I am having problems displaying text with my duemilanove on a 16x2 lcd. I did wire the setup based on this http://arduino.cc/en/uploads/Tutorial/lcd_bb.png . I am 100% sure the setup is correct. I also used GND and +5 V from the arduino to turn on the blacklight using pins 15 and 16. I uploaded the code on the arduino( Hello world ), but it does not display on the lcd panel. I tried turning the pot both ways to adjust the contrast but no text. The blacklight works fine though. What am I doing wrong? Both the lcd and arduino are brand new. Thanks in advance.
The tutorial is sound so if it is not working you have done something wrong or your components are faulty.
I know you said:-
I am 100% sure the setup is correct.
But it is easy to miss something, like miss identifying pins or missing a ground wire or your breadboard being faulty.
Have you got at least a voltmeter so you can check voltages. When you turn the contrast control do you see the solid block or is there nothing?
No I don’t see the solid block. The pot is 10 K. Let me ask you: pin 16 ( - ) of the lcd is wired to one of the two GND inputs on the arduino and pin 15 of the lcd gets power from the 5 volts of the arduino right? Of course the pot gets power from the 5 V of the arduino too. i did not miss that. I wired things for the second time. I doubt I missed something
Yes I have a multimeter. Which voltage should I check?
UPDATE: I got it working. I don't know, something was not wired correctly. anyway, can someone please give me the code to get the arduino w/ lcd show what you are typing from the pc keyboard?
pin 16 ( - ) of the lcd is wired to one of the two GND inputs on the arduino and pin 15 of the lcd gets power from the 5 volts of the arduino right?
No if you are connecting the power the the back light you normally need a current limiting resistor.
You can get code examples from:-
to get stuff from the keyboard you have to read the serial port and then send this to the LCD
What value should the limiting resistor be? And how do I read the serial port?
Check your data sheet. Each display can vary depending on who made it and where and part numbers.
I have been using backlights without current-limiting resistors ;) ;D. I agree I should use one. If there's no datasheet, pick any value that works for you. I have one 220Ohm with one of my LCDs. Its backlight is barely noticable under normal indoor illumination but if I walk into a darkroom, the backlight is bright enough to make the panel readable. That's my way to tell.
I have been using backlights without current-limiting resistors
Yes and a lot of people have had their back lights burn out. As the LEDs in them are normally in series the resistors tend to be in the low ohm range 10 to 50R but check the data sheet.
how do I read the serial port?
Since I hadn't had a 100 ohm resistor, which my friend suggested, I used a pot without the middle pin. The backlight did not turn on. 100 ohms must be a lot for the backlight. so yea, 10 to 50R is probably the appropriate value. thanks. i will read for now and if I need add help i'll post.