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Absolute noobie - please accept my ignorance - looking to learn. Question regarding results of Uno and LCD w/I2C Controlled + Keypad Shield kit (Adafruit PID# 772)

Assembled LCD assembly w/o any apparent problems. Shield sits well ontop of UNO.  Uploaded the Adafruit specified "Hello World" sketch. Upon applying power (8x1.5 alkaline AA) the LCD screen lights a bright blue for app 0.5 sec then goes dark.  The words "Hello World" display faintly, along with the counter which increments 1 per second.

Question one:  Is the blue background that initially displayed, supposed to remain lit?

If I press the "Select" buttion, the blue screen illuminates, the word "Select" is displayed, and the counter continues to increment.

Question 2:  Is this what is supposed to occur?

I'm sure there are more queries to come, but need to wrap my head around this first.

Thanks.

Ken

Welcome to The 'Duino Zone.  The chances of finding someone to help with experience with your exact equipment or probliem is much greater over at the vendor's forum.

Even LadyAda endorses this policy when she says: "If you need help getting other LCDs to work, please contact the place you purchased it from, they'll be happy to help!"

Photo

Important Info

Never the less, I will endevor to assist you. Point number ONE:  Zee little orange pot on zee right hand side is for adjusting zee contrast of zee LCD display screen.  You should gently  adjust it as needed.   Point number TWO:  One or more of your batteries could  be bad, which usually results in diminished voltage level and/or current capacity.   Point number THREE:  According to the data sheet for the HD44780 you are over driving the display voltage wise.  It says: Power supply for LCD drive VCC –V5 = 11 V (max).  That might be confusing but the other way that is said is easy to understand:  Wide range of liquid crystal display driver power is 3.0 to 11V Your battery power pack is 8*1.5=12 V.  I would find a way to cut back on the voltage a bit; I think it will help the display to last longer.   Point number FOUR:  The data sheet for the I2C port expander chip makes mention that the chip will function as intended when the circuit design meets these requirements: Operating voltage: - 1.8V to 5.5V @ -40°C to +85°C - 2.7V to 5.5V @ -40°C to +85°C - 4.5V to 5.5V @ -40°C to +125°C And I don't see any voltage regulator chips installed on that shield.  The user guide should have indicated to you the appropriate input voltage.   Point number FIVE:  IMHO, optimum care and feeding of this shield calls for 4.5 volts.  That is only three 1.5 volt cells and the shield will even function reliably under most conditions with only 3 volts.

And just so you know:

-=Syntax Matters=-

See that little trimmer above the switch. Turn it with a screw-driver it should adjust the screen contrast.

Did you load a sketch onto your Arduino? What were you expecting it to do?

As to the other questions - Billabot is right - join the Adafruit forum, they are pretty good.

Explore!

Thank you for the replies.

Point number ONE:  aware of same, can see change in contrast of characters when turned. No blue however.

Point number TWO:  I understand.  Same results when using USB cable as power

Point number THREE: See #2

Point number FOUR: User guide recommended power supply used. It is drawing 5V from the UNO.

See that little trimmer above the switch. Turn it with a screw-driver it should adjust the screen contrast. See #1

Did you load a sketch onto your Arduino? What were you expecting it to do?

1. Yes.  I was expecting the words “Hello World” to display on the LCD, against the blue background (as per the photo).

Sorry I bothered you folks – I’ll go seek a bit of support elsewhere.

Thank you for the replies.

Point number ONE:  aware of same, can see change in contrast of characters when turned. No blue however.

Point number TWO:  I understand.  Same results when using USB cable as power

Point number THREE: See #2

Point number FOUR: User guide recommended power supply used. It is drawing 5V from the UNO.

See that little trimmer above the switch. Turn it with a screw-driver it should adjust the screen contrast. See #1

Did you load a sketch onto your Arduino? What were you expecting it to do?

1. Yes.  I was expecting the words “Hello World” to display on the LCD, against the blue background (as per the photo).

Sorry I bothered you folks – I’ll go seek a bit of support elsewhere.

It is no bother at all.  So, it appears that the only issue is the voltage going into zee back light circuit. 

It is a curious challenge and we like challenges - especially curious ones.

One possibility I can think of is a cold solder joint that is intermittant after power on.  Suggest you do the wiggle test on all components.  Otherwise you might try putting the circuit in a sealed bag in the freezer for 30 minutes and then plug it in and see if it takes longer for the thermal expansion of the hypothetical troublesome joint to cause a loss of continuity; UNLESS you have a can of  MULTICOMP DIAGNOSTIC FREEZE AEROSOL on hand then you could use it.  Hope this helps to solve this curious problem.

Another possibility is that your sketch contains code similar to the code in the A.S.S. below and may be the cause of your "problem".  It is very clear that the backlight is being turned OFF via the sketch.  Hey, Ken, here is a little something for you to remember: "Technical problems can only come from one of three sources:  Hardware, Software, or Operator."

Sourced from here.

