contrast fade on GLK12232-25-SM

[rfhaley]

I am delighted with my display and it is working BUT can you tell me where my brain failed?
I want a 120 pixel bar graph to represent a one line picture from my TSL1401 optical linear array.
My array, photo, is loaded with unsigned char data in my program.

Code: Select all

	// Data defined in photo. Now display on LCD
	//                  
	write_LCD(254);		// Command prefix
	write_LCD(88);		// Clear screen
	for (i=0; i <= array_size; ++i)
	{
		write_LCD(254);		// Command prefix
		write_LCD(108);		// draw a line
		write_LCD(i);		// from x-location
		write_LCD(photo[i]);	// height = measured data
		write_LCD(i);		// vertical line at x
		write_LCD(0);		// reference location y=0
	}

The above code displays the graph. It works and things wobble around as I block the light.
My problem is: The display fades accross the screen. Pixels in the first column are dark and they gradually fade off to nothing by column 80.
Any clues? array_size is not the problem.

[Tom]

What board revision do you have?

[rfhaley]

I have rev. 1.4
I tried using I2C and RS232 both are the same. I think it is the refresh of the screen because when I put a one second delay between writing data screens it works OK. The fade seems to solidify after some 500ms. Is there a cable length limit I should avoid when using I2C?
So new question ... is there a faster way to write a graphic screen of 100 vertical lines. Right now I send 6 chars per vertical line X 100 lines.