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### Topic: New to LCDs (Read 3714 times)previous topic - next topic

#### liuzengqiang

#15
##### Jan 14, 2012, 10:40 pm
It's obvious that you can't pass step one since you didn't follow it. You didn't connect LCD pin 1 and 2 to ground and 5V. Disconnect LCD pins 15 and 16 now.

#### janeik

#16
##### Jan 15, 2012, 12:37 am
Hello.
You can nearly spot the backlight connection pins at the right side of dpy.
If he's eager to continue, he dont need the light unless its environment is dark?

best regards

Unfortunately, all of those resistors are too high to use as a series resistor for the backlight. [EDIT: the first is 1.5K, the second is 15K and the third is 3?K, I think you misread Silver because it doesn't make sense in that position.]

If you have a multimeter, you can check whether the LCD includes a backlight or not. Disconnect the wires to pins 15 and 16 of the lcd, then measure the resistance between each of those pins and the LED A and K connections (these are the two soldered connections at one end of the LCD). If you find that each of pins 15 and 16 is directly connected to one of the LED pins, then there is no built-in series resistor, and you risk burning out the backlight by not using one.

#### janeik

#17
##### Jan 15, 2012, 12:45 amLast Edit: Jan 15, 2012, 12:56 am by janeik Reason: 1
Congrat with Your arduino and display.

This guy is telling some about LCD if You understand english http://youtu.be/oIiDseJO4dM

In the tech. manual for display, You can read the typical voltage for the background light.
My display has maximum 4,6 volt and typical 4,2 volt ( You should try to achieve your display typical background voltage by connecting a serial resistor, as another poster said).

best regards

#### liuzengqiang

#18
##### Jan 15, 2012, 03:35 am

Congrat with Your arduino and display.

This guy is telling some about LCD if You understand english http://youtu.be/oIiDseJO4dM

In the tech. manual for display, You can read the typical voltage for the background light.
My display has maximum 4,6 volt and typical 4,2 volt ( You should try to achieve your display typical background voltage by connecting a serial resistor, as another poster said).

best regards

I know you want to help but if you read my post and inspected the picture, you should conclude that the OP failed to power the LCD. Unless OP powers the LCD, there is no need for more discussion.

#### bperrybap

#19
##### Jan 15, 2012, 10:10 am

I know you want to help but if you read my post and inspected the picture, you should conclude that the OP failed to power the LCD. Unless OP powers the LCD, there is no need for more discussion.

LIghten up a bit, it is supposed to be fun.
I thought the tutorial video was actually pretty informative.
If you look at the tutorial it goes really slow.
Step 1 does not use pins 1 or 2 (controller power and ground).
It only hooks up the back light.
The first step is even called: "Power and backlight"

The only danger with the tutorial on ladyada's site is that it assumes
that the lcd does not need a current limiting resistor as it is geared
towards the lcd she sells.

Yep, the wiper is hooked up, in preparation for the next step:
"Contrast circuit", be we are still on the first step of getting the backlight
to work.

Zippyvinman,
that last resistor color pattern maybe it is really
orange, gray (not silver), orange, brown, gold.
That would make it 3830 ohms which is still too high for current limiting resistor.

Best thing to do if you are stuck and don't have an ohm meter to check
for a current limit resistor on the lcd and really want to start playing with the lcd "now",
is to simply disconnect the backlight and then
proceed without it. With the type of display you have you will be able to see
the pixels without a backlight.

You can then come back later and deal with the backlight.

--- bill

#### floresta

#20
##### Jan 15, 2012, 03:11 pm
Quote
The only danger with the tutorial on ladyada's site is that it assumes
that the lcd does not need a current limiting resistor as it is geared
towards the lcd she sells.

Actually this was partially fixed a month or so ago.  There is now a paragraph that describes the need for a series resistor and how to calculate it.  The photograph, however, has not been replaced (and is still upside down).  Her current LCD module does require the resistor.

Don

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