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### Topic: LCD 16x2 showing strange (Read 2510 times)previous topic - next topic

#### quincy

##### Apr 14, 2012, 08:43 am
Hi, I bought my lcd from here http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130668615164&ssPageName=ADME:X:RTQ:US:1123 connect it like in tutorial http://arduino.cc/en/Tutorial/LiquidCrystal upload code
Code: [Select]
`#include <LiquidCrystal.h> LiquidCrystal lcd(12, 11, 5, 4, 3, 2);void setup() {     lcd.begin(16, 2);   lcd.setCursor(0, 0);    lcd.print("hello, world!");}void loop() { }`

but hello world starts in 1,0 and every empty cursor are lighting. When I try type text to second line it show some nonsense letters.

thanks for help

#### quincy

#1
##### Apr 14, 2012, 09:01 am
oh finaly I resolve it, I connect power to my external power suply, cause I thought that arduino doesnt have so much power, but that is the problem, why I can power display from external power source?

#### Grumpy_Mike

#2
##### Apr 14, 2012, 09:16 am
Quote
why I can power display from external power source?

Do you mean can't?

You can if you connect the ground of your supply to the ground of the arduino and the external supply is 5V. Most are not.

#### quincy

#3
##### Apr 14, 2012, 02:50 pm
ok thanks

I try to use termistor, I measure value by voltage divider use Steinhart & Hart equation to calculate tempereature. But when I try put thermistor to boiling water, it shows only 97,43C. I think that problem can be 5V voltage source on arduino board, is it exactly 5.00V or it can be less?

#### liudr

#4
##### Apr 14, 2012, 05:58 pm

ok thanks

I try to use termistor, I measure value by voltage divider use Steinhart & Hart equation to calculate tempereature. But when I try put thermistor to boiling water, it shows only 97,43C. I think that problem can be 5V voltage source on arduino board, is it exactly 5.00V or it can be less?

That amount of difference is possibly due to other things, not arduino 5 volt. Do you have a reliable multimeter to directly get the resistance and calculate the temperature? Chances are, the thermistor has accuracy of +-2 degree. Thermistors need some calibration since every single one is different. If you interchange two, they read different numbers. What is the interchangeability parameter of the thermistor?

#### Grumpy_Mike

#5
##### Apr 15, 2012, 10:30 am
As well as the above:-
What is your altitude above sea level, this and the current atmospheric pressure affects the temperature of when water boils.

#### liudr

#6
##### Apr 15, 2012, 05:50 pm

As well as the above:-
What is your altitude above sea level, this and the current atmospheric pressure affects the temperature of when water boils.

#### gsub

#7
##### Apr 15, 2012, 06:30 pm
Also keep in mind that "boiling" water has pockets of steam at 100C, hence the bubbles, but the total average temperature of the water will be slightly lower. If it were all 100C it'd be steam, not liquid.

#### liudr

#8
##### Apr 15, 2012, 09:08 pm

Also keep in mind that "boiling" water has pockets of steam at 100C, hence the bubbles, but the total average temperature of the water will be slightly lower. If it were all 100C it'd be steam, not liquid.

Not correct. At boiling the water reaches 100DegC but to turn into steam, liquid molecules pay latent heat of vaporization. Simply reaching 100DegC won't turn liquid water to gaseous water.

http://en.wikipedia.org/wiki/Latent_heat

The bubbles are absorbed air being released as water at higher temperature can dissolve less air as it does at lower temperature. They are NOT steam. Steam only comes out of the surface. Welcome to the world where everything makes sense only if you know physics! Good intent to help but please read next time before you try to explain something you aren't sure about.

#### Grumpy_Mike

#9
##### Apr 15, 2012, 11:43 pm
Quote
Welcome to the world where everything makes sense only if you know physics!

#### quincy

#10
##### Apr 16, 2012, 11:31 am
to liudr:
I have only cheap voltmeter, so I cant measure it precisely. I have only one... I dont know what you mean by interchangeability, look at datasheet. Is there some more accurate solution to measure temperature, like using LM35 or digital DS18B20?

my altitude is 570mas check it here http://mapy.cz/s/3zQq

#### liudr

#11
##### Apr 16, 2012, 08:27 pm
LM35 has about 1 DegC accuracy around 100DegC. Interchangeability refers to when you take another unit and replace the first unit, what it the different in reading. Say sensor 1 says 100 and sensor 2 says 98.

Arduino's 5V reference is probably around 5.05V. You need a good voltmeter (3.5 digits or 4.5 digits) to get an accurate reading of the voltage. If you have a 2.5 digit meter (shows 3 digits but leading digit is only 0 or 1), you won't get an accurate reading of the arduino 5V.

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