16x02 display first try... help?

OK So I wired up a QC1602A to my arduino like this (taken from another help topic)
VSS to GND
VDD to 5V
V0 to a 10k pot
RS to pin 7
RW to GND
E to pin 8
D0-D3 blank
D4-D7 to pins 9-12 respectively
V to 5V
K to GND

and I used this code (also from another topic)

#include <digitalWriteFast.h>
#include <LiquidCrystal.h>

#define LED 13

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
pinMode(LED, OUTPUT);
digitalWrite(LED, HIGH);

// set up the LCD’s number of columns and rows:
lcd.begin(16, 2);

// Print a message to the LCD.
lcd.print(“Sad Arduino!”);
}

void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis()/1000);
}

And so long as that’s all wired up, my UNO won’t power. Not even the ON light
-Removing the wire back from the breadboard’s + to 5V allows it to power
-So does removing the breadboard-to-GND wire
-So does removing either wire going from K or V to the + or - lines of the breadboard
That indicates its the backlight?
Please help thanks (Im a little new to this whole thing but I pretty much get it)

Looked up some datasheet, backlight is reported 16mA.
That's no reason for it not to work, but you might want to consider using a resistor to limit the backlight current.
Check polarity / wiring again.

And print some happy message when you're done.

backlight is reported 16mA.

This means that the rated current is 16 mA.

but you might want to consider using a resistor to limit the backlight current.

No. You must use a resistor to limit the backlight current to no more than 16mA.

Don

floresta:

backlight is reported 16mA.

This means that the rated current is 16 mA.

but you might want to consider using a resistor to limit the backlight current.

No. You must use a resistor to limit the backlight current to no more than 16mA.

Don

Ok... so If thats the only thing in my Uno, what sorta resistor should I use (and on what pin)
Thanks for the help

The datasheet i found (click) is on the sparkfun site.
It states that the voltage to the backlight is 1.9 Volt, and not 5 volts (i didn't look for that).
This is an indication that there is no resistor built in the backlight circuit, and you indeed have to use a resistor.
If you don't know whether a resistor is present or not, assume it is not.
if you are powering it from 5 volts, and the LED needs 1.9 volts, then you have to select a resistor that burns the other 3.1 volts.
Using the formula U=I*R, you can use I=0.016 and U=3.1.
R would be R=I/U so 3.1/0.016= 193.75
So you take the next higher available value, which results in 220 Ohm in most cases.

220 Ohms is a value that you'll see more often while playing with your Arduino and LEDs.

MAS3:
The datasheet i found (click) is on the sparkfun site.
It states that the voltage to the backlight is 1.9 Volt, and not 5 volts (i didn't look for that).
This is an indication that there is no resistor built in the backlight circuit, and you indeed have to use a resistor.
If you don't know whether a resistor is present or not, assume it is not.
if you are powering it from 5 volts, and the LED needs 1.9 volts, then you have to select a resistor that burns the other 3.1 volts.
Using the formula U=I*R, you can use I=0.016 and U=3.1.
R would be R=I/U so 3.1/0.016= 193.75
So you take the next higher available value, which results in 220 Ohm in most cases.

220 Ohms is a value that you'll see more often while playing with your Arduino and LEDs.

OK Thanks for the help man. Originally the backlight was coming on for a moment but now it isn't, does that mean I have fried it? I can't try with a 220ohm right now as I don't have any. If I replace the wire from the backlight to ground with a 150ohm resistor, it is allowing the arduino to power (which is a start), but is not lighting up the display.
The earliest I can get my hands on a 220 ohm resistor is Monday, so I will have to wait until then if that is the reason. Thanks for your help.

It would help to know if the datasheet that MAS3 found is actually the correct one for your LCD module.

Don