Review on SunFounder I2C LCD Module Shield for Arduino R3 Mega2560 - 2004 20x4 Serial TWI by Tommy Willis

After connecting to Arduino UNO, MEGA. SDA on A4 and SCL on A5 then +5 and Gnd, turned on the device and got a blue screen, no icons. This seemed to be a problem. After adjusting the variable LCD contrast resistance below, the characters became clear. Both of my boards have been set up to blur the display. Download the library from the "Sketch" menu, then "Include Library", add the zip file "LiquidCrystal_I2C_LIB.zip". Test the sample code using File, Examples, LiquidCrystalI2C. Looks very useful. Doctor T