Thanks to all those who replied. As Lynn said, it's probably in your
hardware. I had not realised the Vo lcd voltage was Vss referenced or that
the display was only visible over such a small range. The optimum Vo
voltage seems to be around 0.47V, with all pixels on at 0.3V and all off
at 1.5V. I didn't have a potentiometer handy and so for many hours
laboured over software with Vo tied to Vdd!

Ron

On Sat, 21 Feb 1998, Lynn Richardson wrote:

> It may not be just a program problem, Ron.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Ron Kreymborg                   Computer Systems Manager
 Monash University               CRC for Southern Hemisphere Meteorology
 Wellington Road
 Clayton, VIC 3168               Phone     : 061-3-9905-9671
 Australia                       Fax       : 061-3-9905-9689
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