TAKEN:
Hi, I'm currently doing a project that involves a USB keyboard which is interfaced using a USB Host Shield then the output is displayed in an LCD. It is working fine given that the microcontroller is connected to a PC and a running serial monitor. My question is how can I make use of the USB keyboard WITHOUT plugging my prototype to a PC ?
If the output is displayed in an LCD, why do you need the serial monitor?
Which Arduino are you using?
I have achieved what you want. If you don't want to plug your prototype to a PC you have to use an external supply for powering the Arduino.
You just need an input (Keyboard and usb shield), an output (LCD) , an external supply (AC/DC adapter 9V) and the Arduino.