Need some help for Phico M-0 LCD

Hey folks.
I am re-building something I had actually build successfully before with the Phico M0 LCD, however, I lost the data-sheet, so I start to google it.

in my original code I wrote some comment like this :

The circuit:

  • LCD RS pin to digital pin 12
  • LCD Enable pin to digital pin 11
  • LCD D4 pin to digital pin 5
  • LCD D5 pin to digital pin 4
  • LCD D6 pin to digital pin 3
  • LCD D7 pin to digital pin 2
  • LCD R/W pin to ground
  • 10K resistor:
  • ends to +5V and ground
  • wiper to LCD VO pin (pin 3)

// include the library code:
#include <LiquidCrystal.h>

Here I didnt find any datasheet with the D4-7(but D0-4)

and on the data sheet I googled above, there’s something called D0-4, and some ‘unnecessary pins’

Here’s my original pics for testing (it’s working)

(1-23 above 2-24 )

at that time I was using the ‘unnecessary pins’ for the LCD input,
and use:
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {

lcd.begin(16, 2);//rows and cols
lcd.print(" Hello!")

But now, my LCD cannot print anything, but display some black blocks (I believe there’s no bug in my code)

I tried both ‘unnecessary pins’ & D0-D3 on the datasheet I googled, D0-D3 could only display black block at the first line.

Is this indicate my LCD is broken? are the ‘unnecessary pins’ same as D0-D3?

*ps: i’m using sparkfun instead of Arduino Uno, pin 13 seems are specified for a LED on the sparkfun board. Will this a problem?

Nowhere have you mentioned LCD pin 5 (R/W). This pin must be connected to GND for your LCD to display anything other than the row of boxes.

LCD pins 7,8, 9, and 10 (D0, D1, D2, and D3) should be left unconnected.

Arduino pin 13 has an on-board LED attached on most implementations including the 'real' UNO.

You will have to provide a better photograph, one that will let us follow each wire from the LCD back to the Arduino, if you expect to get any help beyond educated guesses.



I'll post a better pic soon. Should both 1&24 goes to 5V?

it just works!(thx for you guys.

For anyone reading up on the Phico display - if you have the 16x2 display with a 24-pin header, 4 push-buttons and 3 leds (2 red, 1 yellow), then I have a small number of PCBs available that I had manufactured in China that present all of the functionality of the display, switches, LEDs, over the I2C interface, so all that you need is power, SDA/SCL and designate a discrete for resetting the I/O extender chip. All you need is a MCP23017 (IIC variant) - 28 DIL package, a couple of SM resistors and 100nF chip capacitor. PM me if you want a board.