[zeta]

Hi Chaps
I'm looking for some guidance about the charge-pump setup in EMC. I have found in the setup docs how to assign a parallel port pin to the charge-pump, but that's all. A search on CNCzone yields a post about setting up a torch system in which there is mention of "the 15 kHz output" (but nothing about how to enable it) and searches of the EMC docs (and the Sherline docs) add nothing further. My conclusion is that I'm looking in the wrong place.
So, can anyone answer:

• Where is the charge-pump set up documentation?
• What's the charge-pump output amplitude (voltage)?
• What's the charge-pump output frequency?
• Is there anything else I need to know in order to set up a controller which expects a charge-pump signal?

Grateful thanks for any info.

Z

[Gads]

zeta some better explanations than i can give are at the bottom of the page when viewing your post. (http://www.cnczone.com/forums/showthread.php?t=40932) my breakout board has control of my motor drivers and external relay/spindle controls etc. if board dosn't see signal it will disable motor drivers etc.. I can disable this feature on the board with jumper. you can also search for charge pump on this site and get a lot of hits
hope this helps
gads

[zeta]

Hi Gads
Thanks for helping. I understand the principle of charge pumps and how to wire up my controller board given a charge-pump input. What I can't find is anything specific to EMC. Suppose I have set up (say) parallel pin 1 as the charge-pump output pin in EMC, then what appears at pin 1? Is it 15 kHz, 12kHz? And what amplitude? Or must I also tell EMC what signal to send to the pin? The documentation doesn't seem to provide the answer.
I was looking for something like the following, found in "Setting up a basic three axis milling machine", in the Mach3 documentation:

About halfway down there is a signal called Charge Pump. Put a 1 in the Port # and the Pin # to which the circuit is connected, in this example pin #1. Then make sure the function is enabled (a green checkmark in the Enabled column). Check that no other output signals are enabled. Now, when ever Mach3 is running AND is not in E-stop mode there will be 12.5kHz square wave on pin 1 of the parallel port.

Any clues?

Regards

Z

[Gads]

Hi zeta
? are you switching from a mach3 system to emc2.
if this is all your doing then the charge pump pin used in your working mach settings would be the same pin you pick in your emc stepconfig setup,
I did need to select invert but it works fine.
If you are looking for specs I don't know the exact, but if you have a digital multimeter you could probly measure it for yourself. maybe have mach running and change settings to turn on and off to verify your looking at the right pin. Hz should be accurate but voltage may not be the same disconnected from a board that uses a charge pump (volt drop).
no electronics expert but this might give you what your looking for.
Gads

[zeta]

Thanks again Gads :cheers:

I'm sure there are more pressing needs for the documentation team than describing in detail the charge-pump parameters in detail. Probably it will appear in a subsequent iteration. Meanwhile I'll install Mach and experiment as you suggest.

Regards,

Z

[leo.dearden]

Zeta,

I don't know what a charge pump is, but I'm comfortable with EMC, so I'll talk about that, and let you fill in the details.

I'm assuming that you're using EMC2.x, such as comes with Ubuntu. If you're using v1.x I can't help you.

EMC is mind bogglingly general. The hardest thing for me was to get my head round quite how general it is. EMC will send exactly the signals that you tell it to, to whichever pins you tell it to.

So: EMC uses a Hardware Abstraction Layer to map between the abstract world of G-codes, motion planning, etc, and the physical world of signals on pins. The HAL configuration is defined by one or more .hal files that you select when you start up EMC. That configuration 'wires' up a bunch of software modules to generate signals, and then 'wires' those signals to specific hardware inputs or outputs. If you already have a mostly suitable .hal for your set up that makes things easier. If not, then read the relevant parts of the User's Guide and Integrator's Guide.

From the POV of the HAL, there is no 'charge pump' output. Instead there is (amongst other things) a generalised mechanism for outputting a square wave at (broadly) whatever frequency you want. You can use that to drive your charge pump output in whatever way it needs to be driven. Since there is no way to control the parallel port voltage from software, you can only output square waves, and they'll be at whatever voltage your parallel port produces (usually about 4.3V), and this would be true whatever software you were using.

AFAICS, the module you need is called pwmgen and you can find an example of how to use it in Section 13.3.5, and a more complete reference in S 14.3 of the Integrator's Guide. If that doesn't make sense, try reading S1,5,6,7 of the same.

Hang in there, it will all make sense soon, and then you'll have a really powerful and versatile tool to play with.

HTH,

Leo

[zeta]

That's great Leo, exactly what I needed! Now I know how it hangs together I'm a lot happier wiring it up.
Regards,
Z