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Topics - BobG

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Character LCDs / ST7066U with ROM 0B
« on: March 07, 2017, 10:10:35 AM »
Is it possible to obtain LCD displays such as the NHD-0420E2Z-NSW-BBW with the ROM code 0B English/European character set?  These would be more useful in the US and Europe.

OLEDs / B/W cursor problem on NHD-0420CW-AB3
« on: March 02, 2017, 04:20:07 PM »
I'm running this display using 100KHz I2C at 5V (Iv'e also tried 3.5V) and am not observing any data corruption problems.  But I am having trouble with the operation of the B/W bit in the Extended Function Set.  If I write data on the display, then position the cursor over an existing character, then turn on the cursor (Display on with C set), the character is underlined as expected.  If I now issue an Extended Function Set with the B/W bit set, I expect to see the character image pixels inverted (on <-> off).  In fact, what I see is the cursor line vanish and the character stays the same.  If I issue another Display on with C and B set, the entire block alternates between all on (block) and the original character (cursor line still absent). If I now issue an Extended Function Set command with the B/W bit cleared, I get a display with the character alternating with a full-on block - with the cursor line on steady beneath it.  If I turn off the cursor and the blink, then changeing the B/W bit has no visible effect.  This doesn't seem to agree with the description in the manual.  What's happening?

OLEDs / 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.

OLEDs / NHD-0420DZW user-defined characters
« on: February 28, 2017, 04:28:48 PM »
Although the Newhaven manual for this family of displays describes the definition of up to 8 user-defined characters in GCRAM (page 19), the preceeding font tables show 16 addresses in CGRAM.  Could there possibly be space for 16 different characters, or does the proprietary controller operate like the ST7066U and essentially ignore bit 3 when accessing GCRAM?  The ST7066U manual shows this by repeating the addresses 0- 7 in the font tables.  (Sure would be nice to have 16 CGRAM characters.)

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