It doesn't sound like the LCD is being powered up on it's Vcc Pin (2)... and the device is getting it's power through input protection diodes (Diodes from input pins to BOTH Vcc and Ground)... Pulling D4 should NOT make the LCD Quit working. The LCD is almost CERTAINLY, NOT wired correctly as the LCD will show a black bar where the characters are displayed with pins 1 (Gnd), 2 (Vcc) and 3 (Contrast) connected ONLY. R/S, E, R/W and data lines would NOT change that. It sounds like the contrast pot is wired correctly (Pot Wiper pin to 3, Pot CCW pin to 2 (Vcc) and Pot CW pin to 1 (Gnd). However even if those connections are good on the LCD the LCD Vcc pin Must be connected to +5V (Arduino) and the LCD Gnd Pin Must be connected to the Arduino Ground (All at the Arduino board) FIRST. IMO
i desoldered all pins except pin 15 (a) and pin 16 (k). acording to the tutorial the backlight should power when connecting pin 15 to 5v through a resistor (220 ohms in my case since i cant find the datasheet) and when pin 16 is connected to ground.
results: just like i said before - > no backlight..
here are some pictures in case you was going to say im not wiring my pins correctly..
We need a single (one) photograph that will let us unambiguously see both ends of all of the connections. It has to be bright enough to reveal detail and it also has to be in focus.
Also - 220 ohms is probably way too high for an LCD backlight. Is that the size you were using when it worked before?
From the tutorial:
If you can't find the data sheet, then it should be safe to use a 220 ohm resistor, [b]although a value this high may make the backlight rather dim.[/b]
No. I need at least one picture that shows both ends of each of the wires. It has to be in focus and it has to be correctly exposed. DSCF5878.JPG might have been suitable except it is is too dark and it is out of focus.
A close-up of your solder connections (both sides) would be helpful as well. DSCF5891.JPG is close but it is also out of focus and so dark that the black wire is almost invisible.
no, i am afriad i had killed the fuse of my multimeter some while ago
The voltmeter function frequently works even if the fuse is bad. Measure the voltage across the resistor and calculate the current.
& no i have no smaller resistors.
Do you have another resistor that you can put in parallel with the 220 ohm resistor?
oh yes, ill look into the resistor to put them parralel with another resistor,
anyway, how come you didn't mention DSCF5903.JPG and DSCF5917.JPG since i thought these were my best pictures sended
edit; i used the voltage meter to messure the voltage on a led, but it just keeps showing 0.00 volt so its broken somehow (i did try to messure both current and voltage on the lcd but it show 0.00)
anyway, how come you didn't mention DSCF5903.JPG and DSCF5917.JPG since i thought these were my best pictures sended
DSCF5903.JPG - The resolution is too low. I cannot tell where the black wire goes at the Arduino end or at the LCD end. I cannot read the resistor value.
DSCF5917.JPG - The black wire is not visible against the black table. The resistor value is obscured by the black wire. The Arduino terminals are not identifiable.
The devices were moved between the times that these two pictures were taken. Who knows what else changed?
edit; i used the voltage meter to messure the voltage on a led, but it just keeps showing 0.00 volt so its broken somehow (i did try to messure both current and voltage on the lcd but it show 0.00)
That means that there is no current flowing (assuming that the voltmeter is OK).
Did you try measuring the voltage coming out of the Arduino? If you measure 5 volts there then you know that the meter is good and something else is causing the problem. You could have blown out the LED backlight or you could have a poor connection to that backlight.
massive breakthrough:
i bough new fuses and replaced the old fuses in my multimeter, i started some tests and i noticed that there was no flow at all.
to be sure i hooked up a 220 ohm resistor and a led, to the power lines on the breadboard. when i powered the circuit from arduino it didnt do anything, no led was going on.
now when i changed the power jumper wires from the arduino to the breadboard ... led led went onn! now that is exciting
anyway i took a closer look at the jumper wires and noticed that one of the pins on the black jumper has broken off and was not connected in the inside rubber end.
now i hooked up the backlight circuit of the lcd and powered arduino: lcd backlight works just fine! so you guys were correct from the beginning: my connections failed!
anyway ill let you know when i got the lcd working and i will never doubt anybody's opinion here ever! :3
thanks alot for all efford, and sorry for being a bit frustrated..
