User Manual

3/6/2018 I2C LCD2004 - Wiki
http://wiki.sunfounder.cc/index.php?title=I2C_LCD2004 5/5
}
else if (error==4)
{
Serial.print("Unknow error at address 0x");
if (address<16)
Serial.print("0");
Serial.println(address,HEX);
}
}
if (nDevices == 0)
Serial.println("No I2C devices found\n");
else
Serial.println("done\n");
delay(5000); // wait 5 seconds for next scan
}
Change I2C Address
When a conflict happens on the I2C address, you can change the I2C address by setting the A0, A1, A2 pins to 1 or 0 on the PCF8574 chip.
There is a red module on the back of the I2C LCD, the main chip is PCF8574 or PCF8574T, pin A0, A1, A2 has been extended, as shown below.
For PCF8574T chip, I2C address format: 0 0 1 0 0 A2 A1 A0. The default address is: 0x27
For PCF8574 chip, I2C address format: 0 0 1 1 1 A2 A1 A0. The default address is: 0x3F
If you want to modify the default address, just need connect pinA0, A1, A2 to GND respectively.
For PCF8574T chip, I2C address range: 0x20-0x27
For PCF8574 chip, I2C address range: 0x38-0x3F
If you are not sure, you can use the above code to scan the changed address.
Resources
I2C_LCD2004 test code
PCF8574T_datasheet
LiquidCrystal_I2C library