Problem: Ethernet shield + LCD with shift register

Community General Discussion
1

Hello guys, I need your help, please any idea for this problem?

I have an Arduino Uno R3 , an ethernet shield, and an LCD keypad shield (on the protoboard using pins 8,9,4,5,6,7)
I have no problem with the lcd using 4bit_mod or using a shift register 74ls164 (3 wires with pins 5,6,7), however when I put the ethernet shield on top of the arduino and wire the lcd and upload the helloworld example , the text is not clear at all even when I adjust the contrast.

Arduino+lcd(4bit_mod)-->good
Arduino+lcd(shift register)-->good
arduino+ethernet+lcd(4bit_mod)-->blury text
arduino+ethernet+lcd(shift register)-->nothing

is it because of lack of power ? should I use an extra 5V source for the LCD?
sorry for my English

2

morning guys, whenever you have a similar problem you need an external 5 volts for the lcd from another USB port (I used the cable of an old joystick)