I do not know if you are still there. The LCD + i2C display with a simple sketch works and the display shows the characters correctly, but using lcd + i2C in my sketch, i have the same problem as the LCD 1602 without i2C module, and the lcd does not shows anything and i understand that the cause is because the serial does not turn on, in fact the if (Serial.available ()) returns value False, while disconnecting the i2C module the serial works regularly.
No! I went on holiday... We're allowed to do that you know!!
As you may already know... I don't really follow Arduino.. I do pic's.. The Arduino system has very few pins so interfacing two or more shields will always be a headache.. I thought that the I2C pins on an Arduino were on AD4 and 5 so they shouldn't affect serial atall..
looking at the PDF for the keyes shield.... The MAX_LCD library uses the digital pins on the shield to drive an LCD as the shield itself uses eight Arduino pins.. The MAX_LCD library is built into the host shield library..
I can try it out because a USB_Host_Shield library is already included and it also contains the max_LCD files, although they know that they have different sizes.