Comments: Graphic LCD Hookup Guide

-------------------- Tech Support Tips/Troubleshooting/Common Issues --------------------

PCB and Screen Dimensions

The overall size of the board is 45mm vertically and horizontally. For the screen, it's about 40mm horizontal and 34mm vertical. The depth I measured from the top of the screen to the front of the board is about 3.75mm. If you measure the overall height, it's about 5.1mm high from the top of the screen to the legs of the screen.

Here is an image of the dimensions


Contrast

If the display is not showing pixels even with the correct logic levels and example code, it may just have slight variances in the way that they were manufactured. You can see the pixels faintly on the screen at an angle or pushing down on the LCD. You will need to try and set the contrast where it says setContrast(40) on line 87 to a value of 60. There is probably some variances in the LCD’s contrast which might explain why certain LCDs have issues displaying defined pixels on the screen.

Scrolling Text

For code to scroll text, try looking at this blog post => [ http://blog.stuartlewis.com/2011/02/12/scrolling-text-with-an-arduino-and-nokia-5110-screen/comment-page-1/ ].

I only got the code sample to work by restoring the commented code in the LCDWrite() function.

//Send the data
  digitalWrite(scePin, LOW);
  SPI.transfer(data); //shiftOut(sdinPin, sclkPin, MSBFIRST, data);
  digitalWrite(scePin, HIGH);

I simply dropped the SPI.transfter call and left the commented code of shiftOut.

//Send the data
  digitalWrite(scePin, LOW);
  shiftOut(sdinPin, sclkPin, MSBFIRST, data);
  digitalWrite(scePin, HIGH);

In addition, I used the following setting in the lcdBegin() function to get the best results of contrast and other capabilities:

LCDWrite(LCD_COMMAND, 0x21); //Tell LCD extended commands follow
LCDWrite(LCD_COMMAND, 0xc8); //Set LCD Vop (Contrast)
LCDWrite(LCD_COMMAND, 0x12); //LCD bias mode 1:48 (try 0x13)
LCDWrite(LCD_COMMAND, 0x20); //chip is active, horizontal addressing, use basic instruction set
//We must send 0x20 before modifying the display control mode
LCDWrite(LCD_COMMAND, 0x09); //temperature control
LCDWrite(LCD_COMMAND, 0x0C); //Set display control, normal mode.

Great tutorial! However (at least IMHO) you have missed the best 5V to 3.3V level translation option which is usually the 74ahc family. In this case the 74ahc367 hex tristate buffer provides the necessary 5 outputs (with one section unused) for the translation in a single 16 pin DIP package. Note despite some information on the net, the 74HC series is not (at least safely) 5V tolerant. On 74hc there is a clamp diode to vcc on the input which will draw a lot of current when driven with a 5V input. The secret is this line on the data sheet:
Not 5V tolerant 74hc367 (at least not without heavy current draw!):
Input clamp current, IIK (VI < 0 or VI > VCC) (see Note 1) ±20 mA
5V tolerant 74ahc367
Input clamp current, IIK(VI< 0) –20 mA
the -20 ma indicates no output clamp diode present as does the lack of VI > VCC on the ahc parts.
    Note the 74ahc transceivers (such as the 74ahc245) are not 5V tolerant, the possibility the pin can be an output apparently requires the vcc clamp diode, but the buffers, 4 bits 74ahc125, 6 bits 74ahc365/367, 8 bits 74ahc240-244 and 74ahc541 (better pin out!) are all 5V tolerant on their input pins and are all available in dip packages. 
    For the Nokia this setup is working for me (I pulled all the 367 inputs up to 3.3v via a 100K 9 pin SIP bussed resistor pack, pulling up to 5V works as well but requires an extra wire for no real gain assuming 3.3v is above the Arduino input threshold).
Arduino pin 74ahc367 pin           nokia lcd            signal name
gnd        1          -        oe1/     tristate enable active low
 7                 2          -            sce/     chip select in  (5V)
 -                 3          3        sce/     chip select out (3.3v)
 6                 4          -        rst/     reset in  (5v) 
 -                 5          4        rst/     reset out (3.3v) 
 5                 6          -        d/c              data/command in  (5v)
 -                 7          5        d/c              data/command out (3.3v)
gnd        8          2        gnd      Ground
 -                 9          6        dn(mosi) mosi out (3.3v)
 11       10          -        dn(mosi) mosi in  (5v)
 -                11          7        sclk     sck out  (3.3v)
 13       12          -        sclk     sck in   (5v)
 -                13          -        unused   (3.3v output)
gnd       14          -        unused   tie to gnd or 3.3/5v (not floating!)
gnd       15          -        oe2/     tristate enable active low
3.3v              16          1        vcc      3.3V vcc

