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Messages - BobG

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1
Character LCDs / Re: ST7066U with ROM 0B
« on: March 09, 2017, 03:10:16 PM »
Thanks for your reply, Saurabh_B.  Looks like I'll have to round up 499 or more of my closest friends if I want to make that happen. -Bob

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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.

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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?

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OLEDs / Re: Light Streaking on NHD-0420CW-AB3 Display w/ I2C rewrites
« 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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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.

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OLEDs / Re: NHD-0420CW I2C interface
« on: February 28, 2017, 05:04:12 PM »
I've just finished working on an I2C driver for the US2066 contoller, and I treated the Co and D/C#flags as described in the manual section 5.1.4.2.  I preceeded each command byte with a control byte with C#.  Each control byte has the Co bit set if there is a control byte (for data or command) following the command.  A string of data bytes is preceeded with a control byte with D only.  I did not try to send any commands following the data in the same I2C message (to do so, I presume one would need control bytes interspersed with each command or data byte - and all but the last control would have Co set.  Basically, I implemented 4 simple routines:  command (sends one C# control byte and one one-byte command), cmdData (sends one C# + Co control byte, one command byte, one D control byte, and one data byte - used for the Func. Select A/B commands), extCmd (sends one C# + Co control byte, one command byte, one C# control byte, and one command byte), and write (sends one D control byte, and any number of data bytes).  Actually, I quite arbitrarily limited the number of data bytes in write to 5.   I cut this down to 1 data byte at one point to see if it would cure a light-streaking problem when doing fast rerwrites (3/sec), but it didn't help - so I put it back up to five - and may try higher.   This is running on an Arduino at 100KHz serial rate.

Note: I'm unable to reproduce the problem of light streaking/flashes.  I hope it's not true that "problems that go away by themselves come back by themselves."

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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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OLEDs / Re: NHD‐0420CW‐AG3: blinking part of text?
« on: February 28, 2017, 03:27:02 PM »
You can blink the user-defined characters.  Check out the US2066 controller manual, available from the product description page.
If you're not otherwise using those characters, you coud redefine them any time you want - so long as you don't need more than 8 different characters/letters at the same time.  Also, make sure you are using one of the fonts that lets you "see" the CGRAM characters.   Look at the Function Selection B command and Section 5.13.

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