Hello a few weeks ago I purchased a generic LCD keypad shield from ebay and after receiving it and toying around with it I was not able get it to work. After a while I removed the LCD from the shield to connect directly to the LCD pins, and I got the same result where either the back light would turn on or not, every displaying anything therefore I figured the LCD was broken.
I decided I purchased a cheap shield, and decided to buy a more expensive with proper documentation. so I purchased this:
and upon plugging it in I go the same result as with the last shield. I then found this thread.
Warning to users of some vendors LCD keypad shields:
http://forum.arduino.cc/index.php?topic=96747.0
I ran the program and although my backlight lights up and pulses it is not displaying any characters.
I've tried various codes that claim to work with this shield and I am not getting any display, including
the liquidcrystal library. I am aware I must change the
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
to
LiquidCrystal lcd(8 ,9, 4, 5 ,6 ,7);
I appreciate the help, thank you.
Have you tried Example 1 from the wiki page?
Yes I actually have, and I've been toying around with it and for an unkown reason to me, I now can see characters
in the first row of, seems as if I have to restart my board a few times and then the characters show.
How after using the code from the wiki, instead of receiving the "Push the buttons" message I am receiving
"Pus' t'e buttgfs" and the second line is not displaying anything.
#0-7 are displayed properly while 8 and 9 show 0 and 1 instead.
Here is the code I used:
Thank you for the help.
/*************************************************************************************
Mark Bramwell, July 2010
This program will test the LCD panel and the buttons.When you push the button on the shield?
the screen will show the corresponding one.
Connection: Plug the LCD Keypad to the UNO(or other controllers)
**************************************************************************************/
#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7); // select the pins used on the LCD panel
// define some values used by the panel and buttons
int lcd_key = 0;
int adc_key_in = 0;
#define btnRIGHT 0
#define btnUP 1
#define btnDOWN 2
#define btnLEFT 3
#define btnSELECT 4
#define btnNONE 5
int read_LCD_buttons(){ // read the buttons
adc_key_in = analogRead(0); // read the value from the sensor
// my buttons when read are centered at these valies: 0, 144, 329, 504, 741
// we add approx 50 to those values and check to see if we are close
// We make this the 1st option for speed reasons since it will be the most likely result
if (adc_key_in > 1000) return btnNONE;
// For V1.1 us this threshold
if (adc_key_in < 50) return btnRIGHT;
if (adc_key_in < 250) return btnUP;
if (adc_key_in < 450) return btnDOWN;
if (adc_key_in < 650) return btnLEFT;
if (adc_key_in < 850) return btnSELECT;
// For V1.0 comment the other threshold and use the one below:
/*
if (adc_key_in < 50) return btnRIGHT;
if (adc_key_in < 195) return btnUP;
if (adc_key_in < 380) return btnDOWN;
if (adc_key_in < 555) return btnLEFT;
if (adc_key_in < 790) return btnSELECT;
*/
return btnNONE; // when all others fail, return this.
}
void setup(){
lcd.begin(16, 2); // start the library
lcd.setCursor(0,0); // set the LCD cursor position
lcd.print("Push the buttons"); // print a simple message on the LCD
analogWrite(10, 255);
delay(500);
}
void loop(){
lcd.setCursor(9,1); // move cursor to second line "1" and 9 spaces over
lcd.print(millis()/1000); // display seconds elapsed since power-up
lcd.setCursor(0,1); // move to the begining of the second line
lcd_key = read_LCD_buttons(); // read the buttons
switch (lcd_key){ // depending on which button was pushed, we perform an action
case btnRIGHT:{ // push button "RIGHT" and show the word on the screen
lcd.print("RIGHT ");
break;
}
case btnLEFT:{
lcd.print("LEFT "); // push button "LEFT" and show the word on the screen
break;
}
case btnUP:{
lcd.print("UP "); // push button "UP" and show the word on the screen
break;
}
case btnDOWN:{
lcd.print("DOWN "); // push button "DOWN" and show the word on the screen
break;
}
case btnSELECT:{
lcd.print("SELECT"); // push button "SELECT" and show the word on the screen
break;
}
case btnNONE:{
lcd.print("NONE "); // No action will show "None" on the screen
break;
}
}
}
Sounds like one of the data lines is dead. Check the board for a bad connection on 4, 5, 6, or 7
I had a similar problem and found that my power supply was not supplying enough power
Will do johnwasser, and once again I am not seeing any characters displayed, I think I am having issues with pin 7.
Edit: I have tried external power supplies and I am getting the same result...
Alrighty then, Pin 7 is dead :-(.....that's a bit sad
SuperCartman:
Alrighty then, Pin 7 is dead :-(.....that's a bit sad
Pin 7 on the Arduino?
Did you look at the solder connections?
Perhaps it is just a bad solder joint.
Maybe re-heat the suspected connection(s) or maybe just
do all the LCD connections and see if it clears up.
--- bill