Info on HAL device driver

[MarcoG]

Hi all,
I'm new to Linux and EMC2 world,so I'm very noob, but I'm very interested on using it.

I read the docs and the wiki, and I know that EMC can actually support only a limited number of IO board.

My question is: if i want to use any athor board, i have to write a real time driver for it? So the best way is to start from zero or from source code (of course in case the maker release it)?
I found a reseller selling a board that have all the functionality I need (analog output for servo, incremental encoder counter, some digital IO). He make me available a RTAI driver, can I use it directly in EMC? (in fact I know that both have a "HAL" layer, is the same?)

The question arise because I'm italian (sorry for my english), and I'm looking for an interface board from a reseller/producer in Italy or at least in Europe.

[CalG]

Marco

Post this same question here: emc-users@lists.sourceforge.net

Lot of really knowledgeable EMC2 people there.

EMC can do anything....if YOU know how.

Cheers

CalG

[chester88]

Marco

You would need to write a driver that interfaces with EMC's HAL (which interfaces with RTAI).
Do you have information about the board you can share?
An existing RTAI driver (source code) certainly would help, as long as it is GPL licenced.

[MarcoG]

Thank to all for the reply.

I would like to use the PCI-8136 by ADLink.
http://www.adlinktech.com/PD/web/PD_detail.php?pid=134
In the case that I have the realtime driver (I mean the RTAI module from reseller), is possible to build an HAL component that interface between EMC and the module? Can be this a valid solution?

Being new to this world, I don't understand your last statement:

Originally Posted by chester88 Marco ... An existing RTAI driver (source code) certainly would help, as long as it is GPL licenced.

This means that I can't use a non-GPL module in EMC?

Would be grateful if you could clarify me the situation.

Thanks in advance.

Marco

[chester88]

Sorry you can use whatever you want for personal use.
I was thinking if you offered your driver to be included with EMC2, then it would need to be GPL.
It would be nice if you could offer it to be included with EMC2.

Chris M

[jmelson]

Originally Posted by MarcoG Thank to all for the reply. I would like to use the PCI-8136 by ADLink. Marco

Most likely, that driver is designed for data acquisition purposes, for taking multiple analog
samples at regular intervals. Probably it would not be possible to use their driver as-is
for use with EMC. It certainly could be used as a guide for the low-level code to access
the device's registers, however.

The basic mode of operation of a servo interface driver with EMC2 is like this:

1. trigger all encoder counters to simultaneously capture the encoder position.
2. read all encoder counts
(the PID routine now calculates a new velocity)
3. output velocity to whatever controls the servo amps (analog DAC, PWM, steps)

Repeat above cycle at the next SERVO_PERIOD.

[MarcoG]

Thanks for the reply jmelson.

I already know the basic/general servo control scheme loop, but a confirmation from another user is always welcome!

I'm waiting for the delivery of the board and the driver, for now I'm studying the driver (yet supported and developped) of the vitalsystems board, for a better understandig.

Marco