Lpc2000

Hi Sean,
do you make a proper initialization of S1D13305?
I mean before to write to the memory. Have you issue
commands SystemSet, ScrollToAddress and etc. with
proper parameters?



--- Sean <embeddedrelated@...> wrote:

> Hello all,
> 
> I am having an issue here and I hope someone has
> some suggestions.  I'm 
> trying to interface some LCDs to my micro, I have a
> graphical 128x64 which 
> has an embedded controller chip interfaced fine,
> using P1.16-P1.23 as 8-bit 
> parallel IO.  However when I try to hook up a
> SED13305 the data seems to 
> get corrupted.  I'll issue a write to the device to
> store something in 
> VRAM, then immediately try to read it back.  Here's
> where things get weird.
> 
> If I try to use the WR and RD signals like they
> should be used (RD always 
> high, Clear WR, Set Byte, Set WR), the write appears
> to work, however 
> repeated reads of the same memory area return
> different results each 
> time.  Enough reads show that the data was written
> successfully.  However 
> if I modify only the write routine to use the WR and
> RD signals in a 
> different (wrong) way (Clear WR, Set RD, Set Byte,
> Set WR, Clear RD) then 
> repeated reads return the same data every time,
> however bits 7:8 are always 
> "10".  Note that the read routine is the exact same
> both times.
> 
> How is it possible to have a small change to the
> write routine effect how 
> the read routine works?
> 
> I have tried playing with timing to no avail.  I
> looked at everything with 
> an oscilloscope and the timing and data look
> correct.  I've verified all 
> connections with a multimeter. I have both the micro
> and the SED running 
> off of 3.3V.  Note that if the SED is running at 5V
> then I get complete 
> garbage on read (meaning probably nothing worked),
> even though the SED says 
> it works from 2.7V to 5.5V.
> 
> I think I'm going to have to try to make another
> test board, but before I 
> run out to do that does anyone have any ideas as to
> why this is happening?
> 
> Thanks,
> 
> -- Sean
> 
> 


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