Hey all
I just got LED 16*1 displays off eBay and for some reason I can not get it to work
I used tutorial here:
followed all as guided but now luck I also tried to power up LED back light and it did not work (i looked at the PCB and realize that I have to swap + with - and now i have back light ,... but datasheet definitely is has error
ok will become photographer in few min
I actually was looking specifically for a single line display
ok photos are attached and here is the code:
// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int ledPin = 13; // LED connected to digital pin 13
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 1);
// Print a message to the LCD.
lcd.print("hello, world!");
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
//***lcd.setCursor(0, 1);
// print the number of seconds since reset:
//***lcd.print(millis()/1000);
digitalWrite(ledPin, HIGH); // sets the LED on
delay(1000); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(1000); // waits for a second
}
Once you get it 'working' you will probably find that only the left half of your display actually displays anything. In that case you will have to set it up as an 8x2 and put the information for the right half of your display on the second 'line'. There's a complete explanation if you follow the LCD Addressing link at http://web.alfredstate.edu/weimandn.
ok so if i send 16 characters to output now, i should get 8 outputted right?
so "hello world" has 11 characters and it I should at least see something on the screen and I don't
ok so if i send 16 characters to output now, i should get 8 outputted right?
so "hello world" has 11 characters and it I should at least see something on the screen and I don't
Correct.
You could try following the tutorial at Arduino Tutorial - connecting a parallel LCD . If you get only 8 blocks when adjusting the contrast then you have one of the 8x2 type displays.
You may damage your LED and/or the Arduino output pin if you don't use a series current limiting resistor. Why did you connect an external LED to pin 13 anyway, there's already one on the board (with the appropriate resistor)?
If varistor is adjusted you see segments, in my case nothing happens? Perhaps Pins 1 and 2 are swapped too? I didn't try changing +/- as i afraid to fry the board.
floresta:
Why did you connect an external LED to pin 13 anyway, there's already one on the board (with the appropriate resistor)?
Don
Someone some time ago posted such a tutorial on arduino website that tells everyone to stick an LED like that. (I tried to find it:() and it has not been removed since.
Your potentiometer seems to have 4 pins, does it? Strange. Plus, you don't need that resistor in series with the potentiometer. Do you have a multimeter to confirm the thing is a pot instead of something else? What is the value of the resistance?
floresta:
Why did you connect an external LED to pin 13 anyway, there's already one on the board (with the appropriate resistor)?
Don
Someone some time ago posted such a tutorial on arduino website that tells everyone to stick an LED like that. (I tried to find it:() and it has not been removed since.
as to potentiometer: it is actually 3 pin . There are big holding pins but they not connected anywhere (so i assume they sit there for mounting purposes)
Potentiometer is 10k, so i added another 10k resistor in series to achieve 10-20k as datasheet specifies. I measured and confirm that it what I get.
Also I measured voltage on Pin 3 of LCD to the GND, I get voltage ~3-5V depending on knob position
Perhaps Pins 1 and 2 are swapped too? I didn't try changing +/- as i afraid to fry the board.
That was my original thought. I didn't mention it because if they are swapped, and you currently have them backwards, then you may have already fried the board and you should have felt heat and/or seen smoke. I have seen some LCD datasheets that do show these voltages reversed from the normal orientation. At this point it's worth a try swapping the connections. Put your finger on the IC or epoxy blob when you make the connection and remove the power if you feel any heat.
So I swapped power connectors PIN 1-2 and IC got extremely hot, where in documented position it is total cold. So I guess i burned the module? I put power connectors back to described position and now it is cold again. [Good thing that I ordered 2units ]
Now as to potentiometer. Mine is 10k end to end. So do i need extra 10k attached? (By end to end I mean on one end its ~0 Ohm and on another its 10K
Now as to potentiometer. Mine is 10k end to end. So do i need extra 10k attached? (By end to end I mean on one end its ~0 Ohm and on another its 10K
No you cannot use the extra resistor and expect the circuit to work. Connect one end of the potentiometer to pin 1, the other end to pin 2, and the center terminal to pin 3.
As to voltage on pin 3 i dont know what to say
Connect the potentiometer as I described above. With anything greater than a volt or so on pin 3 you will see nothing on the display (which is what you are seeing).
So I swapped power connectors PIN 1-2 and IC got extremely hot, where in documented position it is total cold. So I guess i burned the module?
They are pretty robust. If you removed the voltage immediately you may not have made it any worse than it already was.
When I try to connect something for the first time, I stick my nose very close to the components to sniff around for a while to make sure no magic smoke is coming off the component. Unless it breaks in an instance, like an IR receiver I fried (I could feel the bang on my finger while inserting it into the board, and heard bang), you can save it by sniffing and touching it to see if it's happy there.
(I was too slow in reply)
As pointed out by floresta, the suggested pot value is 10 to 20Kohm TOTAL, not what you tried. If you can get the black boxes by removing the 10Kohm resistor and turning the potentiometer, you can proceed to the next step on the adafruit tutorial.
