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61  Using Arduino / Displays / Re: LCD display not working anymore : how to know where the problem comes from ? on: June 30, 2014, 08:33:19 pm
What happens if you put pressure on the bezel (the metal frame around the LCD glass)?  Make sure the power is applied and don't press too hard.

Don
62  Using Arduino / Displays / Re: LCD display not working anymore : how to know where the problem comes from ? on: June 30, 2014, 11:59:31 am
What do you see if you connect the power, contrast, and backlight (pins 1, 2, 3, 15, 16) only - no Arduino involved except to possibly supply the power?

Don
63  Using Arduino / Displays / Re: More trouble with my LCD on: June 28, 2014, 08:04:45 pm
Quote
But do you know that lots of these larger breadboards have a separation in the center of the power rails ?
If you did not know that, you should check if that is the case with your breadboards.
The breadboards with a separation in the center of the power rails also have a separation in the red and blue lines next to those rails so at least that is not part of his problem.

Don
64  Using Arduino / Displays / Re: 16x2 LCD Display 1 line only! Help! on: June 25, 2014, 04:21:08 pm
It looks like the library is ignoring your lcd.begin(0,0) statement and using the default which is for a 16x1 display. 

This is an unfortunate choice for a default value since there aren't many 1-line displays out there, 16x1 or otherwise.  The vast majority of 16x1 displays are configured as 8x2 and must be initialized as such.


Don

65  Using Arduino / Networking, Protocols, and Devices / Re: Problems with AT commands to Bluetooth HC-06 on: June 24, 2014, 02:39:07 pm
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so  how can I change the baud rate again?
Use another terminal program such as 'Br@y's Terminal' which apparently is now just called 'Terminal'.
https://sites.google.com/site/terminalbpp/


Don
66  Using Arduino / Displays / Re: LCD keypad shield (dfrobot) doesn't work on: June 23, 2014, 05:45:30 pm
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I think that the LCD is defective.
I doubt it since you are getting the single row of blocks.  This means that it internal routines have (incorrectly) initialized the controller and your program code, which would correctly initialize the controller, has not done it's job.

Don
67  Using Arduino / Displays / Re: LCD tutorial hello world on: June 23, 2014, 05:40:21 pm
Just connect power to pins 1 and 2 and see if the ICs or black blobs on the back of your LCD module are getting very hot.

If they are hot then reverse pins 1 and 2 and check again. 

When the device is cool with the power applied you can follow the rest of my generic procedure.

Here is my generic step by step approach that should work:

(1) If the module has a backlight then get it working properly.  This involves only pins 15 and 16 on most LCD modules.  Make sure to use a current limiting resistor if there is none on the LCD module.

(2) Get the power and contrast working properly.  This involves only pins 1, 2, and 3 on most LCD modules.  You should be able to just barely see blocks on one row of a two row display and on two rows of a four row display. 

NOTE:  The Arduino has not been used yet, except as a possible source for the power needed for the first two steps.  Do not try to go any further until this is working.  If you don't see the blocks then no amount of program code will help.

(3) Connect the LCD R/W pin (pin 5) to GND.

(4) Connect the six control and data wires between your LCD module and your Arduino.

(5) Upload your sketch and it should work.


Troubleshooting:

If you have a 16x1 display and there are blocks only on the left half of the row in step 2 then use lcd.begin(8, 2); in your sketch.

If you still don't get a display then make sure that your wiring matches the numbers in the descriptor (or vice versa).


Code:
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);      // put your pin numbers here

If you get a display but it is garbled or has some other problems then try again with a 'static' sketch, one that displays a simple message on the top row of the display and then stops.  All of your code should be in setup() and loop() should be empty between the brackets.

Code:
#include <LiquidCrystal.h>

//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);      // put your pin numbers here

void setup()
  {
  lcd.begin(16, 2);                          // put your LCD parameters here
  lcd.print("hello, world!");
  lcd.setCursor(0,1);
  lcd.print("it works!");
  }

void loop()
  {
  }

If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module.  We also need a copy/paste version of the code that you are actually using, not a link to the code that you think you are using.

Don


68  Using Arduino / Displays / Re: LCD 16x2 + PCF8574T black boxes problem on: June 23, 2014, 10:42:54 am
Quote
Don't kill me for my creativity
Resistor symbols should have three complete zigs and three complete zags.

Don

Sorry, I couldn't resist.
69  Using Arduino / Displays / Re: LCD keypad shield (dfrobot) doesn't work on: June 23, 2014, 10:36:46 am
Once again... Are you sure that the program code is being downloaded into your Arduino?

Add some code to loop() that will blink an LED to find out.  Make sure that it is a different LED or a different blink rate than the default 'blinky'.


Don
70  Using Arduino / Displays / Re: LCD tutorial hello world on: June 23, 2014, 10:28:33 am
Quote
Pin1 should be the Ground and pin2 should be Vcc(5V).
For most, but not all, LCD modules.

Are the ICs or black blobs on the back of your LCD module getting very hot?



Don
71  Using Arduino / Displays / Re: Need help to drive RGB backlight in a RG12864A Graphic LCD on: June 22, 2014, 08:04:19 pm
Quote
But why it was flickering?
Possibly because the resistor shouldn't have been there.

Don

72  Using Arduino / Displays / Re: Need help to drive RGB backlight in a RG12864A Graphic LCD on: June 22, 2014, 04:02:07 pm
Quote
How can i measure milliamperes at led terminals? I should desolder all the backlight module, or there's another way?
Circuit Theory I - Ohm's Law.
Measure the voltage across the resistor pairs that you identified in the photo....


Don
73  Using Arduino / Displays / Re: LCD keypad shield (dfrobot) doesn't work on: June 22, 2014, 03:49:19 pm
Quote
Do you think that the potenciometer is the problem?
No, because you can see the black rectangles on the first line of your display.

Your display is not being initialized properly.  Are you sure that the program code is being downloaded into your Arduino?


Also, have you read the very first thread in this section of the forum?  It is the one that is 'sticky' so it always appears first, the title is 'bold' so it stands out, and it says "Warning to users of some vendors LCD keypad shields".

The particular shield that initiated that thread is a DF Robot LCD Keypad shield although it might be an earlier model than the one you have.


Don
74  Using Arduino / Displays / Re: Need help to drive RGB backlight in a RG12864A Graphic LCD on: June 22, 2014, 12:19:41 pm
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I tought maybe i need a resistor on the backlight VCC and nothing on the R G B pins...
According to the circuit diagram there already are current limiting resistors in series with each LED.  Of course the diagram already is suspect so we can't be sure.

Do you have a milliammeter?  You could measure the backlight current with each individual LED enabled and see if the value is reasonable.  That would enable you to determine if there are resistors on the pc board.

Putting a single resistor in series with the backlight VCC will limit the current but the results may not be visually acceptable.  It is difficult to choose a resistance that will be correct for each color LED and for each combination of parallel LEDs.


Don
75  Using Arduino / Displays / Re: Need help to drive RGB backlight in a RG12864A Graphic LCD on: June 22, 2014, 09:43:33 am
The diagram shows PNP transistors connected the way one would normally connect NPN transistors. 

My guess is that the description is correct and the diagram is incorrect.  What happens if you just connect the R (or the G or the Y) pin directly to GND?


Don
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