Mach3 works with my G540 CP but Unbuntu doesn't

We have had quite a discussion on the Yahoo DIY_CNC group about my problem with Unbuntu changing the state of my parallel port on my Dell GX260 PC from EPP with my G540 during boot up.
With the same PC and same PP cable and same G540 with the CP switched on Windows and Mach3 work fine and the Charge Pump takes the G540 out of the Fault state. In Unbuntu and linuxcnc and with the cable connected to the G540 the G540 will not come out of the fault stage. If however during boot up I have the PP cable disconnected and after Unbuntu is booted up and at the desktop I plug in the PP cable and then start EMC I get the green power light on the G540.
To prove that Unbuntu was the problem I connected my Tectronics scope to a breakout board and watched the CP pin 16 . With the cable connected you can see that during boot up the PP changes the setting and shows a different amplitude . When the cable is disconnected and the PC rebooted then the port stays in the EPP mode and thus when connected to the G540 the CP works and the G540 comes out of Fault.. It looks like if pin 1 stobe is low Unbuntu thinks there is no printer attached and disables the PP.

The guys had me try several things and we ran a program called showport and dmesg. We found that either par_port or lpt is the cultprit because those are the two unbuntu files that control the PP during boot up.

If someone can tell me ( I am not a unix persome) how I can disable one of those programs or both of them one at a time we can solve this issue.
Dan Mauch

Hi

Have you seen this thread?
www.linuxcnc.org/index.php/english/compo...4788&limit=6&start=6

Whilst it relates to a PCI parport card, the principle may be the same. Pin voltages seem to be at the root of it.
This charge pump / fault state requiring EPP seems peculiar to the G540.
It's not quite clear what the outcome was.

We found that either par_port or lpt is the cultprit because those are the two unbuntu files that control the PP during boot up. If someone can tell me ( I am not a unix persome) how I can disable one of those programs

The simplest temporary way is to rename them.

You will need to look at the module dependency chain, they may not actually be loaded explicitly, but via the loading of another module.

Off the top of my head I think parport_pc loads ppdev and lp as well
My /etc/modules only lists lp by default however.

regards

Kirk Wallace wrote a stand-alone utility to set a parallel port into EPP mode (and other things)
This should be useful here.
wiki.linuxcnc.org/cgi-bin/wiki.pl?Startech

Yes I have read the thread. My PC has an onboard PP and the Bios is defineitely set to the EPP mode. Again the pc work perfect with the G540 and mach3

What is happening is that either Par_port or LPT is looking at the strobe pin and if it is low it disables the PP. Unbuntu should not be checking that pin.
My test prove that.

I see modules in the /etc directory but it is black letters and wouldn't let me try to open it. How do I open it?

Thanks for the help.
Dan

ArcEye wrote:

Hi

Have you seen this thread?
www.linuxcnc.org/index.php/english/compo...4788&limit=6&start=6

Whilst it relates to a PCI parport card, the principle may be the same. Pin voltages seem to be at the root of it.
This charge pump / fault state requiring EPP seems peculiar to the G540.
It's not quite clear what the outcome was.

We found that either par_port or lpt is the cultprit because those are the two unbuntu files that control the PP during boot up. If someone can tell me ( I am not a unix persome) how I can disable one of those programs

The simplest temporary way is to rename them.

You will need to look at the module dependency chain, they may not actually be loaded explicitly, but via the loading of another module.

Off the top of my head I think parport_pc loads ppdev and lp as well
My /etc/modules only lists lp by default however.

regards

My PP works the CP just fine with Mach3 so the current is the problem. The problem is that Unbuntuy is checking the strobe pin 1 and seeing it low and thus disables the PP.
Yes I have checked dozens of tiomes and my bios is set to the EPP mode for the PP. 378
I really don't want to add a pci card or other hardware including pullup resistors because again it works in windows and Mach3. Why doesn't Unbuntu?
Dan

andypugh wrote:

ArcEye wrote:

www.linuxcnc.org/index.php/english/compo...4788&limit=6&start=6
Whilst it relates to a PCI parport card, the principle may be the same. Pin voltages seem to be at the root of it.{/quote]

The same thing is discussed here:
thread.gmane.org/gmane.linux.distributio...er/34941/focus=34963

It seems that the G540 charge-pump requires more current than most parports source. Some parports source more current in EPP mode than they do in SPP mode.

Have you tried setting the port to EPP in the BIOS? This _might_ work.
There has been talk of modifying the parport driver to force EPP mode on demand, but that hasn't been done yet, and would only be future releases.

One solution (though an expensive one) would be the Mesa 5i25 which is a bit like a parport (and has 24mA drive current) . It is a lot more expensive ($80) than a parallel port card, though it does have the significant advantage of moving step generation into the card hardware, and you can connect hundreds of pins of extra IO to it (at extra cost). Depending on your machine the hardware step generation might be an enormous advantage. However, Mach3 can't currently work with the 5i25 if you are in the habit of switching between them.

I see modules in the /etc directory but it is black letters and wouldn't let me try to open it. How do I open it?

You either need to be logged in as root or use sudo.
Use a decent file-manager / editor like mc
Be very careful what you change and make a copy before doing so.