... so I initially followed this guide:
The fact that the guide is an 'instructable' should have been a warning.
As soon as I hook up pins 1 & 2 the display blanks out.
As it should if you haven't got the contrast set up properly.
There's also advice to just hook up pins 1,2 and 3 but given the fact the display text uses the backlight I don't think running without it will tell me much?
That advice is correct if the display does not have a backlight or does not require that the backlight be on to see the display.
Where did you get the advice to provide a contrast voltage on pin 3 without also providing power to the controller via pins 1 and 2?
The Adafruit guide is one of the best but you have to follow it carefully. Did you see (and follow) the comment directly above where the 'Bus Wiring' section begins.
Here are my generic step-by-step instructions which roughly parallel those of Adafruit:
(1) If the module has a backlight then get it working properly. This involves only pins 15 and 16 on most LCD modules. Make sure to use a current limiting resistor if there is none on the LCD module.
(2) Get the power and contrast working properly. This involves only pins 1, 2, and 3 on most LCD modules. You should be able to just barely see blocks on one row of a two row display and on two rows of a four row display.
NOTE: The Arduino has not been used yet, except as a possible source for the power needed for the first two steps. Do not try to go any further until this is working. If you don't see the blocks then no amount of program code will help.
(3) Connect the LCD R/W pin (pin 5) to GND.
(4) Connect the six control and data wires between your LCD module and your Arduino.
(5) Upload your sketch and it should work.
Troubleshooting:
If you have a 16x1 display and there are blocks only on the left half of the row in step 2 then use
lcd.begin(8, 2);
in your sketch.
If you still don't get a display then make sure that your wiring matches the numbers in the descriptor (or vice versa).
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // put your pin numbers here
If you get a display but it is garbled or has some other problems then try again with a 'static' sketch, one that displays a simple message on the top row of the display and then stops. All of your code should be in setup() and loop() should be empty between the brackets.
#include <LiquidCrystal.h>
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // put your pin numbers here
void setup()
{
lcd.begin(16, 2); // put your LCD parameters here
lcd.print("hello, world!");
lcd.setCursor(0,1);
lcd.print("it works!");
}
void loop()
{
}
If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module. We also need a copy/paste version of the code that you are actually using, not a link to the code that you think you are using.
Don
