Lpc2000

Sean,

are you sure about having enabled the 8080 mode of the SED13305 (and not 
the 6800 mode) ???

If you have accidently enabeld the 6800 mode writing gets ok, but reading 
gives stupid values - I had that effekt already by myself and it costed me 
nearly three days to find out what's wrong - in my case a LCM with a 
built-in S1D13700 claimed to work with the 8080 mode, but there have been 
undocumented jumpers on the LCM which were set to 6800 mode :-(

Hope that helps.

Regards
Herbert


At 22:26 15.02.2006 -0500, you 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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