Subject: Re: I2C via parallel port?
To: Dan McMahill <>
From: John Clark <>
List: netbsd-users
Date: 08/18/2005 09:18:50
Dan McMahill wrote:

> Anyone have code they'd like to share which implements an I^2C host by 
> bit-banging of the parallel port?  For that matter, anyone know if the 
> parallel port drivers for i386 even support such a thing?  I'm wanting 
> to play around with a chip which needs to be programmed (via I^2C) to 
> get it to do anything.
> Thanks
> -Dan
I've not tried to implment a I2C line, but I have recently used the 
'standard' parallel interface to
perform 'general I/O'. In my case all I had to do was to set the BIOS up 
to allow the
interface to do the simplest 'bi-directional' setup. 'General' meaning 
here that one can set the port
to either output or input, not individual bits... However, there are 
some bits which allow for
both input and so one can have some 'bi-directionality' at the same time.

Here's a link for info on the varieties of parallel port configurations, and
details on such things as the availability of a Open Collector output, 
which I think
is needed for I2C.

John Clark