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Author Topic: PCD 8544 5110 Nokia display hardware troubles - blurry image  (Read 917 times)
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I'm running two ebay'ed 5110 displays @5v on a Nano using the adafruit libraries. Connection works, example code is running fine, however display quality is horrible.
Playing with contrast, the display goes from "all pixels black" to "all pixels white". At optimum values (contrast=14 in this case), the pixels are clearly readable, however the display shows blurry horizontal stripes of lesser intensity. Also, adjacent contrast values (12,16) immediately worsen image quality further. I've also tried playing with the library and the BIAS value, but no success. Running the display from a voltage divider to go to 3.3v didn't help.

The blurry image and the narrow usable contrast range sound like a hw issue to me but I'm entirely lost on what to check. Any ideas? smiley-cry
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That display is 3.0V I believe, not 5V - does the module you have have a voltage
regulator and level shifting?  Which module are you using?  Since its not TFT display
you will always expect some degree of pixel-bleeding that is pattern sensitive.
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I got this one which claims 5v compatibility: http://www.ebay.de/itm/2x-LCD-Blau-Display-Screen-fuer-Nokia-5110-LCD-Module-fuer-Arduino-DIY-project-SPI-/400505726343?ssPageName=ADME:L:OC:DE:3160
The problem is that it's not "some bleeding", but really crap image- I'll try to take a picture.
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Dee Why NSW
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I understand these displays are factory surplus, so that might explain a few things......

I found that the quality of the display depended much on what was being displayed. Most notable was that I could never get a bold font display that compares with that on my 5110 phone. (Read the first line again). Further, if I could adjust it to get a satisfactory display with one programme, it didn't work too well with another.  I could never get a result with the 4 digit clock by Pawel Kadluczka yet I saw a pretty good display of it on Youtube.

I proved up my first 5110 with the Stuart Lewis programme, sans library.
 Vital settings finished up as:
Code:
 LcdWrite(LCD_CMD, 0xBf);  // Set LCD Vop (Contrast). //B1
  LcdWrite(LCD_CMD, 0x04);  // Set Temp coefficent. //0x04
  LcdWrite(LCD_CMD, 0x14);  // LCD bias mode 1:48. //0x13

I now use the standard Philips PCD8544, set to
Code:
this->send(PCD8544_CMD, 0x13);  // bias system (1:48)

    if (model == CHIP_ST7576) {
        this->send(PCD8544_CMD, 0xe0);  // higher Vop, too faint at default
        this->send(PCD8544_CMD, 0x05);  // partial display mode
    } else {
        this->send(PCD8544_CMD, 0xc2);  // default Vop (3.06 + 66 * 0.06 = 7V)
    }

Some stuff here          http://forum.arduino.cc/index.php?topic=137026.0
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I think upgrading to a Nokia 6610 display (colour STN) or a TFT would
be more fun...
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Dee Why NSW
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There is a serious difference in the price, very little material benefit, and the 5110 is better supported - probably because of the aforementioned. I have four 5110s and find them excellent, but I think the blue background LEDs are a bad idea.
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Nicks comments started a thinking process (thanks!). Now- running the display from the Nano's 3.3V pin with the signals still connected to 5v both displays are running fine. At the price I've paid I'm not troubled by surplus- they're good enough for testing purposes.
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