LiquidCrystal I2C

by platypus on Mon Feb 04, 2013 10:48 pm

The LiquidCrystal-I2C sketch wont compile and gives this error ..no matching function for call 'LiquidCrystal::LiquidCrystal(int)'

The 'regular' Liquid Crystal sketch in the same Examples folder compiles OK - no errors.

All the support .c and .h files are in the new (I2C) LiquidCrystal library folder and the regular LiquidCrystal compiles.

Any ideas?
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Re: LiquidCrystal I2C

by adafruit_support_bill on Tue Feb 05, 2013 6:13 am

Did you remove the old LiquidCrystal Library?
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Re: LiquidCrystal I2C

by platypus on Tue Feb 05, 2013 7:46 pm

Yes eventually, but first I just renamed the folder and later decided to place this folder within another folder.

Then it worked as the compiler could not see it.

My bad - should have followed your notes to the letter. Thanks for your reply.
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LiquidCrystal I2C - background light intensity

by platypus on Tue Feb 05, 2013 7:52 pm

Do you have a method to reduce the intensity of the background light?

The Contrast only affects the characters leaving the "blind your eye" background light.

I read somewhere that pin 15 via a resistor/pot might work.

If so, can you recommend a suitable trimpot size and or procedure to effect a reduced intensity level?
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Re: LiquidCrystal I2C

by adafruit_support_bill on Tue Feb 05, 2013 8:02 pm

You would probably need a few hundred ohms or so, depending on how much you want to dim it. It would be tough to get at on that board though without de-soldering the display. Another option would be to put it behind a smoked acrylic faceplate.
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Re: LiquidCrystal I2C

by platypus on Tue Feb 05, 2013 8:37 pm

Thanks, that's exactly where it's going - behind dark tinted 3mm polycarbonate. However I still want to dim the backlight.

But is it pin 15 that should be broken - easy to do before assembly. The pot can be mounted between the screen and I2C pcb as I have lifted the I2C board 3mm using two short pieces of heat shrink at the end terminals before soldering from the center outwards. This also gives a nice space between the two boards.

For anyone there who is interested, I had to stop the annoying update blink screen refresh by this method - if anyone knows of another I would be interested.

In void loop()

lcd.setCursor(0,0); //sets beginning of line 1
lcd.print( your code for line 1);
lcd.setCursor(0,1); //sets beginning of line 2
lcd.print(your code for line 2);
// no more blink
Comment - this causes a refresh of each line without any blinking, giving a nice update of the sensor data.

If lcd.clear();
is used the whole display will blink annoyingly - at least with this 2 line charactor lcd screen.
With my older Freetronics lcd screens that use 6 lines there is no blinking. Different tech.
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Re: LiquidCrystal I2C

by adafruit_support_bill on Tue Feb 05, 2013 8:59 pm

Pin 15 should work. But if it is an RGB backlight, the colors may shift a bit as you dim it. To balance the colors, you would need individual trim-pots on pins 16, 17 & 18.
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Re: LiquidCrystal I2C

by platypus on Tue Feb 05, 2013 9:38 pm

I used the 1K trimpot that came with the white on blue 2 line character screen.

I cut the pin 15 header - as I had lifted it 3mm it was easy to just take out a piece to break the line. Then just added the trimpot across the board terminals - works perfectly.

Thanks for your help.
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LiquidCrystal I2C

by zdendule on Thu Feb 07, 2013 8:30 am

Hallo,
Can anybody help me? I have plugged converter from I2C to 4bit for LCD, I implemented your library and compile is OK. But LCD not show characters and backlight blinking chaotic. The wires are plugged by right. Which format I must write the number of adress I2C to sketch. A7 or 0xA7? I don´t know where is problem.
Last edited by zdendule on Thu Feb 07, 2013 10:33 am, edited 1 time in total.
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Re: LiquidCrystal I2C

by adafruit_support_bill on Thu Feb 07, 2013 8:49 am

Post photos showing the front and back and all your connections and we will check it out.
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Re: LiquidCrystal I2C

by zdendule on Fri Feb 08, 2013 8:32 am

OK, thank you. There are photos.
IMAGE_123.jpg
I2C
IMAGE_123.jpg (758.18 KiB) Viewed 1090 times
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Re: LiquidCrystal I2C

by zdendule on Fri Feb 08, 2013 8:34 am

And second photo.
IMAGE_124.jpg
interface
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Re: LiquidCrystal I2C

by adafruit_support_bill on Fri Feb 08, 2013 8:37 am

That doesn't look like one of our display backpacks.
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Re: LiquidCrystal I2C

by zdendule on Mon Feb 25, 2013 4:36 am

Yes, I firstly found interface on web and past it I found library for it. But during the search I found your forum.
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Re: LiquidCrystal I2C

by adafruit_support_bill on Mon Feb 25, 2013 5:56 am

You should contact the manufacturer. Unless their hardware implementation is identical to ours, there is no guarantee that our library will work.
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