I am using a Pro mini clone, 1602A v2.0 white on blue LCD, and a unmarked I2C backpack with PCF857 chip; all purchased cheaply via auction site.
The screen displays BUT, it appears to be blue text instead of white, like the text is inverted and nearly impossible to read. Adjusting the potentiometer on the backpack will dim the display to nothing, but that is all. In the first pic you can see a faint 'Hello, world!'. That is the best readability I could get. (The unconnected LCD and backpack in the pics are identical to the ones in use (that I soldered together before testing).)
The second pic shows an interesting accident - I disrupted the wiring to the backpack while troubleshooting using a more complex sketch and the screen displayed two updating characters - but at full brightness and contrast! Proof of operation? Any clues?
The simple sketch on the first pics is:
//YWROBOT
//Compatible with the Arduino IDE 1.0
//Library version:1.1
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2); // set the LCD address to 0x27 for a 16 chars and 2 line display
void setup()
{
lcd.init(); // initialize the lcd
// Print a message to the LCD.
lcd.backlight();
lcd.print("Hello, world!");
}
void loop()
{
}
This is only my second arduino project and electronics is a new hobby for me.
CEG003400.rar (1.08 MB)
Y679???.pdf (852 KB)
