AVR-Chat

On Wed, 2005-08-31 at 20:51 -0500, Don Jackson wrote:
> Dennis wrote:
> >>>Data sheet definitions are sometimes wrong as are manuals. I found
> >>>that out the hard way with the mega168.
> Would you be so kind as to let us know what is wrong in the mega168
> data sheet?  I'm about to use this one...

  Indeed.  I lost an entire potential second career developing
micrcontroller-based applications for musem displays as a result of such
bad data sheets.

  In my case, it was Philips.  The designer and the veidographer had
discovered a commercial DVD player from Philips that included an RS-232
port on the back panel, which coul dbe used to "control" the deck.
Then, they found some sweet industrial 3" trackballs from Happ Controls
(check them out through Google if you get a chance, some wonderful
products), with serial and USB cables.  Thought they could just plug the
trackballs into the DVD deck abnd have a shole new approach to
interactive kiosk control.   Didn't work.

  Why?  Well, primarily because the morons at Philips chose to implement
an obscure, antiquated mouse protocol known s a"microsoft Mouse
Protocol."   Bizarre peice of crud, with 7 bits per byte, and bits from
different control fields allmixed up throughout the multiple byte
control sequences.  A real mess.  Suffice to sy that thre trackballs
were incapable of sending this mess, so they wouldn;t alk tot he DVD
decks
 
  Enter: me.  I spent a few weeks trying to make the trackballs talk to
the DVD deck, and quickly realized that without some very expensive
diagnostics equipment (which I do not own) and some very expensive
engineering time (which they couldn't afford) this was NOT gogin to
happen.

   So, I redesigned their entire Kiosk control system, and used some
8515s to provide an interface.  First cointroller worked fine.  It
simply selected one of 5 menu items and executed it.  The other two
(three kiosks in all) would NOT work.  As the interface on the DVD
player was "dumb," (e.g., no acklnowledgemane of data received.  If you
sent it somehting it didn't understand or like, it simply ignored you) I
had no way of knowing WHY it wasn;t working.   When I hoooked the
controllers up to my PC, and sent the controller output directly to the
screen, the "correct" sequence of ASCII characters appeared on the
screen.   Yet, no response from the DVD decks.

   Finally, after several months of calling NA Philips and talking to
clueless "support techs," I ***FINALLY*** got bumped up a grade, and
spoke with a support engineer.  I descibed my problem.  His response:
"OK, so you're sending the ctornl header, then you're sending it a three
byte control code, right?"   ***HOLD THE PHONE***   ***STOP THE
PRESSES***   "THREE byte contorl codes?"   "What three buyte control
codes?" says I to the engineer.  "*DOH* <sounf of forehead being
slapped>  They still haven't fixed that in the manual, have they?"  It
turns out that the manual does not specific three bytes ANYWHEER, and
worse yet, the example they show in the manual is WRONG< as it shows a
command being sent explicitly with a TWO BYTE control code.

   "I have been pestering them for over a year to change that error" he
tells me.   Now mind you, we're not talkign abiout expensive printed
manuals that would be a bloody hassle and huge expense to change.  NO,
there manuals are ONLY available as PDF files, downloaded from the NA
Philips web site.

   Cut the chase: as a result of this misinformation, I was unable to
meet deadline, despite several 60-90 hour marathons in the museeum
overnight, trying desperately to get something to work. and the museum
display was forced to open with only two out of three kiosks
funcitoning.   

   I managed to think of a workaround the day AFTER the display opened,
which helped, but even so.  (the workaround was rather clever, once it
occured to me. I had to let go of my focus on getting MY controller
working, and focus on getting the DISPLAY working.  I took the handheld
remotes for the DVD players, opend them up, and surgically modified
the,m bringing out wires fromthe buttons on their keypads that performed
the desired functions.  I then wired these buttons to the industrial
strength buttons on the consoles of the kiosks, and duct taped  (OH, NO!
It's another duct tape story!!!!!) the damend remotes down on the shelf
in front of thre DVD player, inside the kiosk.  Kludgy, but it worked,
kept them running for the several more weeks it took me to find the
solution and get the working correctly.  MY only embarassment at this
point is that I should have let go of my ego earlier in the game, and
looked for the workaround so that the displays were functioning on
opening night.  *sigh*

   I embarassed myself, my friend the videographer, who had brought me
in to the project,and worse yet, the professional museum display
designer, who had a valuable reputation to uphold.  Suffice to say that
he won't even talk to me, much less use my services again.  And we had
been talking about work worth upwards of $65,000/year, prior to this.

  The response from NA Philips?  They have a disclaimer printed in the
front of their manuals which disclaims any responsibility for errors, so
I can just go fish.  Oh...and not too long ago, a 4th version of that
DVD deck was released.  I went and looked and guess what?  **STILL**,
over 3 years later, that damned manual has not been corrected!

tom

  Sometimes, even RTFM *AIN'T* enough!!!!    )-: