Problem With Interfacing LCD with Arduino

Hi guys,

i have a problem interfacing the Arduino board with the LCD display.

I am 100% sure my connections are correct following what is being described in this page

http://www.arduino.cc/en/Tutorial/LiquidCrystal

The only modification is I replaced the potential-meter, with a fixed voltage divided @ 50% of supply voltage. ( dont have potential meter.)

[u]the LCD shows nothing, not even sign that it is powered on.[/u]

The only observation is that the edge of the LCD screen that is nearer to the Vdd supply pins feels warmer than the other side

I am purely powering it through the USB, w/o external supply, could this be the reason?

Can anyone advise me? I am totally clueless,

I am using the following LCD

http://singapore.rs-online.com/web/p/lcd-displays-alphanumeric/7200207/?origin=PSF_238209|fp

SPLC780D built in controller, which is compatitble to Hitachi HD44780.

Short answer is get a 5k pot,

50% is unlikely to give enough bias for the contrast and i suspect thats why your not seeing anything, try linking contrast adjust to gnd, it might make the display too dark but enough for you to see if it's working.

Hi,

when i short V0 to ground, i manage to see some shaded block .

But it fade away after 1-2s.

I wont display " hellow world" when i upload the example

[u]Is it a must to have the POT?[/u]

Yes you must have the pot. Its a very fine line between too much or too little voltage on the contrast line.

The only modification is I replaced the potential-meter, with a fixed voltage divided @ 50% of supply voltage. ( dont have potential meter.)

That will almost always result in a blank display.

Most LCDs work best when the voltage at pin 3 is around 0.5 volts but many of them work acceptably when the voltage is 0 (pin 3 connected to GND).

Is it a must to have the POT?

No.

See if the LCD works acceptably with pin 3 connected to GND. If not then experiment with a different voltage divider - you want to start with about a 10 to 1 resistance ratio between the two resistors with their sum somewhere between 5 and 20 K ohms.

Don

Hi,

i have used a 10k pot and tried from max voltage down to 0V.

Still i cant display “hellow world”

The best i can achieve is some shaded blocks, and disappear 5-10s later.

could it be a manufacturer fault?

i received the product 3 days ago.

thanks

No If you insist on not using a pot try a 4K7 resistor from Vcc to pin 3 and a 330R resistor from pin 3 to ground (courtesy of PH Anderson) If you insist in not reading others advice you are likely to be a while getting the displays working... It would also have helped if you had taken the time to read the documentation so generously provided free of charge here for your edification. "Most LCDs work best when the voltage at pin 3 is around 0.5 volts but many of them work acceptably when the voltage is 0 (pin 3 connected to GND)." I am reasonably certain the poster that gave you that good advice did so because he was a little more familiar with LCD's than you... and you ought to leave the [u]bold colored lines out of your posts[/u], they may look good on your Etch a Sketch... however you don't see many others use them here... Maybe there's a reason, Ya Think? Really Look UGLY, Don't they?. IMO, THEY DO

Doc

There are lesser quality lcd's but the chances of getting a broken one are rare but not impossible, as your getting the blocks at switch on i'd say yours is working and if your using usb for power then the 5-10 sec you mention would fit in with the blocks appearing and disappearing while the usb port goes through the device ID proceadure, please post your code and check your wiring, especially RS & E pins 4 & 6, if they are the wrong way round it will give strange behaviour.

At the very least disconnect the whole lcd so there is no Arduino influence and just connect Power & contrast to be sure thats working first, then control lines and data

Sorry about the font, i just want to highlight the message. No other intention.

Actually, i tried to hovering around 0.5v but i just could not get the display.

I experimented from 0-1v paying extra attention when nearing 0.5v.

The reason why i am posting here is because i followed the requirement given by the tutorial, but still it could not

display " hellow world ", even with the 10k potential meter.

Thats why i am very clueless now. The best display i can get is just blocks that appear during initial power up and after

5-10s fades away.

P18F4550: There are lesser quality lcd's but the chances of getting a broken one are rare but not impossible, as your getting the blocks at switch on i'd say yours is working and if your using usb for power then the 5-10 sec you mention would fit in with the blocks appearing and disappearing while the usb port goes through the device ID proceadure, please post your code and check your wiring, especially RS & E pins 4 & 6, if they are the wrong way round it will give strange behaviour.

At the very least disconnect the whole lcd so there is no Arduino influence and just connect Power & contrast to be sure thats working first, then control lines and data

Thanks I will try solely powering just the LCD.

I am using the "hellow world" example provided. So coding is good to go.

I am using the "hellow world" example provided. So coding is good to go.

one thing i have learnt from open source is nothing is ever good to go

a lot can change between the time the tutorial page was posted and the liquidcrystal library included with the Arduino IDE so it really might help if you posted your example code,

to be sure of compatability use the hello world example included in your version of IDE paying attention to this line LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

yours might be different, it represents lcd pins like this

LiquidCrystal lcd( RS, E, D4, D5, D6, D7);

It's all a learning curve, which is good, if everything worked first time round we'd never learn anything

Hi ,

yes, they are in the order of 12,11,5,4,3,2

The attachment contain my connection diagram.

D4-D7 : PIN 2-5
E: PIN 11
RS: PIN 12
RW: GND

I see no problem in them ( both connections and coding)

MyConnection.png

FYI

Red wires : 5v Blue wires: GND Orange Wires: RS,E, D4-D7 Pink wire: VO

I will try with another LCD screen and see what is the outcome

Are your wires soldered to the LCD module. If not you are doomed.

Don

Nope, they are not. I solder a row of connectors. and connect dem using jumpers to the arduino board

May i know what's wrong?

thanks

May i know what's wrong?

If the wires are tight in the connectors then you may be OK. If any wires are loose then you will have problems.

Could you submit a new photograph and avoid covering up the important part with unnecessary labels.

Don

Hi, i did my connection with a breadboard , i use jumpers is to show my connections clearer in this post.

I have removed the label,

Red 5v
blue GND
orange rs,e,D4-D7
Pink v0

Thanks

several of the wires in the lcd module header holes look like they are either not soldered
or not soldered very well.

— bill

Hi,

The soldering is done on the other side of the lcd, those are jus connectors