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 16 Using Arduino / Displays / Re: LCD current draw on: July 20, 2014, 04:45:02 pm Quotei just said what is thew maximum voltage for the back light to operate according to the data sheet !!!You still don't understand the difference between a 'rating' and a 'characteristic'.  Once again, the 4.6 volts is not the maximum voltage that you can or should apply to the LED.  Rather, it is the maximum voltage drop that will appear across any of this type of LED when it is operating within it's ratings.  If you have a box full of these devices and you measure the voltage across each of their backlight LEDs when they are operating within their ratings you can expect to measure a wide range of voltages, but none of them should be more than 4.6 volts.What this actually means is that when you are selecting a power source you must make sure that it delivers more than 4.6 volts if you want to be certain that you can get every backlight to function.QuoteThe datasheet doesn't mention any current rating for the back light!!!Did you look at reply #3 or #5?QuoteAlso , something i didn't say before, i tried twice to turn on the back light ,at 4V, by pins 15-16 and nothing happened!!!!Because, as explained above, you must use a supply greater than 4.6 volts (with a current limiting resistor) to be sure to be able to get the LED to conduct.Don
 17 Using Arduino / Displays / Re: trying to understand the crystal library library on: July 20, 2014, 02:28:25 pm Quotewell i understand what the digits on the right of the letter B are for , but not the letter B itself and the zero to its leftThe initial zero is there to inform the compiler that this is a number.The 'B' tells the compiler that this is a 'Binary' number.Don
 18 Using Arduino / Displays / Re: Can't figure out how to use special segments at bottom of LCD 8X1 display on: July 20, 2014, 11:09:40 am QuoteCode:LiquidCrystal lcd(12, 11, 5, 4, 3, 2);Is called a C++ constructor.It is creating a global "object" from the LiquidCrystal class called lcd and the parametersare being passed to the LiquidCrystal library and are used to fill in other data fields insidethat object.QuoteThe library allows controlling more than a single instance of the hardware. (multiple LCDs)Each instance would get its own object.Let me try this without using any C jargon.  (Bill: Correct me if this simplification is incorrect)The 'lcd' part of the statement is really what we are discussing here.  This is the name that the programmer has arbitrarily given to his display.  He could have just as well called it 'mario' or 'plugh'.If your application calls for more than one display you can control any or all of them using the same library.  You would differentiate between them by giving each a display different name.Code:LiquidCrystal lcd(12, 11, 5, 4, 3, 2);LiquidCrystal mario(12, 10, 5, 4, 3, 2);LiquidCrystal plugh(12, 9, 5, 4, 3, 2);For a complete example see this thread: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1265969050What Bill is saying is that his code snippet only works with one display and you must use the name lcd for that display.  It's as simple as that.DonEdit: If you wind up in a cave it isn't my fault.  If you don't understand this disclaimer then don't worry about it, your hair probably isn't grey either.
 19 Using Arduino / Displays / Re: LCD current draw on: July 20, 2014, 10:31:14 am QuoteHowever it's not the same for the back light which has a maximum of 4.6V.You don't really understand the datasheet.  The voltage to which you refer is not a rating, it is a characteristic.   You do not apply a specific voltage to an LED, instead you apply enough voltage to get it to function and then you limit the current to its rated value, typically with a series resistor.When the current through the LED has been limited to the proper value you can then measure the voltage across the LED and it should be somewhat near the value in the datasheet.QuoteLCD 5V, Back light never lighted through pins 15-16, instead it destroyed some pixels.. Back light was ok through A and K on 3.3V and about 4V(external power source)... You may have damaged the backlight by applying a non current limited voltage directly to the A and K backlight pins but the destruction of any pixels is unrelated - unless you inadvertently applied the voltage elsewhere as well.  Don
 20 Using Arduino / Displays / Re: LCD black boxes problem! on: July 19, 2014, 11:52:55 am QuoteI have tried all of the above but still no good.Show us what the set-up and the display look like after step (2).Don
 21 Using Arduino / Displays / Re: 2004 LCD partially doesn't work on: July 19, 2014, 09:16:50 am QuoteIt is possible, during i2c scanning, ...Where did the original poster mention anything about I2C?Don
 22 Using Arduino / Displays / Re: Displaying date on LCD with DS1307 using button inputs on: July 18, 2014, 04:25:51 pm QuoteOkay. So what would be the cause of this conflict? The conflict is that you have chosen to use the same pin for both the push-button and for the LCD.QuoteBad = Pins 2,3,4,5,11,12,13Pins 2,3,4,5,11,and 12 are 'bad' because you are already using them for the LCD.Pin 13 may be bad because the on-board LED is connected to that pin.Don
 23 Using Arduino / Displays / Re: Lcd missing pixels on: July 18, 2014, 04:20:38 pm Quoteim gonna buy a new one. it was cheap anyway ... I still can't understand how it happened !!Try to find one that is inexpensive but not cheap.Don