Re: [Libphidget-devel] First stab at the 888 ik

[Tom B. <tb...@ba...>]

On 1 Jul 2003, Jack Strohm wrote:

> Ok, I made a few more changed.  For those that are CVS impaired I've put
> a copy of the latest code at 
> 
> http://iris.homeip.net/~jstrohm/libphidget.tgz
> 
> Let me know how much of it works for the 888

ok, as I said off list, digital in and analog in continue to look good.

Digital out is not working correctly.

The api currently uses a set/clear bit function, but the phidget takes an
8 bit value ....

The code below correctly _sets_ a single bit, but doing that resets all
7 other bits.

[whoops, I just realized, I'm messing with code that probably is working
correctly for the other interface kits??, I guess we need a new function.]

   enum ELPError phidgetInterfaceKitWrite(struct phidget *phidgetDevice, 
     int index, int value )
   {
	   char buffer[4];

	   // TODO - This doesn't work for the 888 yet, need to
	   // rework some internal data structures to get it working.

	   // isn't this horribly simplistic? don't we need to
	   // maintain a bitmap of the set bits? Either that or pass
	   // the responsibility for that to the application?
	   // afaik, the 8 bits of buffer[0] are the 8 outputs

	   //buffer[0] = index+(value << 3);
	   buffer[0] = value << index;
	   buffer[1] = 0;
	   buffer[2] = 0;
	   buffer[3] = 0;
	   return(phidgetWrite(phidgetDevice,buffer,4));
   }

all the comments but the TODO are mine. The simplest fix seems to
be to maintain a byte containing the expected value in the
phidget. If there is a command for querying the current value in
the phidget, a better solution would be to query the phidget,
then write out the updated bit mask. The best solution would
probably be a combination.

I think the API would benefit from a command to query value
of either the 8 bit register, or the phidget directly.

Comments?

My apologies if the HID docs tell how to query the phidget, but
they are more than a little intimidating :-(

I'll go implement a static char register ...

-Tom




> 
> -- 
> Jack Strohm <js...@ja...>
> 
> 
> 
> -------------------------------------------------------
> This SF.Net email sponsored by: Free pre-built ASP.NET sites including
> Data Reports, E-commerce, Portals, and Forums are available now.
> Download today and enter to win an XBOX or Visual Studio .NET.
> http://aspnet.click-url.com/go/psa00100006ave/direct;at.asp_061203_01/01
> _______________________________________________
> Libphidget-devel mailing list
> Lib...@li...
> https://lists.sourceforge.net/lists/listinfo/libphidget-devel
> 

----------------------------------------------------------------------
tb...@Ba...   | Put all your eggs in one basket and 
http://BareMetal.com/  |      WATCH THAT BASKET!
web hosting since '95  | - Mark Twain