hye there... i have buy lcd and arduino uno... i had wiring it... but only black box appear in lcd...
after i burn the coding in arduino using IDE... nothing happen... can u see what the problem?
I think you need to connect some wires to convey data to the display.
...
From the Arduino.
@paul
That's not even his set-up. The picture is from the Lady-Ada tutorial (Wiring a Character LCD | Character LCDs | Adafruit Learning System).
can u see what the problem?
Did you follow the rest of the steps in that tutorial?
Don
mine not display anything too.
the code is from arduino example
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);
void setup()
{
lcd.print("hello, world!");
}
void loop() {}
I'm sure I wired it right, after upload, power cycle board. nothing showed up
xianwu,
The example code on that constructor page is wrong.
It is missing the begin() call to initialized the LCD in the setup()
function.
I'll report the bug/issue to try to get them to update the web page.
See the example code on the tutorial page:
for an example of how to use the begin() function.
--- bill
thank you Bill, I try your example. still nothing showed. I wonder if my LCD is Hitachi HD44780 (or a compatible) chipset.
I do see 16 DIP pins, see my picture, pin1 GND, pin 15, 16 backlight .(I apply voltage at pin 15, 16, LCD lights up )
but nothing show up.
How could I determine it's Hitachi HD44780 (or a compatible) chipset.?
or Is there any advice?
thanks
Where did you get that display ?
Is there any text printed on the board (and what is it ) ?
Identifying the display is the first thing to do.
it says MTC-20200B made in Taiwan.
I found MTC-20200X datasheet.
and 16 pin is same as arduino's example. the only diff is pin 3. in arduino pin3 is contrast, but
MTC-20200X datasheet.
pin 2 VDD Logic Circuit Power Supply
pin 3 VO Power Supply for LCD Panel
any advice?
from looking at your photo, I see no potentiometer.
What is the brown wired connected, on the arduino end it looks
like it is connected to 3v?
Can you take some closer photos of your Arduino and LCD
so we can see where all the wires are connected and see
the connections and sholder joints?
--- bill
bill,
the brown wire connects Arduino GND, ----> LCD pin5 R/W
the grep wire Arduino 3.3V ---> LCD pin3 Vo
and this LCD is 20x2 chars. let me change lcd.begin(20,2), see if make any diff.
thanks
Xianwu
lcd.begin(20,2) still won't work.
Slightly unusual board then, but no matter.
Pin 3 goes to a potentiometer to set the contrast, something like 10k to 50k, which is powered from Vcc (+5V) and ground, but the wiper will need to be set very close to ground. It is usually appropriate to approximate this with a pair of resistors with say 22k from pin 3 to Vcc and 2.2k from pin 3 to ground. (The exception is if it happens to be a special "extended temperature" version, but it most likely is not).
The fact that the display shows nothing, not even the set of "blocks", tells us that you are not setting the necessary contrast voltage on pin 3.
I thought contrast voltage could be any between 5V--0V so I just connect it to 3.3V.
let me try a 10k potentiometer.
cheer!
thanks Paul__B
I saw "hello world" with 22K, 2.2K .
but too dim.
I connect pin 15 to 5V pin16 to GND, then perfect!
thank you all for helping.
xianwu
Now that the hijack is over I wonder how the original poster is doing?
Don
I wonder why Vo has to be low to make it work.
in my case Vo = 0.45, if Vo is high(3.3V) then nothing show up.
what's the relationship between Vo(pin3) and LCD contrast?
Xianwu
It is measured with respect to the logic supply voltage (pin 2) and it is typically around -4.5 volts.
Don
xianwu:
I wonder why Vo has to be low to make it work.
in my case Vo = 0.45, if Vo is high(3.3V) then nothing show up.
what's the relationship between Vo(pin3) and LCD contrast?
You certainly will not get anything showing up with Vo at 3.3V.
floresta:
It is measured with respect to the logic supply voltage (pin 2) and it is typically around -4.5 volts.
That is the trick. And it is quite sensitive also, so if your supply voltage drops significantly below 5V, say just to 4.75V as on the (apparently!) heavily loaded USB port next to me, this has the same effect as changing Vo from 0.45V to 0.7V and whilst the LED is almost as bright as ever, the contrast is fading badly.
Now there are some LCD displays available which operate from a 3.3V supply. This is interesting - they do this by incorporating a "charge pump" IC on the display module - you will notice the SOP "footprint" for this option labelled "U3" on the back of your LCD module and a soldered jumper "J1" which bypasses the charge pump (so if you have a 3.3V module, you could switch it to 5V and back if you wanted to). This charge pump boosts the internal supply voltage to 5V while the HD44780 happily accepts the 3.3V logic inputs. You still adjust the Vo to about 0.45V as before, though with the potentiometer now connected across 3.3V rather then 5, its position will be somewhat different.
TM_Soundhararajan:
Sure.
Welcome to this forum.
First guide to forums like this is to not hijack (ongoing) threads.
If you have an unrelated question, start your own thread.
Now you are distracting from the OP's question with a totally new question which isn't nice and isn't needed in any way.
Then your problem.
Did you initialize the display correct, telling that you have 16 characters and 2 lines ?
Read the "How to use this forum", found on top in every subforum over here.
Then start a new thread, remove above post (i will remove this one after that) and post it in a new thread.
Or ask a moderator to move the question to a new thread.
Put your code (all of it) in that thread and use code tags.