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46  Using Arduino / Displays / Re: Problem combining Servo library with LCD and Wire Library. on: March 25, 2014, 09:34:14 am
After doing some trouble shooting, the problem doesn't occur until I specifically include the lcd.print("String") command for the lcd screen. Once I include that in my code, but servos become jittery when they should be stationary.

LCDs, especially those run via I2C, use lots of time delays.  Depending on how those delays are implemented in the library they very well could be having an influence on the operation of the servos.

47  Using Arduino / Displays / Re: Problem with pin congurations on: March 25, 2014, 09:25:52 am
... however, there is no indication of MISO or MOSi or DC or backlight pin.

Since that is a shield one would hope that they wired the board to match up with the corresponding pins on your Arduino.  After all that's the whole idea of using a shield.

One would also hope that you got some more information with your shield ....

48  Using Arduino / Displays / Re: Problem with LCD Shield. on: March 25, 2014, 09:09:51 am
What could be the problem? The compatibility with LiquidCrystal Library? I should use LCD 4-bit library? Or another thing?

We really need to know more about the specific device you have.  Is it really a 'shield' that plugs directly into your Arduino or is it a separate pc board that has to be connected with jumpers?

I think that is a 'Powertip' part number and as I recall some of them are use a non-standard pinout.

The LiquidCrystal library should work if you connect things correctly and set up the parameters correctly.

The LCD 4-bit library should be deleted from your computer so that you don't use it by mistake.  It is a poorly written library (read the comments if you want proof) that was cobbled together before the standard LiquidCrystal library was updated several years ago.

49  Using Arduino / Displays / Re: Help about phi_panel using analog pins. on: March 25, 2014, 08:58:28 am
Link is ok,  but from some strange reason last ")" is not notices as part of url.
That often happens to me when I use the editing buttons so maybe it's a feature of the forum software.

Go back and edit your post to put the last ")" before the "[/url]". 

It's always a good idea to preview your posts and check out the links before you actually submit them.

50  Using Arduino / Displays / Re: Help about phi_panel using analog pins. on: March 24, 2014, 09:24:46 pm
I appreciate any help since I new to arduino and phi_panel!
If that's a real phi-panel then you should be able to get help from the developer of the panel, liudr, here -->


PS: You might want to fix your link.
51  Using Arduino / Displays / Re: Help. LCD Stopped working when DC Motor is connected on: March 24, 2014, 09:16:58 pm
Any thoughts guys and gals?? This is a school project due in a week!
You could try searching this forum for other similar cases.  The same problem crops up with relays, solenoids, and anything else that's basically a coil of wire.

The search function provided with this forum software is slightly better than useless.  Try a Google search using this syntax:
--> search phrase

52  Using Arduino / Networking, Protocols, and Devices / Re: Wireless connection between two Arduino's on: March 24, 2014, 06:49:48 pm
So, if possible, please help!
If you search for Arduino mailbox notifier you might get a few hundred thousand ideas!

53  Using Arduino / Displays / Re: scrollDisplayLeft() with Yellow IIC/I2C/TWI 1602 Serial Backlight LCD Display on: March 24, 2014, 02:37:59 pm
Can someone please confirm that scrollDisplayLeft() is supported for LCD connected via I2C
That would depend upon the specific I2C library that you are using.

Most of them are based upon the regular LiquidCrystal library so they should perform in a similar manner.

Unfortunately the library usage of the term 'scroll' corresponds to the LCD controller term 'shift' which may not do exactly what you expect.  What actually happens is that entire display, all of the lines, are shifted simultaneously.

54  Using Arduino / Displays / Re: from 16x2 to 16x4 frequency analyzer on: March 24, 2014, 12:59:59 pm
You should start out by changing   lcd.begin(16, 2);    to     lcd.begin(16, 4);    

Now, in a perfect world,  you should be able to set the cursor with lcd.setCursor(j, 2); or lcd.setCursor(j, 3); for the appropriate line.

Unfortunately the LiquidCrystal library does not deal with 16x4 displays correctly so without some changes to your code or to the library your output is going to be offset by four spaces.

Here are some previous threads dealing with the problem.      September 19, 2009      March 13, 2010      June 06, 2011      August 20, 2011      February 26, 2012       September 28, 2013

There is a thread with a very simple fix.  Look at reply #18   June 17, 2012

55  Using Arduino / Displays / Re: DV-20208 on: March 24, 2014, 08:44:57 am
Why?  The pinout is provided on the link in his second post.

56  Using Arduino / Displays / Re: DV-20208 on: March 23, 2014, 08:24:53 pm
It looks like you should skip step 1 since:
   (1) your backlight requires more than 5 v to operate.
   (2) the seller recommends a 14 pin connection so apparently this LCD is visible without a backlight.

If you don't have a potentiometer for the contrast then try it with pin 3 connected to pin 1.  The display will be blank if you let pin 3 float.


57  Using Arduino / Displays / Re: Variables not showing on LCD screen on: March 23, 2014, 05:13:18 pm
Your LCD screen does not display your 'msg' the way that you expect.

Although it can display a total of 32 characters the messages do not wrap from the first line to the second the way you would think.

If you send 40 sequential characters to a 16x2 display the first 16 will be displayed on the top line and the next 24 will not be displayed at all.

For the reasons behind this unusual behavior follow the LCD Addressing link at

You will have to break your messages into two 16 character chunks and send the first to the first line and the second to the second line.

58  Using Arduino / Displays / Re: Using the LCM1602, What is the REAL Code for the Adruino Leonardo? on: March 23, 2014, 03:38:11 pm
Another related problem is that many vendors are now using terms such as "Arduino compatible" and "for Arduino" in their descriptions. 

This will eventually cause their web pages to show up in a search for Arduino and the phrasing is is not really incorrect since these devices will indeed work with the Arduino (and just about every other microcontroller as well).   

My feeling is that they are also counting on the fact that prospective purchasers will assume these terms as meaning that their devices will connect as easily as a 'shield' and maybe even work with the libraries provided with the Arduino IDE (Integrated Development Environment) which is typically not the case.

59  Using Arduino / Displays / Re: DV-20208 on: March 23, 2014, 02:52:04 pm
When I hook it all up to the "Hello World" sketch for testing purposes I'm not getting anything on the display what-so-ever.
If it is really HD44780 compatible then it should work if you connect it correctly.

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 but I think yours is different.  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 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.

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

//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.

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.

60  Using Arduino / Displays / Re: Help!! Unknown GLCD pinouts. Can not find datasheet on: March 23, 2014, 10:21:35 am
Even on the board the last two pins (17 and 18) where not even connected. So it uses only 16 pins including the backlight.
Are you sure that this isn't a multilayer board?

Connect power to pins 1 and 2 and measure the voltage between pins 1 and 18.  Hopefully you will find a negative voltage at pin 18 with respect to pin 1.

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