Re: [Emc-users] Possible bug in Mesa 5I20 for polarity of DAC

[Peter C. Wallace]

On Fri, 11 Apr 2008, How Lin Hoo wrote:

> Date: Fri, 11 Apr 2008 06:46:07 +
> From: How Lin Hoo <[EMAIL PROTECTED]>
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: emc-users@lists.sourceforge.net
> Subject: [Emc-users] Possible bug in Mesa 5I20 for polarity of DAC
> 
>
> Dear all,
>
> I am currently implementing Mesa 5i20, 7i33 and 7i37 cards for my 
> self-designed machine. I have a problem with regards to the polarity of the 
> DACs from the Mesa 7i33 card.When I set the voltage of DAC to a value 
> (example: 5V) using EMC, the DAC sent out from the 7i33 card is -5V which is 
> of opposite polarity. I had rectified by using a scale function to change my 
> gain to -1. However, this is not an ideal solution as other users will think 
> the gain is -1.
>
> Is there anyone who has encountered the same problem? Is there is a possible 
> bug in the Mesa driver? Thank you for your attention.Regards,Daniel

Its either a bug in the driver or the FPGA firmware (depending on who 
you wish to blame: PeterV or PeterW) At this point its probably better to live 
with the bug than have a update that will break existing configurations (in a 
_really_ bad way = servo runaway).

If you can live with the -gain for a couple of months there is a new 
5I20 configuration available (HostMot2) and the driver for that will have the 
correct output polarity. HostMot2 also improves the 7I33 performance somewhat 
because is has a selectable 12 bit PDM mode and PDM frequency selectability 
(low to 100 MHz) to get the best ripple/linearity tradeoff in the 7I33.


Peter Wallace
Mesa Electronics

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.


-
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
Don't miss this year's exciting event. There's still time to save $100. 
Use priority code J8TL2D2. 
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Possible bug in Mesa 5I20 for polarity of DAC

[Anders Wallin]

> Is there anyone who has encountered the same problem? Is there is a 
> possible bug in the Mesa driver?  

do you have an optoisolator somewhere between the fpga output and the
DAC? optos tend to reverse the logic.


-
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
Don't miss this year's exciting event. There's still time to save $100. 
Use priority code J8TL2D2. 
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

[Emc-users] Possible bug in Mesa 5I20 for polarity of DAC

[How Lin Hoo]

Dear all,
 
I am currently implementing Mesa 5i20, 7i33 and 7i37 cards for my self-designed 
machine. I have a problem with regards to the polarity of the DACs from the 
Mesa 7i33 card.When I set the voltage of DAC to a value (example: 5V) using 
EMC, the DAC sent out from the 7i33 card is -5V which is of opposite polarity. 
I had rectified by using a scale function to change my gain to -1. However, 
this is not an ideal solution as other users will think the gain is -1.
 
Is there anyone who has encountered the same problem? Is there is a possible 
bug in the Mesa driver?  
Thank you for your attention.Regards,Daniel
_
Help Splitzo Sally Before It’s Too Late! 
http://www.thegirlwhosplitinto5.com/-
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
Don't miss this year's exciting event. There's still time to save $100. 
Use priority code J8TL2D2. 
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users