Author Topic: Light Streaking on NHD-0420CW-AB3 Display w/ I2C rewrites  (Read 800 times)

BobG

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Light Streaking on NHD-0420CW-AB3 Display w/ I2C rewrites
« on: February 28, 2017, 05:34:18 PM »
I'm driving an NHD-0420CW-AB3 display with an Arduino Uno via I2C at the nominal serial rate of 100KHz.  When I rewrite a line (or partial line) of the display at a rate of about 3-5 times per second, I get random light-streaking across the line.  I've tried 5-character I2C frames and 1-character frames, but the problem persists.  If I cut the rate down to 1 per second, I don't see the problem.  The burst rate of the I2C frames is the same at both rates.  The actual displayed information does not appear corrupted (except by the streaks).  Am I overloading the controller, or is it perhaps noise induced between the breadboard jumpers, or what ?
Other than this problem, it's a really nice display with great flexibility.

Saurabh_B

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Re: Light Streaking on NHD-0420CW-AB3 Display w/ I2C rewrites
« Reply #1 on: March 01, 2017, 08:23:04 AM »
I've used a jumper board with this display, and i wasn't seeing any streaking.
Would it be possible to post a picture of the display with the streak?


BobG

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Re: Light Streaking on NHD-0420CW-AB3 Display w/ I2C rewrites
« Reply #2 on: March 02, 2017, 10:43:50 AM »
Saurabh_B:
The streaks are not permanent.  I should have decribed the effect as flashes appearing across the display as the line is written and rewritten.  I just tried the problem program again, and I didn't see the effect any longer, even when I only write one character per block.  (I do see some flicker when I push the rewrite rate, but I don't see any flashes where characters shouldn't have dots lit.)  I wonder if I had a bad power/ground connection?
Thanks for your reply.
-Bob

 

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