 9        - 330 resistor  8        LED      led backlight 


in the hookup doc a minor typo (the info is elsewhere, just not right here) pin numbers are missing in the "The data pins are connected as follows:"  box:
sclk
LED
should be:
7 sclk
8 LED
as well in Example Code 1: LCD Demo
the url on the codebender reference would be better as
https://codebender.cc/static/walkthrough/page/1
which will step you through autoloading and testing the necessary drivers (which the download  button doesn't!) to make codebender work (at least on Firefox). Very handy application for  quickly trying some code!
Peter Van Epp

Concerning the off-by-one error...

The line defining the bitmap for the backslash character will cause problems if there isn't a space after the backslash character:

  ,{0x02, 0x04, 0x08, 0x10, 0x20} // 0x5c \

Without a space after the \ the following line will be treated as part of the // comment and thus ignored and this will cause an off-by-one error for all following characters.

Hey all - I found Russky's comment extremely helpful. Changing

SPI.transfer(data); //shiftOut(sdinPin, sclkPin, MSBFIRST, data);

to this:

shiftOut(sdinPin, sclkPin, MSBFIRST, data);

solved my problems.

Also regarding the off-by-one character issue: there seems to be an error in the ASCII[] array. The array item for the character ']' is listed twice:

  ,{0x00, 0x41, 0x41, 0x7f, 0x00} // 0x5d ]
  ,{0x00, 0x41, 0x41, 0x7f, 0x00} // 0x5d ]

Deleting one of those lines solves the off-by-one problem.

Cheers!

For those interested, I was able to scroll images across the screen by simply adding a simple new function of getPixel that allowed me to essentially loop over my image, getting the current value at a location, then placing that value slightly left or right on the display, over and over, scrolling the image left or right.

// get a single pixel
int getPixel(int8_t x, int8_t y, char *image) {
  if ((x < 0) || (x >= LCD_WIDTH) || (y < 0) || (y >= LCD_HEIGHT))
    return 0;

  return (image[x+ (y/8)*LCD_WIDTH] >> (y%8)) & 0x1;  
}

Hope this helps others!

Anyone know how to write a function that would scroll a bitmap (such at the sample xkcd cartoon) across the screen coming from completely off the screen on one side to off the screen on the other side?

I've done something simple with using GotoXY, but that has problems with the wrapping of the image. I think I need to write parts of the xkcd bitmap to parts of the displayMap array but I'm finding that difficult to calculate how to do that.

I followed the writeup for the hookup and copied the code provided into a sketch. The code compiles and runs, but I don't see anything on the display. I DO see the LED backlight brightness changing, so the coad has uploaded and runs...

I've played around with a few things. I can modify the LED backlight, and can send data to the serial monitor with debug statements configured to show the bytes that LCDWrite is sending out the data line. So it's TRYING to do something. I've experimented with the screen contrast and have tried changing the write method from SPI back to the commented out shiftOut statement.

I've also downloaded the sketch: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/LCD/Monochrome/Nokia_5110_Example.pde which runs and displays to the LCD, but there is something weird going on with the ASCII table. Sometimes it works, but also I'm getting values that are off by one, and other values that are gibberish.

Any suggestions?

When I click on the link to download LCD Assistant I get a message that I'm being blocked. Anyone else getting that or am I just special?

For me the PCD8544 is what I use instead of the typical 16x2 lcd screens. Not only can you do more with it, I think ease of use and connecting it up is about the same.