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Topics - wbeals

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Graphic LCDs / NHD-320240WG-BxTGH-VZ#-3VR initialization sequence
« on: April 27, 2016, 10:17:53 PM »
I am having trouble getting the above display to light up.  I've brought up close to a dozen other displays before, but been completely stumped by this one.  By outward appearances, the display never comes out of sleep, my reference is the YDIS pin on the S1D13700 that never goes high.  V0 is at -18.8V, VDD at 3.3V, and I have all the digital signal timing extremely conservative (50us between any IO Bus signal changes, 3ms for Reset).  All have been verified with an oscilloscope.  The only thing I see as strange is that the example initialization code in the datasheet is for 6800 signalling and the display is wired for 8080 signalling.  I'm using 8080 signalling and have measured out the CNF pins on the module to confirm it should be 8080 signalling. 

I fear I did destroy one display as while probing signals I think my probe slipped and shorted the V0 signal to one of the control signals.  I have two other displays still and using those.

I am sure the displays are fine (or at least hope so!!) and there is something extremely fundamental I'm overlooking.  I've been at it three weekends now and still no luck so finally asking for help.  All DC voltages look good, Reset timing is good, and timing/data for writing out the initialization strings look good (verified each bit on the scope too).  I have tried an experiment where I try to read back data written to DDRAM.  I get zero's back always, but not as confident of that code.

Thanks in advance.  Can't figure out why this display is stumping me.  Any suggestions appreciated.

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