Alcohol Tester with display - Beginner needs Assistance for Uni-Project

Hi guys,

i need a little help for my Uni Project…

What i want to do? An Alcohol Tester which displays the real amount of promille on a 16,2 LCD Display.

I just wanted to start and try to get the display working - unfortunately with no success…here are some screens.
Can you see a mistace?

My Code in Arduino:

#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,10,7,6,5,4);

void setup()
{
lcd.begin(16,2);
lcd.noCursor();
lcd.setCursor(0,0); // charakter, zeile
lcd.print(“Hallo Welt!”);
lcd.setCursor(0,1);
lcd.print(“by Michi!”);
}

void loop() {

}

Nobody an idea what could be wrong? :~

Two concerns.

One: That LCD is a little unusual - have you the reference for it?

Two: There are more than one "Liquid Crystal" libraries - have you the reference for this particular one?

Those wires poked through the holes are soldered?

Good to see that you are taking this one step at time.

What are you getting on the screen? Rows of boxes?

I see only one ground connection and I expected to see two. My LCD screen needed to have an additional pin to ground that wasn't in my documentation before it would work.

Can you tell us the pinout and your connections on that LCD?

Edit: This is a good resource:

http://learn.adafruit.com/character-lcds/overview

Thx for the answers!

Information to the display:

http://datenblaetter.physicalcomputing.at/121.PDF http://datenblaetter.physicalcomputing.at/121s.pdf

Unfortunately i don't know if i use the right Liquid Crystal Libraries - i just took the one from the arduino menu.

The output from the display is a row of boxes yes. (And after some time, the USB Slot from my laptop break down cause of too much need of energy.)

The wires in the holes are not soldered, i just put them in. (I solder them when there are no mistakes)

mrohrboeck: Information to the display: http://datenblaetter.physicalcomputing.at/121.PDF http://datenblaetter.physicalcomputing.at/121s.pdf

Those link to something entirely different.

mrohrboeck: Unfortunately i don't know if i use the right Liquid Crystal Libraries - i just took the one from the arduino menu.

I would suspect that you are using the wrong library, but without reviewing the actual pinout of your display, I can't be sure.

mrohrboeck: The output from the display is a row of boxes yes.

Which means it is alive and the contrast is set approximately correct.

mrohrboeck: (And after some time, the USB Slot from my laptop break down cause of too much need of energy.)

The backlight uses a lot of current.

mrohrboeck: The wires in the holes are not soldered, i just put them in. (I solder them when there are no mistakes)

Could be a cause of problems. Jam a toothpick alongside each wire as they go through the holes.

Did you get this running yet?

No, unfortunately not.

http://physicalcomputingaustria.blogspot.co.at/2011/02/serielles-16x2-lcd-display.html

(in german - maybe you can translate it with your browser)

There are instructions for the code and connection from the shop where i ordered it. Problem is that they are using "byte" in the code. I figured out that i have to use serial.write, but don't know how i can implement this in my code.

The next thing is that the display is connected completely different than i connect it. But for the connection in the URL, i'm missing the components. I'm asking myself if the way i connect it is also right?

anyone got an idea? ^_^

Yeah, I have a few.

The page you reference shows and describes a display with a serial converter integrated with it. The associated links are the ones you posted earlier, which refer to a SparkFun serial interface board or "backpack" which clearly is not what is mounted on that board.

I can only conclude that the board in question has integrated the SparkFun design to make it a serial interfaced board. As such, it will probably only work when you use the serial interface - those three pins on the side of it.

What I am puzzled by, is what information you used to make the connections you have, to the other two pinouts on the board. Are you working from another description that you found somewhere and have not yet disclosed, or just how do you think you need to connect it a certain way?

YOu should start soldering the wires on the LCD side. On the breadboard side you can still switch them. Can you post a jpeg from the bottom side of the screen? are there any notes on it, or a special IC?

ok, i made it, the display is running :slight_smile:

But now there is the next problem - i want to use a 9v battery. I connect it to the Arduino, but nothing happens… :~
The battery is completely new

It certainly looks liek nothing on the photo! No power LED.

Start by removing all connections to the pin outs. Does the power LED now glow?

You have a multimeter? Test the battery first.

Test the voltage on the barrel of the connector that goes into the Arduino. It should be positive in the centre (I cannot imagine how you could have obtained one wired otherwise!).

Test the voltages on the pinouts using your little jump wires. Test the Vin and Vcc voltages. If you get your Power LED to light, run the "blink" ("blink without delay") sketch to blink the "L" LED. If success, try wiring it all up again, see if it is still lighting and blinking.

I tried out another connection and another 9v Battery - nothing...

I think the problem is the arduino...i will take a new one on monday from my university