Analogue-sequencer

After many years I finally got #33 put together last nite. 
Unfortunately, the PLED display that I bought a few years ago seems to
be DOA.  I'm assuming that if it is getting proper power and I have
the brightness turned all the way up I should see something, right? 
Could there be a control issue that causes the display to be black? 
(I know I'm reaching here but I really want to play with this thing.)

dave

I have more info now.  The RS, R/W, and CE signals for the display
only output 3us pulses.  According to the PLED datasheet they should
remain high/low for the duration of the read/write.  Also, only
DB0-DB2 show any activity.  Any ideas?  Thanks

dave

--- In analogue-sequencer@yahoogroups.com, "faldska" <faldska@...> wrote:

>
> After many years I finally got #33 put together last nite. 
> Unfortunately, the PLED display that I bought a few years ago seems to
> be DOA.  I'm assuming that if it is getting proper power and I have
> the brightness turned all the way up I should see something, right? 
> Could there be a control issue that causes the display to be black? 
> (I know I'm reaching here but I really want to play with this thing.)
> 
> dave
>

> I have more info now.  The RS, R/W, and CE signals for the display
> only output 3us pulses.  According to the PLED datasheet they should
> remain high/low for the duration of the read/write.  Also, only
> DB0-DB2 show any activity.  Any ideas?  Thanks

The communication between the CPU and PLED module amounts to:
"wait for the LCD to be ready"
"read/write to/from the selected register"

If the module is disconnected or bad, the CPU can wait forever for it to be
"ready", and will not appear to boot.
The "ready" bit is DB7.
Zero is ready, one is busy.
You can fool the CPU into thinking it has a working PLED attached by
connecting pin 14 of the LCD interface (DB7) to pin 1 (ground).
If that doesn't make it boot and flash its LEDs, you could have a problem
with the main PCB or the code on the CPU.

Best regards,
Colin Fraser
Sequentix Music Systems Ltd
http://www.sequentix.com

OK, I had the Logic Analyzer connected without the
display.  When I connect the display I get what seem
to to be correct waveforms.  But, alas, still no
display.  So, I'm going with my first assumption that
the display is broke.  The rest of the P3 seems to
work.  I press Play and the lights dance around.  Just
no display.  

As far as the code, it is whatever was shipped with
#33.  I'll have to wait until I get a display to check
the version.  Then I'll have all kinds of questions on
how to upgrade to v4 from whatever I have.  I know
there were some bootloader changes along the way that
I don't have.

thanks

dave


--- Colin Fraser <colin@sequentix.com> wrote:

>  
> > I have more info now.  The RS, R/W, and CE signals
> for the display
> > only output 3us pulses.  According to the PLED
> datasheet they should
> > remain high/low for the duration of the
> read/write.  Also, only
> > DB0-DB2 show any activity.  Any ideas?  Thanks
> 
> The communication between the CPU and PLED module
> amounts to:
> "wait for the LCD to be ready"
> "read/write to/from the selected register"
> 
> If the module is disconnected or bad, the CPU can
> wait forever for it to be
> "ready", and will not appear to boot.
> The "ready" bit is DB7.
> Zero is ready, one is busy.
> You can fool the CPU into thinking it has a working
> PLED attached by
> connecting pin 14 of the LCD interface (DB7) to pin
> 1 (ground).
> If that doesn't make it boot and flash its LEDs, you
> could have a problem
> with the main PCB or the code on the CPU.
> 
> Best regards,
> Colin Fraser
> Sequentix Music Systems Ltd
> http://www.sequentix.com
> 
> 
>

> I'm going with my first assumption that the display is broke.

I'm sure you have already checked this... but the PLED does need the 
contrast trimmer turned to almost full value before it lights up.

It'd be nice if it was this though.

Tony

> Yeah, I thought of this too, especially after I
> noticed that the contrast trimmer was all the way
> down.  But, turning it up didn't help either.  I'm
> going to look at the two display controllers today and
> see if the replacements I found will work.

I have just received some of the ribbon cable adaptor boards to fit to LCD
modules to supply for warranty failed PLED modules.
I have a stock of the EA white-on-blue modules to fit these to, along with
suitable spacers for the mounting posts.
Give me a few days and I'll be able to sell you one, if you can't find a
reasonable alternative.

Best regards,
Colin Fraser
Sequentix Music Systems Ltd
http://www.sequentix.com

Yeah, I thought of this too, especially after I
noticed that the contrast trimmer was all the way
down.  But, turning it up didn't help either.  I'm
going to look at the two display controllers today and
see if the replacements I found will work.

dave
--- Oakley Sound <tonyallgood@btinternet.com> wrote:

>  > I'm going with my first assumption that the
> display is broke.
> 
> I'm sure you have already checked this... but the
> PLED does need the 
> contrast trimmer turned to almost full value before
> it lights up.
> 
> It'd be nice if it was this though.
> 
> Tony
>

After reading about the KS0066U vs HD44780 I found
that while they may be command compatible they have
some timing differences.  Others have found that you
can't just drop one in where an HD44780 was.  I wonder
if the timing is still within the operating range of
the P3 control.  If not, I may be taking you up on
those EA blue-on-white displays (though I was really
looking forward to my red display).

dave

--- Colin Fraser <colin@sequentix.com> wrote:

>  
> > Yeah, I thought of this too, especially after I
> > noticed that the contrast trimmer was all the way
> > down.  But, turning it up didn't help either.  I'm
> > going to look at the two display controllers today
> and
> > see if the replacements I found will work.
> 
> I have just received some of the ribbon cable
> adaptor boards to fit to LCD
> modules to supply for warranty failed PLED modules.
> I have a stock of the EA white-on-blue modules to
> fit these to, along with
> suitable spacers for the mounting posts.
> Give me a few days and I'll be able to sell you one,
> if you can't find a
> reasonable alternative.
> 
> Best regards,
> Colin Fraser
> Sequentix Music Systems Ltd
> http://www.sequentix.com
> 
> 
>