I would be ever so interested in seeing the sketch, Ken.  Would you provide a link or paste the sketch into your reply here as I could not locate it on the Adafruit site?  An easy test for you to do and could help you learn is put your own sketch together with the above snippet and run it; then comment out the last line with the write(18) so that the backlight stays on.  Good luck.

As always, please remember that:

-=Syntax Matters=-

Thank you, Sir, for your reply.  As a new kid to the world or soldering (its been 30 some odd years since I soldered a board!) I wondered if a cold joint might be the culprit.  Especially since the blue screen will illuminate upon the application of power, then extinquish.   The text “Hello World” does display on the screen, albeit in dark grey characters, absent of the bright blue illumination.

I will take another look at the joints and see if the challenge lies there.

Again, this LCD shield is attached directly onto of the Arduino UNO.

For the sketch, here it is, from the Adafruit LCD assembly and wiring website:

/*********************

Example code for the Adafruit RGB Character LCD Shield and Library

This code displays text on the shield, and also reads the buttons on the keypad.

When a button is pressed, the backlight changes color.

**********************/

// include the library code:

#include <Wire.h>

#include <Adafruit_MCP23017.h>

#include <Adafruit_RGBLCDShield.h>

// The shield uses the I2C SCL and SDA pins. On classic Arduinos

// this is Analog 4 and 5 so you can't use those for analogRead() anymore

// However, you can connect other I2C sensors to the I2C bus and share

// the I2C bus.

Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();

// These #defines make it easy to set the backlight color

#define RED 0x1

#define YELLOW 0x3

#define GREEN 0x2

#define TEAL 0x6

#define BLUE 0x4

#define VIOLET 0x5

#define WHITE 0x7

void setup() {

  // Debugging output

  Serial.begin(9600);

  // set up the LCD's number of rows and columns:

  lcd.begin(16, 2);

  // Print a message to the LCD. We track how long it takes since

  // this library has been optimized a bit and we're proud of it

  int time = millis();

lcd.print("Hello, world!");

  time = millis() - time;

Serial.print("Took "); Serial.print(time); Serial.println(" ms");

lcd.setBacklight(BLUE);

}

uint8_t i=0;

void loop() {

  // set the cursor to column 0, line 1

  // (note: line 1 is the second row, since counting begins with 0):

  lcd.setCursor(0, 1);

  // print the number of seconds since reset:

lcd.print(millis()/1000);

  uint8_t buttons = lcd.readButtons();

  if (buttons) {

    lcd.clear();

lcd.setCursor(0,0);

    if (buttons & BUTTON_UP) {

lcd.print("UP ");

lcd.setBacklight(RED);

    }

    if (buttons & BUTTON_DOWN) {

lcd.print("DOWN ");

lcd.setBacklight(YELLOW);

    }

    if (buttons & BUTTON_LEFT) {

lcd.print("LEFT ");

lcd.setBacklight(GREEN);

    }

    if (buttons & BUTTON_RIGHT) {

lcd.print("RIGHT ");

lcd.setBacklight(TEAL);

    }

    if (buttons & BUTTON_SELECT) {

lcd.print("SELECT ");

      lcd.setBacklight(VIOLET);

    }

  }

}

Hope this may shed some light on the issue – and my lack of understanding.

But hey, we all have to start somewhere.

Thanks again!

That's cool.  The two header files (#include xxxx.h) can be accessed from github.com. 

The sketch you are attemping to use is really designed to demonstrate the capabilities of the RGB LCD which you do not have.  So go forth and learn or ask LadyAda's team to provide a more appropriate sketch for the product you purchased from AdaFruit.

Some suggestions for Adafruit as to modification of the LCD DEMO SKETCH:

Query the LCD module (user input) for its Identity and conditionally jump to a code segment to show the new users what it is capable of.  In the case of the blue and white LCD, I would think that the buttons should demo the blinking, left and right scrolling, and custom character capabilities.  Many of these capabilities are demonstrated on youtube and other sites across the internet.

Additionally,  I want to thank Ken Quimby most sincerely for his question, because I believe he has helped me to uncover a veritable Gold Mine of Arduino Sketches at Parallax.com. http://learn.parallax.com/kickstart/27977

Bill, you are most kind.  I'm glad you perhaps found an additional resource as a result of my inquiry.  As they say here in Arkansas - "Every now and then, even a blind hog finds an acorn."  I feel as though I'm that hog, having stumbled upon this site.

Thanks again.

Ken  (in AR)

You're welcome, Ken.  (Go Razorbacks!)

I am so impressed with what Parallax.com has come up with and made availlable beginning in May of 2012 that I want to share it with everyone.  They have a 'Duino shield called Board of Education Shield (for Arduino) and the price is around $30.  But it is not just the hardware, the real added value is the beginner's content that totally fulfills the  STEM (Science, Tech, Engineering, and Math) curriculum needs of our young people.  This is AWESOME!  The complete kit to learn and build a 'Duino BOE-BOT is around $120.