Pin Assignments
Here are some useful links:
The Linux I/O port programming mini-HOWTO, including a section about timing issuers
tons of great parport documentation
ledblink, a unix command line tool if you attach LEDs to the parport.
mailblink, acutally the same as ledblink, but specialized to blink you mail count.
What I have attached right now to my parport is a switch to start / stop
playing my music collection, skip the current song or shut down the PC.
I can boot it without a monitor and use it as a music box, with one single
switch. (code is at svn://log2.ch/code/fernd)
Other ideas / things I did:
Here is an extract from a Mail by JimVela@aol.com:
At any rate, on to a quick summary. Here are some URLs that I've come across
in searching. First, here's a way to read and write to the parallel port
under Linux:
http://www.bitwizard.nl/par/index.html
With some work, this stuff could be used to read the status of various
switches attached to the input ports of the parallel port (or, similar
techniques could poll the serial port, although there are fewer readable
signal lines on serial)
Next, here's a spot on sunsite:
http://sunsite.unc.edu/pub/Linux/system/status/!INDEX.short.html
There is a whole bunch of software here to display status to LED and LCD
hardware attached to the parallel port. I will be experimenting with this,
and hope to be able to display load (CPU, or interface) on LEDs.
Next, check out this site:
http://ugrad-www.cs.colorado.edu/~boggs/pbus/pbus.html
These guys have actually been building a parallel BUS interface around the
parallel port. I'm especially intrigued by this because the colorado.edu (CU
Boulder) is about a 5 minute drive for me... I may drop some mail to these
guys to see if I can stop by and look around...
Also, I found this helpful:
http://www.jb.man.ac.uk/~dm/tech/linux_pport.html
One or more of the above may link to each other; that's how I found them...
My thoughts are that the following MIGHT be usefull:
1) a LED bargraph display that could attach to the parallel port, and display
some metric (CPU utilization, WAN/LAN utilization, routing speed, etc...).
This could even be built by lopping the connector off of the ribbon cable, and
then soldering up the display directly to the wires. You could also then
seperate the input lines and attach switches, etc... (would not require
attaching things to the parallel port and then running cables back inside the
case...)
2) as mentioned above, some mechanisim to read the status of the parallel (or
serial,
as Chris suggests above...) port input lines, and take action upon them. The
possibilities for this are endless- bring up or take down a line, monitor some
other device and take action (security, alert, monitoring, etc.)
3) with an LCD pannel as described in the articles in the URLs above, you
could put up displays. Imagine scrolling something like these messages to the
display:
"Router OK"
"PPP Connection UP"
"Ethernet 0 10 Mbps 30% utilization"
"Ethernet 1 100 Mpbs 03% utilization"
I'm going to start experimenting with this stuff, so will contribute more as I
learn more...