify the multi-IO chip(s)? Perhaps a datasheet may offer a
solution, or at least an explanation. BTW, were your voltage
measurements taken with your device connected or not connected?

FWIW, I found this URL to be a useful primer:
http://www.beyondlogic.org/spp/parallel.htm


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.